Alleviation of waterlogging stress in upland cotton (Gossypium hirsutum L.) by exogenous application of potassium in soil and as a foliar spray

Abstract

The effectiveness of exogenous application of K in ameliorating the adverse effects of waterlogging on cotton plants was assessed under greenhouse conditions. Forty-day-old plants were subjected to continuous flooding for 1 week and then K (60 kg ha–1) was applied either as soil application, foliar spray, or in combination. The waterlogging treatment significantly reduced plant height and fresh and dry biomass, photosynthetic pigments, gas exchange parameters and nutrient accumulation (N, K+, Ca2+) in stem, root and leaves of cotton plants, Although Mg2+ content in roots increased significantly due to waterlogging, it was not affected in stem or leaves. In contrast, Mn2+ and Fe2+ contents generally increased under waterlogged conditions. All water relation parameters were also significantly influenced by waterlogging stress. Waterlogged plants supplemented with K showed a significant improvement in growth, photosynthetic pigments and photosynthetic capacity. Potassium supplementation also improved nutrient uptake of waterlogged plants and resulted in significantly higher accumulation of K+, Ca2+, N, Mn2+ and Fe2+ than those plants not supplied with K. Although all modes of K application were effective in mitigating the inhibitory effects of waterlogging, the combined application through soil + foliar spray yielded the best results and the foliar application (alone) being the least effective.