The regulatory effects of different irrigation amounts under shallow-buried drip irrigation on post-anthesis carbon metabolism and photosynthetic nitrogen use efficiency in maize

Water scarcity is a major bottleneck restricting sustainable agricultural development, and studying efficient water-saving irrigation techniques is crucial for ensuring food production. This study, conducted at an agricultural experimental site in Sichuan Province, used a randomized block design to compare traditional border irrigation (control group, irrigation amount 4000 m³/hm²) with different irrigation levels under shallow-buried drip irrigation (W1: 40%, 1600 m³/hm²; W2: 50%, 2000 m³/hm²; W3: 60%, 2400 m³/hm²). The effects on maize yield, photosynthetic characteristics, key enzyme activities of photosynthetic carbon metabolism, photosynthetic nitrogen use efficiency, and non-structural carbohydrate accumulation were systematically analyzed. The results showed that shallow-buried drip irrigation with 60% irrigation amount (W3) significantly reduced water usage while maintaining a high yield, comparable to traditional border irrigation and significantly higher than the W1 and W2 treatments. The W3 treatment significantly enhanced post-anthesis photosynthetic capacity, key enzyme activities of photosynthetic carbon metabolism, and nitrogen use efficiency in maize leaves, promoting the accumulation of non-structural carbohydrates, with sucrose and soluble sugar contents being significantly higher than those in other treatments. In contrast, the W1 treatment resulted in a significant reduction of yield due to insufficient water supply and weakened photosynthetic function and physiological activity. The study indicates that shallow-buried drip irrigation combined with a 60% irrigation level is a water-saving and yield-stabilizing irrigation strategy, providing theoretical and practical guidance for the development of efficient water-use technologies in arid agricultural regions.