Document Type : scientific research article
Authors
1
Department of Horticultural Sciences, Gorgan University of Agricultural Sciences and Natural Resources
2
Sari Agricultural Sciences and Natural Resources University-Genetics and Agricultural Biotechnology Institute of Tabarestan
3
Department of Basic Sciences, Faculty of Animal Science and Fisheries, Sari University of Agricultural Sciences and Natural Resources
4
, Department of soil and water research, Mazandaran Agricultural and Natural Resources Research and Education Center
Abstract
Background and objectives: Waterlogging stress is a major factor limiting plant growth, primarily due to oxygen deficiency, which disrupts physiological processes, impairs aerobic respiration, and ultimately reduces plant performance. Due to the oxidative nature of waterlogging stress, which is caused by the production of free radicals in the plant. In this study, to deal with this stress, some compounds with antioxidant properties were used as a way to control the harmful effects of stress.
Materials and methods: This study was conducted as a factorial experiment based on a completely randomized design, incorporating two factors and three replications three in the year 2021 at the Genetics and Biotechnology Research Institute of Tabarestan, Mazandaran. The first factor was water treatment at two levels: waterlogging stress and field capacity. The second factor involved three elicitors, each tested at two concentrations. The elicitors were melatonin (50 and 100 μM), gamma-aminobutyric acid (GABA) (5 and 10 mM), and potassium phosphite (Kphi) (2 and 3 g L⁻¹). Distilled water was also used for control plants. Waterlogging stress was applied to the plants for four weeks, and the elicitors were sprayed weekly. At the end of the experiment, various growth, biochemical, and photosynthetic traits of sour orange were evaluated.
Results: Waterlogging stress significantly reduced both the fresh and dry weights of roots and leaves compared to control plants. However, the application of 10 mM GABA led to an increase in the fresh 15% and dry weight 6% of leaves, as well as an increase in the dry weight of roots 23% compared to controls. In field capacity conditions, both concentrations of GABA significantly increased root dry weight. The lowest crown diameter (2.98 mm) was observed in the waterlogged control, while the largest was recorded in plants treated with 2 g L⁻¹ Kphi under stress. Waterlogging stress also caused a marked increase in leaves vapor pressure deficit, with the highest values observed in plants treated with melatonin 100 μM (68.51 Pa kPa⁻¹), melatonin 50 μM (65.89 Pa kPa⁻¹), and GABA 10 mM (64.23 Pa kPa⁻¹), accompanied by a significant reduction in stomatal conductance. Under field capacity conditions, the highest CO₂ assimilation rates were observed in plants treated with Kphi 3 g L⁻¹and GABA 10 mM (3.74 and 3.88 µmolCO2 m⁻² s⁻¹, respectively), while the lowest rate was found in the waterlogged control. The highest water use efficiency under waterlogging stress was observed in plants treated with 100 μM melatonin and GABA 10 mM (2.37 and 2.26 µmol CO2/mmol H2O, respectively). Additionally, the highest photosystem efficiency under field capacity was recorded in plants treated with GABA 10 mM and melatonin 100 μM.
Conclusion: This study demonstrates that waterlogging stress significantly reduces plant biomass. However, the use of GABA 10 Mm as an elicitor improved several growth traits. The results suggest that elicitors can enhance plant tolerance to stress by modulating stomatal behavior and increasing photosynthetic capacity. Improved stomatal water use efficiency helps prevent water loss, thereby enhancing plant resilience under stress conditions.
Keywords: Field capacity, Gamma-aminobutyric acid, Melatonin, Oxidative stress, Potassium phosphite
Keywords
Main Subjects
)