The effect of drought stress was studied to determine the effect of different moisture stress levels on the yield, protein contents and the activity of glutamine synthetase, a key enzyme of ammonia assimilation in four tomato varieties i.e Roma, Bunhong, Lyp-1 and Eva. Among four moisture stress levels (M1, MM2, MM3 and MM4 at 40, 50, 60 and 70% depletion of available moisture). MM1 (40% depletion of available moisture) proved the best level for attaining the maximum yield of all the tested varieties. Among varieties, Lyp-1 gave the best yield at all moisture stress levels followed by Eva, Roma And Bunhong. Glutamine synthetse activity at flowering stage in the tested varieties was low at MM1 and MM2 but increased after irrigation application. It was high at MM3 and MM4 but decreased on rewatering. Protein contents of leaves at the flowering stage were low at the tested moisture stress levels before irrigation but increased after application of water.
Khizar Hayat Bhatti , Tahir Rashid and M. Fayyaz Chaudhary , 2000. Effect of Drought Stress on the Yield, Glutamine Synthetase Activity and Protein
Contents in Four Varieties of Tomato . Pakistan Journal of Biological Sciences, 3: 1772-1774.