Sex-differentiation and number of female flowers for polygamous inflorescences of Jatropha curcas in two drainage basins.

Abstract

Based on random samples（30 trees for each area） and tracking observations，sex-differentiation characteristics and female flower numbers of semi-wild Jatropha curcas in the hot，dry valleys of the Jinshajiang and Red River Basins during the first and second flowering periods were studied. Results showed only a few polygamous inflorescences growing on one-year-old branches in both river basins. Polygamous inflorescence differentiation in both river basins was more than the male inflorescence during the first flowering with slightly less than the male inflorescence in the second flowering. Male flowers more than female flowers in polygamous inflorescence（＞15 ∶ 1）. In both river basins，during the first flowering，most of the polygamous inflorescences had 6－10 female flowers，and only 2% － 3% had more than 16 female flowers；during the second flowering，the female flowers numbered fewly with more than 80% of the polygamous inflorescences having 1－5 female flowers and no polygamous inflorescences having more than 16 female flowers. Polygamous inflorescence number，female flower number，and the rate of fruiting during the first flowering periods were greater in the Jinshajiang River Basin.［Ch，4 fig. 2 tab. 17 ref.］