Reproductive Mechanism And Adaptive Significances Of Hosta Ventricosa ’Excess Flowers Production, But Few Fruit Set’

The plant reproduction ecology has made remakable progress during last several decades. Now this phenomenon of "excess flowers production,but few fruit set" research focuses on the effect of diffusion and fruit plant evolutionary sense, While this research is to plant the reproductive mechanisms involved in areas such as reproductive biology to further delve into layers.We investigated within inflorescences of Hosta ventricosa in Bi Feng Mountain in Ya’an, Sichuan and Shan Wang Ping farm in Nan chuan,Chongqing. We also explored the reason for the "excess flowers production,but few fruit set". The results showed as follows:(1) The patterns of fruit set and seeds per flower within racemes of H. ventricose were various among populations under natural pollinations. Fruit set was highest in middle flowers, seeds per fruit was lowest for baseal position and seeds per flower was lowest in distal position in population BYS. but seeds per fruit and seeds per flower increased from basal to distal positions in population SNC1. Seeds per fruit varied significantly with flower position in population SNC2, but seeds per flowers was highest for middle position and lowest for distal position. It was caused by variation in the relative importance of pollen limitation and resource limitation.(2) Fruit sets of remaining flowers in treatment FRm+a, FRb+d and FRb+m in population BYS did not differ significantly from each other (χ2=1.141, P=0.563), but all were significantly higher than those at corresponding positions on control racemes (Z=3.544,2.791,6.691; all P<0.01), which means that fruit abortion was more intense for distal positions on control racemes. Both position and flower removal significantly affected fruit set in population SNC1, but a significant interaction was not detected, therefore, fruit abortion was similar for three positions on control racemes. Seeds per fruit in population BYS was significantly affected by position, and not by flower removal, but a significant interaction between them was detected. This is because flower removal had little effect on seeds per fruit of basal and middle positions, whereas it marked reduced seeds per fruit at distal positions. Seeds per fruit in population SNC1was significantly affected by position, but not by flower removal. It was caused by variation in the relative importance of resource limitation.(3)The flower number per raceme in natural pollination and supplementary pollination treatment in population BYS2-10was25.2±0.7(SE)and26.3±0.4respectively, and there was no significant difference between treatment(Z=-1.032, P=0.305). Fruit sets at basal, middle and distal positions in supplementary pollination treatment was not significantly different from those at corresponding positions in natural pollination treatment (Z=0.488,1.636,0.293; all P>0.10). Seeds per flower was significantly affected by position (F=111.123, P=0.000)and its interaction with pollination treantment (F=4.803, P=0.009), but not affected by pollination treatment (F=0.174, P=0.667). This is because supplementary pollination markedly increased seeds per flower of basal position, but had little effect on seeds per flower of middle and distal positions. We did not analyze the effect of supplementary pollination on seeds per fruit, because three racemes in supplementary pollination treatment did not produce any fruit at distal position.lt was caused by variation in the relative importance of pollen limitation.