Development of High Yielding Saffron Mutant
I.A. Khan
G.B. Pant University of Agriculture & Technology
Saffron Cultivation and Marketing Project
Chaubatia-263651
Almora
India
Keywords: 5-Branched stigma, mutation, triploidy
Abstract
Saffron (Crocus sativus L.) is a temperate, medicinal and low growing
herb. Its dried stigma is used as Bio-medicine, dyes and perfumes. All allies of
genus Crocus are diploid but Crocus sativus L. is a triploid in genetic make up
(2n = 3x = 24). Due to triploidy, meiosis in C. sativus is highly erratic and
genetically unbalanced gametes are formed which lead to the formation of sterile
gametes and ultimately no sexuality is involved which is an essential
phenomenon for seed production. Due to absence of sexuality in Saffron, a non
conventional mutation breeding was initiated to develop improved mutants of
Saffron at Horticulture Research Centre, Chaubatia, Almora, India, located in
Himalayan region. Corms with different doses of gamma rays (Co60) were
subjected to induce the variability in Saffron. Five sets, each consisting of 100
uniform corms of 5-6 g in weight, were irradiated with 0.5, 1.0, 1.5, 2.0 and 2.5
krad doses of gamma rays. Variability in respect of sprouting time, plant height,
induction of flowering, shape of petals and number of filaments in a stigma was
noted. Plants exhibiting mutations were identified and bulbs produced from
mutants were harvested separately to further the generations. An outstanding
mutant which was isolated was, a mutant with five branched stigma, instead of
three as in normal plants. On evaluating this mutant, it was found superior in
respect of number of branches in stigma. Average length of filaments in five
branched stigma noted to be 2.75 cm whereas in three branched stigma it is 2.70
cm. Dry weight of normal three branched stigma is 5 mg. whereas in five
branched stigma it was noted to be 6.950 mg which is higher than control.
Development of 5 branched stigmas is result of gene mutation due to induction
effect.
INTRODUCTION
Saffron (Crocus sativus L.) is a temperate medicinal and low growing herb. Its
dried stigma is used in Bio-medicine, dyes and perfumes. More recently Saffron’s
use as antitumour, cardiovascular protective agent and use of extract of Saffron corms
against malignant cells indicate the importance of this plant (Escribano et al, 1999;
Abdullaev, 2002).
Saffron plant is sterile and has no capability of proudcing seeds. Propagation
is made by under ground vegetative part called corm. Genetically it is triploid in make
up (2N=3x=24). Due to triploidy, no recombination of genes occurs and consequently
no variants are developed. Moreover transportation, storage and packing of corms
increase the cost of cultivation. Further more, corms are also affected by virus which
deteriorate quality of Saffron. Keeping importance of the plant and affecting factors
for cultivation in view, present investigation was undertaken to induce the variability
by physical irradiation. Main objectives of employing physical irradiation were
development of polyploid forms and tetrafid or pentafid or hexafid stigmatic plants.
MATERIALS AND METHODS
Experiment was conducted during 2004-2005 at Chaubatia garden,
Horticulture Research and Extension Centre, Chaubatia, located at 6000 feet height
from sea level in Central Himalaya. Five sets, each consisting of 100 uniform corms
and each corm 5-6 gm in weight, were irradiated with 0.5, 1.0, 1.5, 2.0 and 2.5 krad
doses of gamma rays at N.B.R.I., Lucknow. A set of 100 untreated corms was used as
control. After irradiation, corms were planted in raised beds at 10x15 cm dimension
and at 8-10 cm deep. Beds were covered with grass mulch. All cultural practices were
made to raise the normal crop.
Observations on sprouting, plant height, days to flower, flower size, flower
shape, flower colour, flowering percentage, branches of stigma and weight of dry
stigma were taken into consideration. Individually all plants of VM1 generation were
examined and identified mutants were harvested to advance the next generation.
