Refinement of in vivo and in vitro pollination techniques in turmeric (Curcuma domestica Val.)
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Date
2001
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Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara
Abstract
Investigations on "Refinement of in vivo and in vitro pollination
techniques in turmeric (Curcuma domestica Val.)" were carried out at the
Department of Plantation Crops and Spices and the Centre for Plant Biotechnology
and Molecular Biology, College of Horticulture, Vellanikkara during the period
from 1998 to 2000.
The plant materials used for the study consisted of six short duration
cultivars viz., VK 70, VK 55, VK 76, Suguna, Sudharsana and Suvarna and four
medium duration cultivars viz., Kanthi, Sobha, Prabha and Pratibha. Studies
conducted among them showed significant variability with respect to pseudostem,
rhizome and quality characters. The genotypes identified for high curcumin are
Sobha (7.24%), Kanthi (6.98%), VK 76 (6.31%) and Prabha (6.37%) and those
identified for high curing percentage are VK 70 (22.00%), Suvama (19.17%) and
VK 76 (18.02%).
The investigations to improve flowering showed that the size of the seed
material used influenced flowering behaviour of turmeric cultivars. The plants of
short duration cultivars from T3 group (200 g) was the earliest to flower followed
by T2 (45-50 g) and TJ (15-20 g). The flowering season in T3 group was extended
for 85 days while it was only 48 days in TJ group and 57 days in T2 group. The
flowering intensity in turmeric cultivars were significantly high in open condition
(77.61%) compared to shade (26.13%).
Pollen viability studies were conducted in modified ME3 medium at
pH 6. Viability was low during early flowering season (18.88%) compared to mid
(25.05%) and late (25.84%). The mean pollen viability in short duration cultivars
was 33.51 per cent while it was low in medium duration cultivars (14.30%). The
mean pollen tube growth also followed the same trend.
Dry pollen grains can be stored in cyclohexane and methanol at -15°C
for one month with mean pollen viability percentage of 20.18 and 20.09
respectively.
Natural fruit set and seed set were observed in short duration cultivars
and not noticed in medium duration cultivars.
Through controlled in vivo pollination, seed set was obtained in crosses
involving short duration cultivars. But failed in crosses involving short and
medium duration cultivars. Seed set was not obtained through in vivo stylar and
intraovarian pollination.
Pollen pistil interaction studies after in vivo cross pollination of short
and medium duration cultivars showed pollen germination on stigma and pollen
tube passing through style and reaching the ovules. So lack of seed set can be due
to some other factors.
In vitro pollination was done by pollen grains suspended in the modified
ME3 medium. Among the various methods of pollination tried, ovule/seed
development was observed in intraovarian, placental and modified placental
pollination techniques. Among them, placental pollination is the best as number of
ovules developed per culture was maximum in this. These techniques can be used
for conducting crosses inv.olving short and medium duration cultivars provided
medium duration cultivars as female parents.
The medium identified for the development of in vitro pollinated ovules
are (1) Yz strength MS + 3% sucrose + BAP 1 mg r1 + kinetin 1 mg r' + NAA
0.5 mg r'. (2) Modified Yz strength MS + 3% sucrose + BAP 0.5 mg r' + kinetin
0.5 mg r' + NAA 1 mg r'. The first medium was the best for increasing the size of
the ovules. The organic supplement coconut milk extract at five per cent
concentration and addition of double the quantity of vitamin stock of MS medium
favoured ovule development.
Two hybrid seeds from the in vivo cross (VK 70 x VK 76) germinated
under in vitro on moist filter paper in test tubes. They were multiplied under in
vitro and six plantlets were successfully planted out in the field and the rest were
multiplied further under in vitro.
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Citation
171763