The Effect of Water Stress on Carbon Metabolism in the Rhizospheric Microbiome of Greenhouse Grape

【Objective】 Microbiome in the rhizosphere is associated with plant species and mediated by soil moisture. It plays an essential role in modulating biogeochemical reactions and nutrient and carbon cycles. The objective of this paper is to elucidate how carbon metabolism in microbes in the rhizosphere of grape responds to change in soil water content induced by drip irrigation. 【Method】 The experiment was conducted in a greenhouse in a region with semi-arid climate. The grape was drip-irrigated with the dripping rate varying to create a mild to moderate water stress to the crop; sufficient irrigation was taken as the control. In each treatment, we analyzed the metabolism of different carbon sources in the rhizospheric microbiome. 【Result】 Microbial utilization of monosaccharides, glycosides, polymerized sugars, amino acids, alcohols and acids was relatively high. The representative carbon sources were glucose-1-phosphate and D-cellobiose, Glycyl-L-glutamic acid, I-erythritol, 4-hydroxybenzoic acid, r-hydroxybutyric acid. Water stress increased the metabolization of all carbon sources. Carbon metabolization was the highest at early stage under mild water stress, while under moderate water stress, carbon utilization peaked in the middle and late stages of the treatment. Imposing a mild water stress increased total yield and average weight of single fruit by 11.95% and 2.62%, respectively, compared to the CK. In contrast, occurrence of moderate water stress led to a reduction in fruit yield. 【Conclusion】 Water stress increased microbial activity and boosted carbon metabolization in rhizospheric microbiome of the grape. Imposing a mild water stress affected the metabolic activity most strongly at the initial stage of the treatment, while a moderate water stress led to a surge in carbon metabolization in the middle and late stages of the treatment.