The effect of simulated drought on stem-stored carbohydrate characteristics in winter wheat
by Sami Reda Saber Sabry
A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in
Crop and Soil Science
Montana State University
© Copyright by Sami Reda Saber Sabry (1989)
Abstract:
The use of chemical desiccants to simulate drought stress has been effective in differentiating wheat
cultivars for drought tolerance. The objective of this work was to study the effect of simulated drought
on stem-stored carbohydrates in winter wheat.
Seven winter wheats (Triticum aestivum L.) varying in average grain yield and other agronomic
characteristics were planted in RCB design with four replications at two field locations in 1987 and
1988. A 3% sodium chlorate desiccant solution was applied to four of the seven winter wheat cultivars
at the boot stage, and to all seven cultivars at the early dough stage. Stem samples were taken twice at
each growth stage, immediately before and 10 days after the desiccant application. Samples from the
early dough stage were divided into lower stems and peduncles.
Calibration of the high performance liquid chromatography (HPLC) system enabled quantification of
TNC and fructan content in wheat stems. Application of the desiccant at the early dough stage in wheat
reduced TNC and fructan content, increased net depletion rates of TNC and fructans, and decreased the
average degree of polymerization.
There was a positive correlation between the boot and mid-dough stages for TNC and fructan content.
In addition, there was a positive correlation between net TNC depletion rate and grain yield following
desiccant application. TNC depletion rate in wheat stems (peduncles) provided a reliable measurement
to identify tolerance to drought stress in wheat. There were significant GxE interactions for TNC
content, net rate of TNC depletion, fructan average degree of polymerization, and grain yield. There
were few or no significant cultivar x desiccant interactions for TNC content, net rate of TNC depletion,
and grain yield. A significant cultivar x desiccant interaction was observed for lower stem fructan
average degree of polymerization.
Chemical desiccant differentiated wheat cultivars for their ability to translocate TNC to the grain,
imposed homogeneous stress and simulated drought in wheat.
THE EFFECT OF SIMULATED DROUGHT ON STEM-STORED
CARBOHYDRATE CHARACTERISTICS
IN WINTER WHEAT
by
Sami Reda Saber Sabry
A thesis submitted in p a r tia l fu lfillm e n t
o f the requirements fo r the degree
of
Doctor o f Philosophy
in
Crop and Soil Science
MONTANA STATE UNIVERSITY
Bozeman, Montana
October 1989
ii
APPROVAL
of a thesis submitted by
Sami Reda Saber Sabry
This thesis has been read by each member o f the graduate committee
and has been found to be s a tis fa c to ry regarding content, English usage,
form at, c ita tio n s , bibliographic s ty le , and consistency, and is ready
fo r submission to the College o f Graduate Studies.
/ / J / / o f $9_ _ _ _ _ _ _ _ _ _
J lI.
Date
Chairperson, GraduateKCommittee
Qrx
Approved fo r the Major Department
Date
Approved fo r the College o f Graduate Studies
Date
Graduate Dean
iii
STATEMENT OF PERMISSION TO USE
In presenting th is thesis in p a r tia l f u lfillm e n t o f the re q u ire ­
ments fo r a doctoral degree at Montana State U n iv e rs ity , I agree th a t
the Library shall make i t a v a ila b le to borrowers under rules o f the
L ib rary .
I fu rth e r agree th a t copying o f th is thesis is allowable only
fo r scholarly purposes, consistent with " f a i r use" as prescribed in the
U.S. Copyright Law.
Requests fo r extensive copying or reproduction o f
th is thesis should be re fe rre d to U n iv e rsity M icrofilm s In te rn a tio n a l,
300 North Zeeb Road, Ann Arbor, Michigan 48106, to whom I have granted
"the exclusive rig h t to reproduce and d is trib u te copies o f the
d is s e rta tio n in and from m icrofilm and the rig h t to reproduce and
d is trib u te by abstract in any form at."
Signature
Date______ / c?
A p A fa
I 0
—
*5%%.
iv
I dedicate this work to the memory
of my father, mother, and aunt
for their love, patience and sacrifice.
V
ACKNOWLEDGEMENTS
I wish to express my deepest g ra titu d e and sincere appreciation
to the follow ing in d iv id u a ls :
Dr. G. A llan Taylor fo r his advice and guidance, and fo r provid­
ing a ll f a c i l i t i e s needed fo r my research while serving as my major
professor in pursuing my degree;
Dr. J.H . Brown fo r his help and guidance in the laboratory work
while serving on my committee;
Dr. J.M. M artin fo r his time and s ta tis t ic a l consultation when­
ever needed while serving on my committee;
Dr. R.L. D it t e r lin e and Dr. James Sims fo r t h e ir tim e, consulta­
tio n and friendship while serving on my graduate committee; and
Dr, Abdel Sal am Gomaa, Undersecretary of the M in is try o f A g ri­
c u ltu re , Arab Republic o f Egypt, fo r his help, encouragement, and
moral support since I began my career.
My profound g ra titu d e is extended to my w ife , Shadia, fo r her
patience and love; and f in a l ly , special thanks to my lo v e ly daughters,
Somaya and Rokaya, and my son Muhammad, fo r th e ir love and fo r missing
me on weekends and vacations.
vi
TABLE OF CONTENTS
Page
APPROVAL..................................................................................................................
STATEMENT OF PERMISSION TO U S E .......................
ii
Ill
ACKNOWLEDGEMENTS................................................................................... .... .
v
TABLE OF CONTENTS..................................................................................................
LIST OF T A B L E S ...............................................................................
vi
. . .
v iii
LIST OF FIGURES...............................................................................................
xi
ABSTRACT.........................................
INTRODUCTION
x iii
....................................................................................................
I
LITERATURE REVIEW ...........................................................................................
2
Screening Techniques fo r Drought Tolerance in Wheat . . . .
The C ontribution of Stem-Stored Carbohydrates to
Grain Y ield Under Drought Stress Conditions .....................
C haracteristics o f Fructans and Th eir Role in
Osmoregulation ...............................................................................
2
MATERIALS AND METHODS ..................................................................
. . . .
5
8
co co o t
F ield W o r k ..................... .
C u ltiva rs .....................
Experimental Design .
Sodium Chlorate A pplication ......................................................
Sampling the Stem P a r t s ..............................................................
Laboratory Work .......................................................................................
Total Nonstructural Carbohydrates (TNC)
E x t r a c t i o n .................................
H y d r o ly s is .......................................................................................
The HPLC System Used fo r TNC and Hydrolyzed
Samples Analysis ..................................................................
Quantifying HPLC Peak Areas ......................................................
S ta tis tic a l Analyses ...........................................................................
4
10
10
11
11
12
13
14
15
v ii
TABLE OF CONTENTS--Continued
Page
RESULTS AND DISCUSSION
...............................................................................
17
Q u an tific a tio n o f Stem-Stored Carbohydrates in Wheat . . .
Total Non-Structural Carbohydrate (TNC) Content .....................
The Boot S t a g e ............................
The Early Dough S t a g e .........................................
The Relationship Between TNC Content a t Boot and
Mid-Dough Growth Stages ......................................................
Net Rate o f TNC D e p le tio n ..................................................................
Average Fructan Degree o f Polymerization . . ............................
17
21
21
26
37
40
44
SUMMARY..........................................................................
48
LITERATURE CITED
50
...........................................................................................
APPENDICES:
A.
TABLES
B.
FIGURES..................................................................
..............................................................................
<
54
67
v iii
LIST OF TABLES
Table
1.
2.
3.
4.
5.
6.
7.
8.
9.
Page
C u ltiv a r name, id e n tific a tio n number, actual
mean y ie ld , number o f lo ca tio n s , number o f
days to heading, plant height, and w inter
survival score o f seven hard red w inter wheat
c u l t i v a r s ........................................................................... . .
8
Environmental conditions a t the Montana State
U n iversity Post Research Farm and Fort E llis
s i t e s ................................................................................... .... .
9
Mean TNC content (percent dry weight) o f four
untreated w in ter wheat c u ltiv a rs at the boot
stage in three e n v iro n m e n ts ..............................................
22
Means o f TNC frac tio n s (percent dry weight)
o f four w inter wheat c u ltiv a rs TO days a fte r
a p p licatio n of,chemical desiccant at the boot
stage in three environments ..............................................
23
The e ffe c t o f chemical desiccant on TNC
fra c tio n s (percent dry weight) over four
c u ltiv a rs 10 days a fte r desiccant application
a t the boot stage in three e n v iro n m e n ts .....................
24
Means o f TNC fra c tio n s (percent dry weight)
in the lower stem o f seven untreated w inter
wheat c u ltiv a rs at e a rly dough stage
.........................
27
Means o f TNC frac tio n s (percent dry weight)
in the peduncle o f seven untreated w inter
wheat c u ltiv a rs at e a rly dough stage
.........................
28
Means o f TNC frac tio n s (percent dry weight)
in the lower stem of seven w inter wheat
c u ltiv a rs 10 days a fte r app licatio n of
chemical desiccant at e a rly dough stage .....................
29
Means of TNC frac tio n s (percent dry weight)
in the peduncle of seven w in ter wheat c u ltiv a rs
10 days a fte r application o f chemical desiccant
a t e a rly dough stage
..................................... . . . . .
30
ix
LIST OF TABLES--Continued
Table
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
Page
The e ffe c t o f chemical desiccant on TNC
fra c tio n s (percent dry weight) 10 days a fte r
desiccant a p p lic a tio n , averaged over c u ltiv a rs
. .
33
C orrelation c o e ffic ie n t ( r ) fo r TNC and fructan
content a t boot stage versus mid-dough stage o f
four c u ltiv a rs in three environments
.........................
38
Means o f TNC and fructan net depletion rates
from the stem (ug • mg'1 • day'1) during the 10
days follow ing application o f chemical desiccant
............................................
a t e a rly dough (maine ffe c ts )
41
TNC and fructan net depletion ra te (ug • mg'1 day'1) from the stem during the 10 days fo llo w ­
ing app licatio n o f chemical desiccant, averaged
over a ll c u ltiv a rs
............................................................
43
Average degree o f polym erization 10 days a fte r
a p p licatio n o f chemical desiccant at e a rly
dough stage ..........................................................
45
E ffe c t o f chemical desiccant on the average
degree o f polym erization 10 days a fte r the
desiccant app licatio n a t e a rly dough stage,
............................................................
over a ll c u ltiv a rs
46
Means of grain y ie ld , harvest index, and
kernel weight o f seven w inter wheat c u ltiv a rs
55
. . .
C orrelation c o e ffic ie n ts ( r ) among y ie ld and
carbohydrate c h a ra c te ris tic s in the lower
stem o f seven w inter wheat c u ltiv a rs ,
combined over 1987 and 1988
56
C orrelation c o e ffic ie n ts ( r ) among y ie ld and
carbohydrate c h a ra c te ris tic s in the peduncle
of seven w inter wheat c u ltiv a r s , combined
over 1987 and 1988
.............................................................
57
Mean squares fo r stem TNC, fructan s, sucrose,
glucose, and fructose contents o f four w inter
wheat c u ltiv a rs 10 days a fte r application of
chemical desiccant a t the boot stage in three
environments
..........................................................
58
X
LIST OF TABLES--Continued
Table
20.
21.
22.
23.
24.
25.
26.
27.
Page
Mean squares fo r TNC and fructan content o f
seven w inter wheat c u ltiv a rs in the lower
stem and the peduncle 10 days a fte r a p p lica­
tio n o f chemical desiccant at the e a rly dough
s t a g e ...........................................................................................
59
Mean squares fo r TNC and fructan net depletion
rates from the stem fo r the 10 days follow ing
a p p licatio n o f chemical desiccant at e a rly
d o u g h ..........................................................................
60
Mean squares fo r TNC and fructan content in
stems o f w in ter wheat 10 days a fte r a p p lica­
tio n o f chemical desiccant a t the boot stage,
combined over three environments and four
c u l t i v a r s ..................................................................................
61
Mean squares fo r TNC and fructan content in
the lower stem and the peduncle o f w inter
wheat 10 days a fte r a p p licatio n o f chemical
desiccant at the e a rly dough stage, combined
over lo ca tio n s , years, and c u ltiv a rs
.........................
62
Mean squares fo r TNC and fructan net deple­
tio n rates in the lower stem and the peduncle
10 days a fte r application o f chemical
desiccant at the e a rly dough stage
.............................
63
Mean squares fo r fructan average DP in the
lower stem and the peduncle 10 days a fte r
app licatio n of chemical desiccant at the
e a rly dough stage, averaged over two lo ca­
tions and two y e a r s ..............................................................
64
Mean squares fo r fructan average DP in the
lower stem and the peduncle 10 days a fte r
app licatio n o f chemical desiccant at the
e a rly dough stage, averaged over two loca­
tio ns and two years ...................................................... .... .
65
Mean squares fo r grain y ie ld in two locations
averaged over 1987 and 1988 ............................. ....
66
xi
LIST OF FIGURES
Figure
1.
2.
3.
4.
5.
6.
7.
8.
9.
Page
The re la tio n s h ip between peak area (mv IO"3)
and concentration (ug IO"2 ul"1) o f sucrose,
glucose, and fructose ..........................................................
18
The re la tio n s h ip between peak area (mv IO"3)
and concentration (ug IO"2 ul'1) o f DP3, DP4,
DP5, and DP6
..........................................................................
is
The re la tio n s h ip between peak area (mv) and
concentration (ug IO"2 ul'1) o f f r u c t a n s .........................
19
Means o f y ie ld (gm « row"1) main e ffe c t o f
seven w inter wheat c u ltiv a rs at Post Farm
and Fort E l l i s , averaged over 1987 and 1988
36
. . . .
The re la tio n s h ip between boot stage and mid­
dough stage fo r TNC content, treated by the
chemical desiccant and untreated
. ......................... ....
38
The re la tio n s h ip between boot stage and mid­
dough stage fo r fructan content, treated by
the chemical desiccant and untreated
.........................
39
The re la tio n s h ip between TNC at the boot
stage and fructans at the mid-dough stage,
trea te d by the chemical desiccant and
u n t r e a t e d ...................................................................................
39
The re la tio n s h ip between ra te o f TNC deple­
tio n in the peduncle and y ie ld a fte r t r e a t ­
ment a t e a rly dough with the chemical
desiccant a t Fort E llis and Post Research
Farm
.......................................................... .................................
43
HPLC chromatograms o f stem-stored carbo­
hydrates: (A) P ro file o f the mixture of
seven c u ltiv a rs (F, fructose; G, glucose;
S, sucrose; and DP3, DP4, DP5, and DP6);
(B) DP6; (C) DP5
68
xii
LIST OF FIGURES--Continued
Figure
10.
11.
12.
13.
14.
15.
16.
17.
18.
