Arbuscular mycorrhizal fungi and nematodes are involved in negative feedback on a dual culture of alfalfa and Russian wildrye
Arbuscular mycorrhizal fungi and nematodes are involved in negative feedback on a dual culture of alfalfa and Russian wildrye
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DOI：
10.1016/j.apsoil.2008.03.004
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发表时间：
2008-09-01
影响因子：
4.8
通讯作者：
Germida, J.
中科院分区：
文献类型：
--
作者：
Atul-Nayyar;Hamel, C.;Germida, J.
土壤-植物系统中发生的复杂生物相互作用有时可能改变生态系统的功能。在一个8年的田间试验中，我们研究了丛枝菌根（AM）根定殖、线虫种群和植物竞争之间的关系，比较了紫花苜蓿（Medicago sativa L.）和新麦草（Psathyostachys juncea菲施.）Nevski）（RWR）在不同土壤磷素肥力水平下，在加拿大萨斯喀彻温省的棕红壤上进行了盆栽试验。试验包括三个磷水平：0，20和40公斤P2 O 5公顷（-1）（0 P，20 P和40 P）每年施加，并在种植季节采样三次：6月30日，9月1日和30日。较高的AM共生发展补偿了土壤磷肥力降低苜蓿林没有RWR和牧草干物质产量不受磷率。但在RWR存在下，0 P和20 P土壤P肥力降低导致牧草产量降低。施肥处理修改土壤微生物群落结构，只有在RWR的存在下，揭示了土壤脂质提取物和功能线虫组中的微生物磷脂脂肪酸的配置文件的判别分析。在有和没有RWR的情况下，施用磷肥都降低了丛枝菌根的根定殖水平。在RWR的存在下，较低的植物AM根定殖与较高丰度的总，真菌和杂食性线虫。我们的研究结果是一致的负反馈模型，从植物相关的土壤微生物区系的存在下，RWR增加了食真菌线虫和放牧的AM菌丝的人口。在低磷土壤中，促进AM共生发展的负面影响较大。苜蓿-RWR双培养产量在0 P和20 P施肥水平下的意外下降归因于在RWR存在下通过增强线虫对AM真菌的摄食而产生的碳流失。(C)2008 Elsevier B. V.保留所有权利。
The complex biological interactions taking place in soil-plant systems may sometimes alter the functioning of an ecosystem. We examined the relationship between arbuscular mycorrhizal (AM) root colonization, nematode populations, and plant competition in an 8-year-old field experiment comparing alfalfa monoculture to dual culture of alfalfa (Medicago sativa L.) and Russian wildrye (Psathyostachys juncea Fisch. Nevski) (RWR) grown under different soil P fertility levels, in a Brown Chernozemic soil in Saskatchewan. The experiment included three P rates: 0, 20 and 40 kg P2O5 ha(-1) (0P, 20P and 40P) applied annually and was sampled three times during the cropping season: 30 June, 1 September and 30 September. Higher AM symbiotic development compensated for reduced soil P fertility in alfalfa stands without RWR and forage dry matter yield was not affected by P rates. But in the presence of RWR, reduced soil P fertility at 0P and 20P led to forage yield reduction. Fertilization treatments modified the soil microbial community structure only in the presence of RWR, as revealed by discriminant analysis of the profiles of microbial phospholipids fatty acid in soil lipid extracts and functional nematode groups. Arbuscular mycorrhizal root colonization level was reduced with P fertilizer both in the presence and absence of RWR. In the presence of RWR, lower plant AM root colonization was concurrent with higher abundance of total, fungivorous and omnivorous nematodes. Our results are consistent with a model of negative feedback from the plant-associated soil microflora where the presence of RWR increased the population of fungivorous nematodes and grazing of AM hyphae. Negative impacts were larger in low P fertility soils promoting AM symbiotic development. The unexpected decrease in alfalfa-RWR dual culture yield under 0P and 20P fertilization levels was attributed to a carbon drain created by enhanced nematode feeding on AM fungi in the presence of RWR. (C) 2008 Elsevier B.V. All rights reserved.