MODIFICATION OF SALT TOLERANCE LEVEL IN GROUNDNUT (ARACHIS HYPOGAEA L.) THROUGH INDUCED MUTATION

Three experiments were carried out in pots under glass house conditions of Bangladesh Institute of Nuclear Agriculture (BINA) to assess tolerance levels of groundnut mutant genotypes/mutant varities to salinity stress. The first experiment assessed salinity levels based on reduction in shoot biomass under 8 desi siemen per meter (dS/m) salinity imposed during flowering till harvest stages of 41 mutants, 4 mutant varieties and 5 non mutant varieties including the parent of the mutants and mutant varieties. Based on the result of the first experiment 22 mutants/varieties with higher, moderate and lower shoot biomass reductions were further screened based on pod number and pod weight under the same salinity level and growth stages. It was observed that the mutants and mutant varieties attained different levels of salinity tolerance in contrast to to their parent Dacca-1 which was highly sensitive. From the third experiment, it was also revealed that the tolerant mutant/variety accumulated increased total sugar contents to that of unstressed control treatment when exposed to salinity stresses during flowering and pod filling stages and free amino acid during pod filling stage, helped maintaining turgor of guard cell and intake of CO2 through opened stomata. This CO2 in presence of undamaged chloroplast helped maintaining photosynthesis and mobilization of assimilates to reproductive organs, particularly kernel. Finally, it was concluded that it is possible to modify salinity tolerance level of a sensitive groundnut through induced mutation by. directly irradiating its seed or seeds of mutant(s) derived from it.