Effect of soil moisture levels on activity of nitrogen assimilating enzymes in post-anthesis flag leaves and grain protein content of different gluten content of wheat.

Effects of soil water on activity of nitrogen assimilation enzymes in post-anthesis flag leaves and grain protein content of different gluten content of wheat were studied in pot experiments.The results showed that nitrate reductase(NR) activity in post-anthesis flag leaves of Yumai 34,a strong gluten cultivar,changed as follows: it was the strongest when soil water content was 60% field capacity(FC),it was the lowest when the water content was 80%FC,and it was in between when the water content was 40%FC.The order of GS(glutamine synthetase) activity and GOGATE(glutamate synthase) activity were both as 80%FC60%FC40%FC.The maximum activity of NR and GS activity in flag leaves of Yumai 49,a medium gluten cultivar,appeared when water content was 60%FC.The order of NR activity in flag leaves of Yumai 50,a weak gluten was generally as 60%FC40%FC80%FC.The maximum activity of GS in flag leaves of Yumai 50,a weak gluten cultivar,appeared when water content was 80%FC.Soil water stress improved grain protein content.The grain protein content of Yumai 34 was the highest when water content was 60%FC,and for Yumai 49 and Yumai 50 the highst protein content appeared when water content was 40%FC.Protein content was positively correlated to NR and GS activities in the flag leaves,but was not significantly and negatively correlated to GOGATE activity at different water levels.