Improving drought tolerance in maize by foliar application of boron: water status, antioxidative defense and photosynthetic capacity

ABSTRACT

Boron (B) plays a vital role in cell division and elongation in apical meristem. Drought stress (DS) severely reduced the B-uptake and thus growth and crop-productivity of plants. The aims of this study were to evaluate whether foliar application of B corrects physiological-disorders under DS in two contrasting maize genotypes i.e. Dekalb-6525 (drought-tolerant) and Yousafwala-hybrid (drought-sensitive). Initially, foliar rate of B (0, 2, 4 and 6 mg L⁻¹) was optimized in terms of improved plant growth under drought-stress. Then, optimized rate of B (4 mg L⁻¹) was applied to assess the physiological and biochemical basis of B-induced improved growth of maize under deficit-moisture supply. Drought-stress reduced the growth of plants by lowering in water-status (leaf water-relations), photosynthetic capacity (gas-exchange aspects, photosynthetic-pigments), membrane permeability, imbalance in redox potential (oxidative-stress, antioxidant-defense system) and tissue-B concentration. Application of B considerably improved maize growth by improving water-status, photosynthetic capacity, tissue-B concentration as well as up-regulation of antioxidative defense-system. Moreover, ameliorative effects of B on maize was also evident from stress relieving indicators such as slight decrease in accumulation of proline, total free amino-acids, total soluble-sugars and MDA content under water-deficit conditions. In addition, cultivar Dekalb-6525 showed considerable improving response to B application over Yousafwala-hybrid.

KEYWORDS:

• Foliar spray
• water stress
• nutrient deficiency
• antioxidant potential
• osmotic adjustment

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We are grateful to Higher Education Commission (HEC), Pakistan for financial support of conducting this study.