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During climate change, various unparalleled perils to agricultural systems have been observed worldwide. The detrimental impacts of heavy metal toxicity (HMs) lead to a considerable decrease in crop productivity and yield, thereby putting the agricultural system at risk and exerting a significant impact on food production. This has sparked significant worry regarding the achievement of the sustainable development goals (SDGs) pertaining to ensuring food and nutritional security for the constantly growing global population. In the current study, we have endeavored to reveal the significance of salicylic acid (SA) under arsenic (As) stress conditions in rice (Oryza sativa) plants. Being a toxic metalloid, As has adverse effects on the efficiency of photosynthesis and the assimilation of nitrogen (N) and sulphur (S) growth, and also causes alterations in defense systems and ethylene biosynthesis. The study revealed that the positive influence of SA in promoting nutrient metabolism, photosynthesis and growth under As stress was the result of its interplay with ethylene biosynthesis and the enhanced capacity of defense systems to reduce oxidative stress-mediated cellular injuries and cell deaths. In conclusion, SA can be considered a crucial physiological criterion for the development of As-tolerant rice plants.

In the present study, the potential of ethylene as ethephon (an ethylene source) was investigated individually and in combination with split doses of nitrogen (N) and sulfur (S) soil treatments for removal of the damaging effects of salt stress (100 mM NaCl) in mustard (Brassica juncea L.). Plants were grown with 50 mg N plus 50 mg S kg−1 soil at sowing time and an equivalent dose at 20 days after sowing [N50 + S50]0d and 20d. Ethephon at 200 μL L‒1 was applied to combined split doses of N and S with or without NaCl. Plants subjected to NaCl showed a decrease in growth and photosynthetic characteristics as well as N and S assimilation, whereas proline metabolism and antioxidants increased. The application of ethephon to plants grown with split N and S doses significantly enhanced photosynthetic efficiency by increasing the assimilation of N and S, improving the concentration of proline and induction of the antioxidant system with or without NaCl. The regulation of ethylene and/or split forms of N and S application may be potential tools for not just overcoming salt stress effects in this species and in related Brassicaceae but also enhancing their photosynthesis and growth potential through increased nutrient assimilation.

Heavy metal (HM) contamination of agricultural soil is primarily related to anthropogenic perturbations. Exposure to high concentration of HMs causes toxicity and undesirable effects in plants. In this study, the significance of ethylene was studied in response of mustard (Brassica juncea) to a high level (200 mg kg&minus, 1 soil) of zinc (Zn) exposure. Plants with high Zn showed inhibited photosynthesis and growth with the increase in oxidative stress. Application of ethylene (as ethephon) to Zn-grown plants restored photosynthesis and growth by inhibiting oxidative stress through increased antioxidant activity, the proline metabolism glyoxalase system, and nutrient homoeostasis. The results suggested that ethylene played a role in modulating defense mechanisms for tolerance of plants to Zn stress.