| Popis: |
Although scientists consider jatropha as a potential energy crop, not much achievement has been made on its genetic improvement mainly due to its low genetic variation. Attempts have been made to cross J. curcas with the other Jatropha species to enhance its variation. Although there are roughly 175 Jatropha spp. known, less than 10 species were reported to set fruits with J. curcas. Yet all crosses were achieved only when J. curcas was used as the female plant, except with J. integerrima (peregrina) that enabled a limited number of successful reciprocal crosses. The cross J. curcas × J. integerrima is the most promising and being studied in many aspects of genetics and breeding. Cytologically, the F1 hybrids show disorder of chromosome segregation during meiosis, causing almost half of the microspores to contain irregular number (10 and 12) of chromosomes. Most F2 plants have more chromosomes of J. curcas than J. integerrima, and yet interspecific translocation was frequently found. When the progenies were further intercrossed, the resulting clones exhibited many characters not found in the J. curcas germplasm. They were traits related to seed and oil yield, fatty acid composition, plant architecture, biomass yield and quality, and ornamental characteristics. The clones show much higher genotypic and phenotypic variation in seed yield, oil content, 100-seed weight, and canopy size as compared to J. curcas and thus serve as promising genetic resources for Jatropha improvement in the future. |
