Maize Genomics and Genetics 2025, Vol.16, No.4, 167-181 http://cropscipublisher.com/index.php/mgg 168 efficiency and dry matter accumulation are ideal (Feng, 2024). However, deviations from this range, especially extreme heat, disrupt the balance between photosynthesis and respiration, ultimately reducing yields. Studies in northern regions indicate that moderate temperature increases during planting and seedling stages can promote growth, but extreme high temperatures during the grain-filling stage can significantly reduce grain-filling rates, thus impacting yield quality (Qi et al., 2022). Heat stress not only affects photosynthesis but also induces oxidative stress, which can damage cell structures. Under extreme heat, maize plants exhibit symptoms like leaf wilting and stunted growth, compromising overall plant development. Research from the Brazilian Cerrado shows that projected temperature increases due to climate change may drastically reduce maize dry matter accumulation, particularly during reproductive stages, thereby lowering yields (Camilo et al., 2018). Additionally, elevated nighttime temperatures can negatively impact maize by increasing respiratory activity, leading to greater energy expenditure at night that could otherwise be stored through photosynthesis. Studies in Northeast China reveal that sustained high nighttime temperatures increase nighttime energy loss in maize, suppressing net photosynthate accumulation and ultimately affecting yields. Developing varieties that can tolerate high nighttime temperatures could be a strategy to address this challenge (Zhang et al., 2022). 2.2 Precipitation and water availability for maize Water availability is crucial for maize, especially during sensitive stages like flowering and grain filling, when maize demands substantial water. Precipitation is the primary water source, and its distribution and seasonality significantly impact water supply. Studies in the Czech Republic have shown that summer rainfall, especially in July, is positively correlated with maize yield. Increased rainfall during this period promotes grain formation and yield, whereas water deficits lead to yield reductions, underscoring the importance of sufficient rainfall during critical growth stages (Maitah et al., 2021). In drought-prone regions, irrigation is an effective measure to alleviate water shortages, particularly during maize's flowering and grain-filling stages. Research in Northeast China shows that drought stress during flowering can have the most severe impact on maize yield, highlighting the importance of irrigation during these critical stages. In areas with limited water resources, using drought-resistant varieties and optimizing irrigation can improve productivity (Yin et al., 2015). However, extreme changes in rainfall patterns, such as heavy or uneven distribution, can adversely affect root development and water use in maize. Studies in Central Europe indicate that excessive soil moisture from concentrated rainfall can hinder root respiration, while prolonged drought limits water supply during flowering and grain filling, severely impacting yield. Adapting water management strategies to changing precipitation patterns is crucial to ensuring that maize receives adequate water under various climate conditions (Tang and Liu, 2020). 2.3 Solar radiation and photoperiod on maize development Solar radiation is the primary energy source driving photosynthesis, directly influencing biomass accumulation and yield potential in maize. Research in Northeast China has shown that increased solar radiation during the grain-filling stage promotes kernel development and increases grain weight, partially offsetting the adverse effects of high temperatures on yield. This indicates that under optimal solar radiation, maize achieves better growth outcomes (Wei et al., 2023). The length of daylight, or photoperiod, also influences maize growth patterns. Maize varieties adapted to specific regions often exhibit photoperiod sensitivity, with longer daylight hours promoting robust vegetative growth. In Central China, summer maize benefits from extended daylight and higher radiation, forming a strong plant structure. However, excessive radiation and high temperatures during the grain-filling period can hinder kernel filling, ultimately reducing yield (Ge et al., 2022).
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