Associations Between Grain Nitrogen Accumulation and Maize Yield Formation Under Foliar Fertilization—An Exploratory Multivariate Analysis

This study aimed to evaluate the comprehensive effects of foliar fertilization on maize-related traits and to identify nutrient-related factors associated with yield variation. A single-site field experiment was conducted during the 2024 growing season using maize cultivar ‘Zhengdan 958’. Two fertilization treatments, conventional fertilization (CF) and conventional fertilization combined with foliar fertilization (OF), were applied, with each treatment consisting of three replicate plots. Thirty variables related to yield, yield components, plant nutrient status, and grain nutrient accumulation were measured and included in subsequent exploratory analyses. Analysis of variance (ANOVA) combined with exploratory multivariate statistical analyses was employed to evaluate treatment effects, examine statistical associations among measured variables, and develop the exploratory yield regression models. Compared with CF, OF significantly increased several yield component traits, including kernels per row, ear length, and grain weight per ear, with increases ranging from 9.8% to 20.5%. OF increased grain nitrogen and carbon accumulation by 17.8% and 26.8%, respectively, and increased maize yield, gross revenue and net profit by 20.3–20.5%. Exploratory multivariate statistical analyses indicated that foliar fertilization under conventional fertilization conditions significantly improved several maize yield-related traits. Grain nutrient accumulation, yield components, and yield and economic performance were all important variables that distinguished fertilization treatments and exhibited progressively increasing relative contributions. Further analyses indicated a hierarchical pattern of statistical associations among yield components, grain nutrient accumulation, and maize yield. Grain nitrogen, phosphorus, and carbon accumulation were nutrient-related variables showing statistical associations with maize yield, and their associations with yield were mainly mediated through key yield components. Among the evaluated nutrient variables, GNA showed a strong mathematically coupled statistical association with GY within the evaluated dataset. These findings provide new insights into the statistical relationships between nutrient accumulation and maize yield under foliar fertilization and may contribute to the optimization of nutrient management strategies in maize production.