Effects of Sowing Date Adjustment on Spring Maize Yield and Quality in the Loess Plateau of Eastern Gansu

To clarify response rules of spring maize yield and grain quality to climate change in the Loess Plateau of eastern Gansu and optimize the high-yield and high-quality cultivation technology system for local spring maize, field experiments of spring maize with different sowing dates conducted at Xifeng Agrometeorological Experimental Station from 2022 to 2024 are adopted in this study. Under identical test varieties, soil conditions and cultivation management measures, regulating effects of variations in light, temperature and water resources caused by different sowing dates on growth process, grain-filling dynamics, dry matter accumulation, yield components and grain quality of spring maize are systematically analyzed. Key meteorological limiting factors for spring maize production and the regulation mechanism of optimal sowing date in rain-fed agricultural areas in the Loess Plateau of eastern Gansu are determined. Results show that the growth process of spring maize and the allocation of light, temperature and water resources are significantly altered by sowing date adjustment. With the delay of sowing date, the duration of growth period is shortened, the average air temperature at each growth stage is increased, while the total precipitation and sunshine hours during the whole growth period are decreased. The growth rhythm of maize is further affected by the changed matching pattern of light, temperature and water. Yield formation is affected by sowing date through regulating grain-filling rate and dry matter accumulation. The highest yield is obtained in the treatment with sowing date delayed by 10 d (Treatment B2). Insufficient dry matter accumulation is observed in the early sowing treatment (Treatment B1) due to the uncoordinated allocation of light, temperature and water at the seedling stage. Effects of meteorological factors on yield are stage-specific. Yield is positively correlated with precipitation, accumulated temperature above 0 ℃ and average temperature throughout the growth period. Stages from seven-leaf stage to jointing stage and from milk-ripening stage to maturity stage are identified as the most sensitive periods of maize responding to light, temperature and water factors. Grain quality formation is also significantly affected by sowing dates, and contents of tyrosine, cystine, glutamic acid and other components are obviously changed. Precipitation is regarded as the core climatic factor regulating fat accumulation and amino acid composition, while temperature mainly dominates the synthesis of starch and fat. In this study, response mechanisms of yield and grain quality of spring maize to sowing-date-induced variations in meteorological factors in the Loess Plateau of eastern Gansu are elucidated. Key theoretical basis and technical support are provided for rational sowing arrangement, stress resistance, stable yield and high-efficiency quality cultivation of spring maize in the target region.