Defoliation, Harvest,
and Cotton Quality….
Philip Jost
University of Georgia
Fiber Quality
Determined by Many Factors
•
•
•
•
•
Physiology of the plant
Variety
Defoliation Timing
Harvest Timing
Agronomic Practices
Schubert, A.M., 1975
Fiber Development
• Initiated at pollination of the cotton flower.
• 3 stages of
development
– Elongation
– Secondary wall
thickening (maturation)
– Drying
Fiber Development
• Cotton fibers originate from the outer
epidermal cells of the ovule. “Seed Hair”
FIBER ELONGATION
Stage 1
Fiber Elongation
Stage 1
• Elongation of the fiber is driven by the
internal water pressure of the elongating
cell.
• Length
– Determined in the 18 to
21 days after pollination.
– Cell expansion.
– Variety sets the bar
• influenced by
environment.
Schubert, A.M., 1975
Fiber Quality
Length
• Reported to the
nearest 32nd of an
inch.
• Upper ½ mean length
Upper 1/2 mean length
Mean length
Fiber Quality
Length
• Base is 34
– Below 34 incurs discounts
– Above 34 may incur premiums depending on color.
• How bad can it hurt?
– 33 = -2.2 cents
– 32 = -3.85 cents
– 35 = 1.40 cents
Factors Influencing Fiber
Elongation
• Temperature
– Affected by extremes in temperature early in
development.
• Plant Nutrition
– K is essential for maintaining internal water pressure.
• Variety!
• Water
– Length usually not affected by water deficit, yield is
much more susceptible. ??
K+ accumulates
in primordial
fiber cells at
initiation of
expansion
Fiber Length (1993 - 2003)
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
33
33.5
34
34.5
35
35.5
% Short Staple (1993 - 2003)
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
0
10
20
30
40
Southwest
Central
Southeast
East
%Short vs
Rainfall
2002
50
40
% Short
Rainfall (in)
30
20
10
Southwest
Central
Southeast
East
Rainfall vs Staple
2001 and 2002
35
Staple length
34.5
34
33.5
33
32.5
32
13
15
17
19
21
Rainfall May thru September
23
25
Timing of Defoliation
4 NACB
7 NACB
Both 60% open
AFIS-Length(n) 1999
0.73
a
a
a
ab
abc
bcd
0.7
0.69
bcd bcd
cd
bcd
100
0.71
a
100
L(n) inches
0.72
a
d
0.68
P>F 0.0006
% Open Boll
100
100
100
97
83
80
64
60
55
31
0.66
17
0.67
AFIS-Length(n) 2000
0.77
ab
a
abc
bcd cd
defg defg de
0.75
efg
g
g
100
fg
0.74
100
L(n) inches
0.76
cd
0.73
F = 8.70**
% Open Boll
100
100
100
94
88
80
76
58
57
30
0.71
9
0.72
Fiber Quality
Length Uniformity
• Reported as a ratio of
mean length to upper ½
mean length.
• Base is 81
• Indirect measure of short
fibers.
• How bad can it hurt?
– 79 = -.35 cents
– Mill problems – short
fibers
Upper 1/2 mean length
Mean length
Uniformity =
Mean
Upper 1/2
Fiber Quality
Short-fiber content
• Problems
–
–
–
–
Lower yarn strength
Reduce spinning efficiency
Limit the use of the yarn
Increase imperfections in the yarn
• Causes
– Weathering
– Ginning
Fiber Uniformity in the S.E.
1999-2003
85
83
1999
2000
2001
2002
2003
81
79
77
75
Macon
Memphis
Florence
B'ham
abc
abc
ab
abc a
abcd
P>F 0.0071
bcd
% Open Boll
100
100
100
100
100
d
97
64
d
83
d
80
d
60
bcd
55
cd
31
9.6
9.4
9.2
9
8.8
8.6
8.4
8.2
8
7.8
7.6
17
SFC(w) %
AFIS-SFC(w) 1999
AFIS-SFC(n) 2000
28
ab
25
cde
bc
100
def
a
abc
efg def
fg
fg
57
26
30
SFC (n) %
bcd
94
27
a
24
g
F = 9.24**
% Open Boll
100
100
100
100
88
80
76
58
22
9
23
FIBER THICKENING
Stage 2
Fiber Thickening
Stage 2
• Secondary wall thickening occurs
from 17 to 53 days after
pollination.
