Abiotic soil attributes and their relation to morphological root characteristics and mycorrhizal colonization of grasses

Abstract

This study evaluated soil properties and their relation to root production and arbuscular mycorrhizal fungi (AMF) colonization of grasses. Soil samples were collected from surface layers to determine the volume, total length, specific length, diameter and dry mass of roots, and grain size and chemical properties of the soil. Sampled roots were used to evaluate mycorrhizal colonization and 50 g of soil to extract spores. A second sampling was conducted to measure soil penetration resistance, macroporosity, microporosity, total porosity and bulk density. Of the morphological traits of the roots, only specific length and diameter were significantly related to soil physical attributes. Root volume was positively related with P, Ca, Mg and organic matter. Almost all of the mycorrhizal variables had no correlation with the physical properties of the soil; only total colonization was positively related to soil penetration resistance (to 0.10 m). AMF had a negative correlation between root colonization and total length of the roots, while the number of spores was inversely related to roots finer than 0.5 mm in diameter and positively related to roots larger than 0.5 mm in diameter. The data were highly variable, indicating the influence of environmental heterogeneity on the investigated characteristics.