RESULTS AND DISCUSSION
Effect of irradiation was studied on the basis of various morphological
characters. Induction of early sprouting in 0.5 krad, 1.0 krad and 1.5 krad and delayed
sprouting in higher doses was observed. Induction of flowering and plant height in
lower doses and decrease in plant height in higher doses was also observed. Higher
percentage of sprouting in lower doses and poor sprouting in higher doses was also
noted. Cent percent survival in 0.5, 1.0 and 1.5 krad and reduced survival percentage
in higher doses was also recorded (Table 1). On the examination of treated
population, serrated petal mutant plant and 3-petal plant was identified and a plant
having five branched stigma, instead of three as a normal plant was found. Average
length of filament in five branched stigma noted to be 2.75 cm whereas in three
branched stigma it is 2.70 cm. Dry weight of normal three branched stigma is 5 mg
whereas in five branched stigma it was noted to be 6.950 mg which is higher than
normal (Table 2).
Corms of identified mutants (petal mutants and five branched stigma mutant)
were harvested separately and advanced to VM2 generation to bring them true to type
form and also to compare, with parental lines. All identified mutants including
mutation in petals and stigma number failed to inherit the characters indicating
reversible mutation. No polyploid forms were observed.
Gamma irradiation affects the sprouting, growth and flowering of the plants.
Delayed sprouting, slow growth in higher doses, increase/decrease of plant height at
lower and higher doses respectively and induction of flowering in VM1 generation at
lower doses are due to auxin synthesis whereas at higher doses it is inhibited resulting
into delayed and stunted growth. Present findings are in conformity with the reports of
others (Gordon, 1957; Khan, 2003). Stunted growth, reduction in survival and
reduced fertility is also attributed to genetic loss due to chromosomal aberrations and
gene mutation (Sparrow et al, 1961; Datta and Gupta, 1980; Khan, 2003). Flowering
induction in lower doses of gamma irradiation in VM1 generation is result of
mutation in bio-chemical pathway which assists in the synthesis of flower inducing
substance leading to formation of flower whereas same process is not inherited in the
next generation.
Formation of five branched stigma is result of somatic mutation where apical
cell responsible for making three branched stigma divide in five cells instead of three,
due to induction effect. Plant with five branched stigma also reported to be found
some time in natural growing conditions which is also result of environmental somatic
mutation. In present investigation we failed to produce permanent mutation but
mutant with heritable five branched stigma if developed, definitely increase the yield
of Saffron.
Literature Cited
Abdullaev, FI. 2002 Cancer chemopreventive and tumoricidal properties of Saffron
(Crucus sativus L.) Exp. Biol. Med. (May wood) 227(1):20-25.
Datta, S.K. and Gupta, M.M. 1980. Effect of gamma irradiation on rooted cuttings of
small flowered chrysanthemum. New Botanist VII:73-85.
Escribano, J., Rios, I. and Fernandez J.A. 1999. Isolation and cytotoxic properties of
novel glycoconjugage from corms of Saffron plant (Crocus sativus L.). Biochim
Biophys Acta 1426(1):217-222.
Gordon, S.A. 1957. The effect of ionising radiation on plants: Biochemical and
physiological aspects. Quart Rev. Biol. 32:3-14.
Khan, I.A. 2003. Induced mutagenic variability in Saffron (Crocus sativus L.) Proc.
1st International Symposium on Saffron Biology and Biotechnology, Albacete,
Spain. Oct 22-25, 2003 P. 21.
Sparrow, A.H., Gunay, R.L., Micksche, J.P. and Schairer, L.A. 1961 Some factors
affecting the responses of plant to acute and chronic radiation exposure. Rad. Bot.
1:10-34.
Table 1. Effect of Irradiation on various characters
S. No.
Characteristics
Control
0.5
krad
1.0
krad
1.5
krad
2.0
krad
2.5
krad
1.
Days to sprouting
42
39
40
41
50
55
2.
Days to flowering
65
60
64
66
-
-
3.
Plant height (cm)
12.25
13.50
14.50
13
11
10
4.
Sprouted bulbs (%)
100
100
100
100
75
60
5.
Survival plant (%)
100
100
100
100
60
49
6.
Flowering plants
(%)
40
50
60
55
-
-
Table 2. Data on 5 branched stigma mutant
S. No.
Characteristics
Control
Mutant
1.
Average length of stigma (cm)
2.70
2.75
2.
Weight of dry stigma (mg)
5.00
6.950