Page
HPLC chromatograms o f stem-stored carbo­
hydrates: (A) DP4, (B) D P 3 ..............................................
69
HPLC chromatograms o f fiv e concentrations
o f sucrose
.........................................
70
HPLC chromatograms o f fiv e concentrations
o f glucose
........................
71
HPLC chromatograms o f three concentrations
o f f r u c t o s e ...............................................................................
72
HPLC chromatograms o f two concentrations
o f f r u c t o s e ...........................................................................
73
HPLC chromatograms o f three concentrations
o f DP3
.....................................
74
HPLC chromatograms o f three concentrations
o f DP4
.......................................................................................
75
HPLC chromatograms o f three concentrations
o f DP5
.........................................................
76
HPLC chromatograms of three concentrations
o f DP6
. ...................................................................................
77
x iii
ABSTRACT
The use o f chemical desiccants to simulate drought stress has
been e ffe c tiv e in d iffe r e n tia tin g wheat c u ltiv a rs fo r drought t o le r ­
ance. The ob jective o f th is work was to study the e ffe c t o f simulated
drought on stem-stored carbohydrates in w inter wheat.
Seven w inter wheats (Triticum aestivum L .) varying in average
grain y ie ld and other agronomic c h a ra c te ris tic s were planted in RCB
design with four re p lic a tio n s at two f ie ld locations in 1987 and 1988.
A 3% sodium chlorate desiccant solution was applied to four o f the
seven w inter wheat c u ltiv a rs a t the boot stage, and to a ll seven
c u ltiv a rs at the e a rly dough stage. Stem samples were taken twice a t
each growth stage, immediately before and 10 days a f t e r the desiccant
a p p lic a tio n . Samples from the e a rly dough stage were divided into
lower stems and peduncles.
C a lib ra tio n o f the high performance liq u id chromatography (HPLC)
system enabled q u a n tific a tio n o f TNC and fructan content in wheat
stems. A pplication o f the desiccant a t the e a rly dough stage in wheat
reduced TNC and fructan content, increased net depletion rates o f TNC
and fructan s, and decreased the average degree o f polym erization.
There was a p o s itiv e c o rre la tio n between the boot and mid-dough stages
fo r TNC and fructan content. In a d d itio n , there was a p o s itiv e corre­
la tio n between net TNC depletion ra te and grain y ie ld follow ing
desiccant a p p lic a tio n . TNC depletion ra te in wheat stems (peduncles)
provided a r e lia b le measurement to id e n tify tolerance to drought
stress in wheat. There were s ig n ific a n t GxE in tera c tio n s fo r TNC
content, net ra te o f TNC depletion, fructan average degree o f polymer­
iz a tio n , and grain y ie ld . There were few or no s ig n ific a n t c u ltiv a r x
desiccant in te ra c tio n s fo r TNC content, net ra te of TNC depletion, and
grain y ie ld . A s ig n ific a n t c u ltiv a r x desiccant in te ra c tio n was
observed fo r lower stem fructan average degree o f polym erization.
Chemical desiccant d iffe r e n tia te d wheat c u ltiv a rs fo r th e ir
a b il it y to tran slocate TNC to the g ra in , imposed homogeneous stress
and simulated drought in wheat.
I
INTRODUCTION
I t is necessary to increase the food production as long as world
population increases.
Famine has been observed in recent years in
several developing countries.
Wheat {Triticum aestivum L .) is the
staple crop in many o f those countries.
In many parts o f the world
increasing the area planted with wheat is lim ite d by a b io tic stress
conditions, e s p e cia lly drought.
. Plant breeders have tr ie d d iffe r e n t ways to increase the drought
tolerance o f wheat.
A major problem in breeding fo r drought tolerance
is estab lishing a r e lia b le screening technique.
Chemical desiccation
was suggested as a screening technique to simulate natural drought.
This damages the leaves and increases the dependence on stem-stored
carbohydrates.
The major storage form of to ta l nonstructural carbohydrates (TNC)
in the Graminae fam ily is fructans (Pontis and Cam pillo1 1985).
Fructans are w ater-so luble, stored in the vacuole o f the c e l l , and
composed o f a chain o f fructose sugars with one glucose a t the terminal
end.
A lte ra tio n s in the average degree o f polym erization o f fructans
may be involved in cryoprotection and osmoregulation.
The objective o f
th is work was to study the e ffe c t o f simulated drought, caused by
chemical desiccation, on stem-stored carbohydrate c h a ra c te ris tic s in
w inter wheat.
2
LITERATURE REVIEW
Screening Techniques fo r Drought
Tolerance in Wheat
S c ie n tis ts have approached the v a r ia b ilit y among drought to le ra n t
genotypes in d iffe r e n t ways.
Some have emphasized morphological and/or
physiological c h a ra c te ris tic s re la te d to drought.
Fischer and Wood
(1979) studied the association between y ie ld performance under drought
and some morpho-physiological t r a i t s .
They concluded th a t the best
p redictio n fo r y ie ld under drought conditions could be estimated by a
lin e a r model containing to ta l dry weight, kernel weight, and le a f
waxiness.
Tan and Halloran (1982) studied the v a ria tio n o f proline
!
accumulation in spring wheat c u ltiv a r s .
They found th a t water-stressed
plants accumulated fre e p ro lin e in t h e ir tissues and th a t c u ltiv a rs
d iffe re d in t h e ir p o te n tia l to accumulate p ro lin e .
Keim and Kronstad
(1981) compared the response of 10 w in ter wheat c u ltiv a r s ' grain y ie ld
and y ie ld components to moisture stress conditions a t three lo catio ns.
They found s ig n ific a n t association o f osmotic p o te n tia l measured from
le a f samples taken during the grain f i l l i n g period.
The e ffic ie n c y o f other drought tolerance screening techniques has
been examined.
Clarke (1983) compared the e x cised -!e a f water reten tio n
c a p a b ility o f P it ic 62 and three other c u ltiv a rs under controlled
conditions in the greenhouse and the growth chamber to f ie ld condi­
tio n s .
He found no s ig n ific a n t d ifferences in water loss between the
3
two controlled environments, but the ra te o f water loss from the
excised leaves d iffe re d markedly between the f ie ld and the controlled
environments.
Clarke and McCaig (1982) compared the e x c is e d -!eaf water
reten tio n c a p a b ility method with le a f d iffu s iv e resistance and le a f
temperature methods.
They found th a t the excised -!e a f water reten tio n
c a p a b ility method was the most r e lia b le method.
Chemical desiccation has been used to simulate natural drought.
Blum e t a l . (1983b) studied the e ffe c t o f magnesium chlo rate applied 14
days a fte r anthesis oh the kernel weight in two successive years fo r 38
and 26 c u ltiv a rs , re s p e c tiv e ly .
The e ffe c t of chemical desiccation in
a non-stress environment was compared with the e ffe c t o f post-anthesis
drought stress in a drought environment.
They found a p o s itiv e corre­
la tio n between the simulated drought in ju ry and the natural drought
in ju ry fo r reduction in kernel weight.
0.62 fo r the two years, re sp ec tiv e ly .
The r 2 values were 0.65 and
Bruckner (1985) studied the
■effect of chemical desiccant sodium chlorate on spring wheat c u ltiv a rs .
He concluded th a t chemical desiccation is a promising technique to
id e n tify genotypes which tran slocate more carbohydrate reserves from
the vegetative tissues in to the grain under stress conditions.
Sabry
and Taylor (1989) compared the e ffe c t of I , 2, and 3% sodium chlo rate,
applied at heading and 14 days post-anthesis, on grain y ie ld and y ie ld
components o f three height near isogenic lin e s of two w in ter wheat
c u ltiv a rs .
They found the 3% concentration applied a t e ith e r heading
or post-anthesis reduced y ie ld and affected y ie ld components; 1% and 2%
concentrations affected y ie ld and y ie ld components to a lesser degree.
4
The medium height near isogenic lin e s yield ed more than the t a l l and
short lin e s under simulated drought conditions.
The Contribution o f Stem-Stored Carbo­
hydrates to Grain Y ield Under
Drought Stress Conditions
S c ie n tis ts have compared the contrib ution o f stem-stored carbo­
hydrates to grain y ie ld under stress and non-stress conditions.
Bidinger e t a l . (1977) found th a t the contrib ution o f stem-stored
pre-anthesis assim ilates to grain y ie ld in wheat was 12% under non­
stress conditions compared to 22% under drought conditions.
Gallagher
e t a l. (1975) presented even higher estimates fo r c o n trib u tio n o f stemstored pre-anthesis assim ilates o f 50% and 70% fo r wheat and barley
(Hordeum vuTgare L . ) , re sp ec tiv e ly , under extreme stress conditions.
Austin e t a l . (1980) reported estimates fo r stem-stored carbohydrate
movement in to grain of 44% in a very dry year and 11% in a wet, cool
year.
In a d d itio n , McCaig and Clarke (1982) compared the seasonal
changes o f nonstructural carbohydrates (NSC) in stems o f two wheat and
two oat c u ltiv a rs under water stress conditions.
carbohydrates (TNC) is the same as NSC.
Total nonstructural
They found s ig n ific a n t d i f f e r ­
ences in stem carbohydrate le vels between wheat and oats, and among
c u ltiv a rs w ith in each species.
Their re s u lts in d icate th a t the stem
may provide temporary storage fo r NSC needed by the developing grain i f
photosynthate production is in terru p te d .
5
C haracteristics o f Fructans and Their
Role in Osmoregulation
Fructans (fructosans) are fructose polymers th a t contain terminal
glucose residues [G -F(F)n] .
levans (p h le in s ).
They occur in two forms:
in u lin s and
In u lin s are polymers o f Beta 2-1 linked D-
Fructofuranose th a t occur in c e rta in Asteraceae species.
Phleins are
polymers o f Beta 2-6 linked D-fructofuranose and occur in the vegeta­
tiv e tissues o f tem perate-origin grasses o f the Graminae fa m ily .
Fructans are highly water soluble and are very acid la b ile .
Although
phleins appear to be p rim a rily lin e a r molecules, they may be branched.
Phleins have a low degree o f polym erization (DP) and occur in a homolo­
gous series in grass tissues with the maximum length o f the fructan
molecule varying with the grass species.
The longest fructan molecule
in grass stem bases varies from a DP o f about 26 in bromegrass {Bromus
in e m is L .) to about 260 in timothy {Phleum pratense L . ) .
The
mechanism o f synthesis and degradation o f fructans in the Graminae
fam ily is not as well defined as in the Asteraceae fa m ily .
little
Also,
is known about the mechanisms involved in t h e ir m obilization
under adverse environmental conditions.
Some in vestig ato rs suggest a ro le fo r fructans in osmoregulation
under drought stress conditions.
Derbyshire and Henry (1978) studied
the d is trib u tio n o f fructans in onions [Anium cepa L .) and found a
decline in the to ta l fructans from 51% to 21% going from the oldest
to the youngest leaves, while the percentage of fructose increased
simultaneously from 7% to 31%.
The researchers ascribed th is to the
hydrolysis o f fructans to free fructose which causes osmotic adjustment
6
as the base c e lls expanded during the bulbing o f onions.
Wagner e t a l.
(1983) induced wheat leaves to accumulate fructans in large amounts.
They found a ll fructans o f DP3 and above and the sucrose-sucrose tran s ­
ferase (SST) enzyme in the vacuole o f the mesophyll c e lls .
Sucrose-
sucrose transferase (SST) is the f i r s t enzyme involved in fructan
synthesis.
Also, they enumerated the advantages o f storing fructans in
the vacuoles over starch:
( I ) fructans are highly soluble in water,
and (2) the molecular size o f fructans can be changed e a s ily using only
a simple transferase system.
This makes fructans id ea l fo r osmoregula­
tio n during water or temperature stress.
Blacklow e t a l. (1984)
studied the polym erization and depolymerization o f fructans in the
w inter wheat stem internodes during grain f i l l i n g .
maximum fructan chain length o f DP9.
They reported a
In additio n , they found th a t the
amount of long chain (DP > 5) fructans reached a peak 24 days a fte r
anthesis and then decreased to almost zero, while sucrose and fructose
increased.
Thome and Kuhbauch (1985) studied the q u a lita tiv e and q u a n tita tiv e
changes in the carbohydrate pattern o f wheat stems during g ra in ­
f i l l i n g , using high performance liq u id chromatography (HPLC).
They
found th a t the main carbohydrate reserve in the wheat stem was
fructan s, with a maximum average DP o f 7 -8 .
Also, they concluded th a t
before anthesis the value o f fructans composed 16% o f dry m atter in the
bottom segment o f the stem and 22% in the upper segment, with an
average DP o f about 3.
A fte r anthesis, one week before the m ilk stage,
fructans reached the maximum o f 30% o f the dry m atter, with a maximum
average DP > 5 in the lower and upper parts o f the stem.
Schnyder et
7
a l. (1988) studied the changes in the fructan content o f spring wheat
kernels during the period from anthesis to m atu rity.
They concluded
th a t the fructan content o f the kernel reached it s maximum 10 days
post-anthesis, and th a t most o f the fructan content was lo c a lize d in
the pericarp and the embryo (71%) and lesser amounts in the endosperm
(29%).
8
MATERIALS AND METHODS
F ield Work
C ultivars
Seven w inter wheat c u ltiv a rs (Table I ) were chosen from the 1986
Montana A g ric u ltu ra l Experiment S tation In tra s ta te Winter Wheat Y ield
T r ia l based on t h e ir actual mean grain y ie ld .
The c u ltiv a rs varied in
th e ir actual mean grain y ie ld from 2.3 to 3.7 t.h a '1.
The c u ltiv a rs
also varied in other agronomic c h a ra c te ris tic s (number o f days to 50%
heading, plan t height, and w inter survival score). *
Table I .
C u ltiv a r name, id e n tific a tio n number, actual mean y ie ld ,
number o f lo catio n s, number o f days to heading, plant height,
and w in ter survival score o f seven hard red w in ter wheat
c u lt iv a r s .*
C u ltiv a r
ID number
Redwin
Tiber
Norwin
Centurk
Froid
Crest
Brawny
Cl
PI
PI
Cl
Cl
Cl
SR
17844
517194
1491533
15075
17832
13880
4714
Mean
y ie ld
(t.h a '1)
Number
locations
3.4
3.7
3.6
3 .5
3:0
3.1
2.3
168
140
132
180
114
69
55
HDa
168
168
170
165
170
166
161
PHb
(cm)
WHc
86
89
64
84
102
79
69
3 .4
3 .5
4.1
2.5
3 .9
2 .8
2.0
*Taylor (1986)
aHD = Number o f days to 50% heading a fte r January I
bPH = Plant height in cm
cWH = Winter hardiness on a scale o f 1-5; 5 = very hardy, I = non-hardy
9
Experimental Design
The c u ltiv a rs were arranged in a randomized complete block design
with four re p lic a tio n s .
