Morphological and biochemical changes in maize under drought and salinity stresses in a semi-arid environment

Abstract

This study investigated some morphological and biochemical responses of maize to drought and salinity in open field in Tunisia with the aim of gaining insights into tolerance mechanisms. After seedling emergence, five treatments were applied until maturity: optimal water supply (control, 100% of maximum evapotranspiration - ETM); irrigation at 70% ETM (moderate drought) and at 35% ETM (severe drought); optimal supply of water containing 3 g NaCl L⁻¹ (moderate salinity) and 6 g NaCl L⁻¹ (severe salinity). Here, we demonstrated that extreme drought and salinity severely decreased the leaf area (−74% and −55%, respectively) and the above-ground biomass (−35% and −31%, respectively) at silking stage, indicating that the photosynthetic leaf apparatus is highly sensitive and that drought has a greater effect than salinity. Grain yield losses were also exacerbated under extreme stress conditions, viz. severe drought (−85% versus controls) and severe salinity (−73%), while productivity under moderate salinity approximated that of moderate drought, possibly due to increases in leaf chlorophyll and carotenoid content and K/Na ratio. The leaf area and its relative water content were positively correlated with grain yield under both salinity and drought stresses, and may therefore be used as markers for effective screening of maize genotypes for better stress tolerance.

Keywords:

• Carotenoids
• chlorophyll
• drought and salinity stress
• maize hybrid
• leaf area
• proline

Acknowledgements

The authors wish to thank Prof. Sifi Bouaziz, head of the Laboratory of Agronomic Sciences and Technical at the National Institute of Agronomic Research (INRAT) in Tunisia. Our sincere thanks also to Tessa Say for revising the English text.

Disclosure statement

No potential conflict of interest was reported by the authors.