Efects Of Resource Budget For Reproduction On Size-dependent Sex Allocation In Cardiocrinum Giganteum (Liliaceae)

The sex allocation theory mainly studies the optimal allocation of reproductive resources between male function and female function, which is hot topic of the plant life history theory. In most classical studies, researchers have explored sex allocation among species), among populations of a given species, among individual plants within a given population and among flowers within a plant. Up to now, there are many theoretical models on the effects of resource pools on size-dependent sex allocation at either flowering or fruiting, but there are few empirical studies which explore the effects of stored organs and/or current foliar photosynthesis on sex allocation and especially size-dependent sex allocation at either flowering or fruiting. In order to understand the mechanism of the effects of resource pools on size-dependent sex allocation, we studied the effects of reserved resources and current foliar photosynthesis on the size-dependency of floral allocation, sex allocation, and fruit and seed productions in an understory monocarpic perennial, Cardiocrinum giganteum, through experimental defoliation.The results are as follows:(1) In flowering of the control treatments, the average leaf area was1321.88±558.11cm2(mean±SD), maximum and minimum leaf area was2478.00cm2and601.65cm2respectively. Leaf area per plant increased with increasing flower number, and showed significant correlation with total flowers.(2) Similar average numbers of flowers per plant were observed in the control and defoliation treatments, maximum and minimum numbers of flower number per plant were also similar. However, there was significant difference in the average mass of stamens, pistils, tepals per plant in the control and defoliation treatments, as compared to defoliation treatments, the maximum and minimum mass of stamens, pistils, tepals per plant was higher in the control treatments. Mass of stamens, pistils, tepals per plant increased with increasing flower number and showed extremely significant correlation with total flowers, significant effects of treatment were not detected, but extremely significant interactions between flower number and treatment were found.(3) Similar average ratio of pistil to stamen mass were observed in individual level in the control and defoliation treatments. Defoliation significantly decreased the ratio of pistil to stamen mass of individual plants, from0.48±0.06(mean±SD) in intact plants to0.41±0.06in defoliated plants. The ratio of pistil to stamen mass did not increase with increasing flower number and was not related to flower number irrespective of treatment, significant effects of treatment were detected, but interactions between flower number and significant effects of treatment were not detected, but extremely significant interactions between flower number and treatment were found were not found.(4) Similar average numbers of flowers per plant were observed in the control and defoliation treatments, maximum and minimum numbers of flower number per plant were also similar. Backtransformed fruit number per plant in control and defoliation treatments was8.3(LSE=4.0, USE=16.0) and5.0(LSE=3.0, USE=7.0) respectively. Fruit number increased with increasing flower number and was extremely significantly related to flower number, and affected by treatment, but a extremely significant interaction was detected.(5) Backtransformed seed number and mass per plant in control and defoliation treatments was2173(LSE=1176, USE=4914),6445mg (LSE=3179mg, USE=14328mg) and656(LSE=317, USE=1480),2248mg (LSE=1141mg, USE=5378mg) respectively. Seed number and mass increased with increasing flower number and was extremely significantly related to flower number, and not affected by treatment, but a extremely significant interaction was detected.