Maize Genomics and Genetics 2025, Vol.16, No.1, 20-33 http://cropscipublisher.com/index.php/mgg 21 genetic and agronomic advancements that support high-density planting tolerance and efficient nutrient management, ultimately aiming to improve food security and economic stability in regions reliant on maize. 2 Growth and Nutrient Requirements of Maize 2.1 Key nutrient needs (nitrogen, phosphorus, potassium) at different growth stages Maize requires a balanced supply of nitrogen (N), phosphorus (P), and potassium (K) for optimal growth and development. Nitrogen is crucial for vegetative growth, particularly in the early stages, as it supports leaf and stem development. Phosphorus is essential for energy transfer and root development, while potassium plays a significant role in water regulation and enzyme activation. During the vegetative growth period, maize plants exhibit high nitrogen absorption, which is critical for the formation of chlorophyll and amino acids. Phosphorus and potassium uptake are also significant during this stage, contributing to root establishment and overall plant vigor. As the plant transitions to the reproductive stage, the demand for phosphorus and potassium increases to support flowering, grain filling, and maturation processes (Liu et al., 2019; 2022). In high-density planting scenarios, the application of nitrogen at optimal levels (e.g., N200) combined with plant growth regulators has been shown to enhance nutrient uptake and translocation, leading to improved grain yield and quality. This approach maintains high enzymatic activities in leaves, which are vital for photosynthesis and nutrient assimilation (Liu et al., 2019; Huang, 2024). 2.2 Role of micronutrients in maize health and stress tolerance (e.g., Zinc, Boron) Micronutrients such as zinc (Zn) and boron (B) play critical roles in maize health and stress tolerance. Zinc is involved in various physiological functions, including protein synthesis, gene expression, and enzyme activation. It also contributes to the structural integrity of cell membranes and the synthesis of auxins, which are essential for growth regulation (Saboor et al., 2021; Suganya et al., 2021). Zinc deficiency can lead to stunted growth, delayed maturity, and reduced grain quality. The use of arbuscular mycorrhizal fungi (AMF) has been shown to enhance zinc uptake and mitigate zinc-induced stress, thereby improving maize growth and yield. AMF symbiosis helps in balancing zinc levels within the plant, ensuring optimal growth conditions even in zinc-deficient soils (Saboor et al., 2021; Ahmad et al., 2023). Boron, another essential micronutrient, is crucial for cell wall formation and reproductive development. It aids in pollen tube growth and seed set, which are vital for successful fertilization and grain production. Adequate boron levels help maize plants withstand environmental stresses, such as drought and high salinity, by maintaining cellular integrity and metabolic functions (Gaikpa et al., 2022; Martins et al., 2023). 2.3 Impact of plant density on nutrient uptake and growth Plant density significantly influences nutrient uptake and growth in maize. High-density planting can lead to increased competition for nutrients, water, and light, potentially reducing individual plant growth and overall yield. However, with proper nutrient management, high-density planting can be optimized to enhance productivity. Studies have shown that the application of nitrogen and plant growth regulators in high-density planting conditions can improve root vitality and nutrient absorption. This approach enhances the concentration and delivery rates of amino acids and mineral nutrients in root-bleeding sap, leading to better nutrient translocation and higher grain yield (Liu et al., 2019). 3 Impact of Planting Density on Maize Yield 3.1 Effects of planting density on photosynthesis and competition among plants Planting density significantly influences photosynthetic parameters and the competition among maize plants. Studies have shown that increasing planting density can enhance the leaf area index (LAI) and the amount of intercepted photosynthetically active radiation (IPAR), which promotes plant growth and crop productivity. However, this increase in density can also reduce the net photosynthetic rate (Pn), stomatal conductance (Gc), and
RkJQdWJsaXNoZXIy MjQ4ODYzNA==