Open Access

ARTICLE

Foliar Application of Cytokinin Modulates Gas Exchange Features, Water Relation and Biochemical Responses to Improve Growth Performance of Maize under Drought Stress

M. Rafiqul Islam^1,*, M. Shahinur Islam¹, Nurunnaher Akter¹, Mohammed Mohi-Ud-Din², Mohammad Golam Mostofa^3,4,*

1 Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, 1706, Bangladesh
2 Department of Crop Botany, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, 1706, Bangladesh
3 Department of Biochemistry and Molecular Biology, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, 1706, Bangladesh
4 Institute of Genomics for Crop Abiotic Stress Tolerance, Department of Plant and Soil Science, Texas Tech University, Lubbock, TX 79409, USA

* Corresponding Authors: M. Rafiqul Islam. Email: ; Mohammad Golam Mostofa. Email: ,

Phyton-International Journal of Experimental Botany 2022, 91(3), 633-649. https://doi.org/10.32604/phyton.2022.018074

Received 27 June 2021; Accepted 30 August 2021; Issue published 26 October 2021

Abstract

Improvement of plant performance under drought stress is crucial to sustaining agricultural productivity. The current study investigated the ameliorative effects of foliar-applied kinetin, an adenine-type cytokinin (CK), on growth and gas exchange parameters, water relations and biochemical attributes of maize plants under drought stress. Eighteen-day-old maize plants were subjected to drought by maintaining soil moisture content at 25% field capacity for 8 days followed by foliar application of kinetin at 0, 75, 150 and 225 mg L⁻¹ (CK0, CK75, CK150 and CK225, respectively) to the plants for two-times at the 9-day interval. Results revealed that drought stress markedly reduced stem diameter, dry weight, chlorophyll content, gas exchange parameters and water balance but increased proline, malondialdehyde and soluble sugar contents, electrolyte leakage and senescence in maize leaves. Application of exogenous CK remarkably improved maize performance by modulating growth, gas exchange- and water relation-related parameters in a dose-dependent manner under drought stress. CK225 increased chlorophyll content (by 61.54%), relative water content (by 49.14%), net photosynthesis rate (by 39.94%) and transpiration rate (by 121.36%) and also delayed leaf senescence but decreased internal CO₂ concentration (by 7.38%), water saturation deficit (by 40.40%) and water uptake capacity (by 42.49%) in both well-watered and drought-stressed plants. Nevertheless, CK application considerably decreased electrolyte leakage, proline, malondialdehyde and soluble sugar levels in drought-stressed maize plants, as also supported by heatmap and cluster analyses. Taken together, exogenous CK at proper concentration (225 mg L⁻¹) successfully improved maize performance under drought conditions, thereby suggesting CK application as a useful approach to alleviate drought-induced adverse effects in maize plants, and perhaps in other important crop plants.

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