Effects of Various Salinity and Water Stress Levels on Physiological and Biochemical Traits of Pepper

Salinity and drought are among the most important abiotic stress factors with vital impacts on plant growth and development. Effects of different salinity and water stress levels on physiological and biochemical traits of pepper were investigated in this study. Five different salinity (S1: 0.3 dS/m; S2: 2.5 dS/m; S3: 5dS/m; S4: 7.5 dS/m; S5: 10 dS/m) and three different irrigation levels (I100: full irrigation; I75: 25% deficit; I50: 50% deficit) were used. Plant water consumption (ET) values decreased in increasing salinity levels. Pepper yield was significantly affected by both salinity and water stress. There was a 62.8% yield loss under salt stress as compared to the control treatment and a 70.1% yield loss under 50% water deficit (I50) as compared to full irrigation (I100). Irrigation water salinity and water deficits caused significant differences in physiological and photosynthetic parameters (plant height, plant fresh and dry weight, leaf area, chlorophyll, and carotenoid content). Salinity and water stress had significant impacts on enzymatic and non-enzymatic contents such as superoxide dismutase (SOD), peroxide (POD), catalase (CAT), proline, malondialdehyde (MDA), total phenolic content (TPC) and total flavonoid content (TFC). It was concluded based on present findings that irrigation waters with a salinity level up to 5 dS/m could be used in pepper cultivation, but water deficits should be avoided.