The f ie ld experiments were grown at the
Montana State U n iversity Post Research Farm and Fort E llis s ite s , both
near Bozeman, in 1987 and 1988.
long and 30 cm apart.
borders.
Each p lo t consisted o f s ix rows 3 .5 m
The f i r s t and s ix th rows were considered
The bordered four rows were used fo r y ie ld determination and
fo r c o lle c tin g the stem samples required fo r the carbohydrate analysis.
The environments a t Fort E llis and the Post Research Farm were
d iffe r e n t based on 30- year averages and 1987 and 1988 weather informa­
tio n (Table 2 ).
Table 2.
Environmental conditions at the Montana State U n iversity Post
Research farm and Fort E llis s it e s .*
Factor
Elevation
Fort E llis
1581 m
Post Farm
1368 m
<......... 30-year a v e ra g e ..............>
Thornthwaite PET
Annual a ir temperature
Annual p re c ip ita tio n
June and July p re c ip ita tio n
528 mm
5.5°C
457-508 mm
129 mm
566 mm
6.6°C
355-406 mm
100 mm
<----------- 1987 s e aso n ----------- r>
Annual a ir temperature
Annual p re c ip ita tio n
June and July p re c ip ita tio n
5.7°C
374.4 mm
114.6 mm
6.8°C
383.3 mm
139.2 mm
<............. 1988 s e aso n ............... >
Annual a ir temperature
Annual p re c ip ita tio n
June and July p re c ip ita tio n
6.4°C
393.3 mm
34.3 mm
*National C lim atic Data Center (1986, 1987, 1988)
7.5°C
295.9 mm
31.2 mm
10
Sodium C hlorate A p p lic a tio n
A 3% sodium chlo rate solution was applied at boot stage (preanthesis) and e a rly dough (14d p o s t-a n th e s is ).
Each 3 .5 m row was
sprayed with 160 ml o f the solution applied a t 0.21 MPa pressure.
During spraying, a plywood sheet 3 .5 m long and 50 cm high was placed
on each side o f the row to prevent d r i f t o f the desiccant.
rows o f a p lo t were sprayed as follow s:
The four
the f i r s t row was sprayed a t
the boot stage, the second row was l e f t fo r sampling the check stem
samples, the th ird row was sprayed at the e a rly dough stage, and the
fourth row was kept in ta c t fo r check y ie ld .
Sampling the Stem Parts
At each o f the boot and e a rly dough stages, stem samples were
taken immediately before spraying from the outer 50 cm from both ends
o f the row.
Ten random t i l l e r s were cut at the s o il surface.
(sheathes and blades) were peeled o f f the stem and discarded.
Leaves
Stems
were cut in to 3-5 cm pieces, placed in p la s tic fre e z e r bags, put in to a
fre e ze r w ith dry ic e , and then tran s fe rred to the la b o ra to ry .
At the
boot stage, stem samples were taken fo r four c u ltiv a rs ( Redwin, Tib er,
Centurk, and Froid) out o f the seven included in the experiment.
1987, boot stage samples were taken only at Fort E ll is .
In
In 1988, the
boot stage samples were taken from both Fort E llis and the Post
Research Farm.
At the e a rly dough growth stage, stem samples were taken from the
seven w inter wheat c u ltiv a rs in 1987 and 1988 at both Fort E llis and
the Post Research Farm.
At the e a rly dough growth stage, stems were
11
fu rth e r divided into tw o,parts:
the peduncle and the lower stem.
Ten
days a fte r desiccant a p p lic a tio n , stem samples were taken again from
the treated and check rows in the same manner explained above.
At harvest, the th ird and fourth rows were trimmed to 2.5 meters,
cut at the s o il le v e l, weighed to determine the b io lo g ic a l y ie ld , and
threshed.
A fte r harvest, grain y ie ld and 100 kernel weight were
recorded.
The weight o f 300 kernels was used to estim ate 100 kernel
weight.
Laboratory Work
Stem samples were stored in a fre e z e r at -40°C, freeze dried at
-65°C, and then dried in an oven fo r 20 minutes at 90°C.
Samples were
ground using a Thomas W illey m ill, 40 mesh.
Total Nonstructural Carbohydrates
(TNG) Extraction
Monosaccharides (glucose and fructose) and the d i saccharide
sucrose are soluble in water and 80% v /v ethanol.
soluble in water.
Fructans are only
Total nonstructural carbohydrate (TNG) frac tio n s in
the stem were extracted using water and 80% v/v ethanol.
Both solvents
were used to guarantee complete e x tra c tio n o f a ll TNG fra c tio n s .
The
follow ing steps were used to e x tra c t TNG in the wheat stems (Thome and
Kuhbauch, 1985; Smith and G rotelueschen, 1966; Smith, 1967):
(1)
Three hundred m illigram s of the ground dry samples were weighed in
5 ml p la s tic tubes.
(2)
Four m i l l i l i t e r s o f 80% v /v ethanol/w ater was added to each sample
and placed fo r a g ita tio n in a water bath shaker at 60°C fo r 15
minutes.
12
(3)
Supernatant was decanted and saved.
(4)
Steps 2 and 3 were repeated once on the p e lle t with only 2 ml 80%
v/v ethanol.
(5)
Steps 2-4 were repeated three more times using 2 ml o f d is t ille d
water in place o f 80% ethanol each tim e.
(6)
The combined supernatant sample was placed into a 60°C oven fo r
about two hours to drive o f f the ethanol and to concentrate the
sample to 3 ml volume.
(7)
Samples were frozen, thawed, and centrifuged in a m icrocentrifuge
at 700 g fo r fiv e minutes.
(8)
Samples were run through two successive types o f re sin beds fo r
cleaning:
5 cm3 Dowex 50 w-x8 20-50 mesh hydrogen form, and then
10 cm3 Dowex l-x 8 20-50 mesh Cl' form.
The two types o f resin
f i r s t were washed by 2N NH4OH, and then rinsed thoroughly with
double d is t ille d water to get the pH to 7.
(9)
Samples were eluded through the resin with 30 ml double d is t ille d
water.
(10)
Samples were concentrated to 3 ml in the oven a t 60°C fo r about
eight hours.
(11)
One-half m i l l i l i t e r o f the sample was passed through a 0.45
micron m ic r o filte r before in je c tio n o f a subsample in to the High
Performance Liquid Chromatography (HPLC).
Hvdrolvsis
Hydrolysis was done to transform the fructan and sucrose
frac tio n s o f TNC to fructose and glucose.
This allowed fo r ca lc u la tio n
o f the average fructan degree o f polym erization.
13
(1)
Samples were hydrolyzed by adding 0.5 ml 0.3 N hydrochloric acid
(HG!) to 0 .5 ml o f the TNC extracted sample, and heating in a
water bath at 80°C fo r 25 minutes.
(2)
One-half m i l l i l i t e r 0.3 N sodium hydroxide (NaOH) was added to
n e u tra liz e the hydrolyzed sample (W ille , 1985).
(3)
Samples were run through two types o f resin as described above,
except th a t washing was with 20 ml o f double d i s t i lle d water, and
concentrated to I ml in the oven at GO0C fo r six hours.
(4)
Samples were freeze dried fo r 24 hours, and dissolved in 0 .5 ml o f
double d is t ille d water.
(5)
Samples were again f ilt e r e d through a 0.45 micron m ic r o filte r
before in je c tio n in to the HPLC.
The samples were ready fo r
in je c tio n in to the HPLC.
The HPLC System Used fo r TNC and
Hydrolyzed Samples Analysis
The HPLC system used in th is study consisted of the follow ing:
(1)
Pump - - Karatos Spectroflow 400 Solvent D elivery System
(2)
Guard column - - Biorad Micro-Guard
(3)
Column - - Biorad Aminex Carbohydrate HPX-42 C
(4)
Detector - - Waters D iffe re n tia l Refractometer R 401
(5)
In te g ra to r - - Shimadzu
These parts were connected and a 100 ul loop placed between the
pump and the guard column.
This volume remained constant in each run.
The 24-minute run fo r each sample allowed complete re so lu tio n o f TNC o f
the non-hydrolyzed samples and provided enough time to include glucose
and fructose in the hydrolyzed samples.
The pressure range allowed
14
before replacing the guard column was 0-5 bars.
The flow ra te o f the
pump was adjusted to 0 .5 ml min'1, and the s e n s itiv ity o f the detector
was adjusted to 16x.
Quantifying HPLC Peak Areas
The HPLC produces chromatograms composed o f peaks whose areas
depend on the r e la tiv e re fra c tio n o f v is ib le lamp lig h t through the
sample c e ll versus the reference c e ll.
only the solvent.
The reference c e ll contained
The peak areas are equivalent to m illiv o lt s (mv).
Although other researchers (Thome and Kuhbauch, 1985; Schnyder e t a ! . ,
1988) used the HPLC fo r carbohydrate (fru ctan s) analysis in wheat, they
did not q u an tify the carbohydrate fra c tio n s with wheat standards.
They
used fructan standards from the base o f timothy {PhTeum nodosum L .)
stems to q u an tify fructan peak area in wheat stems.
They hydrolyzed
the wheat fructans to get two peaks fo r glucose and fru cto se.
By
measuring the peak heights and the r a tio between them, they estimated
fructan average degree o f polym erization.
Since the o b je ctiv e o f the
current study was to look a t the stem-stored carbohydrate character­
is tic s (TNC content, ra te o f TNC d ep letio n , and the average degree o f
p o lym erizatio n), i t was necessary to quantify the in d ivid u al TNC
frac tio n s detected as HPLC peaks.
For c a lib ra tio n , fiv e standard
solutions d iffe r in g in concentration were prepared fo r the monosac­
charides glucose and fructose and also the d isaccharide sucrose from
commercial sources.
Each concentration was re p lic a te d three times
during in je c tio n in to the HPLC.
There are no commercial fructans (DP3 and above) extracted from
wheat to prepare standard solu tion s.
Therefore, samples o f the mixture
15
o f c u ltiv a rs included in the study were run in the HPLC and each single
fructan peak was c o lle c te d .
Four peaks were c o lle cte d :
DP3, DP4, DP5,
and DP6+.
The DP6 peak included fructan chains longer than 6 hexose
polymers.
(The HPLC system could not resolve fructans o f more than
DP6.)
Samples were co llected from the o u tle t of the d e te c to r.
Samples
fo r every peak were concentrated to about 3 ml using a fla s h evapor­
a to r, Rotavapor-Rl10, and freeze d rie d .
Three concentrations o f each
DP were prepared and each was re p lic a te d twice during in je c tio n into
the HPLC.
S ta tis tic a l Analyses
Analyses o f variance were computed fo r a ll t r a i t s in each environ­
ment separately (Steel and T o rrie , 1980).
Analysis o f variance was
combined over years fo r the Post Farm and Fort E llis lo ca tio n s .
Regression analysis was done fo r each environment separately, based on
the means o f the c u ltiv a rs in the combined analysis in each location
over the two years (n=7).
Regression analysis fo r the re la tio n s h ip between the boot stage
and mid-dough stage was done using the means of the four c u ltiv a rs
common in the two stages in a ll three environments (n=12).
The average fructan degree o f polym erization (DP) was calculated
by subtracting fructose and sucrose content in the unhydrolyzed samples
from fructose in the hydrolyzed sample, and also by subtracting glucose
and sucrose content in the unhydrolyzed samples from glucose in the
hydrolyzed sample.
formula:
DP was calculated according to the follow ing
16
Net ra te o f TNC depletion was calculated according to the follow ing
formula:
Net ra te o f TNC depletion =
TNC (b e g in n in g )^ JNC (endl.nq l = ug o mg-i e day-i
17
RESULTS AND DISCUSSION
Q u an tificatio n o f Stem-Stored
Carbohydrates in Wheat
The HPLC separated TNC extracted from the mixture o f seven c u lt i vars in wheat stems in to fructans (DP3, DP4, DP5, and DP6 and above),
sucrose, glucose, and fructose (Figure 9A, Appendix).
Individual
hexose polymers 3 through 6 are shown in Figures 9B-C and IOA-B
(Appendix).
Elution times fo r DP6 and above, DP5, DP4, DP3, sucrose,
glucose, and fructose were 7 .1 , 8 .2 , 9 .1 , 10.3, 12.6, 1 5.2, and 18,6
minutes, re s p e c tiv e ly .
Figures 11, 12, 13, and 14 (Appendix) show fiv e
d iffe r e n t peak areas produced by fiv e concentrations each o f sucrose,
glucose, and fructose.
Figures 15, 16, 17, and 18 (Appendix) show
three d iffe r e n t peak areas produced by three concentrations each of
DP3, DP4, DP5, and DP6.
The re su lts show a s ig n ific a n t p o s itiv e c o rre la tio n between peak
areas and TNC fra c tio n concentrations in ug IO'2 u V (Figures I and 2 ).
C o e fficien ts o f simple determination values ( r 2) fo r sucrose, glucose,
fructose, DP3, DP4, DP5, and DP6 were 0.9931, 0.9868, 0.9980, 0.9986,
0.9934, 0.9928, and 0.9983,. re s p e c tiv e ly .
peak area fra c tio n was 0.8918 (Figure 3 ).
The r 2 value fo r the fructan
18
Sucrose
•+•
_
Glucose
Fructose
r ■ 0 .9 9
160
200
21
Peak Area (mv.)
Figure I .
The re la tio n s h ip between peak area (mv I O'3) and
concentration (ug IO2 u l'1) o f sucrose, glucose,
and fru cto se (n=15).
r - 0 .9 9
Peak Area (mv)
Figure 2.
The re la tio n s h ip between peak area (mv IO"3) and
concentration (ug IO2 u l 1) o f DP3, DP4, DP5, and
DP6 (n=6).
19
r ■ 0.89
Peak area (mv)
Figure 3.
The re la tio n s h ip between peak area (mv) and
concentration (ug IO2 uT1) o f fru ctan s (n=24).
Double d i s t i l l e d water (zero sugar con centration) produced the
base lin e in the HPLC chromatogram; th e re fo re i t seemed reasonable to
force the regression lin e s through the o r ig in .
The fo llo w in g are the equations which re su lte d from the regression
lin e s forced through the o r ig in :
Sucrose* = 2.487 x peak area
Glucose
= 2.435 x peak area
Fructose = 2.526 x peak area
20
DP3
= 3.158 x peak area
DP4
= 2.839 x peak area
DP5
= 2.660 x peak area
DP6
= 2.122 x peak area
Fructans = 2.580 x peak area
^concentration in ug IO 2 u l'1
These equations could be used to quantify the amounts o f TNC fo r
sucrose, glucose, fructose, DP3, DP4, and DP5.
For DP6 i t was not as
accurate due to the presence o f other longer hexose polymers under the
same peak.
