Eco-physiological studies on Indian arid zone plants : II. Effect of salinity and gibberellin on the activity of the enzymes of amino-acid metabolism in leaves of Pennisetum typhoides.

The separate and combined effects of sodium chloride and gibberellin (GA) on growth and the activities of alanine aminotransferase (GPT), aspartate aminotransferase (GOT) and glutamate dehydrogenase (GLDH) have been studied in the aerial parts of Pennisetum typhoides seedlings. Salt concentrations higher than 8.55×103 M inhibited growth and reduced GLDH activity, but strongly stimulated the activity of GPT and, to a lesser extent, that of GOT. GA alone, on the other hand, stimulated growth but did not affect activity of any of the enzymes tested. In combination with salt, however, GA tended to counteract the effect of salt on both growth and enzyme activity. The possible significance of the results in explaining adaptation of plants under conditions of stress has been discussed.