Exogenous Gamma-Aminobutyric Acid (GABA) and Oxalic Acid Enhance Growth and Salinity Tolerance in Zanthoxylum piperitum Plants: Anatomical, Biochemical, and Physiological Insights.

Salinity stress, a major abiotic factor, significantly limits global plant productivity. Exacerbated by population growth, global warming, and climate change, it seriously threatens sustainable agriculture. Addressing its impact on plant systems has therefore become a critical priority. In this context, the present study aimed to assess the potential of foliar applications of gamma-aminobutyric acid (GABA) and oxalic acid (OA), at varying concentrations, in alleviating salinity stress in Zanthoxylum piperitum. The experiment was conducted using a split-plot arrangement within a randomized complete block design at the ornamental nursery in Giza, Egypt, during two successful seasons in 2023 and 2024. The findings demonstrated that salinity stress at any dose hurts physiological, morphological, and anatomical characteristics. Conversely, the GABA and OA are additions that significantly enhanced all characteristics. OA (0.1 g/l) has been shown to promote plant growth, increase biomass accumulation, and nutrient availability, particularly nitrogen. Additionally, it elevates total carbohydrate concentrations, proline accumulation, and mitigates chlorophyll degradation. It also improves key histological characteristics of leaves, thereby reducing physiological toxicity under conditions of severe salinity stress. Moreover, GABA has demonstrated potential in mitigating the adverse effects of salinity by enhancing nutrient uptake, particularly phosphorus and potassium, improving photosynthetic efficiency, and carbohydrate metabolism under moderate salinity conditions. Overall, the application of OA at low doses in combination with moderate or severe salinity stress demonstrated the potential to enhance morpho-physiological and anatomical traits, thereby supporting the growth of Z. piperitum plants. These highlight OA as an effective and environmentally friendly strategy for alleviating salinity-induced stress.