ADAPTIVE SIGNIFICANCE OF POLLINATION MECHANISM IN CAT’S WHISKERS (Gynandropsis pentaphylla L. Syn. Cleome gynandra)
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2012-06-30
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Abstract
The variability of reproductive traits was studied in Gynandropsis pentaphylla (Capparaceae), an important medicinal herb of tropical distribution believed to have originated from Africa, and found that there was no significant difference between the traits in a natural stand and the control. The hierarchical emergence was bisexual homogamous (hermaphrodite) and heterogamous flowers interspersed by unisexual male flowers at a plant level irrespective of branching. Pollination is by vibrations either through anemophily directly or entomophily indirectly. Apis cerena indica and anthophorid bee visit both the anthers and the petals and former was most helpful as a pollinating agent (73% visits to petals), and as they land on the petal they cause vibrations which in turn result to pollen dehiscence. The anthophorid bee is a pollen thief (95.85% visits to anthers without touching stigma of gynophore). The bisexual homogamous flowers had high female success (58.33%) as against anthers clipped (x = 39.01) indicate high selfing ability supports reproductive assurance hypothesis. The bisexual protogynous flowers had same fruit-set when their anthers were removed or intact (x = 71.78 and x = 66.35 respectively). Intriguingly, seed number per pod of selfed pods was higher than those outcrossed. Fresh seeds (2 months old) had more dormancy compared to older seeds (12 months old), which indicates that the older seeds germinate readily compared to fresh seeds. Priming with water, GA3 (250ppm) and Ethrel (50ppm and 100ppm) could improve the germinability of old and fresh seeds up to 16% and 10% respectively compared to control (6.77 and 2.92 respectively). Supplementation of sucrose with 15 per cent had good pollen germination for all types of flowers whilst 30 % was better for pollen from protogynous flowers. The molecular analysis, using OPB – 15 primer of RAPD, confirmed siring of seeds by foreign pollen as compared to selfed homogamous seeds.
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