Seed biopriming mitigates terminal drought stress at reproductive stage of maize by enhancing gas exchange attributes and nutrient uptake

Authors: HAMID NAWAZ, NAZIM HUSSAIN, Moazzam Jamil, AZRA YASMEEN, ASAD BUKHARI, MUHAMMAD AURINGZAIB, MUHAMMAD USMAN

Abstract: Maize (Zea mays L.) is an important cereal crop around the globe. Scarcity of water is one of the major abiotic factors reducing yields in this crop. The development of maize varieties with stress-tolerant traits is time-consuming and laborious work. There is a strong need to develop techniques that could have the effect of reducing irrigation requirements and mitigating waterstress conditions. Biopriming (seed priming with bacterial inoculation) is a newly emerging, simple, and easily adaptable strategy to mitigate drought stress for enhanced crop production. The current trial was executed using a randomized complete block design with factorial arrangements during the spring seasons of 2016 and 2017 at the research area of the Department of Agronomy, Bahauddin Zakariya University, Multan, Pakistan. The experiment consisted of two irrigation levels (normal irrigation and terminal drought stress at reproductive stage) and three seed priming techniques (control, hydropriming, and biopriming). Hybrid maize variety HC9091 was used as a test species. For hydropriming, seeds were soaked in distilled water (ratio 1:5) for 12 h. For biopriming, the hydroprimed seeds were inoculated with bacteria culture (Rhizobium phaseoli-RS-1 + Pseudomonas spp.) at the ratio of 1:5. Seeds were sown on ridges, maintaining a 75-cm row-to-row and 22.5-cm plant-to-plant distance. The results indicated an overall decline in agronomic and physiological attributes of the plants under terminal drought stress. However, seed biopriming considerably ameliorated the droughtinduced deterioration in agronomic (plant height, cobs per plant, cob length, cob weight, grain yield, biological yield, and harvest index) as well as physiological (photosynthesis, transpiration rate, intrinsic water use efficiency, stomatal conductance, relative water content, and nutrient uptake) parameters of plants. It is concluded that seed biopriming is an easy, commercially feasible, cost-effective technique and an ecofriendly way to cope with drought stress at the reproductive growth stage of maize in order to enhance crop productivity.

Keywords: Priming technique, water stress, physiological parameters, yield

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