中文摘要：

为了探索利用茎秆直径微变化诊断玉米水分亏缺状况的最优指标,采用桶栽的方法,开展了不同水分处理条件下拔节期夏玉米茎秆直径微变化中的日最大收缩量（MDS）、日增长量（DI）和当日恢复时间（RT）3个指标的变化规律及其与土壤相对含水率之间相关关系方面的试验研究。结果表明,（1）不同处理间的MDS和DI受水分亏缺影响差异较为明显,RT对土壤相对含水率的响应较为一致;（2）玉米日最大收缩量MDS和日增长量DI受到环境因素的影响较大,与土壤相对含水率θ的相关系数较小;（3）恢复时间RT与土壤相对含水率θ的相关系数最高,且受水分亏缺处理的影响较小,可以作为诊断玉米水分亏缺状况的较好指标。综上可知,与MDS和DI相比,RT更适合诊断夏玉米水分亏缺状况。

英文摘要：

We investigated the feasibility of using variation in stem diameter as an indication to diagnose water deficiency in maize at jointing stage based on pot experiment. During the experiment, the daily variations in maximum stem diameter shrinkage （MDS）, increase in the diameter （D/） and recovering time （RT） for the diame- ter under three different treatments, as well as their relationships with soil moisture content were measured. The results showed that： ① MDS and DI under different treatments were impacted by water deficiency and the re- sponse of RT to soil water content was consistent in all three treatments;②MDS and DI were affected by envi- ronments rather than by soil moisture content;③he correlation coefficient between RT and soil moisture content was high and was consistent in all treatments. Compared with MDS and DI, RT is a robust indicator to diagnose water stress.