基于河北省固城生态与农业气象试验站2013—2015年夏玉米田间水分控制试验资料，分多情景模拟自然环境，研究了水分充足条件下夏玉米穗粒重随发育进程（DVS）的变化特征，对比分析了不同持续时间、不同发育阶段、不同程度水分胁迫对产量的影响，并建立了不同情景水分胁迫下土壤相对湿度与产量的定量关系模型。结果表明，在水分充足条件下，夏玉米穗粒重随DVS的增加呈现“慢—快—慢”的增长特征，其中乳熟—乳熟后10 d的增长幅度和增长速率均为最大；水分胁迫发生在抽雄后10 d—乳熟阶段，粒重减少最明显。夏玉米产量与出苗—拔节（阶段Ⅰ）、拔节—抽雄（阶段Ⅱ）、抽雄—成熟（阶段Ⅲ）以及［阶段Ⅰ+阶段Ⅱ］和［阶段Ⅱ+阶段Ⅲ］ 5个不同时段土壤相对湿度均呈线性显著正相关关系，其关系模型表明，水分胁迫程度越严重、持续时间越长，产量减少幅度越大，不同阶段、相同胁迫程度和持续时间对产量的影响总体表现为:阶段Ⅰ<阶段Ⅱ<阶段Ⅲ<［阶段Ⅰ+阶段Ⅱ］<［阶段Ⅱ+阶段Ⅲ］，以上阶段土壤相对湿度下降10%，产量分别减少89.7 g/m2、122.7 g/m2、129.8 g/m2、133.7 g/m2和144.4 g/m2，减幅为22.8%~36.8%。
Grain weight is the most important factor of yield. Based on the summer maize field moisture control experiments from 2013 to 2015 in Gucheng, the EcologicalMeteorological Integrated Observation Experiment Station, Hebei Province, the natural environment is simulated by multiple scenarios, and the change characteristics of grain weight per spike of summer maize with the development stage (DVS) under watersufficient conditions are studied. As the experiment designed, the water at the three major development stages of summer maize, i.e., emerging to jointing, jointing to tasseling, tasseling to maturity, as well as (emerging to jointing)+(jointing to tasseling), (emerging to jointing)+ tasseling to maturity), and (jointing to tasseling)+(tasseling to maturity), are controlled in turn. By comparing the yield changes between different water treatments, the effects of different durations, different developmental stages and different degrees of water stress on yields are analyzed. The quantitative relationship models between soil relative humidity and yields under different water stresses are established. The results show that under the condition without soil water stress, the kernel weight of summer maize shows a “slowfastslow” growth characteristic with the increase of DVS. During the period from milk ripening to 10 days after milk ripening, the increase range and rate of grain weight are the largest. When water stress occurred from 10 days after tasseling to the stage of milk maturity, the grain weight decreased most. When water stress occurred in the emerging to jointing (stageⅠ), jointing to tasseling (stageⅡ), tasseling to maturity (stage Ⅲ), ［stageⅠ+stageⅡ］ and ［stageⅡ+stage Ⅲ］, the yield of summer maize had a significant linear positive relationship with soil relative humidity in five different periods separately. The relationship model shows that the more severe the water stress and the longer the duration, the greater the reduction in yield is. The effects of water stress on yield at the same level, different stages and different durations are as follows: ［stage II+stage III］ > ［stage I+stage II］ > stage III > stage II > stage I. In the five water treatment scenarios, soil relative humidity went down by 10%, the grain weight reduced 89.7 g/m2、122.7 g/m2、129.8 g/m2、133.7 g/m2 and 144.4 g/m2, respectively, a reduction of 228% to 36.8%.