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

Abstract

Maize (Zea mays L.) is an important cereal crop around the globe. Scarcity of water is one of the major abiotic factorsreducing 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 waterstressconditions. Biopriming (seed priming with bacterial inoculation) is a newly emerging, simple, and easily adaptable strategy tomitigate drought stress for enhanced crop production. The current trial was executed using a randomized complete block design withfactorial arrangements during the spring seasons of 2016 and 2017 at the research area of the Department of Agronomy, BahauddinZakariya University, Multan, Pakistan. The experiment consisted of two irrigation levels (normal irrigation and terminal drought stressat reproductive stage) and three seed priming techniques (control, hydropriming, and biopriming). Hybrid maize variety HC9091 wasused as a test species. For hydropriming, seeds were soaked in distilled water (ratio 1:5) for 12 h. For biopriming, the hydroprimedseeds were inoculated with bacteria culture (Rhizobium phaseoli-RS-1 + Pseudomonas spp.) at the ratio of 1:5. Seeds were sown onridges, maintaining a 75-cm row-to-row and 22.5-cm plant-to-plant distance. The results indicated an overall decline in agronomic andphysiological attributes of the plants under terminal drought stress. However, seed biopriming considerably ameliorated the droughtinduceddeterioration 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 techniqueand an ecofriendly way to cope with drought stress at the reproductive growth stage of maize in order to enhance crop productivity.