绿洲—荒漠过渡带四种植物光合及生理特征的研究

 绿洲－荒漠过渡带植被的恢复和更新在过渡带生态环境建设中具有重要意义。通过对多枝柽柳，梭梭，头状沙拐枣和沙枣的光合特性、水势（ψ）以及生理指标的研究，结果表明，１）４种植物光响应曲线变化趋势基本一致，均表现为净光合速率（Ａ）随着光合有效辐射（ＰＡＲ）的增大迅速增大，当ＰＡＲ 达到了植物的光饱和点之后，Ａ 出现下降的趋势；作为Ｃ₄ 植物的头状沙拐枣和梭梭都具有较高的光饱和点（ＬＳＰ）和光补偿点（ＬＣＰ），体现出了Ｃ₄ 植物特有的高光合的优势，而其他一些光合参数Ｋ，Ａ_max，Ｒ_day的变化规律并不完全一致；２）４种植物中，梭梭具有较低的清晨和正午水势，说明梭梭主要依靠夜间水分恢复能力来应对干旱环境；清晨水势除头状沙拐枣和沙枣之间差异不显著外，其他植物种之间的差异均达到了极显著水平（P＜０．０１），正午水势除多枝柽柳和沙枣之间差异不显著，其他植物种之间的差异也都达到了极显著水平（P＜０．０１）；３）４种植物中脯氨酸和可溶性糖的变化较为一致，头状沙拐枣均显著高于其他３种植物（P＜０．０５）；而丙二醛含量最高的是沙枣，最低的为头状沙拐枣和梭梭，除头状沙拐枣和梭梭之间差异不显著之外，其他植物种之间的差异均达到显著水平（P＜０．０５）；４）在相关分析的基础上运用平均隶属函数法对这４种植物进行抗旱性排序，结果表明，４种植物的抗旱性强弱顺序依次是梭梭＞多枝柽柳＞沙枣＞头状沙拐枣。

Study of the photosynthesis characteristics and physical signs of four plants at the desert-oasis ecotone

The photosynthesis characteristic and the water potential of four plants:Tamarix ramosissma,Haloxylon ammodendron,Calligonum caput-medusae and Elaeagnus angustifolia were studied in the same environment at the desert-oasis ecotone of Moyu county in the south fringe of Takelamkan Desert in August of 2010,we analysed and compared the physiology characteristics of the four plants.1) Among the four plants,light response curves are basically the same trend,showed that photosynthetic rate(A) rapidly increases with the photosynthetic active radiation(PAR) increases,when the PAR reached light saturation point,appear decline trends;as C4 plants,C.caput-medusae and H.ammodendron have higher light saturation point(LSP) and light compensation point(LCP),which embodies the advantage of the high photosynthesis of C4 plants;however,other parameters of photosynthesis,such as Amax,and Rday,are not in complete accord;2) H.ammodendron has a lower early morning and midday water potential,indicating that H.ammodendron rely mainly on water recovery capability at night to cope with drought environment;dawn water potential had a highly significantly except C.caput-medusae and E.angustifolia(P<0.01),midday water potential also had a highly significantly except T.ramosissima and E.angustifolia(P<0.01);3) Changes of proline and soluble sugar are similar,the content in C.caput-medusae is higher than the other three plants(P<0.05);The E.angustifolia has the highest content of MDA,while the content in C.caput-medusae and H.ammodendron are lowest;the content of MDA is differed significantly except H.ammodendron and C.caput-medusae(P<0.05);4) Based on the analysis in the relevant membership function using the average of four plants for drought resistance in this order,the results show that: the four plants in the order of drought resistance is H.ammodendron>T.ramosissima>E.angustifolia>C.caput-medusae.