Seed priming for alleviation of heavy metal toxicity in plants: An overview

Heavy metal (HM) toxicity is vital environmental constraint that limits crop productivity worldwide. Several physiological processes necessary for plant survival have been found to be affected by HM toxicity. In recent farming, advanced mechanisms are being developed to overcome from the stresses to enhance the yield. The seed priming is an affordable method for plants to survive under abiotic and biotic stresses. Priming is useful for commercial seed lots by seed technologists to increase the vigor of the seeds in terms of germination potential and enhance the tolerance against various stresses. It also removes the pollution threats by minimizing the uses of chemical fertilizers. The seeds having deprived of quality in terms of seed germination and seedling characters ultimately affect the growth, photosynthetic performance and yield of the plants under HM stress. On the other hand seed primed with various seed priming methods such as hydropriming, hormonal priming, chemical priming, biopriming, magnetopriming and nanopriming perform well under HM toxicity. Seed priming methods have been considered as a unique approach to get rid of HM stress by enhancing the seed germination, seedling vigor, rate of photosynthesis, biomass accumulation and thus increase the crop productivity. The present review provides an overview of different seed-priming methods and their role in alleviation of adverse effects of HM stress in plants.