Global maximization of Jatropha oil production under semi‐arid conditions by balancing vegetative growth with reproductive capacity

• Published in: Global change biology. Bioenergy 2018-06, Vol.10 (6), p.382-392
• Main Authors: Vaknin, Yiftach, Yermiyahu, Uri, Bar‐Tal, Asher, Samocha, Yael
• Format: Article
• Language: English
• Subjects: Aridity; biodiesel feedstock; Biodiesel fuels; Biofuels; bloom phenology; Crop production; Crop yield; Drought; Evapotranspiration; fatty acid composition; Fruits; growth regulators; Irrigation; Jatropha; Maximization; Oil and gas production; Optimization; Petroleum production; reproductive success; Ripening; vegetative arrest
• ISSN: 1757-1693; 1757-1707
• DOI: 10.1111/gcbb.12497

Jatropha curcas L. is a drought tolerant crop that is globally cultivated under semi‐arid conditions as a biodiesel feedstock. Despite its great potential, however, many projects failed to reach commercially viable seed and oil yields. The aim of the study was to provide globally applicable solutions for maximization of Jatropha oil production under semi‐arid conditions. Under extremely low irrigation (10% of potential evapotranspiration; ETp), fruit production was very low and a surprisingly significant portion of the fruits delayed their maturity up to six months post‐bloom. Increasing irrigation to mid‐level (60% ETp) significantly elevated fruit production and speeded up the ripening rate, whereas further increasing irrigation to a higher level (90% ETp) decreased seed and oil yields, probably due to the increased investment in vegetative growth. Nevertheless, maximal seed and oil yields at 60% ETp remained far below targeted yields. Coupling irrigation at 60% ETp, with induction of vegetative arrest, by soil application of a commercial gibberellin synthesis inhibitor, brought forward the second bloom period by two months, reduced vegetative growth, promoted floral production and significantly enhanced reproductive capacity by more than doubling oil production. The results show that under semi‐arid conditions, commercially viable seed and oil yields of Jatropha can be achieved by carefully balancing vegetative growth with reproductive capacity through the combined application of optimal irrigation regimes and induced vegetative arrest. We showed that under semi‐arid conditions, commercially viable seed yields of Jatropha (above 2000 Kg/Ha/Yr) can be achieved by carefully balancing vegetative growth with reproductive capacity through the combined application of optimal irrigation regimes and induced vegetative arrest using Magic; a gibberellin synthesis inhibitor. In our study, all Magic treated trees, regardless of irrigation level, resulted in seed yields exceeding commercially targeted levels. The highest yields were recorded for mid‐level irrigation (60% ETp) and the lowest ones were for high‐level irrigation (90% ETp). Mid‐level irrigation only, resulted in borderline commercially viable yields.