Author(s):

SN Jadhav, RM Naik and US Dalvi

Abstract: Laboratory and pot culture experiments were conducted to evaluate the levels of osmoprotectant such as proline, glycine betaine, activity of P₅CS and soluble proteins in the leaves of five drought tolerant and five drought susceptible cultivars with segregating crosses of rabi sorghum by the imposed stress created by withholding irrigation as well as by osmotic stress created by PEG-6000. Imposition of osmotic stress was found to increase the mean proline accumulation in leaves from 42.24 to 156.04 μmoles g^-1 fr. wt., an increase of 3.73 folds in tolerant types. Under similar conditions, the mean proline accumulation was found to range from 61.21 to 128.26μmoles g^-1 fr. wt. an increase of 2.15 folds in susceptible types. The crosses involving drought tolerant parents viz CSV 216(DS)x RSV 458(DR) and SPV1502(DS) x RSV 458 (DT) led to increased proline accumulation as evident from higher fold increase. It thus appears that the exploitation of drought tolerant male parent in breeding for drought tolerance can further improve higher proline accumulation and thus endow the plant with improved drought tolerance performance. The mean P₅CS activity was found to increase from 1.55 to 4.01 μmoles of γ -glutamyl hydroxamate formed g-¹ tissue hr-1, an increase of 2.66 fold in tolerant type while it was found to increase from 1.67 to3.01 μ moles of γ- glutamyl hydroxamate formed g^-1 tissue hr^-1,an increase of 1.80 -fold in susceptible cultivars. Similarly, other osmolyte glycine betaine accumulation was found to be an increase of 3.50 -fold in tolerant cultivars and an increase of 1.84-fold in susceptible cultivars of sorghum under stress created by withholding irrigation.

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