IMPROVEMENT OF SALT TOLERANCE IN SOME IMPORTANT PULSE CROPS

Abstract

Cons1derable efforts have made in the last two decades to develop salt tolerant cultivars/lines of important crops. This has been done in view of the evidence that select10n and breeding for salt tolerance is an efficient and economic approach of overcoming salt-affected soils. since various reclamative methods and management practices are highly expensive in terms of money and labour therefore they can not be contemplated in most developing countries.

Presence of variation for salt tolerance is a pre- requisite for t he improvement of any character. Screening of

available germplasm or a crop species provides information regarding the extent of variation for the desired character. With this aim in mind local and exotic germplasm of four pulse crops. lentil. chick pea, mungbean and pigeon pea was screened. 133 accessions of lentil ( Lens culinaris Medic.) :nost of them obtained from ICARDA. were screened at the germination and seedling stages. A great magnitude of variation for salt tolerance was observed in this species at both the growth stages. although degree of tolerance varied significantly at both grow h stages. However two accessions ILL 6451 and ILL 6788 were consistantly superior to all the remaining accessions studied at all growth stages including grain yield. The greater sal tolerance of these two accessions was associa ed wi h e + inclusion of Na and Cl in their leaves. Similarly 32 accessions cf chick pea(Cicer arietinum) .. most of them obtained from ICRISAT. were sc end a hr g OW h

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stages as of lentil. Two accessions CM 663 and 10572 were consistently tolerant at all growth stages as compared with all the remaining accessions tested. Both the salt tolerant + accessions also accumulated high concentrations of both Na and Cl in the shoots as was observed in the salt tolerant accessions of lentil.

Twenty seven accessions of mungbean tVigna radiata(L.)Wilezek) screened at the three growth stages i.e .. germination, seedling and adult stage. Two accessions Pak 45600 and Pak 45603 found relatively salt tolerant in biomass production and seed yield. Both accessions also were accumulators + of Na and Cl in the shoots as was observed in lentil and chick pea. Only three accessions of pigeon pea{Cajanus cajan(L.)Mills screened at three developmental stages. ICPL 151 was the most salt tolerant of all accessions examined. But the tolerance of this accession was associated with its ability to exclude both + Na and Cl from its shoots. Estimation of components genetic variation such as additive dominance and epistasis is crucial to devise an appropriate breeding programme for improvement of salt tolerance.Two salt tolerant and two salt sensitive accessions of pigeon pea were crossed following a diallel crossing design. Only additive effect was found to be significant which suggests that a significant advance in salt tolerance of pigeon pea is expected through rigorous recurrent selection.

For the genetic studies in lentil. chick pea and mungbean pair crosses were made between one salt tolerant and one sal

sensitive accession. Additive and dominance components of variation were estimated using additive dominance model (Mather and Jinks.1971). High additive and dominance components were observed in lentil and mungbean, whereas in chick pea only additive effect was high. Improvement of salt tolerance in chick pea and lentil was made through selection and breeding. 5000 seeds of variable material of lentil and chick pea were screened in salinized

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solution culture at 70 and 100 mol m NaCl respectively. Selection intensity less than 1% was attained.The selected lines of both the species considerably excelled the unselected lines in seed yield and yield components.

This study clearly depict that a significant improvement can be made through repeated cycles of selection since a great magnitude of genetic variation is available in gene pool of all four pulse crops examined.