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 morpho-logical 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 wa-ter 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＆nbsp;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 develop-ment not only increased the healthy index ,but significantly promoted water use efficiency .