Jyoti Chauhan

Rare earth elements (REEs) are traditionally regarded as emerging environmental contaminants. Due to their increasing anthropogenic release and interactions with essential mineral nutrients, they are attracting growing interest for their potential applications in sustainable agriculture. The REEs are a unique group of 17 chemically similar elements, including scandium (Sc), yttrium (Y), and lanthanides. Most existing reviews treat REEs as a single group, with limited emphasis on concentration-dependent uptake mechanisms or species-related responses. However, based on atomic weight, REEs are classified into light and heavy rare earth elements (LREEs/HREEs). LREEs enter the plant system through multiple routes-fertilizer, irrigation, and mining residues; however, their cellular roles and modes of action remain insufficiently understood. Accumulating evidence indicates that LREEs exert concentration-dependent effects on plant growth and metabolism, including decreased growth, oxidative stress, modulation of photosynthesis, chlorophyll and carotenoid accumulation, antioxidant metabolism, secondary metabolite production, and enzyme activities. LREE uptake occurs predominantly via calcium-permeable channels, with limited involvement of transporters, followed by root sequestration and restricted long-distance translocation. At the cellular level, LREEs influence redox balance, membrane stability, chloroplast ultrastructure, and mineral nutrient homeostasis, and interact with multiple signaling pathways, including calcium- and hormone-mediated networks. Most studies on LREEs focused on lanthanum and cerium, attributed to their abundance in soil. Unlike previous reviews addressing REEs broadly, this review specifically focuses on LREE-mediated regulation of plant growth and development, mineral nutrition with emphasis on concentration-dependent responses, uptake and transport, and associated signaling mechanisms and hormonal interactions. Key gaps in current knowledge regarding LREE molecular targets, transport, dose-dependent mechanisms, molecular regulation, and species-specific responses are highlighted to guide future research. By integrating environmental entry routes with cellular and molecular responses, this review provides a mechanistic framework for future studies on LREE plant interactions.

Abiotic stressors are major constraints that affect agricultural plant physio-morphological and biochemical attributes, resulting in a loss of normal functioning and, eventually, a severe decline in crop productivity. The co-occurrence of different abiotic stresses, rather than a specific stress situation, can alter or trigger a wide range of plant responses, such as altered metabolism, stunted growth, and restricted development. Therefore, systematic and rigorous studies are pivotal for understanding the impact of concurrent abiotic stress conditions on crop productivity. In doing so, this review emphasizes the implications and potential mechanisms for controlling/managing combined abiotic stresses, which can then be utilized to identify genotypes with combined stress tolerance. Furthermore, this review focuses on recent biotechnological approaches in deciphering combined stress tolerance in plants. As a result, agronomists, breeders, molecular biologists, and field pathologists will benefit from this literature in assessing the impact of interactions between combined abiotic stresses on crop performance and development of tolerant/resistant cultivars.

An experiment was conducted in both laboratory (germinative attributes) and field conditions (growth attributes) with completely randomized design (CRD) and randomized block design, respectively, to view the responses of different priming treatments in two wheat varieties: HUW-234 (V1) and BHU-3(V2). In the present study, seeds were primed with water (hydro; T2), Mg (NO₃)₂ (T3), ZnSO₄ (T4), and a combination of both salts (T5). Their carry over effects were observed on the germinative and vegetative phases of growth. All treatments were compared with the performance of nonprimed control seeds (T1). Maximum germination percentage (98.33, 100%) was noted with T3, whereas length of shoot (8.83, 10.23 cm) and root (9.47, 10.73 cm) and their fresh (0.34, 0.45 g) and dry weights (0.05, 0.07 g) were recorded maximum in T5 for both varieties; however, the vigor index I and II showed varietal difference, but primed sets were found always superior with respect to nonprimed control. Study of plant height, leaf number and area, fresh and dry weights of total leaves and stem showed the best performance under combined use of both salts, i.e., Mg (NO₃)₂ and ZnSO₄ as priming agents, followed by ZnSO₄, Mg (NO₃)₂, hydro, and the nonprimed one. The study of biochemical parameters such as protein content and nitrate reductase activity of leaves showed the highest increment in combined priming treatment and increased 63.77, 90.37, 37.44% and 12.81, 5.61, 7.75%, respectively, after 35, 45, and 60 days after sowing. It is likely that chlorophyll, nitrogen, iron, and zinc content also followed a similar pattern and were enhanced in combined priming treatments as compared to nonpriming treatment. Therefore, the result suggests that priming seeds with Mg (NO₃)₂ and ZnSO₄ worked synergistically at varietal level and improved growth attributes at field conditions.