Investigating Adaptation Mechanisms in Vachellia nilotica Facing Water Scarcity: Implications for Conservation

Abstract

The study aimed to assess the adaptability and growth behaviour of Vachellia nilotica under varying levels of water deficit. A pot experiment was conducted by utilizing seedlings collected from a forest nursery and subjected to five treatments ranging from 70% to 30% field capacity (FC), with three replicates per treatment. Growth parameters including plant height and stem diameter were measured, alongside biochemical parameters such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and malondialdehyde (MDA) contents, as well as photosynthetic pigments including chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids. Results indicated that plant height and stem diameter were maximum at 70% FC (70.33 cm and 21.33 mm) and minimum at 30% FC (35.33 cm and 8.33 mm) respectively. Conversely, biochemical parameters were maximum at 30% FC (SOD: 34.33 U mg^-1 protein, POD: 4.3 U mg^-1 protein, CAT: 3.6 U mg^-1 protein, MDA: 1.133 mol g^-l FW) and minimum at 70% FC (SOD: 18 U mg^-1 protein, POD: 2.8 U mg^-1 protein, CAT: 2.433 U mg^-1 protein, MDA: 0.653 mol g^-l FW). Similarly, photosynthetic pigments were maximum at 70% FC (chlorophyll a: 0.5 mg g^-l FW, chlorophyll b: 0.248 mg g^-l FW, total chlorophyll: 0.798 mg g^-l FW, carotenoids: 0.376 mg g^-l FW) and were minimum at 30% FC (chlorophyll a: 0.21 mg g^-l FW, chlorophyll b: 0.118 mg g^-l FW, total chlorophyll: 0.325 mg g^-l FW, carotenoids: 0.183 mg g^-l FW). Overall, growth parameters and photosynthetic activity were more pronounced under non-water deficit conditions, while biochemical parameters exhibited an inverse relationship. These findings offer insights for future tree-planting endeavours in marginal lands and aid in climate change mitigation efforts.