Abstract:

Lodging is a major meteorological disaster that significantly affects the yield of summer maize. Investigating the impact of lodging during the milk stage on water use efficiency (WUE) and yield is crucial for accurately assessing lodging-induced losses and guiding summer maize production. Based on crop, meteorological, disaster survey, and CO₂/H₂O flux data collected at the Zhengzhou Agro-meteorological Experimental Station during the 2016-2017 growing seasons, this study constructed models of net ecosystem productivity (NEP) and evapotranspiration (ET) to simulate the population-level WUE. A wind-induced lodging event that occurred in Zhengzhou on August 25, 2016 was analyzed using the model validated by 2017 observations. The results show that under normal conditions, the simulated WUE values agreed well with flux observations, with a mean absolute error of -0.08 mg C·g^-1 H₂O and a relative error of -5.39%. After lodging, the simulated WUE values were markedly lower than those under non-lodging conditions, with a daily average decrease of 0.31 mg C·g^-1 H₂O, corresponding to a reduction of 20.37%. At the yield level, WUE decreased by 3.87%. Both NEP and ET declined following lodging, with a larger reduction in NEP than in ET, leading to a decrease in WUE. Lodging also reduced the hundred-grain weight by 2.8% and the grain weight per plant by 10.8%, resulting in an overall yield reduction of approximately 5.0%.

Key words: summer maize lodging, CO₂ flux, evapotranspiration, eddy covariance, water use efficiency, yield

摘要：

倒伏是影响夏玉米产量的重要气象灾害。深入研究夏玉米乳熟期倒伏对群体水分利用效率（Water Use Efficiency，WUE）及产量的影响，对于准确评估倒伏灾害损失并合理指导夏玉米生产具有重要意义。基于郑州农业气象试验站2016—2017年夏玉米生长季的作物、气象、灾害调查及CO₂/H₂O通量观测数据，选取2016年8月25日郑州地区发生的一次大风倒伏过程，利用2017年无倒伏年份的数据构建夏玉米净生态系统生产力（Net Ecosystem Productivity，NEP）与蒸散量（Evapotranspiration，ET）模型，进而模拟夏玉米群体WUE。通过通量观测数据对模型进行验证后，利用经检验的模型分析倒伏对WUE的影响。结果表明，正常年型WUE模拟值与通量观测结果偏差较小，日平均WUE的模拟绝对误差为-0.08 mg C·g^-1 H₂O，相对误差为-5.39%。倒伏发生后，夏玉米WUE显著降低，日平均WUE减少0.31 mg C·g^-1 H₂O，降幅达20.37%，对应产量水平下降3.87%。倒伏导致NEP与ET均减少，且NEP的降幅大于ET，从而引起WUE下降。倒伏后百粒重较未倒伏降低2.8%，株籽粒重降低10.8%，导致田块总产量减少约5.0%。

关键词: 夏玉米倒伏, CO₂通量, 蒸散量, 涡度相关, 水分利用效率, 产量