Location: Agricultural Systems ResearchTitle: Potassium fertilization mitigates the adverse effects of drought on selected Zea mays cultivars
|ZHANG, LIXIN - Northwest Agriculture And Forestry University|
|LI, SHENGXIU - Northwest Agriculture And Forestry University|
|ASHRAF, MUHAMMAD - University Of Sargodha|
Submitted to: Turkish Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2014
Publication Date: 6/19/2014
Citation: Zhang, L., Li, S., Alva, A.K., Ashraf, M. 2014. Potassium fertilization mitigates the adverse effects of drought on selected Zea mays cultivars. Turkish Journal of Botany. 38:713-723. DOI: 10.3906/bot-1308-47.
Interpretive Summary: Drought stress is a major limitation for plant growth and productivity in water limiting growing conditions. The osmotic stress in plants grown in water limiting conditions results in several biochemical and physiological changes. Nitrate assimilation is decreased while protein degradation is increased under drought stress. Relative water content of the leaves decrease under water limiting growing conditions, hence, is used as an index of drought stress. Mineral nutrition of crop plants influence the plant growth and production as well as plants tolerance to abiotic stresses, including drought stress. Effects of no potassium (K) or plus K (0.42 g K/kg soil) on a drought tolerant and a drought sensitive wheat cultivars subjected to drought stress or no drought stress were investigated in this study. No K application significantly decreased the plant biomass (from seedlings to maturity stages) and grain yields of both cultivars as compared to those of the plus K treatments only under drought stress, but not under no drought stress treatment. Potassium application increased the relative water content, nitrate reductase activity, and concentrations of free proline, soluble protein, and endogenous glycine betaine. These changes are indicative of plant physiological mechanisms in response to drought stress. This study demonstrated the role of potassium in enhancing the above reactions in facilitating increased tolerance to drought stress.
Technical 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’ (S9; drought-tolerant) and ‘Shaandan 911’ (S911; 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 S9 was superior to drought-sensitive cultivar S911 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 S911 than for S9. 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.