Morphological, Physiological and Antioxidant Responses of Five Dryland Maize (Zea mays L.) Genotypes to Water-Deficit Stress

Yonela Sinazo Gwexa ¹, Azile Dumani ^1,2, Ndiko Ludidi ³ and Ifeanyi Moses Egbichi ^1,*
1 Department of Biological and Environmental Sciences, Faculty of Natural Science, Walter Sisulu University,
Mthatha 5099, South Africa
2 Department of Agriculture, Döhne Agricultural Development Institute, Stutterheim 4930, South Africa
3 Faculty of Agriculture and Natural Sciences, University of Mpumalanga, Mbombela 1200, South Africa
* Correspondence: iegbichi@wsu.ac.za; Tel.: +27-0475022274 or +27-834419075
Received: 8 July 2026 Revised: 11 August 2026 Accepted: 12 August 2026 Published: 9 October 2026

ABSTRACT

Maize (Zea mays) is a critical staple for global food security, particularly in developing nations facing a projected population increase to 9.7 billion by 2050, necessitating enhanced agricultural productivity and drought-resilient cultivars. This study provides a comprehensive evaluation of the morphological, physiological, and antioxidant responses of five South African dryland maize genotypes (CY1 DKC71-44B, CY2 DKC72-76BR, CY3 DKC74-26R, CW1 DKC75-65BR, and CW3 DKC78-45BRGEN) to drought stress and identifies genotype-specific antioxidant mechanisms associated with drought tolerance. Morphological (shoot growth), physiological (relative water content—RWC), and biochemical (hydrogen peroxide—H₂O₂, lipid peroxidation, ascorbate peroxidase—APX, and superoxide dismutase—SOD activity) parameters were assessed to identify drought tolerance mechanisms. Drought stress significantly reduced shoot length (28–41%), fresh biomass (up to 41%), and relative water content (19–22%) across the evaluated maize genotypes. However, CY3 (DKC74-26R) and CW3 (DKC78-45BRGEN) maintained higher tissue hydration, suggesting superior drought adaptation. Water deficit also induced oxidative stress, resulting in increases in hydrogen peroxide and lipid peroxidation of up to 245%. In response, APX and SOD isozyme activities increased under drought stress, as demonstrated by enhanced in-gel activity and pixel intensity values. Native-PAGE analysis further revealed differential induction of APX and SOD isoforms, indicating genotype-specific antioxidant responses to drought stress. This study provides critical insights for breeding drought-resilient maize varieties for South Africa’s climate, improving agricultural productivity despite growing climatic variability.
Keywords: drought-tolerance; oxidative stress; reactive oxygen species; antioxidant enzymes; maize hybrids; relative water content