半干旱风沙区玉米关键需水期叶气温差变化特征及影响因素

Characteristics of leaf air temperature difference and the influencing factors during the critical water demand period of maize in semi-arid sandy areas

【目的】分析玉米关键需水期叶气温差的变化特征,明确半干旱风沙区影响玉米叶气温差的主要气候因子。【方法】以内蒙古赤峰市玉米种植区为研究对象,选取玉米关键需水期(7—9月)为研究时段,于田间开展分布式多点叶温连续测量试验,并分析玉米关键需水期内叶温及叶气温差指标的变化特征,利用相关性分析研究风速、空气湿度、降雨、土壤水分等气候因子对叶气温差的影响程度,并揭示关键气候影响因子。【结果】玉米关键需水期的叶温变化随玉米的生长和干旱时长的累积逐渐变得剧烈,日叶温差变大,叶气温差呈现整体上升趋势;风速的整体变化趋势逐渐减小;空气湿度与降雨的变化过程保持一致;土壤水分随着时间的推移整体下降。风速变化对玉米叶气温差的影响主要体现在晴天,二者呈负相关关系,其对玉米叶温的影响呈正相关关系;空气湿度与叶气温差和叶温均有较强相关性且不受天气状况影响。降雨会使叶气温差的变化波动变小且不规律,但会使叶气温差值变大。当玉米所在地块0~80 cm土层土壤水分贮藏量逐渐减少时,叶气温差逐渐变大。各气候因子对玉米关键需水期叶气温差的影响排序为风速>空气湿度>降雨>土壤水分。【结论】叶气温差在玉米关键需水期呈现波动式上升变化趋势,且受气候因子显著影响,风速与空气湿度是导致玉米叶气温差变化的主要气候驱动因子。

【Objective】Analyze the characteristics of leaf air temperature difference during the critical water demand period of maize to clarify the main climatic factors affecting maize leaf air temperature in semi-arid sandy areas.【Methods】During maize critical water demand period(July-September),distributed multi-point leaf temperature continuous measurement experiment was carried out in the field in the maize planting area in Chifeng City,Inner Mongolia.The changing characteristics of leaf temperature and leaf air temperature difference indexes during maize critical water demand period were analyzed.The influence degrees of wind speed,air humidity,rainfall,and soil moisture on the leaf air temperature difference were discovered by correlation analysis to reveal the key influencing climatic factors.【Results】As maize grew and the length of drought duration increased,leaf air temperature change during maize critical water demand period gradually became more drastic,daily leaf air temperature difference increased,leaf temperature difference had an overall upward trend.The overall trend of wind speed gradually decreased.The air humidity was consistent with the process of rainfall changes.Soil moisture decreased with the time progress.The effect of wind speed variation on maize leaf air temperature difference was mainly reflected in sunny days.Wind speed variation had negative correlation with maize leaf air temperature and positive correlation of maize leaf temperature.Air humidity was strongly correlated with both leaf air temperature difference and leaf temperature and was not affected by weather conditions.Rainfall made the fluctuation of leaf air temperature difference became smaller and irregular,but the value of leaf air temperature difference became larger.As the 0-80 cm layer soil moisture storage in maize planting plot gradually decreased,the leaf air temperature difference gradually became larger.The impact of climatic factors on maize leaf air temperature difference during maize critical water demand period were wind speed>air humidity>rainfall>soil moisture.【Conclusion】The leaf air temperature difference showed a fluctuating upward trend during the critical water demand period of maize,and was significantly affected by climatic factors.Wind speed and air humidity were the main climatic driving factors leading to the change of maize leaf air temperature difference.