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Heavy metal (HM) contamination is a serious concern across the globe, and in recent times, HMs’ intensity has significantly increased, posing a serious threat to crop growth and productivity. Heavy metals pose serious health issues in humans by entering the human food chains. Therefore, it is direly needed to reduce the effects of HMs on plants and humans by adapting appropriate practices. In this context, application of micronutrients can be an essential practice to mitigate the toxic effects of HMs. Zinc (Zn) is a crucial nutrient needed for plant growth, and Zn application reduced the HM-induced toxicity in plants. This review highlights Zn’s role in mitigating the HMs toxicity in plants. We have systematically described the potential mechanisms mediated by Zn to mitigate HMs in plants. Zinc application reduced the HMs uptake and translocation plants, which is considered an essential mechanism of HM stress tolerance. Zn application also improves membrane stability, plant water relationship, nutrient uptake, photosynthetic performance, osmolytes accumulation, anti-oxidant activities, and gene expression. In addition to this, the Zn application substantially improves photosynthesis by enhancing the synthesis of photosynthetic pigments, photosystem activities, enzymatic activities, and maintaining photosynthetic apparatus structure, ensuring better growth under HM stress. Therefore, Zn nutrition could improve the plant performance under HM stress by modulating the plant’s physiological and biochemical functioning, anti-oxidant activities, osmolytes accumulation, and gene expression.

Wood anatomy and plant hydraulics play a significant role in understanding species-specific responses and their ability to manage rapid environmental changes. This study used the dendro-anatomical approach to assess the anatomical characteristics and their relation to local climate variability in the boreal coniferous tree species Larix gmelinii (Dahurian larch) and Pinus sylvestris var. mongolica (Scots pine) at an altitude range of 660 m to 842 m. We measured the xylem anatomical traits (lumen area (LA), cell wall thickness (CWt), cell counts per ring (CN), ring width (RW), and cell sizes in rings) of both species at four different sites Mangui (MG), Wuerqihan (WEQH), Moredagha (MEDG) and Alihe (ALH) and investigated their relationship with temperature and precipitation of those sites along a latitude gradient. Results showed that all chronologies have strong summer temperature correlations. LA extremes were mostly associated with climatic variation than CWt and RWt. MEDG site species showed an inverse correlation in different growing seasons. The correlation coefficient with temperature indicated significant variations in the May-September months at MG, WEQH, and ALH sites. These results suggest that climatic seasonality changes in the selected sites positively affect hydraulic efficiency (increase in the diameter of the earlywood cells) and the width of the latewood produced in P. sylvestris. In contrast, L. gmelinii showed the opposite response to warm temperatures. It is concluded that xylem anatomical responses of L. gmelinii and P. sylvestris showed varied responses to different climatic factors at different sites. These differences between the two species responses to climate are due to the change of site condition on a large spatial and temporal scale.

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