Climate change is causing soil salinization, resulting in crop losses throughout the world. The ability of plants to tolerate salt stress is determined by multiple biochemical and molecular pathways. Here we discuss physiological, biochemical, and cellular modulations in plants in response to salt stress. Knowledge of these modulations can assist in assessing salt tolerance potential and the mechanisms underlying salinity tolerance in plants. Salinity-induced cellular damage is highly correlated with generation of reactive oxygen species, ionic imbalance, osmotic damage, and reduced relative water content. Accelerated antioxidant activities and osmotic adjustment by the formation of organic and inorganic osmolytes are significant and effective salinity tolerance mechanisms for crop plants. In addition, polyamines improve salt tolerance by regulating various physiological mechanisms, including rhizogenesis, somatic embryogenesis, maintenance of cell pH, and ionic homeostasis. This research project focuses on three strategies to augment salinity tolerance capacity in agricultural crops: salinity-induced alterations in signaling pathways; signaling of phytohormones, ion channels, and biosensors; and expression of ion transporter genes in crop plants (especially in comparison to halophytes).

Dwarfing is an important agricultural trait for intensive cultivation and effective orchard management in modern fruit orchards. Commercial citrus production relies on grafting with rootstocks that reduce tree vigor to control plant height. Citrus growers all over the world have been attracted to dwarfing trees because of their potential for higher planting density, increased productivity, easy harvest, pruning, and efficient spraying. Dwarfing rootstocks can be used to achieve high density. As a result, the use and development of dwarfing rootstocks are important. Breeding programs in several countries have led to the production of citrus dwarf rootstocks. For example, the dwarfing rootstocks ‘Flying Dragon’, ‘FA 517’, ‘HTR-051’, ‘US-897’, and ‘Red tangerine’ cultivated in various regions allow the design of dense orchards. Additionally, dwarf or short-stature trees were obtained using interstocks, citrus dwarfing viroid (CDVd) and various chemical applications. This review summarizes what is known about dwarf citrus rootstocks and the mechanisms underlying rootstock–scion interactions. Despite advances in recent decades, many questions regarding rootstock-induced scion development remain unanswered. Citrus rootstocks with dwarfing potential have been investigated regarding physiological aspects, hormonal communication, mineral uptake capacity, and horticultural performance. This study lays the foundation for future research into the genetic and molecular mechanisms underlying citrus dwarfing.

Climate change exacerbates flooding problems due to hurricanes followed by heavy rains, particularly in sub-tropical regions. Consequently, submerged plants experience hypoxia stress which limits agronomic and horticultural crop growth and production. Hypoxia causes oxidative damage by accelerating the lipid peroxidation associated with O₂- and H₂O₂ levels. Additionally, hypoxia increases the accumulation of organic osmoprotectants and antioxidant activity, whereas it decreases the macronutrient (N, P, K, and Zn) uptake. This study aimed at investigating the effects of flooding-induced hypoxia stress on the growth and the physiological, biochemical, and nutritional characteristics of the hydroponically grown southern highbush blueberry (cv. Jewel) plants. In addition, the hypoxia-mitigating effects of conventional silicon (Si-C) and silicon nanoparticles (SiNPs) and their application methods (foliar vs. foliar and rootzone application) were also appraised. Both the Si-C and the SiNPs efficiently alleviated hypoxia-induced oxidative and osmotic damage to cells by enhancing the activities of the enzymatic antioxidants (ascorbate peroxidase, catalase, dehydroascorbate reductase, superoxide dismutase, peroxidase, guaiacol peroxidase, monodehydroascorbate, reductase); the non-enzymatic antioxidants (ascorbic acid and glutathione contents); and the accumulation of compatible solutes (proline and glycinebetaine) in leaves and roots. However, the SiNPs were more effective than Si-C at improving antioxidant activities and osmolytes formation. A strong negative correlation between the antioxidant activities and the lipid peroxidation rate was observed in the SiNP-treated plants under hypoxia stress. The SiNPs also regulated nutrient uptake by increasing the K, N, P, and Zn concentrations while decreasing Fe and Mn concentrations to a less toxic level. Blueberry plants treated with SiNPs responded more effectively to hypoxia stress by maintaining higher antioxidant and osmoprotectant concentrations than blueberry plants treated with Si-C. Additionally, the foliar and rootzone applications yielded better results than the foliar applications only.

Frequent and increasingly severe freezing events threaten citrus production in northern Florida, underscoring the need for strategies that enhance freezing resilience in citrus cultivars. Grafting scions onto tolerant rootstocks provides a physiologically integrative approach to improve stress tolerance. This study aims to elucidate how these interactions modulate physiological and metabolic responses under freezing stress, thereby identifying mechanisms that contribute to enhanced freeze resilience in citrus. Here, we grafted Citrus reticulata (cv. UF-950) onto eight rootstocks (Bitters, Blue-1, C-146, Sour Orange, UFR07TC, UFR09TC, UFR5, and US942) to evaluate scion–rootstock interactions under normal (20 °C) and freezing (−6 °C) conditions. Freezing stress caused a sharp increase in oxidative stress markers, lipid peroxidation, and membrane damage while reducing photosynthetic performance across most combinations. Antioxidant capacity, osmolyte accumulation, and carbon–nitrogen metabolic responses varied significantly among rootstocks, revealing strong genotype-dependent modulation of scion physiology. Among the tested combinations, UF-950 grafted onto UFR5 displayed the highest freezing tolerance, characterized by robust activation of antioxidant enzymes, elevated proline and glycine betaine accumulation, reduced oxidative damage, and sustained carbon–nitrogen metabolic fluxes under freezing stress. These results demonstrate that rootstock genotype governs the extent of scion defense activation and metabolic homeostasis under freezing conditions. Our findings identify UFR5 as a promising rootstock for enhancing freezing resilience in citrus and provide mechanistic insight into how scion–rootstock interaction orchestrates integrative stress tolerance pathways. Future work should focus on multi-omics dissection of rootstock-mediated signaling networks and long-term field validation to optimize rootstock selection for enhanced cold resilience under variable climatic conditions.