土壤含水量对麻疯树幼苗生长及其生理生化特征的影响

以麻疯树(Jatropha curcas L.)1年生盆栽幼苗为材料,通过设置3个土壤水分(分别为80%、50%和30%田间持水量(FC))处理,研究土壤含水量对麻疯树幼苗生长及生理生化指标的影响,探讨麻疯树的水分适应性。结果表明:随土壤含水量的降低,麻疯树的株高、生物量等均呈下降趋势,根重比、根冠比和比叶面积无显著变化;蒸腾速率和气孔导度显著降低,净光合速率和PSII的光能转换效率无明显变化;叶片色素含量显著升高。在80%FC下,丙二醛和过氧化氢含量、可溶性糖和游离脯氨酸含量、超氧化物歧化酶活性和抗坏血酸含量均呈现最大值。在本实验条件下:麻疯树作为一种抗旱性较强的树种,30%FC没有对其造成干旱胁迫;而从生理生化代谢方面看,80%FC不能为麻疯树生长提供最适宜的条件,主要体现在体内自由基积累、膜脂过氧化程度加重以及叶绿体色素含量的降低,但体内抗氧化防御系统的积极防御和渗透调节物质含量的增加缓解了水分过多对麻疯树造成的伤害,从而没有对净光合速率造成影响。因此,在当地土壤养分状况下,以30%-50%FC的土壤含水量栽培,更有利于麻疯树的生长。

Effects of soil moisture content on growth, physiological and biochemical characteristics of Jatropha curcas L.

In order to explore different water adaptation capacity of Jatropha curcas L., we investigated changes of the plant in growth, physiological and biochemical characteristics after 3 month experiment. Seedlings were subjected to 3 watering regimes which were watered to 80%, 50%and 30% field capacity (FC), respectively. Companying with decrease of soil water content, significant decreases in height, biomass accumulation, transpiration rate and stomatal conductance, and increases in leaf/area ratio, biomass accumulation and the content of pigments were detected at the end of experiment. However, there was no significant difference in root/shoot ratio, root/weight ratio, specific leaf area, net photosynthesis rate and maximal quantum yield of PS II. In addition, the content of malondialdehyde, hydrogen peroxide (H2O2), soluble sugar, free proline and ascorbic acid, and activity of superoxide dismutase were highest under 80% FC. The results suggested that J. curcas, as a drought tolerance species, could decrease water losing by closing stoma and decreasing transpiration rate, and therefore 30% FC were not caused drought stress to it. However, excessive water supply (80% FC) was not the optimum condition for its physiological metabolize due to the accumulation of H2O2, aggravation membrane lipid peroxidation and the degradation of chlorophyll. So we think that under the local soil nutrient condition 30%-50% FC is the optimum soil moisture content for J. curcas.