Studies on floral display and mode of reproduction in jatropha (Jatropha curcas L.)

Plant flowering and breeding characteristics are important for us to understand the reproduction of plant populations. In this paper, we studied the mode of reproduction of Jatropha curcas. in GKVK, UAS, Bengaluru. The plant produces flowers in dichasial inflorescences. Normally, the flowers are unisexual, and male and female flowers are produced in the same inflorescence. Only a few male flowers are produced in an inflorescence, and fruits are produced only through pollination between different flowers from the same or different plants. Pollination experiment clearly revealed the predominance of cross pollination in Jatropha curcas with the apomixis up to 28.5 per cent. The mean female to male flower ratio in the Jatropha was around 14.4 to 105.73. By the treatments of emasculation, bagging and artificial pollination, which showed that Jatropha curcas could facilitate sexual system geitonogamy up to 75.6% fruit set indicates self-compatibility and xenogamy up to 82.33 per cent fruit set. When the inflorescences were unbagged, unemasculated and with free pollination treatments, or unbagged, emasculated and with free pollination treatments, there were many fruits produced. It showed that out crossing up to 74.97 per cent fruit set, and demanding for pollinators. Normally, the male flowers open first and maximum number of male flowers open from fourth to ninth day. However, a large number of female flowers open from the fourth to the seventh day, with some female flowers opening first in a few raceme. This shows a tendency to promote xenogamy and minimize geitonogamy.