Effects of drought stress on the functional traits and rhizosphere microbial community structure of Cyperus esculentus

Drought is a major factor limiting plant growth. Plants cope with stress via morphophysiological responses. Rhizosphere-related bacteria, fungi and other microorganisms can help plants cope with drought via various mechanisms. We conducted a pot experiment on Cyperus esculentus wherein we subjected it to various drought levels and analyzed the functional traits of its aboveground and belowground organs. High-throughput sequencing was used to study the structure and diversity of the microbial community in the rhizosphere. Drought stress substantially lowered the densities of the leaves, stems, roots and seeds relative to the untreated control. Drought stress inhibited the growth and reduced the yield of C. esculentus. The leaves and seeds have higher water content and are more sensitive to drought stress than the roots. With the aggravation of drought stress, the plant height of C. esculentus decreased significantly, the root:shoot ratio increased and the specific leaf weight had no significant difference. Change in shoot height was the most evident response of C. esculentus to drought stress. Plants under drought stress reduced their leaf area and assumed a specific leaf weight to maintain photosynthetic performance. Rhizosphere fungi were more sensitive to drought stress than rhizosphere bacteria. Drought stress increased the relative abundances of Bacteroidetes, Verrucomicrobia, Patescibacteria, Actinobacteria and Nitrospirae. Drought-stressed C. esculentus maintained their photosynthetic performance by reducing shoot height and leaf area while assuming a stable specific leaf weight. Drought stress exerted a significantly stronger negative impact on rhizosphere fungi than rhizosphere bacteria. The results clarified the response strategies of functional traits and rhizosphere microorganisms of C. esculentus to drought stress.