These long hexose polymers could not be separated by the
HPLC used in th is study.
Blacklow e t a l . (1984) reported a maximum
fructan chain length o f DP9 in the stem internodes o f w in ter wheat.
Thome and Kuhbauch (1985) reported a maximum fructan chain length o f
7-8 in wheat.
This suggests th a t the hexose polymers in wheat are not
very long, and consequently the above equation fo r DP6 should provide a
reasonable estimate fo r hexose polymers 6 and above.
To the best o f our knowledge, th is work is the f i r s t attempt to
prepare standards fo r the d iffe r e n t hexose polymers o f fructans in
wheat.
Thome and Kuhbauch (1985) used standard fructans front the base
o f timothy [Phleum nodosum L .) stems to c a lib ra te t h e ir HPLC system fo r
quantifying hexose polymers in wheat.
Wagner e t a l . (1983) used th in
la y e r chromatography (TLC) to separate the sugars and then used c o lo rim eteic and enzymatic assays fo r q u a n tific a tio n .
21
Total Non-Structural Carbohydrate
(TNC) Content
The Boot Stage
S ig n ific a n t d ifferences were found fo r TNC and TNC frac tio n s among
the three environments (Table 22, Appendix).
The s ig n ific a n t c u ltiv a r
x desiccant in te ra c tio n mean squares were small fo r TNC and a ll the
frac tio n s except fructan s.
The s c a rc ity o f a s ig n ific a n t c u ltiv a r x
desiccant in te ra c tio n fo r stem-stored carbohydrates a t the boot stage
suggests th a t chemical desiccation could be applied to simulate
drought in d iffe r e n t environments without in te ra c tio n w ith s p e c ific
genotypes.
S ig n ific a n t d ifferences (P < 0 .05) were noted among w inter wheat
c u ltiv a rs fo r stem TNC and TNC fra c tio n s both before and 10 days
follow ing the chemical desiccant app licatio n at the boot stage (Tables
3 and 4 ).
Redwin ranked very high in TNC and fructan content in
environments 2 and 3.
In contrast, Froid ranked high in TNC and a ll
frac tio n s in environment I .
This suggests a high genotype x environ­
ment (GxE) in te ra c tio n fo r TNC content in some c u ltiv a rs , e . g . , Froid
in environments I , 2, and 3 (Tables 3 and 4 ).
In co n tra s t, Redwin
and Tiber were less v a riab le in TNC and TNC fra c tio n content than
Froid.
22
Table 3.
Mean TNC content (percent dry weight) o f four untreated
w inter wheat c u ltiv a rs at the boot stage in three environ­
ments.
Mono- and d isaccharides
C u ltiv a r
TNC
<------
Fructans
Sucrose
Glucose
Fructose
- Environment ( I ) , Fort E llis 1987 - --------------- >
Redwin
18.6 ab*
4.1 a
5 .4 a
6 .3 b
2.7 b
Tiber
17.7 ab
3 .9 a
4 .5 a
6.3 b
3.1 b
Centurk
14.7 b
3.3 a
4.1 a
4 .9 b
2.3 c
Froid
21.9 a
4.7 a
4 .8 a
8 .2 a
4.1 a
<-----
- Environment (2 ) , Fort E llis 1988 - - ------------- >
Redwin
18.6 a
5.3 a
4 .6 a
5.4 a
3.3 a
Tiber
14.9 ab
3 .2 ab
4.1 ab
4 .7 ab
2.9 a
9.0 b
0.9 b
2.2 c
3 .6 b
2.3 a
13.4 ab
3 .0 ab
3.2 be
4 .3 ab
3 .0 a
Centurk
Froid
<-----
-- Environment ( 3 ) , Post Farm 1988 - - - ---------------->
Redwin
14.0 a
1.8 a
4 .6 a
4 .5 a
3 .2 a
Tiber
12.2 ab .
1.0 ab
4.0 ab
4.2 ab
3 .0 a
Centurk
6.5 C
0.6 b
2 .4 c
2.0 c
1.5 b
Froid
9.3 be
0.5 b
3.3 be
3 .0 be
2.5 a
*Means w ith in a column not followed by the same l e t t e r d i f f e r at
P < 0.05 le v e l o f sign ificance according to LSD te s t.
23
Table 4.
Means o f TNC frac tio n s (percent dry weight) o f four w inter
wheat c u ltiv a rs 10 days a fte r application o f chemical
desiccant a t the boot stage in three environments.
Mono- and d isaccharides
C u ltiv a r
TNC
Fructans
Sucrose
Glucose
Fructose
<-------------- -- Environment ( I ) , Fort E llis 1987 Redwin
9.1 a*
1.5 ab
2 .4 a
3 .6 ab
1.5
Tiber
8 .7 a
1.9 a
2.1 a
3 .0 be
1.7 b
Centurk
5.6 b
0.6 c
1.4 b
2.3 c
1.3 b
Froid
9.1 a
0 .8 be
1.9 ab
4 .0 a
2.4 a
I
I
I
I
I
Redwin
9.4 a
2.7 a
3 .5 ab
1.9 ab
v-H
C
M
<-------------- - Environment (2 ) , Fort E llis 1988 -
b
Tiber
9.6 a
1.8 a
4 .0 a
2.2 a
1.6 a
Centurk
4.9 b
1.8 a
1.8 c
0 .8 c
0.6 b
Froid
7.9 a
1.8 a
2 .9 b
1.7 b
1.5 a
<-------------- - Environment (3 ) , Post Farm 1988 - - -
a
--
>
3.9 a
5.4 a
2 .8 a
2.1 ab
Tiber
10.0 c
1.2 b
4 .6 a
2.5 ab
1.9 ab
Centurk
10.3 be
4 .0 a
2.6 b
2 .0 b
1.7 b
Froid
13.2 ab
3 .4 a
4 .6 a
2 .8 a
<3-
14.2 a
C
M
Redwin
a
*Means w ith in a column not followed by the same le t t e r d i f f e r at
P < 0.05 le v e l o f sign ificance according to LSD te s t.
Simulated drought reduced TNC content in wheat stems in the three
environments (Table 5 ).
S ig n ific a n t differences (P < 0.05 and P < 0 .01)
were noted between the two treatments (control and 3% sodium chlo rate)
averaged over a ll c u ltiv a rs in the three environments (Table 5 ).
This
supports the suggestions o f Blum e t a l . (1983a) and Bruckner (1985)
24
th a t chemical desiccation probably increases the c u ltiv a r dependence on
stem-stored carbohydrates.
Table 5.
The e ffe c t o f chemical desiccant on TNC fra c tio n s (percent
dry weight) over four c u ltiv a rs 10 days a fte r desiccant
app licatio n at the boot stage in three environments.
Mono- and d isaccharides
Treatment
TNC
Fructans
Sucrose
Glucose
Fructose*
< -........... - Environment ( I ) , F o rt E llis 1987
Control (0%)
3% NaClO3
9.7
**
6.5
1.8
**
0.6
2.3
**
1.7
3 .8
**
2.7
1.9
**
1.5
<--------- - - Environment (2 ), Fort E llis 1988 •
Control (0%)
3% NaClO3
10.6
**
5.2
3.6
**
0.5
3 .7
**
2.4
2.0
**
1.3
1.4
**
1.0
<--------- - - Environment (3 ), Post Farm 1988 -■
Control (0%)
3% NaClO3
13.2
**
10.7
4.4
**
1.8
4.7
*
3.9
2.4
ns
2.7
2.2
**
1.7
*S ig n ific a n t at P < 0.05 level o f sign ificance
* *S ig n ific a n t at P < 0.01 level o f sign ificance
ns = Not s ig n ific a n t
Analyses o f variance o f in divid ual locations showed no s ig n ific a n t
c u ltiv a r x desiccant in te ra c tio n fo r TNC content and it s frac tio n s
(Table 19, Appendix).
The exceptions were the c u ltiv a r x desiccant
in tera c tio n s fo r fructans and fructose at Fort E llis in 1987 and the
25
Post Research Farm in 1988, re s p e c tiv e ly .
The fructan mean square fo r
c u ltiv a r x desiccant in te ra c tio n was less than the c u ltiv a r and
desiccant main e ffe c ts mean squares a t Fort E llis in 1987 (Table 19,
Appendix).
The fructose c u ltiv a r x desiccant mean square was less
i
than the desiccant main e ffe c t mean square but greater than the
c u ltiv a r main e ffe c t mean square fo r fructose a t the Post Research Farm
in 1988.
The absence o f c u ltiv a r x desiccant in te ra c tio n in most cases and
the occurrence o f c u ltiv a r x environment in te ra c tio n fo r some c u ltiv a rs
fo r TNC and TNC fra c tio n s are im portant.
Absence o f c u ltiv a r x
desiccant in te ra c tio n indicates th a t c u ltiv a r rank fo r TNC content
would be the same with or without applying the chemical desiccant.
The
desiccant imposes stress and hence increases the dependence on stemstored TNC.
The degree o f dependence on stem-stored TNC w ill vary in
d iffe r e n t environments.
Selection fo r TNC content among wheat c u ltiv a rs a t the boot stage
without chemical desiccation is possible provided i t is done in harsh,
dry environments.
The major portion o f TNC consisted o f mono and d isaccharides
(sucrose, glucose, and fructose) before and 10 days follow ing the
chemical desiccant application at the boot stage (Tables 3 and 4 ).
Fructan percentage was low at the boot stage, varying from 0.5 to 5.3
(percent dry weight) before the chemical desiccant a p p licatio n fo r four
c u ltiv a rs in three environments (Table 3 ) .
This is s im ila r to the 4.5%
fructan reported by Thome and Kuhbauch (1985) fo r preanthesis in the
spring wheat c u ltiv a r 'A rk a s .'
26
Fructan percentage varied from 0 .6 to 4 (percent dry weight) among
c u ltiv a rs 10 days a fte r the chemical desiccant app licatio n at the boot
stage (Table 4 ) .
ments I and 2.
In g eneral, TNC decreased about 45-50% in environ­
The response was unusual in environment 3, where TNC
and it s components' percentages increased in Froid and Centurk.
The
re su lts suggest th a t TNC content at the boot stage has a small fructan
fra c tio n .
This is probably due to high carbohydrate consumption
r e la tiv e to production at th is stage, with l i t t l e l e f t fo r storage in
the fructan form.
The Earlv Douah Stage
S ig n ific a n t differences were observed fo r TNC and fructan content
between locations and years (Table 23, Appendix).
C u ltiv a r x location
and c u ltiv a r x year in tera c tio n s were s ig n ific a n t and had large mean
squares.
This suggests th a t TNC content in w inter wheat c u ltiv a rs is
affected by the environment.
The large GxE fo r TNC content might allow
selection o f c u ltiv a rs having high TNC content only fo r defined e n v ir­
onments.
fillin g
These c u ltiv a rs are expected to have high p o te n tia l fo r grain
in drought stress environments (Bidinger e t a l . , 1977; Blum e t
a l . , 1983a; Gallagher e t a l . , 1975).
S ig n ific a n t differences (P < 0 .05) were found among the seven
c u ltiv a rs fo r TNC content in the lower stem and the peduncle, both
before app licatio n of the chemical desiccant at the e a rly dough stage
and 10 days a f t e r (Tables 6, 7, 8, and 9 ).
The seven c u ltiv a rs varied in lower stem and peduncle TNC and TNC
fra c tio n content before chemical desiccant application a t Fort E llis
and the Post Research Farm (Tables 6 and 7 ).
Tiber had very high lower
27
stem TNC content (percent dry weight) and Crest had very low stem TNC
content before desiccant application at Fort E ll is .
Redwin had very
high lower stem TNC content (percent dry weight) and Centurk had the
lowest before desiccant application at the Post Farm.
V a ria tio n fo r
TNC and TNC fra c tio n content occurred among c u ltiv a rs .
V a ria tio n was
detected among c u ltiv a rs in both the lower stem and the peduncle.
The
peduncle TNC and TNC frac tio n s were less than in the lower stem (Tables
6, 7, 8, and 9 ).
Table 6.
Means o f TNC frac tio n s (percent dry weight) in the lower
stem o f seven untreated w inter wheat c u ltiv a rs a t e a rly dough
stage.
Mono- and d isaccharides
C u ltiv a r
TNC
21.3
24.4
22.9
21.2
21.1
19.2
22.6
abc*
a
ab
abc
be
C
ab
27.2
22.6
21.3
12.4
19.0
20.9
22.2
Glucose
Fructose
13.2
15.5
16.7
14.9
15.3
13.5
16.2
b
ab
a
ab
ab
ab
ab
5.7
5.9
3.1
4.0
4.4
3.2
3 .6
a
a
d
be
b
d
d
1.5
1.8
1.6
1.2
0 .7
1.5
1.3
abc
a
ab
c
d
be
c
0.9
1.2
1.6
1.2
0 .6
Cd
abc
a
abc
d
1 .1 Cd
1.5 ab
- - - Post Farm 87 and 8 8 ---------------------- >
<----Redwin
Tiber
Norwin
Centurk
Froid
Crest
Brawny
Sucrose
- - - Fort E llis 87 and 88 ------- ------------- >
<—
Redwin
Tiber
Norwin
Centurk
Froid
Crest .
Brawny
Fructans
a
ab
b
C
b
b
ab
17.2
14.8
10.3
7.0
11.8
16.3
14.5
a
ab
Cd
d
be
a
ab
6.2
4 .8
4.0
2.3
4.0
2.5
3.1
a
b
be
d
be
d
Cd
2.1
1.3
2.1
0 .9
1.1
1.0
1.3
a
b
a
b
b
b
b
1.7
1.8
4.9
2.2
2.1
1.1
3.2
*Means w ith in a column not follow ed by the same l e t t e r d i f f e r at
P < 0.05 le v e l o f s ig n ific a n c e according to LSD te s t.
c
c
a
be
be
C
b
28
Table 7.
Means o f TNC frac tio n s (percent dry weight) in the peduncle
o f seven untreated w inter wheat c u ltiv a rs a t e a rly dough
stage.
