A Practical and Economical Strategy to Mitigate Salinity Stress through Seed Priming

Abstract

Soil salinity is one of the significant abiotic threats to crops that deteriorates crop yields, and the world's increasing population faces serious food problems due to abiotic threats. It is one of the major abiotic problems affecting more than 30% of irrigated land across the globe. The concentrations of various salts, such as NaCl, KCl, Na2SO4, and Na2CO3, cause saline stress; however, NaCl is the most abundant salt in the soil. Salinity could affect seed germination due to osmotic potential or due to specific toxic ion effects, and it decreases germination percentage and increases germination time, and high salt stress is responsible for delaying seed germination. Therefore, it is necessary to alleviate the negative impact of soil salinity during seedling growth periods, so the growth of crops in salt-affected soil will be much more enhanced. Seed priming is the utmost effective technique that could mitigate the harmful impact of soil salinity. This methodology not only minimizes the salinity tolerance but also strengthens the defense system of crops. In this technique, the hydration level within the seeds is controlled by applying pre-sowing treatments, allowing specific pre-germinative metabolic processes to occur and preventing radical emergence. Seed priming also decreases the seed germination time and improves antioxidant enzyme activities, stopping or minimizing reactive oxygen species' adverse effects. It enhances the seedling performance with rapid and homogenous germination and vigorous and dynamic growth of the seedling, achieving a physiological situation leading to quick and enhanced emergence and germination of various crops. This review covers the mechanisms of seed priming, salinity tolerance, seed priming crosstalk with salinity tolerance, and seed priming techniques that induce biochemical, physiological, and morphological mechanisms in saline stress. Further research needs to be performed on advanced seed priming methods such as priming with nanoparticles and seed priming with physical agents (UV radiation, X-rays, gamma rays, and microwaves) to minimize the negative impact of salinity stress on different crops under different harsh environmental conditions.