Effects of Post-Anthesis Irrigation on the Activity of Starch Synthesis-Related Enzymes and Wheat Grain Quality under Different Nitrogen Conditions

Abstract

To develop optimal management strategies for water and nitrogen fertilizer application in winter wheat cultivation, we conducted a potted experiment to investigate the effects of different irrigation levels and nitrogen fertilizer treatments on the activity of starch synthesis-related enzymes and the grain quality of winter wheat. The potted experiment consisted of three irrigation levels, with the lower limits set at 50–55% (I0), 60–65% (I1), and 70–75% (I2) of the field capacity. In addition, four levels of nitrogen fertilizer were applied, denoted as N0 (0 kg N hm−2), N1 (120 kg N hm−2), N2 (240 kg N hm−2), and N3 (300 kg N hm−2), respectively. The results revealed the significant impacts of irrigation and nitrogen treatments on the activities of key starch-related enzymes, including adenosine diphosphoglucose pyrophosphrylase (ADPG-PPase), soluble starch synthase (SSS), granule-bound starch synthase (GBSS), and starch branching enzymes (SBE) in wheat grains. These treatments also influenced the starch content, amylopectin content, and, ultimately, wheat yield. In summary, our findings suggest that maintaining irrigation at a lower limit of 60% to 65% of the field capacity and applying nitrogen fertilizer at a rate of 240 kg hm−2 is beneficial for achieving both high yield and high quality in winter wheat cultivation.

Effects of Root Trace Nitrogen Reduction in Arid Areas on Sucrose–Starch Metabolism of Flag Leaves and Grains and Yield of Drip-Irrigated Spring Wheat

“…The above enzyme activities are significantly affected by nitrogen application rates. Insufficient or excessive nitrogen application can lead to varying degrees of decreases in key enzymes involved in starch synthesis, with varying impacts on various stages of starch synthesis [15]. This study found that, under different treatments, the activities of key enzymes in grain starch synthesis (ADPG-PPase, SSS, GBSS, SBE) showed a tendency to increase and then decrease with the increase in days after anthesis, which was in agreement with the findings of Li et al [36].…”

“…Among them, the ADPG-PPase, SSS, GBSS, and SBE under the CK1 (300 kg•ha −1 ) treatment were significantly lower than those under the A1 (255 kg•ha −1 ) treatment, with decreases of 5-23%, 3-20%, 3-20%, and 8-24%, respectively, resulting in a decrease of 7-18% in the starch content. Xin et al [15] believe that wheat can increase ADPG-PPase, SSS, GBSS, and SBE activity and yield at a nitrogen application rate of 240 kg•ha −1 . However, when the nitrogen application rate is 300 kg•ha −1 , both the enzyme activity and yield mentioned above decrease, which may be due to differences in geographical and climatic conditions.…”

“…Yang et al [14] found in their study on changes in the activity of key enzymes involved in starch synthesis that GBSS, SSS, ADPG-PPase, and SBE activities all increased with increasing nitrogen application at a nitrogen application rate of 0-200 kg•ha −1 . Xin et al [15] believe that, compared to non-nitrogen treatment, the soluble sugar content, GBSS, SSS, ADPG-PPase, and SBE activities in winter wheat grains significantly increased after nitrogen application, leading to an increase in starch content, thereby increasing the starch yield. Further research has revealed that a declining nitrogen application rate has a positive impact on the activities of ADPG-PPase, SSS, and GBSS in carbon metabolism, while excessive nitrogen application hinders starch formation, ultimately affecting grain weight [16].…”