Jatropha curcas L. -An alternative oil crop

Abstract

J. curcas L. is able to grow under subtropical and tropical conditions with an annual precipitation that ranges between 1,200 and 2,000 mm. The length of the growing season should range between 5 and 11 month, naturally or prolonged by respective irrigation measures. J. curcas L. produces flowers and fruits continuously, which means that there may be several harvest peaks per year, depending on genotype and climatic conditions. Also fruits at different maturity stages can be found at the same time on the same shrub. The oil content in the seeds reach the maximum when fruits are mature, accordingly of yellow-brown colour. Jatropha curcas L. is capable of capturing 17 to 27 t CO2/(ha a). As a perennial shrub it can capture CO2 for a period of more than two decades, which makes J. curcas L. suitable for long-term CO2-sequestration. The key product of J. curcas L. today is, as mainly toxic varieties are cropped because of their higher yield potential, oil that can be used straight or as a blend for fossil fuels in combustion engines or be converted to a fossil diesel or jet fuel substitute. State of the art in oil extraction technique is mechanical expelling with an subsequent filtration prior to further conversion. Traditionally Jatropha curcas L. is cultivated as "living fences" to protect housings, to fence in livestock and for soil conservation (prevention of wind and water erosion of soil). Nowadays, particularly in the context of bio fuel production, large scale plantations are the normal case. The most prominent form of cultivation in J. curcas L. projects are plantations, typically ranging in a size between 100 and 1,000 ha, most of them are monoculture plantations. Plant protection, weeding and pest control, is of importance particularly in monoculture plantations, also fertilisation and a sufficient water availability plays an important role. Crucial to the success of commercial Jatropha curcas L. projects are cultivars meeting the DUS (distinctiveness, uniformity and stability) criteria. Also paying attention to the selectivity of the harvest process is crucial and describes a major challenge in the development process of mechanical harvest systems.