Environmental impact of genetically modified crops.

Chapter 14 (Page no: 296)

Biofuels: Jatropha curcas as a novel, non-edible oilseed plant for biodiesel.

The negative environmental impacts, the limited sources and rising prices of fossil fuels pose significant environmental and socio-economic challenges. Globally, major national and international initiatives are under way to identify, revive, research and recommend renewable sources of energy. One such renewable source is esterified vegetable oil, i.e. biodiesel. Crop plants yielding edible oilseeds can be diverted to the biodiesel market only to a limited extent due to their value in the food sector. One route to meeting the gap between the demand for food oils and the need for alternative fuel oils is the use of non-edible oilseed plants such as Jatropha curcas. J. curcas or physic nut is a member of the Euphorbiaceae family and has been the subject of much interest as a source of biodiesel due to a number of perceived advantages. For example, the by-products of J. curcas-based biodiesel production have potential as a nutritious seed cake for fodder, as a soil amendment or as a biogas feedstock. Glycerol can be used in a variety of industrial applications and J. curcas leaf, stem and bark extracts have uses in the medicinal, cosmetics, plastics and insecticide/pesticide industries. As an aid to sustainable rural development, J. curcas grows on marginal and wastelands promoting effective land use, gender empowerment and soil rehabilitation. However, neither J. curcas nor any other potentially useful non-edible oilseed plant is currently grown commercially. In fact, such plants are generally undomesticated and have yet to be subject to any genetic improvement with respect to yield quality or quantity. Also, many J. curcas accessions can be toxic to humans and animals due to the presence of toxic compounds such as curcins and phorbol esters. Thus, despite the enthusiasm in some countries for widespread plantation cropping, J. curcas is currently not commercially viable as a biodiesel feedstock without genetic improvement either through conventional breeding or molecular engineering because of unpredictable yield patterns, varying, but often low, oil content, the presence of toxic and carcinogenic compounds, high male to female flower ratio, asynchronous and multiple flowering flushes, low seed germination frequency, plant height and its susceptibility to biotic and abiotic stresses. This paper reviews the potential of Jatropha as a model, non-edible, oilseed plant and the research needed to realize its potential as a bioenergy crop.

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