Organic Acids Exuded From Roots Increase the Available Potassium Content in the Rhizosphere Soil: A Rhizobag Experiment in Nicotiana tabacum

Abstract

Additional index words. root, soil potassium, organic acid, root vigor, stress-resistant enzyme activity Abstract. Organic acid secretion from higher plant roots into the rhizosphere soil plays an important role in nutrient acquisition and metal detoxification; however, their precise functions and the related mechanisms in abiotic stress tolerance remain poorly understood. Tobacco is an important crop plant, so thoroughly elucidating these factors in tobacco is of high priority. In the present study, the activation effect on soil potassium (K), contents of exuded organic acids, and physiological changes in the roots of various tobacco varieties under both normal K supply and K-deficiency stress were investigated. Our results showed that one high-K variety (ND202) exhibited a significantly higher total content of organic acids in the root exudates and the highest available K content in the rhizosphere soil, compared with two common ones (K326 and NC89). Moreover, the high-K tobacco variety was less affected in terms of root vigor under K-deficiency stress, and displayed greater increases in the activities of the stress-resistant enzymes consisting of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). Taken together, these results provide evidence that tobacco roots exude large amounts of organic acids to increase the available K content in the rhizosphere soil and improve the utilization rate of soil K.

Seed Priming and Coating by Nano-Scale Zinc Oxide Particles Improved Vegetative Growth, Yield and Quality of Fodder Maize (Zea mays)

“…The soil macronutrient like available nitrogen (N), Phosphorous (P), Potassium (K), and zinc (Zn) micronutrient contents were also increased in the rhizosphere soil of plants treated with ZnONPs. The increased soil available K, P and Zn contents in the rhizosphere soil may be attributed to enhanced root growth, higher production of the organic acids by the plant roots [41] and occurrence of P-solubilizing microbes [42] as indicated through greater alkaline and acid phosphatase activities which cumulatively led to decrease in the pH in near vicinity of the growing roots thus facilitating improved soil available K, P and Zn contents. The enhancement in the soil N content in plants treated with ZnONPs must be due to enhanced microbial biomass or activity particularly the non-symbiotic N-fixer populations [43,44] which were increased due to seed priming and coating treatments.…”

Potassium Control of Plant Functions: Ecological and Agricultural Implications

“…Further, plants can improve their capacity for K + uptake by mycorrhization [ 212 , 213 , 214 ] and root exudates [ 215 , 216 ]. Some studies have suggested that plants can invest C in root exudates [ 215 , 216 ] or in root mycorrhization [ 217 , 218 , 219 ], specifically to cope with K + soil limitation. However, other studies have not observed a mycorrhization rise related to plant K + limitation.…”

Effects of tobacco–peanut relay intercropping on soil bacteria community structure

“…Flue-cured tobacco is a special type of cash crop, and its root exudates have large effects on soil characteristics (Li et al 2017). Flue-cured tobacco root exudates can increase the content of available nutrients in soil, significantly affect the activities of phytases, catalase, and polyphenol oxidase (Lung et al 2008;Yang et al 2019). In addition, organic acids in fluecured tobacco root exudates can participate in plant growth regulation as chemical attractants to stimulate microbial growth (Faure et al 2009;Fang et al 2016).…”