Evaluation of Salicylic Acid Effects on Growth, Biochemical, Yield, and Anatomical Characteristics of Eggplant (Solanum melongena L.) Plants under Salt Stress Conditions

Abstract

Salt stress is a major issue in agriculture and crop production that influences global food security. Mitigation options to address salt stress through agronomic practices can help manage this issue. Experiments were performed in two summer seasons in an experimental farm to test the impact of three salinity levels (S): 300 (control), 1000, 2000, and 3000 ppm, and two salicylic acid (SA) levels, including 1.0 and 1.50 mM, and their interaction on growth and yield of eggplant (Solanum melongena L.) hybrid Suma. The results showed that increasing S levels up to 3000 ppm reduced plant and fruit physical characteristics, as well as leaf and fruit chemical characteristics, especially leaf total chlorophyll, carotenoids, relative water, fruit nitrogen, phosphorus, and potassium contents, which led to a reduction in total yield per plant. However, an insignificant effect was observed in the control level and 1000 ppm saline water in leaf area, fruit length, leaf total chlorophyll content, fruit phosphorus content, and total yield per plant. In contrast, leaf sugars, proline contents, electrolyte leakage, fruit TSS (total soluble solids), and ascorbic acid contents were improved with S levels up to the concentration of 3000 ppm compared to the control. However, tested parameters were significantly higher due to the SA foliar spray of 1.0 mM besides photosynthetic pigments of leaves enhanced by using 1.0 and 1.50 mM. Using 1.0 mM SA concentration alleviated the adverse impact of S on eggplant plants until 1000 ppm saline water, reflecting an increase in eggplant yield. The anatomical structure of eggplant leaves revealed positive variations in mature leaf blades in both the stressed and SA-treated plants. Based on these results, the use of SA at a concentration of 1.0 mM may lessen the negative impacts of salt on the growth of eggplant, which increases the overall yield.

Internal Fruit Quality Is Maintained in Eggplant under Mild Long-Term Salt Treatment

“…However, as it has been previously reported, great stress is necessary for the eggplant cultivars to significantly reduce their growth parameters [29]. In fact, the capability of maintaining or even elongating primary and secondary roots [11] in response to drought has been noticed, as was observed in this work in some genotypes. In this regard, eggplants share some response mechanisms for drought and salinity, such as growth inhibition, ion movement alteration, and osmotic stress [17,29].…”

“…Eggplants show a huge diversity in fruit morphology, including shape and size [5], which can explain the natural differences in fruit weight observed in this study. However, it is likely to find fruit weight differences due to salinity [11] that were not found in this study. Our hypothesis is that a longer or stronger salinity treatment and a large fruit set are necessary to induce significant changes in fruit weight.…”

“…Also, normal cellular and enzymatic activity can be altered due to the reduction in water availability, ion toxicity, and K + deficiency, which induces osmotic imbalances in the cells and oxidative stress in plants [9,10]. If the stress is prolonged during the season, even mild salinity can remarkably alter yield and fruit quality [11].…”

The impact of biochar addition on morpho-physiological characteristics, yield and water use efficiency of tomato plants under drought and salinity stress

“…Additionally, the use of biochar improved the leaf gas exchange and LWRC under salinity and drought stress conditions, indicating that biochar helped the plants retain firm leaves under abiotic stresses [ 17 ]. In this study, the decreased chlorophyll could be due to damage to the thylakoid membranes, as a result of the destructive effect of reactive oxygen species (ROS) on chloroplasts [ 55 ]. The generation of reactive oxygen species (ROS) was significantly increased due to salinity and water deficiencies [ 50 ].…”