中文摘要：

为研究亏缺灌溉和施氮对小桐子幼树根区土壤硝态氮分布及水分利用的影响。采用4种供水水平（W1：100%ET（ET为蒸散量）;W2：80%W1;W3：60%W1;W4：40%W1）和3种施氮水平（N0：0;N1：0.4g;N2：0.8g）。结果表明：在W1、W2和W3处理中表土层5cm处的土壤硝态氮质量分数均低于表土层10和15cm处,而W4处理中表土层5cm处的土壤硝态氮质量分数均高于表土层10和15cm处;W2处理的平均土壤硝态氮质量分数均低于W1、W3和W4处理。与W1N2相比,节约灌溉量达10.7%时,W2N2处理的平均土壤含水率和硝态氮质量分数及蒸散量分别显著降低22.8%、12.1%和9.6%。而茎粗/株高和壮苗指数分别显著增加24.7%和27.6%,根系、冠层和总干物质质量分别显著增加22.3%、18.3%和19.2%,因此,W2N2处理的灌溉水利用效率和总水分利用效率分别显著增加36.6%和35.0%。可见,在节约灌溉用水的同时,采用W2N2处理提高了小桐子的干物质质量、茎粗/株高和根冠比,而降低了土壤硝态氮质量分数和蒸散量,从而使得壮苗指数和水分利用效率显著提高。

英文摘要：

The demand for energy has risen rapidly due to increasing industrialization and modernization of the world, and the majority of energy is derived from fossil sources such as petroleum, coal and natural gas. However, alternative fuels from renewable feedstock provide alternatives to fossil fuels to solve the problems of the limited reserves of fossil fuel. Jatropha curcas L. has recently drawn the attention due to its tremendous potential as a biodiesel crop. A pot-grown experiment was conducted to investigate the effect of deficit irrigation and nitrogen fertilizer application on soil water content, soil nitrate-nitrogen（NO-3-N） distribution in root-zone, and evapo-transpiration quantity, dry mass accumulation, base stem diameter-plant height ratio, root-shoot ratio, healthy index and water use of young Jatropha curcas L. trees. Four irrigation levels （WI： 100%ET （ET： Evapo-transpiration）; W2： 80% W1; W3： 60% W1; W4： 40% W1） and three added nitrogen levels （NO： 0; NI： 0.4g N/kg; N2： 0.Sg N/kg, respectively） were designed in the study. Results showed that the NO-a-N content in topsoil （0-5 cm） was less than that in 10 and 15 cm under W1, W2 and W3 treatment, respectively; the soil NO-a-N content of topsoil in 5 cm was higher than that in 10 and 15 cm under W4 treatment; the mean soil NO-3-N content under W2 treatment was lower than that under W1, W3 and W4 treatment. Compared to W1 treatment, W2 treatment significantly increased mean base stem diameter-plant height ratio and healthy index, and root, shoot and total dry mass of young Jatropha curcas L. trees, respectively. Meanwhile, W2 treatment significantly decreased mean evapotranspiration, and thus W2 treatment significantly increased irrigation water use efficiency and total water use efficiency of young Jatropha curcas L.trees. But W3 and W4 treatment significantly decreased mean irrigation water use efficiency and total water use efficiency of young Jatropha curcas L.trees. Compared to NO, N2 treatment significantly incre