Biology of Jatropha curcas
Biology of Jatropha Curcas

 

Commonly named the Physic Nut, Barbados Nut, Purging Nut and being a member of the Euphorbiaceae Family, Jatropha curcas (Jatropha) is a shrub with a smooth gray bark that grows up to 6 meters tall. It has large (pale) green and shallow lobed leaves that are arranged alternatively. Native to tropical America, it is also cultivated widely in tropical countries throughout the world, mainly as a living fence and hedge plant.

Jatropha grows on well-drained soils with good aeration and is well adapted to marginal soils with low nutrient content. Its water requirement is low and it can withstand long periods of drought by shedding most of its leaves to reduce transpiration loss. Jatropha has yellow-green monoecious flowers (male and female flowers on the same plant), generally with many more male than female flowers. Flowers are pollinated by insects, especially honey bees. Seeds mature in about two months after flowering. Jatropha can produce seeds from the first year of planting onwards, for as long as 50 years under humid conditions.

A Jatropha fruit contains 2-4 large, black, oily seeds that contain up to 35% of non- edible oil with the following four most abundant fatty acid components: palmitic (C16:0), stearic (C18:0), oleic (C18:1) and linoleic (C18:2) acids. Jatropha seeds contain considerably higher unsaturated fatty acids (oleic and linoleic) than saturated fatty acids (palmitic and stearic).

Jatropha nuts are purgative and toxic. The oil from seeds has been used for illumination, soap, candles and making Turkey red oil. The seed cake after oil pressing is a good organic fertiliser. Jatropha has been a folk remedy for many ailments such as burns, cough, diarrhea, inflammation, rheumatism and yellow fever. Some anti-tumor compounds including jatropham and jatrophone have been recently reported.

Jatropha is gaining international attention in recent years because of its good potential as a biodiesel feedstock plant. First of all, it is regarded as a highly productive oil producing species, with an estimated oil productivity of 1,300 liters per hectare (ha), which is higher than those for the traditional oil crops like rapeseed, sunflower and soy bean. Secondly, it also has an ideal fatty acid profile for the purpose of biodiesel. With much higher proportion of unsaturated fatty acids, Jatropha biodiesel has a lower melting point than that derived from Palm oil, which contains a higher proportion of saturated fatty acids, making it better suited for cold climates. On the other hand, the content of unsaturated fatty acid in Jatropha seed is not too extreme to compromise its oxidation stability. Extensive tests indicated that Jatropha biodiesel is not only suitable for diesel engines on land vehicles; it is also suitable as a blend for airplane engines.

Thirdly, due to its tolerance to marginal soil with poor nutrients and the less water requirement for its growth, Jatropha plantations can be set up in areas not suitable for general crop farming, thus alleviating concerns of competition for crop land. Growing Jatropha in deserted arid land has the additional benefit of claiming eroded and waste land. Fourthly, Jatropha is less demanding for land clearance and presumably requires less fertilizer, herbicide, insecticide and other agrochemicals. Together with its fewer requirements for maintenance, it has a more favorable rating in "energy" balance and "net carbon dioxide emission" index. Finally, in addition to helping achieving energy self- sufficiency, Jatropha plantations will create employment and help rural economies.

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