Induction of Salt Tolerance for Radicle Growth in Groundnut through Gamma Ray Mutagenesis

Groundnut is an important oilseed, food and feed crop of our country whose productivity is curtailed due to biotic and abiotic stresses. Salinity is one of the important abiotic stresses which affects all stages of groundnut growth and finally the yield. Soil amelioration against salinity is a costly and time-consuming procedure. Alternative strategy is to develop salinity-tolerant groundnut genotypes to overcome salinity problem, towards which, success has so far not been attained in groundnut, due to lack of efficient and simple screening protocol for salt tolerance. In the present study, we have developed a simple, cost effective and repeatable protocol for screening large number of mutant/segregating populations for radicle growth. Genetic variability for germination under 400mM NaCl stress was observed, among established TAG 24 mutants. Superior radicle growth in six of the TAG 24 mutants was noted by screening at 125mM and 150mM NaCl. Further, three mutants showed increased tolerance due to greater radicle length and lesser radicle reduction at 125mM and one mutant at 150mM NaCl. Induction of genetic variability for radicle growth under saline conditions in large seed groundnut variety TPG 41 was carried out, through gamma ray mutagenesis. By screening large number of seeds at 100mM NaCl during M 3 generation followed by screening plant wise during M 4 and M 5 generations, 91 true breeding mutants having salt tolerance for radicle growth were isolated. As a result, by screening from F3 to F5 generations, 114 true breeding lines were identified having salt tolerance for radicle growth. These mutants and breeding lines will be evaluated in the salt-affected soils for their salinity tolerance and yield performance.