Effect of salicylic acid on enzymes of nitrogen metabolism during germination of soybean

The effect of different concentrations of salicylic acid (SA) on seed germination and biochemical changes in terms of enzymes of nitrogen metabolism in six day old seedlings of soybean (Glycine max L.) was examined. The results revealed that the germination was decreased with the increasing level of SA. At lower concentrations of SA the soluble protein, free amino acid and free tissue ammonia contents were increased while reverse was true at higher concentrations. Both specific and total glutamine synthetase (GS) and glutamate dehydrogenase (GDH) activities were enhanced at lower concentrations of SA but at higher concentrations, the activities of these enzymes were declined further. However, GDH activity in treatments was always higher than control. On the other hand the glutamate synthetase (GOGAT) activity was less at lower concentrations of SA while at higher concentrations, activity was enhanced.