ESTATE CROPS INNOVATION – Genetic evaluation is needed in order to develop high yielding varieties of physic nut (Jatropha curcas L.), an important oil producing crop needed to support development of renewable energy resources program in Indonesia. The collected genetic data are important for designing the appropriate Jatropha breeding program.
RR SRI HARTATI. Genetic Evaluation of Yield Potential and Other Important Characters in Physic nut (Jatropha curcas L.) to Support New High Yielding Variety Development. Under supervision of SUDARSONO, ASEP SETIAWAN, and BAMBANG HELIYANTO.
Genetic evaluation is needed in order to develop high yielding varieties of physic nut (Jatropha curcas L.), an important oil producing crop needed to support development of renewable energy resources program in Indonesia. The collected genetic data are important for designing the appropriate Jatropha breeding program. The objectives of this research were to evaluate: 1) morphological and yield potential performance of selected J. curcas genotypes, 2) genetic variance and heritabilities of a number of important characters and correlation among recorded characters, 3) combining ability of selected genotypes and their heterotic values, 4) existence of inbreeding and outbreeding depression, and 5) inheritance of hermaphrodite flower characters of monoecious and tri-monoecious types parents. Result of the experiment indicated that 60 genotypes derived from selected J. curcas parents exhibited a wide variation in number of branches, days to flowering, number of inflorescences, number of bunches, number of fruits and nuts per plant. Number of branches, inflorescences and bunches were positively correlated with number of fruits and nuts per plant while days to flowering was negatively correlated with all generative characters. Ten selected genotypes exhibited high phenotypic variation in number of branches, days to flowering, number of inflorescences, number of bunches and number of fruits. The coefficient of variation (CV) for all of these characters were generally > 20 %. Days to flowering, number of inflorescences, number of bunches and number of fruits exhibited wide genotypic variation with genetic variability coefficients (GVC) as high as 21,89; 29,77; 32,08; and 33,75 respectively, wide genetic variability (s2g > 2 ss2g) and high broad sense heritability (h2bs ³ 50). Therefore all of these characters can be used as selection parameters. Moreover, number of total branches was especially usefull for selection parameter since it showed positive correlation to a number of yield component characters. The ten selected parents exhibited different values of combining ability. However, all characters had sDGU/sDGK > 1, indicated a greater additive gene effects than the non-additive ones. High yielding genotypes, such as 3012-1 and PT 15-1, generally exhibited high GCA for a number of characters (days to flowering, width of canopy, number of total branches, number of inflorescences, and number of fruits) while medium yielding genotypes, such as PT 33-2, exhibited high GCA only for number of inflorescences, number of total branches, and number of fruits characters. Those three promising genotypes could be selected and used as a base population to develop high yielding synthetic J. curcas variety with the characteristics of early flowering. Results of the experiment also demonstrated that crossing among high and medium yielding parents were able to potentially produce very high yielding progenies. Depending on the observed characters, either selfing or outcrossing may results in their depression on several F1 populations. Outbreeding depression reduced up to 31 – 76 % of fruit numbers yielded per plant. In the last experiment, hermaphrodite flower occured mostly at 6 months after sowing and the frequencies ranged from 7-83 % of the total flowers. Hermaphrodite flowers of tri-monoecious plant exhibited better fruit set than that of monoecious. Hermaphrodite flowers exhibited higher fruit set (average: 80 %) than those of female flowers (average: 50 %), respectively. Characters of hermaphrodite flower genetically were not maternally inherited and it might be controlled by single dominant gene.
Key words: genetic evaluation, combining ability, inbreeding, tri-monoecious, hermaphrodite, jatropha curcas.