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.