Mono- and d i saccharides
C u ltiv a r
TNC
Fructans
<-------------- ----- Fort
Redwin
Tiber
Norwin
Centurk
Froid
Crest
Brawny
15.9
17.3
14.4
15.9
19.5
16.8
17.6
be*
ab
c
be
a
abc
ab
9 .8
10.8
9.0
10.0
14.9
11.8
12.5
d
bed
d
cd
a
be
ab
<-------------- ----- Post
Redwin
Tiber
Norwin
Centurk
Froid
Crest
Brawny
20.3
22.3
18.7
11.1
19.4
17.6
14.5
ab
a
ab
d
ab
be
cd
12.9
15.0
11.6
7.2
13.9
12.7
9 .8
abc
a
be
d
ab
abc
Cd
Sucrose
Glucose
Fructose
E llis 87 ami 8 8 ------4.6
5.0
3 .4
4.1
4.0
3.2
3.7
ab
a
e
be
bed
e
cde
0 .8
0 .9
1.2
0 .7
0 .4
1.0
0 .7
be
ab
a
be
c
ab
be
0.7
0.6
0 .9
L I
0.3
0 .7
0 .8
ab
ab
ab
a
b
ab
ab
a
ab
a
c
be
ab
ab
0 .8
0.9
1.9
0.7
0.7
0.7
1.0
b
b
a
b
b
b
b
Farm 87 and 88 5.5
5.4
4.1
2.7
4.1
3.2
2.7
a
a
b
c
b
c
c
1.2
0 .9
1.2
0 .5
0 .6
1.0
0 .9
*Means w ith in a column not followed by the same le t t e r d i f f e r at
P < 0.05 level o f sign ificance according to LSD te s t.
TNC and TNC fra c tio n s in the lower stem and the peduncle d iffe re d
at Fort E llis and the Post Farm before the desiccant app licatio n at the
e a rly dough stage (Tables 6 and 7 ).
Lower wheat stem and peduncle TNC
content ranged from 19.2 to 24.4 and from 14.4 to 19.5 (percent dry
w eig h t), re s p e c tiv e ly , at Fort E llis fo r c u ltiv a rs averaged over 1987
and 1988.
At the Post Research Farm, lower stem and peduncle TNC
content ranged from 19.0 to 27.2 and from 11.1 to 22.3 (percent dry
weight) fo r c u ltiv a rs averaged over 1987 and 1988.
This may have been
29
in response to higher average temperatures at the Post Farm (Table 2 ).
Also, the range o f TNC content was g reater than at Fort E ll is .
Reductions in TNC and it s fra c tio n s in the lower stem and the
peduncle occurred in the seven c u ltiv a rs 10 days a fte r the chemical
desiccant a p p licatio n (Tables 6 and 8, 7 and 9 ) .
The c u ltiv a r rank fo r
TNC and TNC fra c tio n s a t both locations was s im ila r to th a t before
applying the chemical desiccant (Tables 6, 7, 8, and 9 ) .
Table 8.
Means o f TNC frac tio n s (percent dry weight) in the lower
stem o f seven w inter wheat c u ltiv a rs 10 days a fte r a p p li­
cation o f chemical desiccant a t e a rly dough stage.
Mono- and disaccharides
C u ltiv a r
TNC
<----Redwin
Tiber
Norwin
Centurk
Froid
Crest
Brawny
15.6
14.9
11.6
8.5
16.1
16.1
16.1
Fructans
13.9
12.5
8 .6
2.4
6.1
10.8
6.1
Glucose
Fructose
------- Fort E llis 87 and 88 ------ --------------------->
a*
a
b
C
a
a
a
7.8
6.3
4.4
3 .0
10.0
10.6
7.6
b
be
cd
d
a
a
b
<--------------------Post
Redwin
Tiber
Norwin
Centurk
Froid
Crest
Brawny
Sucrose
a
ab
cd
e
d
be
d
7 .8
6 .4
4.7
0 .6
2.9
6 .5
1.5
a
ab
be
e
Cd
ab
de
3.5
3.4
2.5
1.7
3.0
2.1
2.5
a
a
b
c
a
be
b
1.5
1.5
1.0
0.9
0.7
1.4
1.1
a
a
c
c
d
ab
be
2.7
3.7
3.6
2.8
2.4
2.4
4.8
d
b
be
cd
d
d
a
2.3
2.7
1.7
0.9
1.6
2.2
2.6
ab
a
be
d
c
ab
a
Farm 87 and 8 8 ......... .
2.9
2.8
1.7
0.7
1.3
1.5
1.3
a
a
b
d
be
be
c
0 .8
0 .7
0 .5
0 .2
0.3
0 .4
0 .6
a
ab
cd
e
e
de
be
*Means w ith in a column not follow ed by the same l e t t e r d i f f e r at
P < 0.05 le v e l o f s ig n ific a n c e according to LSD te s t.
6
30
Table 9.
Means o f TNC frac tio n s (percent dry weight) in the peduncle
o f seven w inter wheat c u ltiv a rs 10 days a fte r application o f
chemical desiccant at e a rly dough stage.
Mono- and d i saccharides
C u ltiv a r
TNC
Fructans
<------------- ------Fort
Redwin
Tiber
Norwin
Centurk
Froid
Crest
Brawny
11.8
10.7
7.9
10.2
14.5
12.2
11.4
b*
b
c
be
a
ab
b
5.6
4 .8
2.7
4.2
9 .0
6 .6
3 .8
be
bed
d
cd
a
b
cd
<------------- ------Post
Redwin
Tiber
Norwin
Centurk
Froid
Crest
Brawny
8 .7
11.5
8 .0
3.2
10.0
11.0
5.5
be
a
cd
e
abc
ab
de
5.2
6 .8
4 .8
1.4
6 .0
6 .8
1.4
b
a
b
c
ab
a
c
Sucrose
Glucose
Fructose
E llis 87 and 88 ------ ------------- >
3.9
3 .4
2.8
2.9
3 .5
2.5
3.0
a
b
Cd
cd
ab
d
be
0 .8
0 .6
0 .7
0 .8
0 .4
0 .8
0 .9
a
be
ab
a
c
ab
a
1.5
1.9
1.7
2.3
1.6
2.3
3 .5
c
be
c
b
c
b
a
Farm 87 and 88 -------- ------------- >
2.4
3.1
2.2
1.2
2.4
2.6
2.0
b
a
be
d
b
b
c
0 .5
0 .4
0 .2
0.1
0.3
0.3
0 .6
ab
be
d
d
d
Cd
a
0.7
1.1
0.7
0.5
1.3
1.3
1.6
c
b
c
c
ab
ab
a
*Means w ith in a column not followed by the same l e t t e r d i f f e r at
P < 0.05 le v e l o f sign ificance according to LSD te s t.
Lower stem and peduncle TNC content ranged from 8 .5 to 16.1 and
from 7.9 to 14.5 (percent dry w e ig h t), re sp ec tiv e ly , fo r c u ltiv a rs
averaged over 1987 and 1988 at Fort E llis 10 days a f t e r desiccant
a p p lic a tio n .
Lower stem and peduncle TNC content 10 days a fte r
desiccant a p p licatio n at the Post Research Farm ranged from 2.4 to 13.9
and from 3 .2 to 11.5 (percent dry w eig ht), re sp ec tiv e ly , fo r c u ltiv a rs
averaged over 1987 and 1988.
31
The d iffe r e n t v a ria tio n in TNC and TNC fra c tio n content and the
range among c u ltiv a rs at Fort E llis and the Post Research Farm could be
ascribed to major d ifferences in lo catio n environmental conditions
(Table 2 ).
Fort E llis generally has Tower temperatures, more p re c ip i­
ta tio n , and less p o te n tia l evapotranspiration (Thornthwaite PET) than
the Post Research Farm.
In a d d itio n , important d iffe re n c e s in June and
July p re c ip ita tio n and temperature occurred at the two locations (Table
2 ).
In both years, average temperatures a t the Post Research Farm
exceeded temperatures a t Fort E llis (Table 2 ).
Although in 1987 the
two locations had s im ila r p re c ip ita tio n , in 1988, a very dry year, the
Post Farm was d r ie r .
Only one s ig n ific a n t c o rre la tio n was observed between TNC or
fructan content (percent dry weight) in the lower stem and the peduncle
10 days a fte r applying the chemical desiccant and grain y ie ld o f the
chemical desiccant treatm ent at e ith e r Fort E llis or the Post Research
Farm (Tables 17 and 18, Appendix).
A s ig n ific a n t negative c o rrelatio n
( - 0 .7 8 *) was noted between fructan content (percent dry weight) in the
lower stem and grain y ie ld a fte r the chemical desiccant treatment at
Fort E ll is .
0.58 ns.
In con trast, the c o rre la tio n at the Post Research Farm was
TNC, fructan content (percent dry w eig ht), and grain y ie ld
were affected by the environment at both lo catio ns.
published reports describe th is re la tio n s h ip .
Thus f a r , no
Bidinger e t a l. (1977)
and Gallagher e t a l . (1975) emphasized the ro le of the increased
percentage o f stem-stored TNC contrib ution to grain y ie ld under drought
stress conditions.
Based on the re su lts o f the current study and the
previously mentioned reports, i t appears th a t high stem-stored TNC
32
content might be p re req u is ite fo r high grain y ie ld under drought or
heat stress during grain f i l l i n g .
Further studies are required to
explore th is re la tio n s h ip .
Reduction in TNC, fructan s, sucrose, glucose, and fructose content
(percent dry weight) in the lower stem and the peduncle occurred 10
days follow ing chemical desiccation a t Fort E llis and the Post Research
Farm (Table 10).
TNC and TNC fra c tio n s in the lower stem and the
peduncle were higher at Fort E llis than at the Post Research Farm fo r
the control (0% sodium chlo rate) and the treatment (3% sodium
c h lo ra te ).
The reduction in TNC content follow ing the application o f
sodium chlorate a t the e a rly dough stage is concordant w ith th a t
obtained at the boot stage fo r four w in ter wheat c u ltiv a rs ( Redwin,
Norwin, Froid, and C enturk).
The reduction in TNC content under simu­
la te d drought conditions caused by the chemical desiccant application
corroborates the findings o f Blum e t a l . (1983a).
They suggested th a t
chemical desiccation causes reductions in stem dry weight due to
rem o bilization o f stem-stored carbohydrates to help grain f i l l i n g under
stress conditions.
Combined analyses o f variance averaged over two years at each
lo catio n fo r TNC and TNC frac tio n s in the lower stem and the peduncle
10 days a fte r app licatio n o f the chemical desiccant displayed sc arc ity
of s ig n ific a n t c u ltiv a r x desiccant in tera c tio n s (Table 20, Appendix).
C u ltiv a r x desiccant in te ra c tio n occurred only a t the Post
Research Farm fo r lower stem fructans and peduncle TNC and fructans
(Table 20, Appendix).
The in te ra c tio n mean squares were small compared
to the main e ffe c ts (c u ltiv a rs and d e s ic c a tio n ).
The s c a rc ity of
33
c u ltiv a r x desiccant in te ra c tio n a t the e a rly dough stage is s im ila r to
th a t observed at the boot stage.
Table 10.
The e ffe c t o f chemical desiccant on TNC fra c tio n s (percent
dry weight) 10 days a fte r desiccant a p p lic a tio n , averaged
over c u ltiv a rs .
Mono- and d isaccharides
Treatment
-
TNC
Fructans
Sucrose
Glucose
Fructose
<..............................- Lower s te m ................ ................ >*
Fort ETlis 87 and 88:
Control (0%)
3% NaClO3
16.9
**
11.4
9.4
**
4 .8
3.0
**
2.4
1.2
*
1.5
3.3
ns
3.1
11.0
**
6.3
6.0
**
2.7
2.0
**
1.4
0 .6
**
0 .4
2.3
**
1.8
Post Farm 87 and 88:
Control (0%)
3% NaClO3
<---------
- - Peduncle ■
Fort ETTis 87 and 88:
Control (0%)
3% NaClO3
13.7
**
8 .8
7.3
**
3.3
3.4
**
2.9
0 .8
**
0 .6
2.2
ns
2.0
11.9
**
4.6
8.1
**
1.2
2.4
**
2.1
0 .4
ns
0.3
1.2
**
0.9
Post Farm 87 and 88:
Control (0%)
3% NaClO3
*S ig n ific a n t at P < 0.05 level o f sign ificance
* *S ig n ific a n t at P < 0.01 level o f sign ificance
ns = Not s ig n ific a n t
34
The s c arc ity o f s ig n ific a n t c u ltiv a r x desiccant in te ra c tio n s , and
the presence o f s ig n ific a n t c u ltiv a r x location in te ra c tio n s and
s ig n ific a n t c u ltiv a r x year in te ra c tio n s , is very important i f wheat
breeders use stem-stored TNC as a selection c r ite rio n in environments
subjected to heat or drought stress during grain f i l l i n g .
The lack o f
any large s ig n ific a n t c u ltiv a r x desiccant in tera c tio n s indicates th a t
c u ltiv a rs reacted in a s im ila r manner in both desiccant and control
treatm ents.
This is an advantage fo r chemical desiccation as a simu­
la to r o f drought since i t causes s im ila r reductions in TNG, y ie ld , and
y ie ld components among wheat c u ltiv a rs in both treatment and control
p lo ts .
In th is study, c u ltiv a rs ranked s im ila rly fo r TNC content under
chemical desiccant induced stress and no desiccant or under controlled
conditions (Table 16, Appendix).
I f most c u ltiv a r x desiccant in t e r ­
actions had been s ig n ific a n t, selection would id e n tify c u ltiv a rs which
respond d iffe r e n tly to the chemical desiccant (which may not neces­
s a r ily be the e ffe c t o f natural drought s tre s s ).
The absence of
s ig n ific a n t c u ltiv a r x desiccant in tera c tio n s and the presence of
s ig n ific a n t c u ltiv a r x location and c u ltiv a r x year in teractio n s
suggests th a t TNC and TNC fra c tio n content phenotypic v a ria tio n was
affected by the environment.
The GxE would be expected to be high.
Selection o f drought to le ra n t lin e s based on TNC content should be
done in breeding nurseries where drought and heat stress occur during
grain f i l l i n g .
This increases the dependence on stem-stored TNC fo r
grain f i l l i n g and d iffe r e n tia te s c u ltiv a rs accordingly (B idinger e t
a l . , 1977; Gallagher e t a l . , 1975).
I f such stress locations are not
a v a ila b le , chemical desiccation w ill simulate natural drought,
35
a ffe c tin g the vegetative parts o f wheat p lan ts, and hence increasing
the dependence on stem-stored TNC fo r grain f i l l i n g .
C u ltiva rs w ill
rank d iffe r e n tly in d iffe r e n t environments due to the s ig n ific a n t
c u ltiv a r x lo catio n and c u ltiv a r x year in te ra c tio n s .
Fructans comprised the major portion o f TNC content in the lower
stem and the peduncle before and 10 days a fte r applying the chemical
desiccant (Tables 6, 7, 8, and 9 ) .
In co ntrast, sucrose, glucose, and
fructose composed the major portion o f TNC a t the boot stage (Tables 3
and 4 ).
Lower stem fructan content ranged from 13.2 to 16.7 and from 7.0
to 17.2 (percent dry weight) at Fort E llis and the Post Research Farm,
re sp ectively (Table 6 ).
The peduncle fructan content ranged from 9.0
to 14.9 and from 7.2 to 15.0 (percent dry weight) at Fort E llis and
the Post Farm, re sp ectively (Table 7 ).
