Sodium chloride-stress induced proline accumulation in attached senescing leaves of rice cultivars

Accumulation of proline under NaCl-stress was studied in attached third leaf of a salt-sensitive (Ratna) and a salt-tolerant (Getu) rice cultivar during dark-induced senescence. The rate ofleafsenescence, as measured by loss of chlorphyll, was enhanced more in the sensitive than in the tolerant cultivar under NaCl-stress both in a concentration-dependent (0–200 mM) and time-dependent (0–8 day) manner. Salinity significantly enhanced the rate of proline accumulation in the senescing leaves of both the cultivars, the trend being more pronounced in the tolerant than in the sensitive cultivar. The results suggest that proline accumulation is not an exact measure of rate of leaf senescence in attached condition as subjected to salt-stress. It also provides additional evidence in support ofthe view that proline accumulates more in the tolerant than in the sensitive genotype under salt-stress.