Radhakrishnan Selvaraj and Dharman Dhakshanamoorthy
Department of Botany, Annamalai University, Annamalainagar-608 002, Tamilnadu, India
The use of biomass to produce energy is only one form of production of renewable energy that can be utilized to reduce the impact of energy production and use on the global environment. Biomass has the largest potential and can only be considered as best option for meeting the demand and insurance of future energy/fuel supply in a sustainable manner. It has been known for decades to be one of the better renewable energy sources that can be used for production of biofuels, since it is an abundant resource, has low environment impact of low Co2 emission, cost effective and renewable. Hence, a wide spectrum of feedstock that can be used to synthesize biodiesel are edible oils, non-edible oils, waste cooking oils, waste frying oils, animal or fish waste oil and microalgae oil. Approximately about 10% of edible vegetable oils globally have been reported to be diverted to the production of biodiesel in 2007. The available reports say that among the plant origin oils, edible oil contributes 95% of the feedstock constituent for production of biodiesel, since it has low free fatty acid (FAA) content which allows single step esterification of the oil. Limited availability of the edible oil in many developing and undeveloped countries poses a question mark to the continuance of production of biodiesel from edible oils.
Jatropha (J. curcas L.) is commonly known as purging nut or physic nut, a perennial deciduous and multipurpose shrub belonging to the family Euphorbiaceae. Primarily Jatropha plant was used for its medicinal values, and in recent years, the seed oil has however gained tremendous significance as a biofuel. There is some controversy about its centre of origin, but Mexico and Central America are considered as the most likely sites. Now, it is widely distributed in America, Africa, India and South East Asia.
The genus Jatropha is morphologically diverse encompassing more that 200 species, which are distributed chiefly in dry tropical regions of America. It has been later introduced into Africa and Asia and now cultivated worldwide. J. curcas is a multipurpose shrub with significant economic importance to provide a source of bioenergy. Since the oil crisis of the 1970s and recognition of the limitation of world oil resources, most of the oil importing countries, including India have been motivated to develop alternative sources of energy. Recently, the attention has been drawn to obtain high oil content (50-60%) in J. curcas seeds that can be easily processed to partial or full replacement of petroleum based diesel fuel. To increase the oil content in plant species, it is likely that there is a prerequisite to create greater genetic diversity in J. curcas by applying conventional breeding techniques, however, with the exception of research using germplasm collections from different regions. Among the conventional breeding techniques, mutation breeding may be suitable for improving the genetic diversity/agronomic traits in crop plants. The rate of spontaneous mutations in nature is too low for plant breeding programme. Therefore, physical and chemical mutagens can be used for inducing mutation in plants. It is possible to increase the genetic variability by inducing mutations in plants with chemical [Ethyl methane sulphonate (EMS)] and physical (gamma rays) agents in both in vivo and in vitro studies of mutation breeding.