From stress to strength: Improving fenugreek seed germination under saline conditions with moringa leaf extract priming as a biostimulant approach

Natural growth-promoting biostimulants are frequently utilized for plant development in standard and stressed conditions. Fenugreek (Trigonella foenum-graecum L.), an aromatic medicinal and vegetable crop that is highly economically important worldwide, has been negatively affected by salinity. According to research studies, moringa leaf extract (MLE) has been demonstrated to enhance resistance to salt stress. However, there is limited data on MLE's impact on aromatic plants, particularly fenugreek, under saline conditions. In this study, conducted in autumn season (mid-October 2024) at the Environmental Physiology Laboratory, Department of Botany, Aligarh Muslim University, we used a completely randomized design with four treatment groups: (1) control (no treatment), (2) 150 mM NaCl, (3) MLE30 (1:30 v:v) without salt stress, and (4) 150 mM NaCl with MLE30. Results indicated that the over accumulation of ROS, Na⁺ and Cl^- ions under salt stress weakened growth or development, physio-biochemical characteristics, and mitotic division. Seeds primed with MLE exhibited significant improvements: seedling height increased by 42.74 %, fresh weight by 26.15 %, dry weight by 20 %, germination by 30.68 %, chlorophyll content by 39.62 %, ROS scavenging by 28.39 %, and proline content by 11.5 %. The seedling vigor index rose by 86.56 % under salt stress. MLE treatment also promoted cell division, increasing the mitotic index by 152.94 % and enhancing enzymatic antioxidant activities (SOD: 21.25 %, CAT: 36.07 %, POD: 13.13 %, APX: 37.34 %). Non-enzymatic antioxidant activities also improved (PPO: 14.70 %, Carotenoids: 24.24 %), along with amylase activities (α-amylase: 39.44 %, β-amylase: 37.24 %) and phosphatase activities (acid phosphatase: 30.92 %, alkaline phosphatase: 32.76 %). Additionally, the salt tolerance index improved by 18 %. The findings suggest that MLE's antioxidant defense mechanism effectively scavenges ROS, providing protection against salt-induced oxidative damage and enhancing the germination of seeds in saline soils. These observations offer valuable insights into the application of plant-based biostimulants like MLE30 to improve crop resilience to abiotic stresses such as salinity.