Morpho-anatomical and physiological studies of floral development of Jatropha curcas L.

Three exploratory studies were done to observe the morpho-anatomical development and flowering physiology of Jatropha curcas L. visual observation of the floral development at the shoot apex revealed that 30 days after bud set the opening of the flowers occur. Microscopic study for the anatomical changes of Jatropha associated with floral development revealed that the terminal buds were observed to pass through two phases; vegetative and reproductive. In these two phases 12 developmental stages were observed with the first two stages belonging to the vegetative phase and the next 10 stages in the reproductive phase. The first observed morphological indication of the transition to flowering is the broadening of the apex followed by doming. Another study on the flowering behavior of Jatropha from 10 different provenances showed that plants from Laguna [Philippines] exhibited shorter number of days to flowering (68 days) compared to those from Quezon [Philippines] (104 days), Kapalong, Davao del Norte (104 days), and Digos, Davao del Sur [Philippines] (106 days) while the rest of the sample plants showed no significant difference from the aforementioned provenances. On the other hand, plants from Sta. Cruz, Davao del Sur exhibited lower number of male flowers (17.8) compared to those from Eastern Samar (91.8) while shrubs from Kapalong, Davao del Norte (2.3) and South Cotabato (2.7) showed lower number of female flowers compared to those from Leyte (8.7). The resulting male to female floral ration showed that shrubs from Sta. Cruz, Davao del Sur have lower male to female flower ratio (5:1) compared to those from South Cotabato (7:1) and Eastern Samar (18:1). Determining the effect of ethylene on flowering, sex expression and fruiting behavior of Jatropha revealed that lower concentrations of Ethrel (333 rpm and 500 ppm) caused a decrease in the number of days to flowering although it has no significant different with the control. The lowest concentration of Ethrel (333 ppm) was noted to cause a significant increase in the number of female flowers but no significant change in the number of male flowers while the highest concentration (1000 ppm) generated high male to female flower ratio. The different concentrations of Ethrel did not have significant effect on the number of male flowers produced per cluster but the lowest concentration caused a significant increase in the number of female flowers per cluster. Similarly, the different concentrations of Ethrel showed no significant effect on both the number of floral clusters and the total number of flowers produced by the plant while high concentration resulted in significant decreases in both fruit set and number of fruit clusters per tree. No significant correlation was observed between the production of flowers and the various climatic factors in the study site.