No abstract

Soil erosion by water has a debilitating effect on crop productivity. Though limited and scattered data is available on loss of production due to water erosion in India, no systematic effort has been made to compute the losses in crop production based upon experimental data, major soil groups, and prevailing erosion rates. The objective of this study is to estimate on-site physical and economic loss of production of major cereal, oilseed, and pulse crops cultivated on rainfed areas of India due to soil erosion by water. The estimation is done by integrating the available experimental data of a crop with the rainfed area of that crop under each erosion intensity category for each of the three major soil groups (alluvial, black and red) in a given state. Following this approach, the total production loss due to water erosion of rainfed areas under major cereal, oilseed, and pulse crops in India was observed to occur at 16%, which in actual physical terms was estimated as 13.4 million t (13.2 million tn) and in economic terms as $2.51 billion (INR 111.3 billion) (the conversion has been given in US dollars as per average conversion rate of 2005 to 2006, i.e., at INR 44.273 per US dollar). Among the six zones of India, the average production loss occurred within a range of 10% (northern) to 24% (southern). At state level, the production loss ranged from 1.4% in Punjab and Haryana states located in alluvial Indo-Gangetic Plains to 41% in the erosion-prone northeastern Himalayan state of Nagaland. In terms of production loss among major groups of crops, cereals contributed 66% to the total loss, followed by oilseeds (21%) and pulses (13%). A similar trend was observed for the monetary losses amounting to 45% for cereals, 33% for oilseeds, and 22% for pulses. Paddy was the most affected among all the crops in terms of both production (4.3 million t [4.23 million tn]) and monetary ($0.56 billion [INR 24.4 billion]) losses. Since the losses are cumulative over time, it is imperative to undertake appropriate soil and water conservation measures for rehabilitation of rainfed areas to prevent huge declines in their productivity levels, which may escalate further due to population pressures.

The present investigation aimed to evaluate the reliability of in vitro propagation methods for elite genotypes of Jatropha curcas L., that maintain genetic integrity of tissue culture (TC) regenerates among two regeneration systems developed through direct shoot bud regeneration using nodal/apical shoot segments (protocol-A) and in vitro-derived leaves (protocol-B) as explants. Random amplified polymorphic DNA (RAPD), intersimple sequence repeat (ISSR), simple sequence repeat (SSR) molecular markers, and flow cytometery (FCM) were employed to evaluate genetic homogeneity in TC-regenerates at different passages of subcultures. RAPD markers showed genetic homogeneity in fifth-generation TC-regenerates of both protocols. ISSR markers showed genetic stability of leaf regenerates (protocol-B) at 10th generation. FCM analysis of TC-regenerates at 10th generation in protocol-B and at 20th generation in both protocols, showed stability of ploidy level. SSR assessment of TC-regenerates at 20th generation in both protocols confirmed genetic homogeneity. The results confirmed the genetic stability of the TC-regenerates and demonstrated the reliability of the regeneration systems developed so far using explants of two different origins, for large-scale multiplication of elite genotypes of Jatropha.

Jatropha curcas L. (Euphorbiaceae) has acquired a great importance as a renewable source of energy with a number of environmental benefits. Very few attempts were made to understand the extent of genetic diversity of J. curcas germplasm. In the present study, efforts were made to analyze the genetic diversity among the elite germplasms of J. curcas, selected on the basis of their performance in field using random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP) and simple sequence repeats (SSR). The plants were selected on the basis of height, canopy circumference, number of seeds per fruit, weight of 100 seeds, seed yield in grams per plant and oil content. Out of 250 RAPD (with 26 primers), 822 AFLP (with 17 primers) and 19 SSR band classes, 141, 346 and 7 were found to be polymorphic, respectively. The percentage polymorphism among the selected germplasms using RAPD, AFLP and SSR was found to be 56.43, 57.9, and 36.84, respectively. The Jaccard's similarity coefficient was found 0.91, 0.90 and 0.91 through RAPD, AFLP and SSR marker systems, respectively. Principle component analysis (PCA) and dendrogarm analysis of genetic relationship among the germplasm using RAPD, AFLP and SSR data showed a good correlation for individual markers. The germplasm JCC-11, 12, 13, 14 and 15 whose yield found to be high were clustered together in dendrogram and PCA analysis though JCC11 is geographically distinct from others. In overall analysis JCC6 (in RAPD), JCC8 (in AFLP) and JCC 6 and JCC10 (in SSR) were found genetically diverse. Characterization of geographically distinct and genetically diverse germplasms with varied yield characters is an important step in marker assisted selection (MAS) and it can be useful for breeding programs and QTL mapping.