These re su lts suggest th a t
production o f TNC in wheat plants a t the e a rly dough stage exceeds
consumption, hence the storage o f TNC in the fructan form.
This is
concordant with the report o f Thome and Kuhbauch (1985) th a t 20%
fructan content (percent dry weight) was noted at a s im ila r growth
stage fo r a spring wheat c u ltiv a r .
McCaig and Clarke (1982) reported
fructan content values ranging from 15% to 35% (percent dry weight) in
the stem, in two successive years, in two spring wheat c u ltiv a rs .
C u ltiva rs varied in grain y ie ld at Fort E llis and the Post
Research Farm (Table 16, Appendix; Figure 4 ).
The c u ltiv a rs ranked
d iffe r e n tly fo r grain y ie ld at the two locations averaged over 1987 and
1988 fo r the check and the treatm ent (Table 16, Appendix).
At the Post
Research Farm, the c u ltiv a r y ie ld ranks were s im ila r to the In tra s ta te
36
Winter Wheat Yield T ria l (Table I ; Table 16, Appendix; Figure 4 ).
Brawny was the only exception.
from the Post Research Farm.
At Fort EU is , c u ltiv a r rank d iffe re d
Centurk and Brawny were exceptionally
high in grain y ie ld at Fort E ll is .
Norwin had the highest y ie ld and
Crest the lowest at the Post Farm.
The d iffe r e n t environmental condi­
tions at both locations affected the c u ltiv a r rank fo r grain y ie ld .
400 r
Redwln
Tiber
Norwln Centurk
Frold
Greet
Brawny
Variety
Figure 4.
Means of y ie ld (gm • row'1) main e ffe c t o f seven
w inter wheat c u ltiv a rs at Post Farm and Fort
E ll is , averaged over 1987 and 1988.
Combined analyses of variance averaged over two years at each
location fo r grain y ie ld displayed absence of s ig n ific a n t c u ltiv a r x
desiccant in te ra c tio n at the Post Farm (Table 27, Appendix).
S ig n if i­
cant c u ltiv a r x desiccant in te ra c tio n was observed at Fort E ll is , but
37
the in te ra c tio n mean square was very small compared to the main
e ffe c ts .
GxE in te ra c tio n plays an important ro le in grain y ie ld and
TNC content.
The s c arc ity o f s ig n ific a n t c u ltiv a r x desiccant in t e r ­
actions suggests th a t chemical desiccation imposes s im ila r stress on
c u ltiv a rs in d iffe r e n t environments.
The re la tio n s h ip between stem-
stored TNC content and grain y ie ld is not conclusive in th is study.
Previous reports by Bidinger e t a l . (1977), Gallagher e t a l . (1975),
and Blum e t a l . (1983a) suggested an important ro le fo r stem-stored TNC
content in contrib ution to grain y ie ld under stress conditions. Further
studies are required to obtain conclusive resu lts on the re la tio n s h ip
between stem-stored TNC and grain y ie ld under stress conditions.
The Relationship Between TNC Content
a t Boot and Mid-Dough Growth Stages
TNC and fructan content were p o s itiv e ly correlated a t boot stage
and at mid-dough (10 days a fte r desiccant application a t e a rly dough)
(Table 11; Figures 5, 6, and 7 ).
Also, TNC content a t the boot stage
was p o s itiv e ly correlated with fructan content at mid-dough (10 days
a fte r the chemical desiccant application at e a rly dough).
The r e la ­
tionship held in the c o n tro l.
The re su lts suggest th a t TNC at the boot stage o f wheat is re la te d
to TNC and fructan content re s u ltin g from simulated drought at mid­
dough.
The re la tio n s h ip was true fo r both drought sim ulation and
the c o n tro l.
This is concordant with the s carcity o f s ig n ific a n t
c u ltiv a r x desiccant in tera c tio n s observed in the boot and e arly
dough stages.
This re la tio n s h ip is important in breeding wheat fo r
stress tolerance.
I t could provide the breeder with information about
38
the carbohydrate content before c ro s s-p o llin a tio n s are made in a
conventional breeding program.
In a d d itio n , th is re la tio n s h ip could
help in p re p o llin a tio n parent choice in a male s t e r ile f a c ilit a t e d
recurrent selection program.
Table 11.
C orrelation c o e ffic ie n t ( r ) fo r TNC and fructan content at
boot stage versus mid-dough stage of four c u ltiv a rs in three
environments (n=12).
Without desiccant
(mid-dough)
With desiccant
(mid-dough)
TNC content (boot)
0 .9 4 **
0 .9 2 **
Fructan content (boot)
0 .7 7 **
0 .7 8 **
♦♦S ig n ific a n t at P < 0.01 level of sign ificance
r " 0.94
r ■ 0.9 2
TN C - Boot Stage (% dwt.)
Figure 5.
The re la tio n s h ip between boot stage and mid-dough stage
fo r TNC content, treated by the chemical desiccant and
untreated (n=12 tre a te d ; n=12 u n tre a te d ).
39
- 4 - Treated
C
16
- + - Untreated
r - 0.77
r • 0.7 8
Fructans - Boot Stage (% dwt.)
Figure 6.
The re la tio n s h ip between boot stage and mid-dough stage fo r
fructan content, treated by the chemical desiccant and
untreated (n=12 tre a te d ; n=12 un treated).
_ -4-- Untreated
—
Treated
r ■ 0 .8 8
r ■ 0 .86
TN C - Boot Stage (% dwt.)
Figure 7.
The re la tio n s h ip between TNC at the boot stage and
fructans at the mid-dough stage, treated by the chemical
desiccant and untreated (n=12 trea te d ; n=12 un treated).
40
Net Rate of TNC Depletion
The net ra te o f TNC depletion is a function o f source TNC
(beginning and ending) and tim e. Net ra te o f TNC depletion equals TNC
(beginning) minus TNC (ending) divided by 10 days equals ug • mg'1 •
day'1.
S ig n ific a n t d ifferences were observed fo r net rates o f TNC and
fructan depletion between locations and years in the lower stem and the
peduncle (Table 24, Appendix).
The c u ltiv a r x lo catio n in te ra c tio n was
s ig n ific a n t fo r net ra te o f TNC depletion in the lower stem and the
peduncle o f wheat.
The c u ltiv a r x lo catio n in te ra c tio n was not s ig n if­
icant fo r net ra te o f TNC depletion in the peduncle.
The c u ltiv a r x
year in te ra c tio n was s ig n ific a n t fo r net ra te of TNC and fructan
depletion except fo r net ra te of TNC depletion in the lower stem.
These re su lts suggest th a t net rates o f TNC and fructan depletion are
affected considerably by the environment.
Net TNC depletion rates in the lower stem and peduncle averaged
40-50% higher a t the warmer Post Research Farm lo catio n than Fort E llis
(Table 12).
The range o f fructan net depletion rates in the lower stem
and peduncle, however, were very s im ila r at the two lo ca tio n s .
C u ltivars d iffe re d in net rates of TNC and fructan depletion at both
locations when averaged over the two years, suggesting the p o s s ib ility
o f selection among wheat c u ltiv a rs fo r th is t r a i t .
41
Table 12.
Means o f TNC and fructan net depletion rates from the stem
(ug • mg'1 • day'1) during the 10 days follow ing application
o f chemical desiccant at e a rly dough (main e f f e c t s ) .
Lower Stem
C u ltiv a r
TNC
Peduncle
Fructans
TNC
Fructans
<........... ........Fort E llis 87 and 88
Redwin
Tiber
Norwin
Centurk
Froid
Crest
Brawny
66
96
113
127
65
73
80
d*
be
ab
a
d
Cd
cd
69
98
122
118
66
64
93
d
be
a
ab
d
d
c
66
84
83
65
70
52
63
a
a
a
a
a
a
a
46
67
75
64
67
53
87
d
abc
ab
cd
be
cd
a
78
85
67
57
82
77
83
a
a
a
a
a
a
a
<------------ ■— Post Farm 87 and 88 - Redwin
Tiber
Norwin
Centurk
Froid
Crest
Brawny
133
131
114
100
129
101
160
ab
ab
b
b
ab
b
a
94
87
65
64
89
98
130
b
be
c
c
be
b
a
116
112
107
79
97
84
90
a
a
a
a
a
a
a
*Means w ith in a column not followed by the same l e t t e r d i f f e r at
P < 0.05 le v e l o f sign ificance according to LSD te s t.
P ositive co rrelatio n s were found between c u ltiv a r grain y ie ld and
net ra te o f TNC depletion in the peduncle under simulated drought
conditions during e a rly dough at Fort E llis and the Post Research Farm
(0 .8 6 * and 0 .7 7 *, re sp ec tiv e ly ) (Figure 8 ) .
This re la tio n s h ip between
the net ra te o f TNC depletion in the peduncle and grain y ie ld under
desiccant-sim ulated drought conditions is very im portant.
I t suggests
42
net peduncle TNC depletion ra te could be used to screen fo r drought
to le ra n t wheat c u ltiv a rs during grain f i l l i n g
b ility .
i f i t has high h e rita -
The net ra te o f TNC depletion probably measures the e ffic ie n c y
o f wheat c u ltiv a rs to tran slocate stem-stored TNC under stress condi­
tio n s .
Further studies are needed to estab lish the net ra te o f TNC
depletion as a screening method fo r drought tolerance in wheat.
The net rates o f TNC and fructan depletion increased s ig n ific a n tly
a fte r the chemical desiccant was applied (Table 13).
S ig n ific a n t
d ifferences (P < 0 .01) were observed between the control net rates o f
TNC and fructan depletion and the desiccant treatment net rates of TNC
and fructan depletion in the lower stem and the peduncle.
Increased net rates of TNC and fructan depletion a f t e r desiccant
application v e r ifie s the hypothesis suggested by Blum e t a l . (1983b)
th a t chemical desiccation simulates natural drought by increasing the
dependence of wheats on stem-stored TNC.
Bidinger e t a l . (1977) and
Gallagher e t a l . (1975) reported estimates of 22% and 50%, respec­
t iv e ly , fo r the contrib ution o f stem-stored carbohydrates to y ie ld
under drought conditions.
No s ig n ific a n t c u ltiv a r x desiccant in te ra c tio n was observed fo r
net rates of TNC and fructan depletion (Table 21, Appendix).
The
absence of s ig n ific a n t c u ltiv a r x desiccant in te ra c tio n and the
presence o f c u ltiv a r x location and c u ltiv a r x year in te ra c tio n suggest
th a t chemical desiccation a ffe c ts c u ltiv a rs s im ila r ly , without in t e r ­
action with s p e c ific c u ltiv a rs fo r net ra te of TNC d e p letio n .
The
s ig n ific a n t c u ltiv a r x lo catio n and c u ltiv a r x year in tera c tio n s
suggest th a t c u ltiv a rs reacted d iffe r e n tly depending on environments.
43
-4 -
F o rt ElMe
r ■ 0.86
- + - Poet Farm
r - 0.77
Rate of TNC Depletion In the Peduncle
Figure 8.
Table 13.
The re la tio n s h ip between ra te of TNC depletion in the
peduncle and y ie ld a fte r treatment at e a rly dough
with the chemical desiccant at Fort E llis and Post
Research Farm (n=7, Fort E llis ; n=7, Post Farm).
TNC and fructan net depletion ra te (ug • mg'1 • day"1) from
the stem during the 10 days follow ing app licatio n of
chemical desiccant, averaged over a ll c u ltiv a rs .
Lower Stem
Treatment
TNC
Fructans
Peduncle
TNC
Fructans
<------- ......... - Fort E llis 87 and 88 ■
Control (0%)
3% NaClO3
65
**
112
72
**
108
50
**
88
51
**
80
<------- ........... Post Farm 87 and 88 -■
Control (0%)
3% NaClO3
102
**
147
74
**
105
**S ig n ific a n t at P < 0.01 level of sign ificance
77
**
119
60
**
91
44
The p o sitiv e s ig n ific a n t re la tio n s h ip between net ra te o f TNC
depletion and y ie ld under desiccant-sim ulated drought conditions
indicates th a t th is t r a i t , although considerably affected by the e n v ir­
onment, could be used as a selection c r ite rio n fo r tolerance to drought
and heat stress during the grain f i l l i n g period.
Chemical desiccants
could be applied to diverse wheat c u ltiv a rs at the e a rly dough stage to
simulate stress conditions during the grain f i l l i n g period since the
in te ra c tio n between the chemical desiccant and c u ltiv a rs usually was
not s ig n ific a n t.
This w ill allow c u ltiv a rs to express t h e ir a b il it y to
rem obilize stem-stored TNC under stress conditions to f i l l the g ra in .
Average Fructan Degree o f Polymerization
The fructan average degree o f polym erization (DP) indicates the
average chain length.
I t is important due to it s re la tio n s h ip with the
molal concentration of the c e ll vacuole.
S ig n ific a n t differences were noted fo r fructan average degree o f
polym erization (DP) in the peduncle between locations and years (Table
25, Appendix).
In the lower stem, s ig n ific a n t d ifferences were
observed fo r fructan average DP between years but not lo catio ns.
C u ltiv a r x lo catio n and c u ltiv a r x year in teractio n s were s ig n ific a n t.
This suggests th a t fructan average degree o f polym erization d iffe re d
between locations and years and was affected considerably by the e n v ir­
onments.
C u ltivars d iffe re d s ig n ific a n tly (P < 0.01) fo r fructan average DP
follow ing the app licatio n o f the chemical desiccant (Table 14).
Fort E ll is , DP ranged from 4.6 to 8.3 and from 4.9 to 7 .6 (hexose
At
45
u n its ) in the lower stem and the peduncle, re sp ec tiv e ly .
At the Post
Research Farm, DP ranged from 4 .9 to 7.0 and from 5.2 to 8 .5 (hexose
u n its ) in the lower stem and the peduncle, re sp ec tiv e ly .
Table 14.
Average degree o f polym erization 10 days a fte r application
o f chemical desiccant at e a rly dough stage.
Fort E llis 87 and 88
Post Farm 87 and 88
C u ltiv a r
Lower
Stem
Peduncle
Lower
Stem
Peduncle
Redwin
6.1 b*
5.4 b
6 .4 a
6.9 b
Tiber
5.0 b
4.9 b
6 .8 a
7.2 b
Norwin
5.0 b
5.3 b
6 .4 a
7.2 b
Centurk
4.6 b
5.6 ab
4 .9 b
5.2 c
Froid
6.7 ab
7.6 ab
6 .6 a
6.4 be
Crest
8.3 a
7.5 a
6 .8 a
8 .5 a
Brawny
6 .5 ab
6.0 ab
7 .0 a
7.1 b
*Means w ith in a column not followed by the same le t t e r d i f f e r at
P < 0.01 level o f sign ificance according to LSD te s t.
