Seed priming with CaCl2 and ridge planting for improved drought resistance in maize

Abstract

Drought-induced losses in crop output have forced the scientific community to develop efficient management strategies to cope with the adversities of drought stress. This field trial was done to assess the role of seed priming techniques and planting methods for improving drought resistance in Pakistani hybrid maize in 2011. Maize seeds were soaked in an aerated solution of CaCl2 (osmopriming; $\Psi$s -1.25 MPa) and distilled water (hydropriming), while untreated dry seeds were taken as controls. Primed and untreated seeds were sown on either ridges or a flat seedbed and were subjected to drought at vegetative and tasseling stages. Drought was imposed by stopping irrigation up to ~50% of field capacity (FC), while well-watered conditions (~75% FC) were taken as control. Drought at different phenophases, the tasseling stage in particular, impaired the root system, leaf score, yield-related attributes, and yield. Seed priming, osmopriming with CaCl2, mitigated the damaging effects of drought on the root system, yield, and related traits. Moreover, ridge sowing helped to maintain its supremacy, securing a well-developed root system, i.e. greater root length and proliferation. This led to notable expansion in yield-related attributes compared with flat sowing under well-watered and stressed conditions. Interestingly, under vegetative drought, hydropriming performed better than osmopriming for 1000-grain weight; however, the supremacy of osmopriming over hydropriming was evident in all other yield-related attributes under vegetative and terminal drought stress. Net returns and benefit-cost ratio (BCR) declined under drought conditions; nevertheless, priming techniques over control and ridge sowing over flat sowing were helpful in improving the net returns and BCR of maize exposed to drought conditions. In conclusion, a combination of ridge sowing and osmopriming with CaCl2 can play a vital role in mitigating the adverse effects of drought stress, increasing the production of maize and net returns under normal and deficit water conditions.