中文摘要：

小桐子是能源作物中最具发展潜力的原料树种，而土壤水分是影响小桐子苗木质量和水分利用效率的关键.设置4个灌水处理（w1：472.49mm；W2：228.79mm；W3：154.18mm和W4：106.93mm），研究灌水量对小桐子幼树生长、形态特征和水分利用的影响.结果表明：与W1相比，W2、W3和W4处理小桐子叶面积和基茎截面面积显著降低，胡伯尔值显著增加，提高了根系向叶片传输水分的效率，提高小桐子抗旱能力；W2处理根系和冠层干物质量显著降低，粗高比增加，但壮苗指数变化不显著，而W3和W4处理壮苗指数显著降低.表明灌水量228.79～472.49mm有利于小桐子壮苗指数的提高.与w1相比，W3处理节约灌水量达67.4％，总干物质量和蒸散量分别显著降低17.4％和68.6％，因此，小桐子灌溉水利用效率和总水分利用效率显著增加153.2％和163.2％.本试验条件下，有利于小桐子水分利用效率提高的最佳灌水量为154.18mm.

英文摘要：

Jatropha curcas is the most promising energy tree, and soil moisture is the key factor which affects the seedling quality and water use efficiency of J. curcas. With aims to evaluate the effect of different irrigation amount on growth, morphological characteristics and water use of J. curcas, a pot experiment was conducted with four irrigation amounts, i. e. , W1 ： 472.49 ram, W2 ： 228.79 mm, W3 ： 154. 18 mm and W4 ： 106.93 mm, respectively. Compared with W1 treatment, the leaf area and stem cross-section area of base significantly decreased in W2, W3 and W4 treatments, but Huber value significantly increased, which could improve the efficiency of water transfer from root to shoot, thus enhance the capability of resistance to drought stress. Compared with Wl treatment, the healthy index of J. curcas seedlings decreased slightly in W2 treatment but significantly decreased in W3 and W4 treatments. Hence, the irrigation amount from 228.79 to 472.49 mm was beneficial to increase the healthy index of J. curcas seedlings. Compared with W1 treatment, irrigation water was saved by 67.4% in W3 treatment, and the total dry mass and evapotrans piration significantly decreased by 17.4% and 68.6% , and the irrigation water use efficiency and total water use efficiency increased by 153.2% and 163.2%, respectively. In the condition of this study, the irrigation amount of 154.18 mm was beneficial to increase water use efficiency.