Gao W, Muñoz-Romero V, Ren T, Ashton R W, Morin M, Clark I M, Powlson D S, Whalley W R
Department of Soil and Water SciencesChina Agricultural UniversityNo. 2 Yuanmingyuan West RoadBeijing100193China.
Eco-efficient Cropping Systems group, Departamento de AgronomíaUniversity of CordobaEdificio C4 'Celestino Mutis' Ctra. Madrid-Cadiz km 39614071CordobaSpain.
Eur J Soil Sci. 2017 Jul;68(4):412-419. doi: 10.1111/ejss.12440. Epub 2017 Jun 22.
We explore the effect of microbial activity stimulated by root exudates on the penetrometer resistance of soil and its elastic modulus. This is important because it is a measure of the mechanical strength of soil and it correlates closely with the rate of elongation of roots. A sandy soil was incubated with a synthetic root exudate at different temperatures, for different lengths of time and with selective suppression of either fungi or bacteria. The shape of the temperature response of penetrometer resistance in soil incubated with synthetic exudate was typical of a poikilothermic temperature response. Both penetrometer resistance and small strain shear modulus had maximum values between 25 and 30°C. At temperatures of 20°C and less, there was little effect of incubation with synthetic root exudate on the small strain shear modulus, although penetrometer resistance did increase with temperature over this range (4-20°C). This suggests that in this temperature range the increase in penetrometer resistance was related to a greater resistance to plastic deformation. At higher temperatures (> 25°C) penetrometer resistance decreased. Analysis of the DNA sequence data showed that at 25°C the number of Streptomyces (Gram-positive bacteria) increased, but selective suppression of either fungi or bacteria suggested that fungi have the greater role with respect to penetrometer resistance.
Effect of microbial activity stimulated by synthetic root exudates on the mechanical properties.We compared penetrometer measurements and estimates of elastic modulus with microbial community.Penetrometer resistance of soil showed a poikilothermic temperature response.Penetrometer resistance might be affected more by fungi than bacteria.
我们探究了根系分泌物刺激产生的微生物活性对土壤贯入阻力及其弹性模量的影响。这很重要，因为它是土壤机械强度的一种度量，并且与根系伸长速率密切相关。将一种沙质土壤与一种合成根系分泌物在不同温度、不同时长下进行培养，并选择性地抑制真菌或细菌。用合成分泌物培养的土壤中贯入阻力的温度响应曲线呈现出变温动物的典型温度响应特征。贯入阻力和小应变剪切模量在25至30°C之间均有最大值。在20°C及更低温度下，用合成根系分泌物培养对小应变剪切模量几乎没有影响，尽管在此温度范围内（4 - 20°C）贯入阻力确实随温度升高而增加。这表明在该温度范围内，贯入阻力的增加与更大的抗塑性变形能力有关。在较高温度（> 25°C）下，贯入阻力下降。对DNA序列数据的分析表明，在25°C时，链霉菌（革兰氏阳性菌）数量增加，但对真菌或细菌的选择性抑制表明，就贯入阻力而言，真菌的作用更大。
合成根系分泌物刺激产生的微生物活性对力学性能的影响。我们将贯入测量值和弹性模量估计值与微生物群落进行了比较。土壤的贯入阻力呈现出变温动物的温度响应。贯入阻力受真菌的影响可能比细菌更大。