– Cellulose is deposited inside the
elongated cell.
– The cellulose is deposited at
slightly differing angles.
• Fiber thickening will determine
fiber fineness, or micronaire.
Fiber Quality
Micronaire
• Indirect measure of
fiber fineness and
maturity.
• The air-permeability
of a specimen
enclosed in a
container of fixed
dimensions.
HIGH
LOW
Fiber Thickening
• Low micronaire cotton – thin fibers
• Insufficient carbohydrate supply.
• Nutrient deficiency
• Excessive vegetative growth
• Heavy boll set
• High micronaire cotton – thick fibers
• Ample carbohydrate supply.
• Poor boll set
• Short fibers
Fiber Quality
Micronaire
Premiums
3.5
3.7
4.2
5.0
5.2
Base Range
-4.15 cents
Deductions
-3.65 cents
Fiber Quality
Micronaire
• How to manage a crop for micronaire.
–
–
–
–
–
Variety selection
Irrigation where possible
Insect control
Harvest preparation
Once-over harvesting
Micronaire Reading
Micronaire in the South East
50
48
46
44
42
40
38
36
34
2001
2002
2003
Macon
Memphis
Florence
B'ham
P>F 0.0011
ab
ab
a
ab
ab
ab
ab
a
100
100
100
100
100
100
100
100
a
ab
bc
c
92
73
69
c
42
4.8
4.7
4.6
4.5
4.4
4.3
4.2
4.1
4
6
Micronaire
HVI Micronaire 1998
% Open Boll
P>F 0.0001
100
100
100
% Open Boll
100
100
97
83
ab
80
abc abc abc ab
64
bcd cd abc abc a
60
e
d
55
e
31
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
17
Micronaire
HVI Micronaire 1999
F = 59.40**
a
de
bc
bcde ab
100
100
bcde cde bcd bc
100
e
94
f
ab
% Open Boll
100
100
88
80
76
58
57
g
30
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
9
Micronaire
HVI Micronaire 2000
Fiber Quality
Strength
• The breaking strength of the cotton fiber is
considered to be the most important factor
in determining yarn strength.
• Fiber strength varies along the length of the
fiber.
• Reported as grams of breaking load per tex.
Fiber Quality
Strength
• Reported in grams per tex.
• Base is ~28
– Below 25.5 = discounts
– Above 29.4 = premiums
a
b
cd
ef
% Open Boll
P>F 0.0001
f
100
100
100
100
92
73
69
f
def
de
100
cde cde
100
c
100
bc
100
c
42
36
35
34
33
32
31
30
29
28
27
6
STR (g/tex)
Strength 1998
Strength 1999
28
ab
STR (g/tex)
27.5
a
a
ab
ab
abc bc
bc
27
cd
26.5
d
26
d
d
d
25.5
% Open Boll
P>F 0.0001
100
100
100
100
100
97
83
80
64
60
55
31
24.5
17
25
a
bcd
% Open Boll
F = 13.91**
fg
fg
fg
g
100
efg
100
bcde
100
88
80
76
58
57
cdef def
100
bc
100
b
94
a
30
27
26.5
26
25.5
25
24.5
24
23.5
23
9
STR (g/tex)
Strength 2000
FIBER DRYING
Stage 2
Fiber Drying
Stage 3
• Once mature the fiber dries.
• Fiber shrinks in diameter by
approximately one-third.
• Drying causes fibers to twist
and crimp.
Fiber Quality
Color
• Determined by the degree of reflectance (Rd) and
yellowness (+b).
