Regulation of Fruit Maturation Pattern in an Annual Legume, Cassia Fasciculata
1982
Lee, T. D. | Bazzaz, F. A.
This study investigated the extent of and basis for selective fruit maturation in the annual legume, Cassia fasciculata Michx. Demographic analysis of flowers and fruit in field populations demonstrated that fruit did not necessarily mature in the order initiated, although early initiated fruit were more likely to mature. Fruit initiated early in the season tended to grow slowly at first, whereas those initiated later tended to grow rapidly; this growth pattern dampened the effect of the order fruit initiation on maturation sequence. Two experiments were conducted to test the hypothesis that more outcrossed fruit matured than selfed fruit, but in both cases the hypothesis was rejected. Other experiments were performed to determine if (a) fruit resulting from pollination by a particular plant mature more rapidly than do those resulting from pollination by other plants, and (b) fruit resulting from mixed pollen loads mature more readily than those pollinated by a single plant. These ideas were also rejected. Two experiments were conducted to test the hypothesis that fruit with a large number of percentage of fertilized ovules are selectively matured. This hypothesis was supported by both glasshouse experiments and field observations. Percentage of fertilized ovules seemed to be more clearly related to fruit growth and maturation than was number of fertilized ovules. Natural selection may favor individuals that selectively mature fully fertilized fruit because such fruit (1) may be more resource—efficient because they contain less pericarp per seed, (2) may provide better dispersal of seed, or (3) may contain high—quality seed owing to increased gamete competition.
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