Salt-induced biochemical changes in germinating seeds of three rice cultivars differing in salt tolerance

A study wag conducted to assess some salt-induced physiological and biochemical changes in the germinating seeds of three rice cultivars (IRRI-6, salt tolerant; NIAB-IRRI-9, moderately salt tolerant; 38/88, relatively salt sensitive) under controlled conditions. The results from different biochemical analyses showed that increase in NaCl concentration in the growth medium reduced the activities alpha-amylase and protease in the germinating seeds of all three rice cultivars examined, however, the reduction in enzymatic activities was more pronounced in cv. 38/88 than that in the other cultivars. A decrease in the concentration of reducing and non-reducing sugars in the germinating seeds of all cultivars was observed, particularly during the period from 24 to 72 h. The decrease in Sugar content in the germinating seeds was found to be attributable to salt-induced reduction in alpha-amylase activity. Similarly, as a result of salt-induced reduction in protease activity, a decrease in the breakdown of reserve proteins and accumulation of amino acids were recorded in the germinating seeds of all cultivars. Under saline conditions cv. IRRI-6 followed by NIAB-IRRI-9 was the highest, whereas cv. 38/88 the lowest in germination, growth, alpha-amylase and protease activities, reducing and non-reducing Sugars. Overall, the three rice cultivars, known for their different degree of salt tolerance at the adult stage, maintained their respective salt tolerance potential at the germination stage.