Impact of Potassium-Solubilizing Microorganisms with Potassium Sources on the Growth, Physiology, and Productivity of Wheat Crop under Salt-Affected Soil Conditions

Salinity adversely affects plant growth and productivity worldwide. To overcome salinity and other abiotic stresses, safe, ecofriendly biofertilizers that stimulate productivity have been experiencing rising demand, alongside decreasing use of mineral fertilizers. The purpose of this study was to examine changes in the growth, yield, physiological and biochemical parameters of wheat crop as a response to two potassium-solubilizing microorganisms (KSMs), <i>Trichoderma asperellum</i> and <i>Bacillus circulans,</i> with 50% or 75% of the recommended amount of K fertilizer (potassium sulphate), combined with no or 25% feldspar as well as 1.5% potassium sulphate (K-leaf) as foliar application, and all treatments were compared with a control treatment under salt-affected soil conditions, during two winter seasons in 2019–2020 and 2020–2021. The randomized complete block design (RCBD) was used to set up the experiment. Results showed that the vegetative growth, yield, physiological and biochemical parameters were affected under salt-affected soil conditions. Nevertheless, inoculation with <i>T. asperellum</i> and <i>B. circulans</i> with potassium application mitigated the deleterious effect of salt-affected soil conditions by improving growth parameters, photosynthetic pigment content, antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, catalase and peroxidase) content, total soluble sugars, relative water content, potassium content in leaves, grains yield, and some biochemical constituents in the grains and straw. Meanwhile, these treatments decreased proline content, Na⁺ content in leaves, and the Na⁺/K⁺ ratio as compared to the control treatment. The most pronounced treatment, inoculation by <i>B. circulans</i> with 1.5% K-leaf as foliar application, significantly increased grain yield by 16.41% relative to the control treatment. It could be concluded that inoculating wheat with KSMs <i>T. asperellum</i> and <i>B. circulans</i> with 1.5% K-leaf as foliar application will increase wheat salinity tolerance and wheat productivity and decrease the detrimental effect of salinity on wheat growth and grain yield quantity and quality under salt-affected soils conditions.