Leaf photosynthetic characteristics and photosystem II photochemistry of rice (Oryza sativa L.) under potassium-solubilizing bacteria inoculation

The current research was performed to investigate the effects of three potassium-solubilizing bacteria (KSB) strains (Pantoea agglomerans, Rahnella aquatilis, and Pseudomonas orientalis) on leaf photosynthetic characteristics in rice (Oryza sativa L. cv. Pajohesh). A pot and a field experiment were conducted in a paddy field. The results indicated that the KSB inoculums significantly enhanced chlorophyll (Chl) a, Chl a+b, SPAD value, and stomatal conductance as compared to the control in both experiments, especially when applied along with half the recommended dose of the potassium chemical fertilizer. KSB inoculations, alone or combined with K fertilizer, significantly increased the value of photochemical quenching, photosynthetic electron transport rate, and the effective quantum efficiency as compared to the control. In conclusion, these native KSB strains could be used as inoculants to reduce consumption of K chemical fertilizer and improve the efficiency of photosynthesis for rice production under the flooding irrigation conditions.