The regulatory effects of water-fertilizer integration on maize canopy uniformity and yield: a comprehensive...

High and stable maize yields are central to ensuring global food security. However, canopy growth differentiation caused by traditional water and fertilizer management patterns remains a key bottleneck constraining maize productivity improvement. This study aimed to elucidate the regulatory effects of water-fertilizer integration on maize canopy uniformity and yield.

Forty maize varieties were used as experimental materials, and two treatments were set up for comparison: water-fertilizer integration (WF) and conventional water-fertilizer management (CK). Based on RGB and multispectral data acquired by an unmanned aerial vehicle (UAV), a three-dimensional canopy uniformity evaluation system encompassing structural, coverage, and physiological dimensions was established. Through significant difference analysis, correlation analysis, and comprehensive evaluation, the regulatory mechanisms of water-fertilizer integration and varietal response differences were systematically investigated.

(1) Water-fertilizer integration significantly enhanced three-dimensional canopy uniformity. Structurally, the spatial autocorrelation coefficient (Moran's I) for plant height increased by 49.9%, while height standard deviation decreased by 50.5%. In terms of coverage, the spatial coefficient of variation for canopy cover decreased by 47.4% and gap rate decreased by 67.3%. Physiologically, the NDVI coefficient of variation decreased by 44.4%, and the standard deviation of estimated chlorophyll content decreased by 55.5%. (2) Canopy uniformity indices showed significant positive correlations with yield. The Pearson correlation coefficient between the comprehensive canopy uniformity index and yield reached 0.88 (P<0.01). Key correlated indicators included the spatial autocorrelation coefficient of canopy height, spatial coefficient of variation of canopy cover, and coefficient of variation of NDVI. (3) Varieties exhibited significant differences in response to water-fertilizer integration. Some varieties showed over 30% improvement in comprehensive uniformity index and 28% yield increase, while a few varieties responded weakly. (4) Water-fertilizer integration enhances yield through a chain mechanism: "uniform water and fertilizer supply → uniform root growth → three-dimensional canopy uniformity → efficient resource utilization → yield increase."

The canopy uniformity evaluation system established in this study provides a novel approach for quantifying crop population phenotypes. The identified regulatory mechanisms and variety adaptability offer theoretical support and practical guidance for precision water-fertilizer management and high-yield cultivation models in maize.