Potassium Improves Drought Stress Tolerance in Plants by Affecting Root Morphology, Root Exudates, and Microbial Diversity

Abstract

Potassium (K) reduces the deleterious effects of drought stress on plants. However, this mitigation has been studied mainly in the aboveground plant pathways, while the effect of K on root-soil interactions in the underground part is still underexplored. Here, we conducted the experiments to investigate how K enhances plant resistance and tolerance to drought by controlling rhizosphere processes. Three culture methods (sand, water, and soil) evaluated two rapeseed cultivars’ root morphology, root exudates, soil nutrients, and microbial community structure under different K supply levels and water conditions to construct a defensive network of the underground part. We found that K supply increased the root length and density and the organic acids secretion. The organic acids were significantly associated with the available potassium decomposition, in order of formic acid > malonic acid > lactic acid > oxalic acid > citric acid. However, the mitigation had the hormesis effect, as the appropriate range of K facilitated the morphological characteristic and physiological function of the root system with increases of supply levels, while the excessive input of K could hinder the plant growth. The positive effect of K-fertilizer on soil pH, available phosphorus and available potassium content, and microbial diversity index was more significant under the water stress. The rhizosphere nutrients and pH further promoted the microbial community development by the structural equation modeling, while the non-rhizosphere nutrients had an indirect negative effect on microbes. In short, K application could alleviate drought stress on the growth and development of plants by regulating the morphology and secretion of roots and soil ecosystems.

Effects of Long-Term Straw Management and Potassium Fertilization on Crop Yield, Soil Properties, and Microbial Community in a Rice–Oilseed Rape Rotation

“…K fertilizer in combination with straw returning could improve the soil available K content [4]. On the one hand, straw returning brings in a large amount of straw K into the farmland; on the other hand, the root secretion of crops and the humification in the process of residual straw rot would weaken the fixation of K + on the clay mineral, promoting transformation of slowly available K to water-soluble K and available K, and maintain a new dynamic balance of various soil K forms [51,52]. Notably, the soil EOC and DOC had significant differences between the straw incorporation and without straw.…”

Role of exogenous-applied salicylic acid, zinc and glycine betaine to improve drought-tolerance in wheat during reproductive growth stages

“…Drought is the most important one of abiotic stress factors that negatively influence the growth and production of various field crops [ 6 – 10 ]. Drought causes various changes in crop plants through different morphological, physiological, and biochemical responses [ 11 – 13 ]. Many studies have reported that the defense system of antioxidant was increased through the synthesis of antioxidants such as ascorbate peroxidase (APX) and glutathione reductase (GR), and enzymatic antioxidants such as peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD), which were stimulated to quench the ROS production in plants during drought stress [ 3 , 6 , 14 – 16 ].…”

Dynamics of phoD- and gcd-Harboring Microbial Communities Across an Age Sequence of Biological Soil Crusts Under Sand-Fixation Plantation

“…Ragot et al (2016) found that pH, organic carbon, and total nitrogen are important determinants responsible for the changes in phoD community structure at different P of grassland soil. Some studies reported that the application of K fertilizer can significantly alter the structure of soil microbial community, and available K is one of the key factors closely related to alterations in the composition of microbial community (Li et al, 2021;Xu et al, 2021). Wang et al (2020) also observed that some soil factors including total K, organic carbon, total N, and available P played key roles in shaping the soil phoD microbial community.…”