MICROBIAL ABUNDANCE IN RHIZOSPHERE - COMPUTER-MODEL
MICROBIAL ABUNDANCE IN RHIZOSPHERE - COMPUTER-MODEL
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DOI：
10.1007/bf00015157
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发表时间：
1977-01-01
期刊：
影响因子：
4.9
通讯作者：
WATSON, A
中科院分区：
文献类型：
--
作者：
NEWMAN, EI;WATSON, A
描述了一种数学模型，其可以预测根际微生物的丰度（以μ g微生物干重/cm 3土壤计）与距根表面的距离和自根开始渗出基质以来的时间的关系。假定土壤中各点微生物的生长速率受可溶性有机基质浓度的控制。基质浓度的变化是由于其由根产生并通过土壤扩散;其在土壤中的产生是由于不溶性有机物质的分解;以及其被微生物利用。从文献中获得所有所需输入参数的值。该模型预测，一个高的人口密度将在根表面附近发展，但密度将急剧下降，从根的距离增加。在根表面，微生物的生长持续许多天，只要根的分泌继续以稳定的速率进行，但在更远的地方，微生物的数量达到峰值，然后下降。这是因为到达表层土壤的基质量不再足以支持种群的维持需求。从2 μ g/cm 3的微生物浓度开始，并使用被认为是其它输入参数的平均值，预测10天后的微生物浓度在根表面处为1509 μ g/cm 3，在距根1.8mm处为2.2 μ g/cm 3。该模型还预测了土壤中的基质浓度。这些在第1天内达到最大值，然后下降，在10天内达到与无根土壤中的值没有很大不同的值。该模型用于预测土壤含水量、根系密度、根系分泌速率、初始微生物浓度以及微生物对基质浓度的响应对微生物和基质浓度的影响。如果模型的预测可以根据观测数据进行检验，则有很好的一致性。
A mathematical model is described which can predict the abundance of microorganisms in the rhizosphere (as .mu.g microbial dry weight/cm3 soil) in relation to distance from the root surface and time since the root started exuding substrate. The growth rate of the microorganisms at each point in the soil is assumed to be controlled by the concentration of soluble organic substrate. The concentration of substrate changes due to its production by the root and diffusion through the soil; its production in the soil by breakdown of insoluble organic matter; and its use by the microorganisms. Values for all of the required input parameters were obtained from the literature. The model predicts that a high population density will develop near the root surface, but the density will fall off steeply with increasing distance from the root. At the root surface microbial growth continues for many days, provided exudation by the root continues at a steady rate, but further away the population reaches a peak and then declines. This is because the amount of substrate reaching the outer soil is no longer adequate to support the maintenance requirement of the population. Starting with a microbial concentration of 2 .mu.g/cm3, and using what are considered to be average values for other input parameters, the microbial concentrations predicted after 10 days are 1509 .mu.g/cm3 at the root surface, and 2.2 .mu.g/cm3 at 1.8 mm from the root. The model also predicts the substrate concentrations in the soil. These reach a maximum within the 1st day and then decline, reaching by 10 days values not very different from those in root-free soil. The model is used to predict the effect on microbial and substrate concentrations of changes in soil water content, root density, root exudation rate, initial microbial concentration and microbial response to substrate concentration. Where the predictions of the model can be tested against observed data there is good agreement.