Effect of air desiccation and salt stress factors on in vitro regeneration of rice (Oryza sativa L.)

Enhancement of callus induction and its regeneration efficiency through invitro techniques has been optimized for 2 abiotic stresses (salt and airdesiccation) using 3 rice genotypes viz. BR10, BRRI dhan32 and BRRIdhan47. The highest frequency of callus induction was obtained for BRRI dhan32(64.44%) in MS medium supplemented with 2, 4-D (2.5 mgL⁻¹) and Kin(1.0 mgL⁻¹). Different concentrations of NaCl (2.9, 5.9, 8.8 and 11.7gL⁻¹) were used and its effect was recorded on the basis of viabilityof calli (VC), relative growth rate (RGR), tolerance index (TI) and relative water content(RWC). It was observed that in all cases BRRI dhan47 showed highest performance ontolerance to VC (45.33%), RGR (1.03%), TI (0.20%) and RWC(10.23%) with 11.7 gL⁻¹ NaCl. Plant regeneration capability wasrecorded after partial air desiccation pretreatment to calli for 15, 30, 45 and 60 h.In this case BRRI dhan32 gave maximum number of regeneration (76.19%) when 4 weeksold calli were desiccated for 45 h. It was observed that air desiccation was 2-3folds more effective for enhancing green plantlet regeneration compared to controls.Furthermore, desiccated calli also showed the better capability to survive in NaCl inducedabiotic stress; and gave 1.9 fold (88.80%) increased regeneration in 11.7gL⁻¹ salt level for BRRI dhan47. Analysis of variance (ANOVA) showedthat the genotypes, air desiccation and NaCl had significant effect on plant regenerationat P < 0.01.