Fructan average degree o f polym erization (DP) decreased follow ing
the chemical desiccant application at both Fort E llis and the Post
Research Farm (Table 1 5 ).
The lower stem and peduncle fructan average
DP in the control and the desiccant treatments (0% and 3% sodium
c h lo ra te , re sp ec tiv e ly ) d iffe re d s ig n ific a n tly (P < 0 .01) at Fort
E ll is .
At the Post Farm, only the peduncle average DP d iffe re d s ig n if­
ic a n tly between the control and the treatm ent.
46
Table 15.
E ffe c t of chemical desiccant on the average degree of
polym erization 10 days a fte r the desiccant app licatio n at
e a rly dough stage, over a ll c u ltiv a rs .
Treatment
Control (0%)
3% NaClO3
Fort E llis 87 and 88
Post Farm 87 and 88
Lower
Stem
Lower
Stem
Peduncle
Peduncle
6 .8
**
6.7
**
6.6
ns
7.4
**
5.3
5.3
6.2
6.5
^ S ig n ific a n t at P < 0.01 level o f sign ificance
ns = Not s ig n ific a n t
Simulated drought using the chemical desiccant sodium chlorate
resulted in reduced average fructan chain length in wheat stems.
The
reduction was from 6 .8 and 6.7 to 5.3 and 5.3 in the lower stem and the
peduncle, re s p e c tiv e ly , a t Fort E ll is .
reduced from 7.4 to 6 .5 in the peduncle.
At the Post Farm, i t was
This confirms the suggestion
o f Wagner e t a l . (1983) th a t the molecular size of fructans could be
changed e a s ily under stress conditions fo r osmoregulation.
They
suggested th a t the transform ation o f fructans to shorter hexose u n its ,
or simple sugars, increases the molal concentration and lowers the
osmotic p o te n tia l.
Consequently, water is held, decreasing the loss
under stress conditions.
Also, the reduction in the average fructan
chain length may play a ro le in the tran slocation o f TNC to the grain
in sucrose form.
Therefore, i t appears th a t the reduction in the
average chain length may impact TNC tran slocation and transform ation.
47
A s ig n ific a n t c u ltiv a r x desiccant in te ra c tio n was observed fo r
fructan average DP in the lower stem and the peduncle a t the Post
Research Farm.
At Fort E ll is , the c u ltiv a r x desiccant in te ra c tio n fo r
fructan average DP was s ig n ific a n t fo r the lower stem but not fo r the
peduncle (Table 26, Appendix).
In con trast, the c u ltiv a r x desiccant
in te ra c tio n fo r stem TNC content and stem net ra te o f TNC depletion
usually was not s ig n ific a n t.
I t appears th a t chemical desiccation a ffe c ts fructan transforma­
tio n by chain length reduction.
tran s lo c a tio n .
This may in d ire c tly a ffe c t fructan
The reduction in average fructan chain length ends with
sucrose form ation.
Sucrose moves to the grain under stress conditions
to help in grain f i l l i n g .
xI
48
.
SUMMARY
This research studied the e ffe c t o f chemical desiccant induced
drought stress on stem-stored carbohydrate c h a ra c te ris tic s (TNC
content), net ra te o f TNC d epletion, and the average degree of
polym erization in w inter wheat c u ltiv a r s .
High performance liq u id
chromatography (HPLC) was used to q u an tify TNC and it s frac tio n s a fte r
c a lib ra tio n with wheat stem TNC and fructan samples.
The re su lts suggest th a t HPLC could be used to qu an tify TNC and
fructan content in wheat stems.
The HPLC provides a r e la t iv e ly fa s t
and accurate technique fo r screening wheat lin e s fo r TNC and fructan
content.
Chemical desiccation at the boot stage caused reduction in TNC and
fructan content in wheat stems.
A pplication at the e a rly dough stage
reduced TNC and fructan content, increased depletion rates o f TNC and
fructans, and decreased the average fructan degree o f polym erization.
The peduncle was lower in TNC and fructan content than the lower
stem, but the trend was s im ila r fo r TNC content, ra te o f TNC depletion,
and the average degree o f polym erization.
There was a p o sitiv e c o rre la tio n between the boot and the mid­
dough stages fo r TNC content and fructan content.
Also, there was a
p o s itiv e c o rre la tio n between TNC depletion ra te and grain y ie ld a fte r
chemical desiccation treatment in the e a rly dough stage.
49
The varying a b il it y o f wheat c u ltiv a rs to tran slocate TNC to the
grain under drought stress conditions and the osmoregulation ro le o f
fructans c ite d in the lit e r a t u r e impact breeding fo r drought tolerance.
S ig n ific a n t GxE in tera c tio n s fo r TNC content, net ra te o f TNC
d ep letio n , and fructan average degree o f polym erization were found in
contrast to low or absent c u ltiv a r x desiccant in te ra c tio n s fo r TNC
content and net ra te o f TNC d epletion.
These c h a ra c te ris tic s could
serve as selection c r it e r i a fo r drought tolerance in wheat i f
h e r it a b ilit y is high.
Chemical desiccation d ir e c tly a ffe c ts TNC
transform ation and in d ir e c tly a ffe c ts TNC tra n s lo c a tio n .
E ffic ie n t TNC
transform ation and tran slo catio n are essential fo r grain f i l l i n g under
stress conditions.
The ra te o f TNC depletion is a function o f source TNC (beginning
and ending) and tim e.
TNC depletion ra te in the peduncle, and lik e ly
in the lower stem, provides a r e lia b le measurement to id e n tify wheat
c u ltiv a rs to le ra n t to drought stress.
50
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Gallagher, J .N ., P.V. Biscoe, and R.K. S cott. 1975. Barley and it s
environment. V. S t a b ilit y o f grain weight. J. Appl. Ecol. 12:
319-336.
Keim, D .L ., and W.E. Kronstad. 1979. Drought resistance and dryland
adaptation in w inter wheat. Crop S c i. 19:574-576.
Keim, D .L ., and W.E. Kronstad. 1981. Drought response o f w inter wheat
c u ltiv a rs grown under f ie ld stress conditions. Crop S c i. 21:1115.
52
McCaig, T .N ., and J.M. Clarke. 1982. Seasonal changes in nonstructu ra l carbohydrate le v e ls o f wheat and oats grown in a semi arid
environment. Crop S c i. 22:963-970.
National C lim atic Data Center. 1986, 1987, 1988.
annual summary, Montana. Vols. 89, 90, 91.
Clim atological data,
Pontis , H.G., and E.D. CampiH o . 1985. Fructans. Pages 205-227 in :
Biochemistry o f storage carbohydrates in green p lan ts. Eds. Dey,
P.M., and R.A. Dixon. London: Academic Press.
Sabry, S .R .S ., and G.A. Taylor. 1989. The response o f w inter wheat
height near-isogeneic lin e s to a chemical desiccant applied at two
growth stages. Western Society o f Crop Science. A bstract. June
19-21. Bozeman, Montana.
Schnyder, H ., V. Ehses, J. Bestajovksy, R. Mehrhoff, and W. Kuhbauch.
1988. Fructan in wheat kernels during growth and compartmentation
in the endosperm and pericarp. J. Plant Physiol. 132:333-338.
Smith, D ., and R.D. G ro telueschen. 1966. Carbohydrates in grasses.
I . Sugar and fructosan composition o f the stem bases o f several
Northern-adapted grasses at seed m atu rity. Crop S c i. 6:263-266.
Smith, D. 1967. Carbohydrates in grasses. I I . Sugar and fructosan
composition o f the stem bases o f bromegrass and timothy a t several
growth stages and in d iffe r e n t plant parts at anthesis. Crop S c i.
7:62-67.
S te e l, R.G.D., and J.H . T o rrie . 1980. P rinciples and procedures
o f s t a tis t ic s . 2nd ed. New York: McGraw-Hill Book C o., Inc.
633 pp.
Tan, B .H ., and G.M. H alloran. 1982. V a ria tio n and c o rrelatio n s of
p ro lin e accumulation in spring wheat c u ltiv a rs . Crop S c i. 22:
459-463.
Taylor, G.A. 1986.
s ity , Bozeman.
MAES annual wheat re p o rt.
205 pp.
Montana State Univer­
Thome, V ., and W. Kuhbauch. 1985. Change in the carbohydrate
pattern in the c e ll content o f wheat stems during g r a in - f i lli n g .
J. Agron. and Crop S c i. 155:253-260.
Wagner, W., F. K e lle r, and A. Wiemken. 1983. Fructan metabolism in
cereals: Induction in leaves and compartmentation in protoplasts
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W ille , M.J. 1985. Carbohydrates, regrowth and chlorophyll as physio­
lo g ic a l in dicators o f w inter hardiness in w inter wheat [Triticum
aestivum L . ) . M.S. th e s is . Montana State U n iv e rs ity , Bozeman.
53
APPENDICES
54
APPENDIX A
TABLES
55
Table 16.
Means o f grain y ie ld , harvest index, and kernel weight o f
seven w inter wheat c u ltiv a rs .
Grain Y ield
(qm/2.5 m row)
C u ltiv a r
T
C
Brawny
259 a
257 a
260 a
242 ab
Froid
157 d
Crest
124 e
207 c
Brawny
188 c
C
- Fort E llis 87 and 8 8 ..............................>
272
291
379
268
250
186
306
b
b
a
b
b
c
b
<---------Redwin
Tiber
Norwin
Centurk
T
24
25
29
28
23
18
32
be
b
a
ab
C
d
a
28
31
36
34
30
24
36
be
ab
a
a
b
d
a
2.3
2.1
2.4
2.4
C
O
b*
a
a
b
b
c
C
C
M
213
261
281
236
201
134
Kernel Weight
(qm/1001
(%)
T
<---------Redwin
Tiber
Norwin
Centurk
Froid
Crest
Harvest Index
be
d
b
b
be
1.8 e
2.7 a
293
297
261
241
a
a
b
b
184 c
184 c
196 c
27 ab
30 a
30 a
28 ab
25 b
21 C
27 ab
29
32
32
33
ab
a
a
a
27 b
26 b
28 b
T = treated with the chemical desiccant
c
d
b
b
b
e
a
■- >
- Post Farm 87 and 88 •
2.4
2 .4
2 .0
2 .0
a
a
be
be
2.1 b
1.9 cd
2 .0 be
*Means w ith in a column not followed by the same le t t e r d i f f e r at
P < 0.05 level o f s ig n ific a n c e , according to LSD t e s t.
C = check
2.5
2.3
2 .8
2 .8
2.7
2.0
3 .0
2.5
2.5
2.1
2.2
a
a
be
b
2.2 b
2.1 be
2.1 be
56
Table 17.
C orrelation c o e ffic ie n ts ( r ) among y ie ld and carbohydrate
c h a ra c te ris tic s in the lower stem o f seven w in ter wheat
c u ltiv a rs , combined over 1987 and 1988.
TNC
AT
T ra its
TNC
C
<----------Y ield T
Y ield C
Kernel weight
Kernel weight
Harvest index
Harvest index
T
C
T
C
-.50ns
-.30ns
- .7 8 *
- .8 7 *
-.45ns
-.53ns
-.53ns
-.69ns
-.72ns
-.20ns
-.29ns
-.29ns
-.45ns
- .9 6 * *
-.71ns
-.69ns
- .8 4 *
- .8 8 * *
Harvest index T
Harvest index C
* ,* *
ns
T
AT
=
=
=
=
.58ns
.61ns
.66ns
.63ns
.19ns
.05ns
Fructans
C
RTD
Fort E llis 87 and 88
<----------Y ield T
Y ield C
Kernel weight T
Kernel weight C
Fructans
AT
-.52ns
- .8 2 *
-.31ns
-.31ns
-.50ns
-.59ns
- - T ---------->
.37ns
.76*
.27ns
.32ns
.49ns
.65ns
Post Farm 87 and 88
.34ns
.43ns
.65ns
.68ns
-.04ns
-.28ns
.58ns
.63ns
.67ns
.65ns
.21ns
.02ns
.21ns
.34ns
.50ns
.57ns
-.19ns
-.30ns
RFD
.59ns
.8 7 **
.49ns
.50ns
.72ns
.8 4 *
-------------------- >
.29ns
-.02ns
-.02ns
- . 18ns
.27ns
-.68ns
-.19ns
-.34ns
.Olns
-0 4 n s
-.30ns
-.18ns
S ig n ific a n t at P < 0.05 and P < 0 .0 1 , resp ectively
Not s ig n ific a n t
Treated a t e a rly dough with the chemical desiccant
Ten days a fte r treatment at e a rly dough with the chemical
desiccant
C = Check
RTD = Rate o f TNC depletion from the stem follow ing treatm ent at e a rly
dough stage
RFD = Rate o f fructan depletion from the stem follow ing treatment a t
e a rly dough stage
57
Table 18.
C orrelation c o e ffic ie n ts ( r ) among y ie ld and carbohydrate
c h a ra c te ris tic s in the peduncle o f seven w in ter wheat
c u ltiv a r s , combined over 1987 and 1988.
TNC
AT
T ra its
TNC
C
Fructans
AT
Fructans
C
RTD
<------:---- ............. Fort E llis 87 and 88
Y ield T
Y ield C
Kernel weight
Kernel weight
Harvest index
Harvest index
T
C
T
C
-.71ns
- .33ns
- .8 2 *
-.48ns
-.37ns
-.68ns
-.68ns
- .56ns
-.03ns
-.04ns
- . 36ns
- .46ns
<----------Y ield T
Y ield C
Kernel weight
Kernel weight
Harvest index
Harvest index
* ,* *
ns
T
AT
=
=
=
=
T
C
T
C
.09ns
-.15ns
.16ns
.16ns
.20ns
.43
-.70ns
- .7 8 *
-.62ns
-.50ns
- .8 1 *
- .7 7 *
------------------>
-.59ns
.86*
-.66ns
-.35ns
-.19ns
-.65ns
-.60ns
.72ns
.64ns
.53ns
.80*
.7 5 *
Post Farm 87 and 88
.41ns
.17ns
.49ns
.58ns
-.20ns
-.45n$
.02ns
.Olns
.24ns
.24ns
.07ns
-.25ns
.00ns
.13ns
.38ns
.46ns
-.29ns
-.38ns
RFD
.15ns
.16ns
.54ns
.60ns
.56ns
.61ns
------------------>
.77*
.76*
.86*
.79*
.44ns
.12ns
.14ns
.15ns
.57ns
.58ns
-.21ns
-.58ns
S ig n ific a n t at P < 0.05 and P < 0 .0 1 , re sp ectively
Not s ig n ific a n t
Treated at e a rly dough with the chemical desiccant
Ten days a fte r treatment at e a rly dough with the chemical
desiccant
C = Check
RTD = Rate o f TNC depletion from the stem follow ing treatm ent at e a rly
dough stage
RFD = Rate o f fructan depletion from the stem follow ing treatment a t
e a rly dough stage
58
Table 19.
