Document Type : Research Article
Authors
1
Department of Horticultural Science and Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran
2
Department of Horticultural Sciences and Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran
10.22067/jhs.2026.93088.1424
Abstract
Introduction
Salinity is one of the most important abiotic stresses that affects the establishment, growth and development of plants, reducing the yield of agricultural products worldwide, especially in arid and semi-arid regions. Almond (Prunus dulcis Mill.) is one of the oldest and most important dried fruits in the world and is native to the Iranian plateau. Salinity stress is one of the most important limiting factors for almond cultivation and production worldwide. Serendipita indica is a novel endophytic fungus in agriculture that increases plant tolerance to biotic and abiotic stress. This fungus is able to improve photosynthesis and plant growth under salt stress conditions by increasing the activity of enzymatic antioxidants such as superoxide dismutase, catalase, peroxidase and non-enzymatic antioxidants such as phenolic compounds and flavonoids, as well as improving water and nutrient uptake and reducing the uptake and transport of toxic ions such as Na+ and Cl- to the aerial parts of the plant. So far, the effect of S. indica on the mechanism of salt stress tolerance in almonds has not been investigated. Therefore, in this study, the effect of S. indica on the improvement of salt stress tolerance in almond cultivar Supernova (a late flowering and self-compatible cultivar) grafted on GF677 (almond-peach hybrid) was investigated under greenhouse and hydroponic conditions. In accordance with the research objectives, morphophysiological parameters and mineral element content were evaluated in almond plants non-inoculated and inoculated with S. indica at different concentrations of sodium chloride-induced salinity.
Material and Methods
This experiment was conducted in the greenhouse and laboratory of the Department of Horticultural Sciences, Faculty of Agriculture, University of Tabriz as a factorial in a randomized complete block design with two factors including the factor salinity at three levels (zero (no stress), 60 (moderate salinity stress) and 120 (high salinity stress) mM) and the factor fungal inoculation at two levels non-inoculated and inoculated with S. indica with 3 replicates. The inoculum of S. indica fungus was obtained from the Department of Soil Science and Engineering, Faculty of Agriculture, University of Tabriz, then cultivated in Hill and Kaffir culture medium in Petri dishes and maintained at 25-29°C in the dark for two weeks. The surface of the culture medium containing S. indica was removed using a sterile spatula and then mixed evenly with sterile sand. For the fungal treatment, about 80 grams of inoculum (the surface of the culture medium containing the S. indica fungus + sterile sand) was added under the location of the roots. Two months after inoculation and to ensure the desired coexistence between the roots and the fungus, the salinity stress treatment was applied for 30 days. Growth indices, Fv/Fm, photosynthetic pigment content, total Phenolics and Flavonoids content, hydrogen peroxide, total antioxidant capacity and nutrient content (phosphorus, sodium and potassium) at the end of the period Salinity stress was assessed. Statistical analysis of data was performed using SPSS 16.0 software and mean comparisons were performed using Duncan's multiple range test (P ≥ 0.05).
Results and Discussion
The results showed that the leaf area of inoculated plants at 60 and 120 mM salinity was significantly higher than that of non-inoculated plants by 19.9 and 24.4%, respectively. Inoculated plants at 120 mM salinity had significantly higher Fv/Fm (9.8%), SPAD index (19.3%), phenolics content (27.31%), and total flavonoids content (23.79%). At high salinity, the inoculated plants showed significantly higher total antioxidant capacity (13%) and lower H2O2 content (27%) compared to the non-inoculated plants. At salinity levels of 60 and 120 mM, sodium content of leaves in the inoculated plants was significantly lower than non-inoculated plants (54.8 and 26.2%, respectively). Inoculation with S. indica improved potassium uptake in almond leaves and roots.
Conclusion
The results of this study showed that under salt stress, the accumulation of Na+ ions in the roots and leaves of almond plants reduced photosynthesis, growth traits, oxidative stress and K+ uptake. Inoculation with S. indica under salt stress conditions improved photosynthesis, some growth parameters and K+ uptake by reducing Na+ accumulation in leaves, which are the most important photosynthetic organs. In addition, this fungus inhibited H2O2 and moderated oxidative stress by increasing antioxidant activity and improving antioxidant capacity, especially in high salinity. The improvement of morphophysiological and nutritional parameters in almond plants inoculated with endophytic fungi indicates the potential of S. indica as a biostimulants for increasing salt tolerance in almond plants in sustainable agriculture.
Keywords
Subjects
