Arbuscular mycorrhizal mediation of biomass–density relationship of Medicago sativa L. under two water conditions in a field experiment
Arbuscular mycorrhizal mediation of biomass–density relationship of Medicago sativa L. under two water conditions in a field experiment
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DOI：
10.1007/s00572-010-0331-5
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发表时间：
2011-05
期刊：
影响因子：
3.9
通讯作者：
Qian Zhang;Liming Xu;Jianjun Tang;Minge Bai;Xin Chen
中科院分区：
文献类型：
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作者：
Qian Zhang;Liming Xu;Jianjun Tang;Minge Bai;Xin Chen
生物量与密度的关系（即单株植物的生物量随着植物密度的增加而减少）一般用资源竞争来解释。丛枝菌根真菌（AMF）能够通过介导资源利用来影响植物相互作用，但这种AMF介导的相互作用是否会改变生物量-密度关系尚不清楚。我们进行了一个实验，以测试的假设，AMF将改变生物量密度的关系，通过影响种内竞争。苜蓿（Medicago sativa L.）被种植在田间。在湿润地区（水充足）和干旱地区（水不足），用水量（1，435或327.7毫米/年）模拟降水。杀真菌剂苯菌灵在一些地块（“低AMF”处理）中被施用以抑制AMF，而在另一些地块（“高AMF”处理）中不被施用。AMF处理对生物量-密度关系的影响取决于水分条件。当水分充足时，高AMF增强了个体生物量随密度增加而减少的趋势（生物量-密度线斜率较陡），但当水分不足时则没有。AMF处理不影响植物存活率或种群规模，但确实影响绝对竞争强度（ACI）。当水分充足时，高AMF处理的ACI显著高于低AMF处理，但当水分不足时，ACI不受AMF处理的影响。我们的研究结果表明，AMF的状态并没有影响生存率和人口规模，但确实改变了生物量密度的关系，通过影响种内竞争。AMF对生物量-密度关系的影响取决于水的可用性。
The biomass–density relationship (whereby the biomass of individual plants decreases as plant density increases) has generally been explained by competition for resources. Arbuscular mycorrhizal fungi (AMF) are able to affect plant interactions by mediating resource utilization, but whether this AMF-mediated interaction will change the biomass–density relationship is unclear. We conducted an experiment to test the hypothesis that AMF will shift the biomass–density relationship by affecting intraspecific competition. Four population densities (10, 100, 1,000, or 10,000 seedlings per square meter) ofMedicago sativaL. were planted in field plots. Water application (1,435 or 327.7 mm/year) simulated precipitation in wet areas (sufficient water) and arid areas (insufficient water). The fungicide benomyl was applied to suppress AMF in some plots (“low-AMF” treatment) and not in others (“high-AMF” treatment). The effect of the AMF treatment on the biomass–density relationship depended on water conditions. High AMF enhanced the decrease of individual biomass with increasing density (the biomass–density line had a steeper slope) when water was sufficient but not when water was insufficient. AMF treatment did not affect plant survival rate or population size but did affect absolute competition intensity (ACI). When water was sufficient, ACI was significantly higher in the high-AMF treatment than in the low-AMF treatment, but ACI was unaffected by AMF treatment when water was insufficient. Our results suggest that AMF status did not impact survival rate and population size but did shift the biomass–density relationship via effects on intraspecific competition. This effect of AMF on the biomass–density relationship depended on the availability of water.