The Effects Of Water And Nitrogen On Starch Synthesis And Activities Of Its Key Enzymes In Wheat

Water and nitrogen are two important factors that affect the growth of wheat, and also a couple of factor which interact each other. Only reasonable water and fertilization operations can improve the yield of wheat. Previous studies mainly focused on the regulating effect of single factor on the photosynthetic characteristics and yield of wheat, but the effects of different water treatment couples with nitrogen levels on the photosynthetic characteristics, the key enzymes of starch synthesis and yield in wheat were still not studied deep enough. Therefore, this experiment researched the effects of different water treatments couples with different nitrogen levels on photosynthetic characteristics, sucrose metabolism, key enzymes activities of starch synthesis and yield components in wheat, to improve the grain yield through the way of improving the water and nitrogen utilization rate, and provide theoretical basis of saving water and fertilizer management of wheat cultivation for the drought area.In this experiment, wheat cultivar Changhan58 was selected under pot conditions, three nitrogen levels(N0, N1, N2) and two water treatments(W1, W2) were set for the pot experiment during post-anthesis. We measured and analyzed the effects of different water treatments couples with different nitrogen levels on photosynthesis characteristics, key enzymes activities involved in starch synthesis, and yield components of grains in wheat. On this basis, the main results are as follows:1. The photosynthetic net rate increased with increasing nitrogen amount application under two water treatments. Under the nitrogen 0 and normal nitrogen level treatments, The water stress treatment can enhanced the flag leaf photosynthetic rate compared to the full irrigation treatment, it shows that under normal nitrogen level treatment, the moderate water stress can improve the wheat flag leaf photosynthetic capacity. While the opposite conclusions was obtained under high nitrogen treatment.2. The water stress treatment induced the increase of SS activities during the early filling stage under normal nitrogen levels, increased the transportation of assimilation after anthesis, and decreased the sucrose content.3. The water stress treatment was good for accumulation of starch in grains during early filling stage, water stress can improve the activities of AGPase and SSS during early filling stage, and reduce their activities at late grain filling stage. The reduction of activities related to starch synthesis because of water deficit stage was the interal enzymatic mechanism lead to the accumulation rate of starch decreased during late filling.4. Different nitrogen treatment significantly influences the final yield of wheat through the spike numbers and the grain numbers, and water stress after anthesis helps improve the yield through improving the grain weight.