Plants are sessile beings, so the need of mechanisms to flee from unfavorable circumstances has provided the development of unique and sophisticated responses to environmental stresses. Depending on the degree of plasticity, many morphological, cellular, anatomical, and physiological changes occur in plants in response to abiotic stress. Phytohormones are small molecules that play critical roles in regulating plant growth and development, as well as stress tolerance to promote survival and acclimatize to varying environments. To congregate the challenges of salinity, temperature extremes, and osmotic stress, plants use their genetic mechanism and different adaptive and biological approaches for survival and high production. In the present attempt, we review the potential role of different phytohormones and plant growth-promoting rhizobacteria in abiotic stresses and summarize the research progress in plant responses to abiotic stresses at physiological and molecular levels. We emphasized the regulatory circuits of abscisic acid, indole acetic acid, cytokinins, gibberellic acid, salicylic acid, brassinosteroids, jasmonates, ethylene, and triazole on exposure to abiotic stresses. Current progress is exemplified by the identification and validation of several significant genes that enhanced crop tolerance to stress in the field. These findings will make the modification of hormone biosynthetic pathways for the transgenic plant generation with augmented abiotic stress tolerance and boosting crop productivity in the coming decades possible.

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Zinc (Zn) fertilization could be a viable approach for minimizing cadmium (Cd) accumulation in the food chain. The present study was carried out to investigate the role of various Zn fertilization treatments (control, foliar application at tasseling stage, foliar application at milky stage, rubber ash application, soil application of ZnSO4) and cultivars (Pop 2004B, Pop 2006, Azam, Sarhad (W), Pahari) on grain yield, grain Zn, and grain Cd concentrations in maize. All Zn fertilization treatments resulted in a significantly higher grain yield, higher grain Zn concentration, and reduced grain Cd concentration. The application of rubber ash remained the best among all Zn fertilization treatments as it resulted in a higher grain yield of 62% and a reduced grain Cd concentration by 57% compared to control. Contradictions were apparent between cultivars, and the cultivars which recorded a higher grain yield had a lower Zn concentration in their grains and vice versa. Regarding Cd accumulation, all cultivars except Azam, retained less Cd with increased grain Zn concentration. Future studies should focus on breeding/selection of high yielding and high quality cultivars. Furthermore, the feasibility of rubber ash maybe tested under different climatic and edaphic conditions against other heavy metals and other crops as well.