Induced mutation and in vitro techniques as a method to induce salt tolerance in Basmati rice (Oryza sauva L.)

Embryogenie callus of indica rice (Oryza sativa L.) cv. Basmati 370 induced on MS medium containing 9.05 μM2,4-D was irradiated at 50 Gy of gamma rays of ⁶⁰Co for creating genetic variability against salinity. Irradiated and non-irradiated calluses were screened in vitro through three consecutive proliferation phases at 4.0, 6.0, 8.0 and 10.0 d/Sm electrical conductivity of NaCl. Growth value and number of adapted mutagenized callus was more than that of non-mutagenized callus. Salinity levels beyond 6 d/Sm and 8 d/Sm were lethal to growth and adaptation of non-irradiated and irradiated callus respectively. NaCl adapted irradiated callus showed 2.0%–4.75% regeneration frequency on MS regeneration medium containing 5.37 MNAA and 9.29 μMKinetin. Non-mutagenized salt adapted callus did not show any regeneration. From gamma ray mutagenized cultures, 2 putative lines (M₂ generation) with moderate salt tolerance were obtained at seedling stage. The results suggest that in vitro technique in connection with gamma rays may be used as a versatile approach to improve the level of salt tolerance in Basmati rice for saline environment.