• Base is 41-4 (white-strict low middling)
– First number determines good middling, strict middling
etc…
– Second number determines white(1), light spotted(2),
spotted(3), tinged(4) or yellow stained(5)
– Number after “-” determines leaf grade, roughly a
percentage.
– Premiums and discounts are relative to length.
Fiber Color
• Most directly linked to growth environment.
– Weathering leads to fiber to darkening and loss
of brightness
• Also correlated with overall fiber quality.
Color Grades
Week
1998
1999
2000
0
41
31
42
1
41
31
41
2
41
31
42
3
51
31
41
4
51
31
41
5
52
41
41
6
52
31
41
7
51
41
41
8
51
41
41
9
51
41
51
10
51
41
51
11
61
41
51
12
61
41
51
Application of Harvest-Aids at
60-80% Open Boll:
• Maximized
•
•
•
•
Length Uniformity
Fiber Length
Lint Yield (1999)
Profit (1999)
• Minimized
• Short Fiber Content
Early Management System?
• Why:
– TSWV has shifted “prime time” for peanut planting from
mid-April to mid to late May,
– Peanut harvest now in October - traditional cotton harvest
time.
– A range of maturity spreads out harvest.
• What: Should we consider planting 10 to 20 percent
of acreage for harvest prior to September 20?
Concerns - Late Summer/Early Fall
Rainfall
inches
3.5
3
2.5
2
1.5
1
0.5
0
Arlington
Aug 1-15
Ft Valley
Aug 16-31
Sep 1-15
Midville
Sep 16-30
Tifton
Vidalia
Oct 1-15
Oct 16-31
What/How Early Management
• Manage for harvest prior to September 20
– Plant by April 20
– Use Pix to encourage earliness
– Avoid excessive N
– Avoid fruit losses from pest management
mistakes (ex. insects, herbicides)
– Be prepared to apply defoliant/boll opener Aug
20 to Sep 5
Risks of Early Management
• April plantings may encounter stand
problems related to cool temperatures
• Significant potential for rainfall events in late
August to early September >> boll rot, hard
lock, reduced color grade
Other Fiber Quality Questions
Misapplications of glyphosate in RR
Cotton adversely affect fiber quality.
True or False?
Misapplications of glyphosate in RR
Cotton adversely affect fiber quality.
FALSE
RR Cotton Response to Glyphosate Systems
System
Timing
Conv
PRE, OTT,
Prec PDIR
RDC Pvt,
lint lb/A
1958 a
Ponder Fm,
lint lb/A
1878 a
Roundup 4 lf OTT
1953 a
Prec PDIR
Roundup 1,4,9 lf OTT 1974 a
Slppy Dir
1881 a
Cotton Fiber Analysis NS
NS
2002 results, DP 555 BG/RR
1749 b
Stinkbug damage in cotton
can adversely affect fiber
quality. True or False
Heavy Stink Bugs in 2003
• TRUE !
Severe Stink Bug Damage
S
Fiber Length as Influenced by
Stink Bug Control, Irwin Co. 2000
Plant Zone
Nodes 18+
Nodes 15-17
Nodes 12-14
Nodes 9-11
Nodes 5-8
0.78 0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94 0.96
Len (w) in
Untreated
Pyrethroid
Aggressive fertilization with N, K, and B
can eliminate fiber quality problems.
True or False?
Aggressive fertilization with N, K, and B
can eliminate fiber quality problems.
FALSE
…….but K needs study
Which is the most important in avoiding
fiber quality problems – variety selection
or environmental conditions?
Which is the most important in avoiding
fiber quality problems – variety selection
or environmental conditions?
ENVIRONMENTAL CONDITIONS
…temperature, water, harvest conditions, etc.
There are fiber quality differences among
varieties. True or False?
There are fiber quality differences among
varieties because of the insertion of
transgenes? True or False?
There are fiber quality differences among
varieties. TRUE
There are fiber quality differences among
varieties because of the insertion of
transgenes? FALSE but….