调亏灌溉对小桐子幼树形态特征与水分利用的影响
Effects of regulated deficit irrigation on morphological characteristics and water use of Jatropha curcas L. sapling

在盆栽条件下，研究调亏灌溉对小桐子幼树形态特征与水分利用的影响。设置2种调亏水平：重度亏缺W1（田间持水量的25%～45%）和轻度亏缺W2（田间持水量的45%～65%）；3种亏水处理时间：D1（亏水120 d）、D2（亏水90 d）和D3（亏水60 d）；CK为常规灌溉（田间持水量的65%～85%）。结果表明：亏水度对小桐子幼树的株高、茎粗、壮苗指数、叶面积、基茎截面积、干物质质量和水分利用效率的影响趋势表现为轻度调亏处理＞重度调亏处理；对根冠比和胡伯尔值的影响趋势表现为：重度调亏处理＞轻度调亏处理。亏水时间对小桐子幼树的株高、茎粗、壮苗指数、叶面积、基茎截面积、干物质质量和水分利用效率的影响趋势表现为60 d＞90 d＞120 d；对根冠比和胡伯尔值的影响趋势均表现为120 d＞90 d＞60 d。与正常灌水相比，轻度调亏60 d的处理节约灌溉用水11.2%，其叶干重和叶柄干重显著下降，根系、茎秆和总干重下降并不明显，而粗高比和根冠比显著提高，因此，灌溉水利用效率和壮苗指数显著增加7.8%和8.1%。可见，苗后期轻度亏水不仅具有明显的壮苗作用，而且促进水分利用效率显著增大。
A pot-grown experiment was conducted to investigate the effects of regulated deficit irrigation on morphological characteristics and water use of Jatropha curcas L. Two water deficit levels were set as severe water deficit W1 (soil moisture maintained at 25%～45% of field capacity) and moderate water deficit W2 (soil moisture maintained at 45%～65% of field capacity) and three water deficit time levels (D1: 120 d, D2: 90 d, and D3: 60 d) were designed in the study. Control treatment was full irrigation (soil moisture maintained at 65%～85% of field capacity). Results showed that effects of light water deficiency were more apparent than those of severe water deficiency on plant height, stem diameter, healthy index of seedlings, total leaf area, xylem cross-sectional area of basal shoot, total dry mass, and water use efficiency of Jatropha curcas L. However, severe water deficit level seemed to have affected the root-shoot ratio and Huber value of Jatropha curcas L. more than light water deficit level. Effects of water deficit time on plant height, stem diameter, healthy index of seedlings, total leaf area, xylem cross-sectional area of basal shoot, total dry mass, and water use efficiency of Jatropha curcas L. were in the following order: 60 d＞90 d＞120 d. Additionally, effects of water deficit time on root-shoot ratio and Huber value of Jatropha curcas L. were as 120 d＞90 d＞60 d. Compared with the control, W2D3 treatment saved irrigation water by 11.2%, leaf and petiole dry mass were significantly reduced, and root, stem, and total dry mass dropped slightly. Nevertheless, base stem diameter-plant height ratio and root-shoot ratio became significantly increased. As a result, irrigation water use efficiency and healthy index of sapling were significantly increased to 7.8% and 8.1.%, respectively. It is clear that light water deficit level t the late stage of seedling development not only increased the healthy index, but significantly promoted water use efficiency.