Response of turmeric Curcuma domestic val. to in vivo and in vitro pollination
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Date
1999
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Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara
Abstract
Investigations on "Response of turmeric Curcuma domestica Val. to in
vivo and in vitro pollination" were carried out at the Department of Plantation Crops
and Spices, College of Horticulture, Vellanikkara during 1997 to 1999.
Research was carried out with turmeric cultivars viz. VK 70, VK 55,
VK 76, Suguna, Sudharsana, Suvarna, Kanthi and Sobha. Among them, Kanthi and
Sobha were medium duration types and the rest were short duration types. The
selected cultivars differed significantly with respect to morphological and qual~ty
characters. The curcurmin content was high in Sobha (7.43%), Kanthi (7.02%) and
in VK 76 (6.38%) while all others recorded <5.1 percentage. The cultivars VK 70
(21.5%), VK 76 (20.0%) and Suvarna (19.5%) were noted for high curing
percentage.
The floral biology and morphology of turmeric were studied. Turmeric
cultivars took 105 to 155 days for flowering and the flowering season ranged from
July to October.
The anthesis started by 5 am and continued up to 6 am. Anther
dehiscence took place between 7.15 am and 7.45 am. Androecium consists of six
stamens in two whorls of three each. The outer whorl is modified as labellum. The
inner whorl is represented by two staminodes and one fertile stamen. Gynoecium
has a long style of mean length 4.43 cm. The ovary measured a mean length of 2.6
mm and diameter of 2.4 mm and recorded a mean ovule number of 29.31. The
ovules recorded a mean length of 611.44 urn and breadth of 436.65 urn at the
middle. At the base of the flower honey secretion is present and ants are the
pollinating agents.
The mean pollen fertility with acetocarmine stain in the studied cultivars
were 78.51 per cent.
Attempts to develop a medium which will support pollen germination
and tube growth in turmeric resulted in the identification of modified MEJ medium
of pH 6 (Leduc et al., 1990). The pH reactions of the medium influenced the pollen
germination .
. Pollen germination was high in short duration type (23.75 to 46.08%)
compared to medium duration types (8.22 to 11.50%). The pollen tube length also
was higher in short duration cultivars (268.48 urn to 576.3 urn) compared to
medium duration cultivars (218.72 urn to 245.45 urn).
Pollen germination was influenced by the position of flowers in the
inflorescence. The germination was high in the flowers at the lower portion
(32.55%) and low in the upper portion (22.93%) of the inflorescence.
The optimum time for collection of roots for mitotic studies in turmeric
was between 6.30 am and 7 am. The somatic chromosome number of short duration
cultivars viz. VK 70 and Suvarna were found to be 2n = 84 and that of medium
duration cultivar Kanthi as 2n = 63.
Natural fruitset and seed set were observed in short duration cultivars
and not noticed in medium duration cultivars. The natural pollinating agent in
turmeric is insects i.e., ants.
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.
The fruit of turmeric is a thick walled trilocular capsule with small black
I
arillate seeds. Seeds are filled with massive endosperm and embryo is seen towards
the upper side of the ovule.
Initial studies for culture establishment showed that the basal medium of
Y2 MS and MS are suitable. The half strength MS being superior to full strength
MS.
Various antibiotics tried for controlling bacterial contamination m
cultures were in effective.
Studies were made to standardize optimum media components for ovule
development. The combination ofNAA 0.5 mg r' with BAP and kinetin both at 1
mg r' induced maximum ovule swelling. On visual assessment, 3 per cent sucrose
concentration was superior to 6 per cent level for ovule development. Organic
. 1
supplements, coconut water (15% v/v) and CH (200 mg I") enhanced ovule
development.
In vitro pollination was done by pollen grains suspended in modified
ME3 medium. Among the various methods of pollination tried, ovules/seeds
development were observed in the intra ovarian, placental and modified placental
pollination techniques. These techniques can be used for conducting crosses
involving short and medium duration cultivars provided medium duration cuItivars
used as female parents.
In the intra-ovarian pollination fruit development occurred. The ovary
developed into fruit and attained a maximum size of 6 mm 20 OAP under in vitro
condition. Ovules/seeds developed after in vitro pollination were creamy white
during the initial stage of development and changed to dark brown colour within a
period of 20 to 30 DAP. In the in vitro developed seed the endosperrn development
was not complete.
The seeds developed under in vivo, germinated under in vitro on moist
filter paper.
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Citation
171557