中文摘要：

[目的]研究玉米对红壤干旱的反应以及红壤干旱程度定量表达和干旱阈值.[方法]在田间小区遮雨条件下种植夏玉米,设置连续干旱12～36 d等6个处理,用FDR水分仪每日测量0～60 cm不同土层含水量,定期观测玉米植株生长状况和气孔导度,收割后考种.[结果]玉米的株高、茎粗、气孔导度、根系数量等测量值在不同干旱天数之后显著降低,在不同土壤干旱程度下出现阈值反应,连续干旱25 d之后,玉米籽粒产量显著降低5%.干旱过程中,土层贮水量和累积相对失水量之间的关系可以用对数线性方程表示,将方程的斜率转换为取值在[0,1]区间的指数D,可以定量表达土壤干旱程度.[结论]D值既可以表示土壤干旱状况又可以表示作物受旱程度,玉米拔节-抽穗期红壤干旱程度D达到0.55则产量显著降低.

英文摘要：

[Objective] The study was conducted to survey the response of maize （Zea may L.） to progressive soil drought, and to investigate the threshold of red soil to drought. [Method] Summer maize was planted in field plots under a rainproof shed, and six treatments were disposed in soil drying form 12 days to 36 days. The soil water contents in 0-60cm layers were measured daily using FDR, and maize plant morphic features and leaf stomatal conduct were also investigated periodically. Scientists checked seeds, and measured grain yields after harvest. [Result] The plant height, stem diameter, leaf stomatal conduct and root number did not decrease significantly until the soil drying lasted 21 d to 29 d, namely, the plant threshold response presented a different soil drought degree. Five percent grain yield reduced significantly after soil drought lasted 25 days. In soil drying development, the relationship between the soil layer water storage and the cumulative relative water loss was expressed reliably as a logarithmic linear equation. We transferred the slope to an index, notated as D, which spans in the interval [0, 1], to explain the soil drought degree. [Conclusion] The index D is an indicator both for soil drought degree and crop water stress status. Maize yield decrease significantly after drought degree D reached 0.55 in the elongation-heading stage in red soils.