Comparing potential of GA and 2, 4-D in increasing fruit yield from Jatropha curcas

Jatropha curcas L. has been accepted world wide as a plant with tremendous commercial importance as a source for biodiesel. It is a monoecious plant with staminate and pistillate flowers on same inflorescence. The number of staminate flowers is higher than pistillate ones resulting in very low fruit yield. Altering the sex ratio, to increase number of female flowers would lead to better yield. Phytohormones are one of the most important factors known to alter sex ratio in plants. The mechanism by which phytohormones alter sex ratio differs in different plant species. Earlier studies from our laboratory have shown effect of exogenous application of GA and 2, 4-D on flowering patterns in Jatropha. Here we report a comparative study of the effect of exogenous application of GA and 2, 4-D (50 and 100 ppm) on flower sex modification in Jatropha curcas. There was considerable increase in total number of flowers and female: male flower ratio by application of GA and 2, 4-D. However, at higher concentration of GA a negative result as far as fruit yield is considered was seen. The reasons for this are reported here. 2, 4-D on the other hand increased the ratio of female flowers in a concentration dependent fashion. Of the four treatments reported here, we have observed that 2, 4-D (100 ppm) shows better results than GA and untreated plants. The reasons for this are discussed.