Combining ability and genetic parameters of physic nut genotypes for morphoagronomic traits

The objective of this work was to determine the general and the specific combining abilities, the genetic parameters, and the correlation between morphoagronomic traits in physic nut (Jatropha curcas) accessions. A randomized block experimental design, with three replicates, was used. The evaluated characters were: Y, yield; PH, plant height; NSB, number of secondary branches; NFF, number of female flowers; SD, stem diameter; W100, weight of 100 seeds; HB, height of branches; and DC, diameter of crown. The general combining ability was significant for Y, NSB, SD, W100, and HB, while the specific combining ability was signicant only for NFF and NSB. Heritability estimates were higher than 70% for NSB, NFF, SD, and HB. Positive genotypic correlations were observed between NSB and SD (0.942), NSB and PH (0.762), NSB and DC (0.798), NSB and Y (0.759), SD and PH (0.738), SD and DC (0.844), SD and Y (0.802), and DC and Y (0.742); and negative ones between NSB and HB (-0.665), and SD and HB (-0.687). The NFF explained over 50% of the variation in the physic nut hybrids. General combining ability preponderates on the evaluated traits.