Effect of salt stress on plant regeneration efficiency in primed and non-primed seed's calli of rice (Oryza sativa L.) variety Swarna.

This study leads with the primed seeds of rice (var. Swarna) with distilled water (D.W.) and various concentrations of Mg(NO₃)₂ (0-8 mM)/Kinetin (0-5 ppm) alone or in combination with screen out the regeneration medium induced tolerance level of NaCl. To fulfill the objective, the primed and non-primed rice seeds were inoculated in MS medium supplemented with 30 gL^-1 maltose + 1 gL^-1 casein hydrolysate and 2 mgL^-1 of 2,4-D for callus induction and cultured up to 45 days in two sets: one set for regeneration purpose in NaCl-induced regeneration medium and another set was used to study the physiological potentiality of the callus. The 45-day-old calli were transferred into regeneration medium MSR (MS medium for regeneration) (BAP: NAA: Kinetin = 4:1:1) containing NaCl with a concentration range of 0 to 300 mM. The number of regenerating calli and shoot regeneration percentage, number of plantlets obtained from one callus, recovery of plantlets from each concentration of NaCl and proline estimation from the leaf of the regenerated plantlets were determined from one set obtained after 45 days. The calli obtained from another set after 45 days, the frequencies of total and embryogenic calli induction percentage, fresh and dry weights, proline content, nitrate reductase and superoxide dismutase activities were measured. The calli obtained from 2.5 ppm kinetin + 4 mM Mg(NO₃)₂ primed seeds were showed best result as compared to the other treatments for the above-mentioned parameters in different concentrations of NaCl-induced medium and survive up to 200 mM concentrations of NaCl.