Evaluation of Nickel (Ni) Induced Stress on Seed Germination, Growth, Photosynthetic Pigments, and Protein in Lens culinaris L.

Lens culinaris L. (commonly known as masoor) is among the oldest leguminous crops cultivated by mankind, holding a vital role in traditional agriculture, especially in semi-arid regions of the Indian subcontinent. Renowned for its drought resistance and nitrogen-fixation ability, this pulse crop is now increasingly exposed to environmental pollutants such as heavy metal contamination. Among these, nickel (Ni) has emerged as a significant concern due to its accumulation in agricultural soils through anthropogenic activities. On the other hand, Ni is an essential micronutrient involved in various enzymatic processes, its elevated concentrations adversely affect to plant physiology. In the present study, the phytotoxic effects of different concentrations of nickel (10, 30, and 50 mg/kg soil) were examined under in vivo conditions on Lens culinaris cultivar L4717. The results indicated a dual response to nickel (Ni) exposure. A lower Ni concentration (10 mg Ni/kg soil) stimulated plant growth parameters, specifically enhancing seed germination and seedling growth. This beneficial effect was accompanied by an increase in photosynthetic pigments (chlorophyll a, chlorophyll b, and carotenoids) and total protein content within the plant tissues. However, higher concentrations (30 and 50 mg Ni/kg soi) exhibited inhibitory effects, leading to visible toxicity symptoms, reduced seed germination, overall growth retardation, photosynthetic pigments, and protein degradation. These findings highlight the dose-dependent toxicity of nickel in lentils, suggesting a narrow threshold between its beneficial and toxic effects. The study emphasizes the importance of regulating heavy metal levels in agricultural soils to safeguard crop productivity and food quality.