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Seed abortion in Pongamia pinnata (Fabaceae) |
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| Authors: | H S Arathi K N Ganeshaiah R Uma Shaanker S G Hegde |
| Institution: | 1. 2Department of Genetics and Plant Breeding, University of Agricultural Sciences, G.K.V.K., Bangalore 560 065, India;2. and
Author for correspondence, current address: Department of Entomology, 219 Hodson Hall, University of Minnesota, St. Paul, Minnesota 55108.;3. and;4. 4Department of Crop Physiology, University of Agricultural Sciences, G.K.V.K., Bangalore 560 065, India;5. and Current address: Department of Botany and Plant Sciences, University of California, Riverside, California 92521. |
| Abstract: | In Pongamia pinnata only one of the two ovules develops into a seed in most of the pods. Since pollen was not found to be limiting and reduced fertilization could not completely explain the observed frequency of seed abortion, it implied an effect of postfertilization factors. Aqueous extracts of developing seeds and maternal tissue (placenta) did not influence abortion in vitro, suggesting that abortion may not be mediated by a chemical. Experimental uptake of 14C sucrose in vitro indicated that both the stigmatic and the peduncular seed have similar inherent capacities of drawing resources, but the peduncular seed is deprived of resources in the presence of the stigmatic seed. This deprivation of the peduncular seed could be offset by supplying an excess of hormones leading to the subsequent formation of two seeds in a pod. The prevalence of single-seeded pods in P. pinnata seems therefore to be a result of competition between the two seeds for maternal resources. The evolutionary significance of single-seeded pods in P. pinnata is discussed with respect to possible dispersal advantage enjoyed by such pods. |
| Keywords: | Fabaceae Pongamia pinnata resource competition seed abortion seed set |