Source
Mean squares fo r stem TNC, fructans, sucrose, glucose, and
fructose contents of four w in ter wheat c u ltiv a rs 10 days
a fte r app licatio n of chemical desiccant a t the boot stage in
three environments.
df
TNC
<—
Rep
C u ltiv a r
Desiccant
C u ltiv a r x
Desiccant
Error
3
3
I
3
21
3
3
I
3
21
75935
4816
231065** 28913**
841915** 106664**
76823
36411
Glucose
22477*
6094
5795
15080
44266**
15725**
29403** . 94503**
3602
3359
10968
9692
373489** 17181
2337662** 735078**
26536
51722
26448
15805
1965
6652
7275
359290*
511060*
3
21
44290
93968
38148
145717**
539500**
110027
32849
1612
17565**
12561**
3237
1335
------------->
6975
75759**
145935**
2540
28274**
35778**
2511
16957**
10082**
1246
5860
1051
1937
827
1022
------------->
- - - Post IFarm 1988 -
3
3
I
Fructose
— ------- >
- - - Fort IE llis 1987
<—
Rep
C u ltiv a r
Desiccant
C u ltiv a r x
Desiccant
Error
Sucrose
- - - Fort IE llis 1987
<—
Rep
C u ltiv a r
Desiccant
C u ltiv a r x
Desiccant
Error
IFructans
1152
117997**
42778*
6981
10817
7906
4110
6617
18915*
2012
9307
19992
5256
11568*
2728
* , * * = S ig n ific a n t at P < 0.05 and P < 0.01, re s p e c tiv e ly
59
Table 20.
Mean squares fo r TNC and fructan content o f seven w inter
wheat c u ltiv a rs in the lower stem and the peduncle 10 days
a fte r app licatio n o f chemical desiccant at the e a rly dough
stage.
Lower stem
Source
df
TNC
<— --------- Fort
Rep
Year
Rep (year)
C u ltiv a r
Desiccant
C u ltiv a r x Desiccant
Year x C u ltiv a r
3
I
3
6
I
6
Year x Desiccant
Year x C u ltiv a r x
Desiccant
6
171495
78
129274
TNC
Fructans
E llis 1987 and 1988 - -------------- >
75036
336327
6990623** 6030719**
548668** 243496*
1438437** 1223807**
8378639** 5910750**
43531
95335
316132**
344849*
208863
40075
6
I
Error
Fructans
Peduncle
193954
90017
102594
1503227**
27583
651327**
6610037**
60485
258087**
70532
62008
2103339**
10661
691003**
4452003**
36820
199201
265082
245371*
127053
93452
30044
<— ----------- Post ; Farm 1987 and 1988 - -------------- >
Rep
Year
Rep (year)
3
I
3
CuTtivar
Desiccant
C u ltiv a r x Desiccant
Year x C u ltiv a r
Year x Desiccant
Year x C u ltiv a r x
Desiccant
6
Error
I
6
6
I
6
78
32041
57616
252924
200614*
13043544** 8064894** 15142312** 13090243**
92854
71222
37349
62996
876549**
2647519** 1205047*? 1447723**
6262245** 2953088**
216383**
277429
1166813** 612895**
152082
119333
6238131**
208453*
806568**
307648*
76523
59326
264070**
143100
75658
77906
* , * * = S ig n ific a n t at P < 0.05 and P < 0.01, re s p e c tiv e ly
3176690**
149233**
426610**
582622**
100264
49508
60
Table 21.
Mean squares fo r TNC and fructan net depletion rates from
the stem fo r the 10 days follow ing a p p licatio n o f chemical
desiccant at e a rly dough.
Lower stem
Source
df
TNC
Fructans
Peduncle
TNC
Fructans
<------ ------ Fort IE llis 1987 and 1988 -■
Rep
Year
Rep (year)
C u ltiv a r
Desiccant
3
I
3
6
I
6
6
I
5295*
73313**
6122**
9334**
60083**
737
6401**
40
C u ltiv a r x Desiccant
Year x C u ltiv a r
Year x Desiccant
Year x C u ltiv a r x
Desiccant
Error
78
:
<------ ------- Post
6
2203
1464
Rep
Year
Rep (year)
C u ltiv a r
Desiccant
C u ltiv a r x Desiccant
Year x C u ltiv a r
3
2208
I
3
6
I
6
6
7137
5174
7178*
57880**
2603
Year x Desiccant
Year x C u ltiv a r x
Desiccant
Error
*
* *
3057*
88982**
890
9620**
35482**
1050
4102**
35
2193
1136
912
2305
2090
2046
40060**
851
1493
2860
984
1121
121
809
1227
2839**
23830**
986
2821**
866
1270
743
Farm 1987 and 1988 - 2012
21095**
1815
7947**
27403**
2246
2978
1875
4351
3326
51424**
1711
1755
9291**
3509*
1603
27259**
1130
4386
5225**
5716**
3560**
I
1208
1019
4637
6196
6
491
460
3020
1626
2639
1711
935
78
S ig n ific a n t at P < 0.05 and P < 0.01, re s p e c tiv e ly
1179
61
Table 22.
Mean squares fo r TNC and fructan content in stems o f w inter
wheat 10 days a fte r app licatio n of chemical desiccant a t the
boot stage, combined over three environments and four
c u ltiv a rs .
Source
df
Environment
. 2
TNC
1640693**
IFructans
Sucrose
301501** 443057**
Glucose
Fructose
202216**
49430**
Rep
3
34859
33435
7608
1303
2284
Rep (environ­
ment)
6
61760
10248
3157
11649*
2974
C u ltiv a r
3
707756**
52449*
169376**
63258**
32482**
Desiccant
I
3331453** 1226841** 192693**
55392**
1872
C u ltiv a r x
Desiccant
3
27939
73586**
2383
5652
5358*
Environment x
C u ltiv a r
6
128044
69681*
20052
10050*
4328*
Environment x
Desiccant
2
179592
77200**
12711
41398
19842**
Environment x
C u ltiv a r x
Desiccant
6
59855
42683*
2239
8677
5137*
63
60700
18249
6175
4615
1695
Error
* , * * = S ig n ific a n t a t P < 0.05 and P < 0.01, re s p e c tiv e ly
62
Table 23.
Mean squares fo r TNC and fructan content in the lower stem
and the peduncle o f w inter wheat 10 days a f t e r application
o f chemical desiccant at the e a rly dough stage, combined
over lo ca tio n s , years, and c u ltiv a rs .
Peduncle
Lower stem
Fructans
TNC
Fructans
df
TNC
Location
I
17358139**
Year
I
19566036** 14021838** 13093760** 12844002**
Rep
3
396072*
199453
34050
29324
Rep (lo ca tio n x year)
9
259732
127563
73674
57395
C u ltiv a r
6
3139326**
1669722**
1380117**
1183431**
Desiccant
I
14563998**
8609833** 12845477**
7575017**
Location x Year
I
468130
73775
3551780
C u ltiv a r x Desiccant
6
128167
110729
99073
Location x C u ltiv a r
6
946631**
759131**
718934**
384121**
Year x C u ltiv a r
6
1040167**
694895**
744515**
488576**
Location x Desiccant
I
76886
254005
2691
53677
Year x Desiccant
I
18009
321972*
41784
438637**
Location x Year x
C u ltiv a r
6
471495**
Location x Year x
Desiccant
I
174148
6223
18
146937
151423*
156
136187
82837
Source
Location x Year x Cult iv a r x Desiccant
Error
4303646**
234132**
4969818**
205230
2349580**
54810
320140**
137235
336396
174029
233005**
158960**
102480
* , * * = S ig n ific a n t at P < 0.05 and P < 0.01, re s p e c tiv e ly
71480
63
Table 24.
Mean squares fo r TNC and fructan net depletion rates in the
lower stem and the peduncle 10 days a fte r a p p licatio n of
chemical desiccant at the e a rly dough stage.
Peduncle
Lower stem
Source
df
TNC
Location
I
72381**
Year
I
17350**
Rep
3
4387
Rep (lo ca tio n x year)
9
C u ltiv a r
Fructans
2
TNC
46020**
11713**
Fructans
5686*
11
2307
3092
588
708
4804*
1561
3248**
1968*
6
5389*
4233**
4414**
2431*
Desiccant
I
117953**
62625**
91130**
Location x Year
I
63100**
CuTtivar x Desiccant
6
Location x C u ltiv a r
51031
98364
4170
7792**
755
729
1261
473
6
11123**
13333**
958
2010*
Year x C u ltiv a r
6
2739
3982**
3522*
3944**
Location x Desiccant
I
10
260
354
57
Year x Desiccant
I
845
718
106
1214
Location x Year x
C u ltiv a r
6
8048**
5346**
3687*
2438*
Location x Year x
Desiccant
I
403
336
7391*
5848*
18
1760
1740
1642
1283
156
2242
1381
1416
961
Location x Year x Cult iv a r x Desiccant .
Error
*
* *
>
S ig n ific a n t at P < 0.05 and P < 0.01, re s p e c tiv e ly
64
Table 25.
Mean squares fo r fructan average DP in the lower stem and
the peduncle 10 days a fte r application o f chemical desiccant
at the e a rly dough stage, averaged over two locations and
two years.
Peduncle
df
Lower stem
Location
I
8.0
4 4 .0 **
Year
I
3 7 2 .0 **
4 9 1.0 **
Rep
3
2.3
12.0*
Rep (lo ca tio n x year)
9
4.1
4.0
C u ltiv a r
6
2 5 .0 **
2 2 .0 **
Desiccant
I
4 7 .0 **
8 0 .0 **
Location x Year
I
0.9
16.4*
C u ltiv a r x Desiccant
6
9 .0 * *
1.6
Location x C u ltiv a r
6
9 .0 *
1 2 .8 **
Year x C u ltiv a r
6
2 9 .0 **
3 3 .6 **
Location x Desiccant
I
15.0*
2.8
Year x Desiccant
I
0.4
4.0
Location x Year x C u ltiv a r
6
1 3 .0 **
Location x Year x Desiccant
I
4 9 .0 **
1 0 .0 **
18
8 .0 * *
9 .4 * *
3.3
4.1
Source
Location x Year x C u ltiv a r x
Desiccant
Error
156
* , * * = S ig n ific a n t at P < 0.05 and P < 0.01, re s p e c tiv e ly
3.8
65
Table 26.
Mean squares fo r fructan average DP in the lower stem and
the peduncle 10 days a fte r application o f chemical desiccant
at the e a rly dough stage, averaged over two locations and
two years.
Fort E llis
Source
Post I: arm
df
Lower stem
Peduncle
Lower stem
Peduncle
Year
I
16 8.0 **
164.0**
205.00**
3 4 3 .0 **
Rep
3
2.0
10.0
0.70
4 .0 * *
Rep (year)
3
12.0
5.0
0.07
5.0
C u ltiv a r
6
2 6 .0 **
1 9 .0 **
7 .3 0 **
1 6 .0 **
Desiccant
I
5 8 .0 **
5 6 .0 **
4.00
2 6 .0 **
C u ltiv a r x Desiccant
6
13.0*
3.0
5 .0 0 **
1 0 .8 **
C u ltiv a r x Year
6
2 9 .0 **
16.0
1 3 .0 0 **
2 1 .6 **
Year x Desiccant
I
2 9 .0 *
0.7
2 0 .0 0 **
1 3.6*
Year x C u ltiv a r x
Desiccant
6
11.0
11.0*
5 .2 0 **
4 .8
78
5.2
4.9
1.40
3.3
Error
* , * * = S ig n ific a n t at P < 0.05 and P < 0 .0 1 , re sp ectively
66
Table 27.
Mean squares fo r grain y ie ld in two locations averaged over
1987 and 1988.
Source
df
Fort E llis
Post Farm
Year
I
41004**
515171**
Rep
3 .
5600*
506
Rep (year)
3
2979
307
C u ltiv a r
6
50558**
39089**
Desiccant
I
124956**
33672**
C u ltiv a r x Desiccant
6
4921*
1206
C u ltiv a r x Year
6
25232**
Year x Desiccant
I
885
1170
Year x C u ltiv a r x Desiccant
6
1657
1127
78
1791
601
Error
* , * * = S ig n ific a n t at P < 0.05 and P < 0 .0 1 , re sp ectively
5741**
67
APPENDIX B:
FIGURES
68
P e a k A r e a (m v .)
6
DP6
DPS
4 8 12 16 2 0
T im e (m in .)
Figure 9.
HPLC chromatograms o f stem-stored carbohydrates:
(A) P ro file of the mixture o f seven c u ltiv a rs
(F, fructose; G, glucose; S, sucrose; and DP3,
DP4, DP5, and DP6); (B) DP6; (C) DP5.
P e a k A r e a (ra v .)
DP 4
DP 3
4 8 12 16 2 0
T im e (m in .)
Figure 10.
HPLC chromatograms o f stem-stored carbohydrates:
(A) DP4, (B) DP3.
70
Sucrose
685
ug IO * u l
IV
—
■ 1 'll
343
r
>
257
I
\--------
(0
0)
a,
171
/I
86
A
4 8 12 16 2 0
T im e (m in .)
Figure 11.
HPLC chromatograms o f fiv e concentrations o f sucrose.
G lu cose
451
P e a k A rea (m v .)
ug IO"8 ul
360
270
180
90
A
I
4
Figure 12.
i
8 12 16 2 0
T im e (m in .)
HPLC chromatograms o f fiv e concentrations o f glucose.
F ructose
901
720
541
4 8 12 16 2 0
T im e (m in .)
Figure 13.
HPLC chromatograms o f three concentrations o f fru c to s e .
P e a k A r e a (mv«)
F ructose
360
180
4 8 12 16 2 0
T im e (m in .)
Figure 14.
HPLC chromatograms o f two concentrations o f fructose.
A DP 3
P e a k A r e a (m v .)
534
267
4
Figure 15.
8 12 1 6 2 0
T i m e ( m in .)
HPLC chromatograms o f three concentrations o f DP3.
P e a k A r e a (m v .)
DP 4
264
1 32
4 8 12 16 2 0
T im e (m in .)
Figure 16.
HPLC chromatograms o f three concentrations o f DP4.
76
P e a k A r e a (m v .)
DP 5
288
144
4 8 12 16 20
T im e (m in .)
Figure 17.
HPLC chromatograms o f three concentrations o f DP5.
A
DP 6
440
ug 10* ul
P e a k A r e a ( m v .)
V
B
220
I---------------------------------------------—
'
c
1 10
4 8 12 16 20
Time (min.)
Figure 18.
HPLC chromatograms o f three concentrations o f DP6.