Tinker P B, Durall D M, Jones M D
Terrestrial and Freshwater Science Directorate, Natural Environment Research Council, Polaris Home, North Star Avenue, Swindon, SN2 1EU, UK.
Plant Mycorrhizal Unit, Natural Environment Research Council, Department of Plant Sciences, Parks Road, Oxford, OXI 3PF, UK.
New Phytol. 1994 Sep;128(1):115-122. doi: 10.1111/j.1469-8137.1994.tb03994.x.
The benefit to a fungus by a mycorrhizal association is that it gains carbon from its host. A benefit to a host is usually a nutritional one, but any resulting increase in dry weight may be counteracted by the carbon consumed by the fungus. The carbon costs of mycorrhizal fungi have been calculated using C pulse-chase experiments in the laboratory or by estimating turnover rates in the field. Both of these techniques have their limitations, but estimates have been remarkably consistent amongst most laboratory studies. Carbon demands of the fungus may not reduce theoretical growth enhancement in plants which are sink-limited but would be expected to do so iii source-limited plants. A model of carbon use efficiency is developed based on the economic concepts of cost and benefit. Efficiency is defined in terms of carbon gained via the growth response to infection, and the carbon expended supporting the fungus. Practical considerations of measuring carbon allocation, and calculating carbon use efficiency are discussed. In an experiment on Salix viminalis L., colonized by Thelephora terrestris (Ehrh.) Fr., the carbon use efficiency calculated by this method was on overage 85% based on shoot tissue production, and 95% based on whole plant production.
菌根共生对真菌的益处在于它能从宿主那里获取碳。对宿主的益处通常是营养方面的，但真菌消耗的碳可能会抵消由此导致的干重增加。菌根真菌的碳成本已通过实验室中的碳脉冲追踪实验或通过估算田间周转率来计算。这两种技术都有其局限性，但大多数实验室研究中的估算结果相当一致。真菌对碳的需求可能不会降低受库限制的植物理论上的生长增强，但预计会降低源限制型植物的生长增强。基于成本和效益的经济概念建立了一个碳利用效率模型。效率是根据通过对感染的生长反应获得的碳以及为支持真菌而消耗的碳来定义的。讨论了测量碳分配和计算碳利用效率的实际考虑因素。在一项对被土生革菌（Ehrh.）Fr. 侵染的垂柳（Salix viminalis L.）进行的实验中，用这种方法计算出的碳利用效率，基于地上部组织产量平均超过85%，基于整株植物产量则为95%。
