Abstract
This study aimed to determine the effects of root pruning on the physicochemical characteristics and microbial activities of poplar rhizosphere soil. The root systems of 5-year-old poplar (Populus×euramericana cv. ‘Neva’) trees were manually pruned at 6, 8, or 10 times diameter at breast height (DBH) from the trunk (severe, moderate, and light, respectively) along both inter-row sides. Moderate root pruning significantly increased the concentrations of amino acids, organic acids, and total sugars in the root exudates and decreased the pH of rhizosphere soil. This treatment also increased the contents of available nitrogen, phosphorus, potassium, and total organic carbon as well as high-, medium-, and low-activity organic carbon in rhizosphere soil. Moreover, moderate pruning increased the contents of microbial biomass carbon and nitrogen, and enhanced basal respiration, in addition to decreasing the metabolic quotients in rhizosphere soil by 8.9%, 5.0%, and 11.4% compared with control, light, and severe root pruning treatments, respectively. Moderate pruning increased the growth rates of DBH, tree height, and volume to the highest levels. Furthermore, these indices were not significantly different between the light root pruning and control groups, but varied significantly between severe and moderate root-pruning treatments. Thus, root pruning, depending on the distance from the trunk, significantly influences the physicochemical properties and microbial activities in poplar rhizosphere soil.
Highlights
A root system is an absorptive and metabolic organ of a plant and displays sensitive reactions to external environmental conditions [1]
The organic acid content in samples treated with light root pruning showed no statistical significant difference with the control group but was significantly higher than that in samples treated with severe root pruning
The present study concluded that moderate root pruning can significantly increase the total organic carbon (TOC) and active organic carbon in the rhizosphere soil compared with the control group
Summary
A root system is an absorptive and metabolic organ of a plant and displays sensitive reactions to external environmental conditions [1]. Soil conditions, such as soil nutrients, water content, and aeration status, directly influence the growth, distribution, absorption function, and metabolic function of root systems, which affect the growth, development, and output of the aboveground parts of the plant [2]. Poplar is the main afforestation tree species of fast-growing and high-yielding plantation projects in China [3].Poplar trees are mainly planted at a density of 830–1100 trees per ha in China [3].As the poplar tree grows, the lateral roots gradually.
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