不同土壤中水分胁迫和AM真菌对油蒿抗旱性的影响

EFFECTS OF AM FUNGI AND WATER STRESS ON DROUGHT RESISTANCE OF ARTEMISIA ORDOSICA IN DIFFERENT SOILS

利用两种不同土壤研究了水分胁迫和接种AM真菌(摩西球囊霉(Glomus mosseae)和油蒿(Artemisia or-dosica)根际土著AM真菌)对毛乌素沙地重要演替物种油蒿生长和抗旱性的影响。结果表明,两种土壤中水分胁迫没有显著影响油蒿的植株形态和含水量,但严重抑制了菌根侵染率。水分胁迫促使油蒿提高叶片保水能力,抑制N、P在地上部的分配。在胁迫前期SOD活性较高,而POD活性在后期较高。同一水分条件下接种AM真菌显著提高了AM真菌侵染率,土壤中孢子数显著增多,提高了植株分枝数并促进侧根发育,显著提高根冠比和植株保水能力,加强了根系对全磷、全氮的吸收。接种AM真菌的植株可溶性糖和丙二醛含量较低,可溶性蛋白含量无显著变化,SOD和POD活性提高,油蒿抗旱性加强。水分胁迫下在不同土壤中接种不同AM真菌对油蒿的促进效应差异较大,接种土著AM真菌的效果优于摩西球囊霉单一接种。干旱导致菌根侵染率下降是宿主植物吸水能力下降的原因之一,在植物生长前期接种AM真菌可以增强植物抵抗生长中后期环境干旱的能力。

Aims Artemisia ordosica is important in vegetation succession in the Mu Us sandland of China. Little is known about the effects of AM fungi and water stress on A. ordosica under non-sterilized soil conditions. Our objective is to explore the effects of AM fungal colonization on growth and drought resistance ofA. ordosica. Methods Glomus mosseae inoculums and the indigenous AM fungi in the rhizosphere of A. ordosica were selected to study the effects of AM fungal colonization on growth and drought resistance ofA. ordosica. We used non-sterilized soil with two water contents： 75%-85% and 35%-45% of field moisture capacity. Important findings Plant morphology and water content were not significantly affected by drought stress, but AM fungal colonization was seriously decreased. Leaf water retention capacity increased under water stress and the allocation of nitrogen and phosphorus to shoots was limited. The activity of superoxide dismutase （SOD） was relatively higher in the early stage of stress, and the activity of peroxidase （POD） was relatively higher in the later stage. AM fungal colonization percent and spore numbers were enhanced under the same water condition. Branch numbers and development of lateral roots, root/shoot ratio, water retention capacity, absorption of phosphorus and nutrients in roots were all improved by AM fungal colonization. Under AM fungal colonization, the contents of soluble sugar and malondialdehyde （MDA） were low, the soluble protein content did not change greatly and the activity of SOD and POD was improved. Therefore, drought resistance ofA. ordosica was strengthened. There was a large discrepancy of promotion effects on A. ordosica under different soil conditions and AM fungal colonization. The effects of indigenous AM fungal colonization were better than the G. mosseae single colonization. Decline of AM infection rates might contribute to decreased plant water absorption capacity, and AM fungal colonization in the early stage of plant growth can improve the capacity for resistance to environmental drought stress at the middle-late growth stage.