In Vitro Influence of drought on some physiological parameters in callus induced from seeds of four Rice cultivars (Oryza sativa L.)
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In Vitro seeds of four rice cultivars, Amber 33, Jasmine, IRRI 132 and IR 06L 144 were surface sterilized by using various combinations of ethanol and sodium hypochlorite. For callus induction, mature seeds were cultured on MS medium supplemented with 2,4-D at four concentrations (0.5,1.0,2.0 and 3.0 mg.l-1). Finally callus were exposed to drought stress condition by using Polyethylene glycol (PEG) at four concentrations (0, 20 , 40 or 80 g.l-1). Results revealed that despite treating mature seeds of all rice cultivars with either (90% Ethanol 2 min +3% NaOCl 45min) or (90% Ethanol 2 min +6% NaOCl 45 min) gave no contamination percentage, yet the last treatment yielded no surviving seeds. Furthermore, responses of rice seeds for callus induction were found to be genotype dependent .However, 3.0 mg.l-1 concentration of 2,4-D was optimum as compare to 0.5,1.0 or 2.0 mg.l-1. Moreover, a significant reduction in fresh weight when callus of rice exposed to 40 or 80 g.l-1 of PEG and significant increase were found in the accumulation of proline and carbohydrate in response to high level of PEG stress.
Keywords: Rice, In Vitro, PEG, Callus , proline, carbohydrate