Effect of Planting Patterns and Fertilization Optimization on Hormonal Profile, Leaf Senescence and Yield in Maize

Limited precipitation and nitrogen (N) deficiency result in accelerated leaf senescence and result in yield losses in maize. The objectives of the experiment were to enhance photosynthetic performance and reduce accelerated leaf senescence in maize. We investigated the effect of traditional flat planting (FP) and ridge and furrow rain harvesting planting pattern (RP) under optimized N (225 kg N ha^–1) application modes (N₁: half of N applied at pre-planting and half applied at tenth-leaf stage (V10), N₂: full dose of N applied at pre-planting, N₃: 40% of N applied at pre-planting, 40% applied at V10, and 20% applied at tasseling stage (VT), N₄: 30% of N applied at pre-planting, 30% applied at V10, 20% applied at VT, and 20% applied at silking stage (R1) in maize. Lower soil water content (%) and higher soil temperature (°C) in FP increased abscisic acid (ABA) and reduced indole-3-acetic acid (IAA) and zeatin riboside (ZR) content. RPN₄ had higher IAA, ZR and chlorophyll content, net photosynthetic rate (P_N), stomatal conductance (g_s), and transpiration rate (E) and lower intercellular carbon dioxide concentration (C_i) and ABA content. RPN₄ significantly improved photosynthetic electron transport rate (ETR), maximal quantum efficiency of photosystem II photochemistry (F_v/F_m) and photochemical quenching coefficient (q_p), and reduced non-photochemical quenching coefficient (q_N) and leaf senescence rate compared with other treatments. Chlorophyll content, P_N, g_s, E, ETR, q_p and F_v/F_m were significantly positively correlated with IAA and ZR content and negatively correlated with ABA content, C_i, q_N and leaf senescence rate. RPN₄ significantly improved yield in maize by enhancing photosynthetic efficiency and reducing accelerated leaf senescence rate.