Beneficial effects of potassium application in improving submergence tolerance of rice (Oryza sativa L.)

• Submergence tolerance with high potassium application was investigated.
• Starch and reactive oxygen species accumulation in plants affected photosynthesis under stress.
• The SUB1 cultivars tolerated submergence by reserving carbohydrates and chlorophyll and maintenance of antioxidants.
• Plants fed with high potassium had higher survival because of less lodging, senescence and higher antioxidants.
• The maintenance of a sufficient K supply can be an effective nutritional strategy to minimize submergence stress-related losses.

The rainfed lowland rice ecosystem is affected by not only water deficit but also excess water. Although the rice plant is well adapted to aquatic environments, it is unable to survive if it is completely submerged in water for an extended period. The impact of submergence on survival, chlorophyll, photosynthesis, post-recovery growth and anti-oxidant capacities in four rice cultivars namely IR 64, IR 64-Sub1, Swarna and Swarna-Sub1 having differential response to potassium application were examined. All the cultivars showed inhibition of photosynthesis, this was accompanied with decrease in stomatal conductance, chlorophyll and carbohydrate contents; the decrease was more pronounced in non-sub1 cultivars. The activity of anti-oxidants was found to be significantly high and lipid peroxidation was low in sub1 cultivars. Potassium application improved the survival mainly because of maintenance of carbohydrates, chlorophyll and contributing to less lodging and leaf senescence. Furthermore, K application resulted in inhibition of lipid peroxidation and increase in catalase and Peroxidase activities. Potassium at higher levels was more beneficial in terms of improving survival, photosynthesis and growth after recovery. The germplasm improvement is beneficial if provided with best management practices, modification in plant nutrition by K application enhance the survival, recovery and growth of rice during complete submergence.