土壤质地对玉米不同生理指标水分有效性的影响

为确定土壤质地对玉米不同生理指标水分有效性的影响，该文利用3种土壤（重壤土、中壤土和砂壤土）的盆栽控水试验和1种土壤（重壤土）的田间小区控水试验，研究了玉米不同生理指标随相对土壤含水率（土壤含水率占田间持水率的比）的动态变化。结果表明：3种土壤中各生理指标相对值在相对土壤含水率降低到土壤水分阈值之前保持不变，低于此阈值时随相对含水率的进一步降低而线性降低，且均可用分段函数来拟合（R2=0.824～0.999）。土壤水分有效性大小排序为：砂壤土＞中壤土＞重壤土，而且瞬时生理指标的土壤水分阈值低于日变化和整个试验阶段的累积指标。因此土壤质地和不同生理指标的时间尺度都会影响玉米生理指标对土壤水分有效性的响应。

Effect of soil texture on soil water availability for different maize physiological indices

For estimating the influence of soil texture on soil water availability for different maize (Zea mays L.) physiological indices, maize plants were grown in pot experiments using three soil textural types (heavy loam, medium loam and sandy loam) and a plot experiment using one soil (heavy loam) under different water regimes. The changes of different maize physiological indices in response to the changes in relative soil water content (soil water content dividing by the field capacity) was studied. Results showed that the soil water availability on various physiological indices in the three textural types of soil remained constant until soil water content decreased below the threshold value and then declined linearly with further soil water depletion. A linear-plateau model well represented the relationships between each relative plant physiological index and the relative soil water content with an R2 value in the range of 0.824-0.999. Soil water availability declined with soil texture in the order: sandy loam > loam > heavy loam. The threshold values for physiological indices at the transient scale were lower than those for the indices at the daily and seasonal scales. Therefore, the responses to soil water availability of different maize physiological indices were found to be affected by soil texture and by the time scale over which the various indicators were determined.