Potassium fertilization mitigates the adverse effects of drought on selected Zea mays cultivars

Authors: LIXIN ZHANG, MEI GAO, SHENGXIU LI, ASHOK KUMAR ALVA, MUHAMMAD ASHRAF

Abstract: In the present study, the role of potassium (K) in mitigating the adverse effects of drought stress (DS) on 2 maize (Zea mays L.) cultivars, 'Shaandan 9' (S_{9}; drought-tolerant) and 'Shaandan 911' (S_{911}; drought-sensitive), was assessed. K application increased dry matter (DM) across all growth stages and grain yield (GY) in both cultivars under DS, but not under control conditions. Drought-tolerant cultivar S_9 was superior to drought-sensitive cultivar S_{911} under DS in terms of DM and GY regardless of K addition. Additionally, K application increased relative water content, nitrate reductase activity, and concentrations of potassium ion, free proline, soluble protein, and endogenous glycine betaine in both cultivars. These positive effects due to K fertilization under DS were greater for S_{911} than for S_{9}. In contrast, the differences in the above parameters between K-treated plants and plants under control conditions were either nonsignificant or marginal. This study provides direct evidence of the beneficial physiological function of K fertilization in mitigating the adverse effects of DS by increased nitrate assimilation and osmotic regulation, but not due to its nutritive role.

Keywords: Relative water content, nitrate reductase activity, osmotic solutes, Poaceae, potassium fertilizer

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