Evaluation of Morphophysiological Characteristics, Nutrient Accumulation and Fatty Acid Profile of Hemp (Cannabis sativa L.) Under Different Salinity Levels

Hemp (Cannabis sativa L.), an annual herb whose seeds contain valuable oil, has been cultivated in a variety of environments where it may be subjected to salinity, a detrimental abiotic stress on plants. Because there is little information regarding how salinity affects hemp’s growth and biochemical characteristics, this study was designed to determine the effects of salinity (0, 2, 4, 6, and 8 dS m⁻¹) on its morphophysiological characteristics, nutrient content, and fatty acid profile. The results indicated that salinity, particularly at 8 dS m⁻¹ led to notable decreases in the plant height (40%), shoot weight (2.6-fold), and root weight (3.5-fold). Compared with the control, salinity at 8 dS m⁻¹ decreased total chlorophyll (43%) and relative water content (RWC, 36%) but elevated proline concentration (97%). The total phenolic content (TFC) and total flavonoid content (TFC) significantly increased with salinity stress up to 6 dS m⁻¹ by 42 and 89%, respectively, relative to the control. In response to salinity stress at 8 dS m⁻¹, potassium (K⁺), magnesium (Mg⁺²), and calcium (Ca⁺²) content in hemp leaves decreased by 40, 25, and 38%, respectively, while 5.8 and 5.5-fold increases in (Na⁺) and chloride (Cl⁻) were observe compared to the control. Despite the fact that salinity had no significant effect on the phosphorus (P) roots of plants, it did marginally enhance the amount of P (14%) in the leaves. The oil content increased at a low salinity level (2 dS m⁻¹) and remained unchanged with increasing salinity levels. The primary fatty acid compositions found in hemp seeds were linoleic acid (C18:2ω6, 30.29–35.22%), stearic acid (C18:0, 19.7–27.73%), palmitic acid (C16:0, 12.1–13.85%), and linolenic acid (C18:3ω6, 12.2–31.1%). The quantitative and qualitative properties of hemp oil were generally enhanced by mild salt (2 dS m⁻¹), which did not negatively impact plant growth and development.