Floral sex allocation and reproductive success within inflorescences of Hosta ventricosa, a pseudogamous apomict  

作　　者：Guo-Xing Cao Ting Xie Bi-Xian Wu Chun-Ping Yang 

机构地区：[1]Department of Forestry,Sichuan Agricultural University,Xinkang Road 46,Yucheng District,Yaan 625014,China [2]Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences,Mengla 666303,China

出　　处：《Journal of Plant Ecology》2015年第2期142-153,共12页植物生态学报（英文版）

基　　金：National Natural Science Foundation of China(30870388,31370436).

摘　　要：Aims Within inflorescences of sexually reproducing hermaphrodites,the production of ovules,fruits and seeds commonly declines from basal(early-opening)to distal(late-opening)flowers,while pol-len production remains constant or only changes slightly,with the result that distal(late-opening)flowers become functionally male.However,few empirical studies have specifically examined whether or not changes in allocation to pollen production actually lead to changes in the number of seeds sired,a more direct measure of male fitness.in pseudogamous apomicts,fitness depends on the number of seeds produced;thus,a contrasting pattern of variation in the pollen-to-ovule(P/o)ratio within inflorescences might be expected.Methods We investigated floral sex allocation and reproductive success within racemes of Hosta ventricosa,a pseudogamous apomictic hermaphrodite possessing flowers that open acropetally.We quan-tified variations in pollen number,ovule number,the P/o ratio and fruit and seed production,from 2007 to 2011,among flowers within racemes of four populations of H.ventricosa in southwest China.Ecological causes for fruit and seed production were evaluated by observing patterns of pollen deposition,flower removal and sup-plemental pollination.Important Findings Pollen number,ovule number and the P/o ratio declined from basal-to-distal positions in all sampled populations(years).Fruit and seed production decreased distally in most populations(years).low fruit and seed set of distal flowers was not due to pollen limitation because pollen deposition never declined distally and the low fruit and seed set of distal flowers remained even after supplementary pollination was provided.The flower-removal experiment indicated that inter-fruit competition for resources among flowers was common.The low P/o ratio of distal flowers in H.ventricosa might be favored because they were unable to obtain fitness by donat-ing pollen and siring seeds on other plants.our study may help to understand the adaptive significance of sex allocation a

关 键 词：Hosta ventricosa pollen limitation pollen-ovule ratio pseudogamous apomict ·resource limitation within inflorescences 

分 类 号：F42[经济管理—产业经济]