Morpho-physiological characteristics by sweet potato cultivars as function of irrigation depth

Abstract The sweet potato is an alternative energy source, but its sustainability depends on efficient water use. The objective of this study was to evaluate sweet potato morpho-physiological characteristics, and water use efficiency (WUE). Irrigation depths of 50, 75, 100, and 125% of crop evapotranspiration (ETc) were applied. The morpho-physiological indicators, WUE, leaf area index (LAI), leaf water potential, leaf temperature, and leaf chlorophyll index (ICF), were evaluated. The WUE of the sweet potato cultivars increased until the 75% water depth of the ETc. The LAI of these cultivars increased with irrigation depth, with higher values at 100% of the ETc. The leaf water potential of the two sweet potato cultivars was lowest with the lower irrigation depth. Leaf temperature was closer to that of ambient temperatures in treatments with greater irrigation depth. The increase of the WUE with the greater accumulation of dry biomass is due to greater CO2 diffusion by stomata. The reduction in the growth of these plants is due to water stress limiting stomatal conductance, transpiration, leaf growth (LAI) and chlorophyll concentration, proportional to soil moisture conditions. The functional relationship between soil moisture and growth is essential to optimize irrigation management at different growth stages.

摘要 甘薯作为一种替代能源，其可持续性依赖于高效的水分利用策略。本研究旨在评估甘薯的形态生理特性与水分利用效率（water use efficiency, WUE）。试验设置了分别为作物蒸散量（crop evapotranspiration, ETc）50%、75%、100%和125%的灌溉梯度。测定指标涵盖形态生理参数、WUE、叶面积指数（leaf area index, LAI）、叶水势、叶温以及叶片叶绿素指数（leaf chlorophyll index, ICF）。供试甘薯品种的WUE在灌溉量达到ETc的75%时达到峰值。各品种的LAI随灌溉量增加而升高，在ETc的100%灌溉量下达到最高值。两个供试甘薯品种的叶水势在低灌溉量处理下最低。灌溉量更高的处理组中，叶温更接近环境温度。WUE随干物质积累量增加而提升的原因是气孔介导的CO₂扩散效率增强。作物生长受抑制则是因为水分胁迫限制了气孔导度、蒸腾作用、叶片生长（LAI）以及叶绿素浓度，且该抑制效应与土壤水分状况呈正相关。土壤水分与作物生长之间的函数关系，对于优化不同生育阶段的灌溉管理具有重要意义。