Allelopathic Potential of Nicotiana glauca Aqueous Extract on Seed Germination and Seedlings of Acacia gerrardii

Abstract

Nicotian glauca is a noxious invasive shrub in Saudi Arabia, and it is well known for its harmful impact on biodiversity, competing with native plants using various strategies. Among their strategies is their allelochemical activity, i.e., the use of chemicals to dominate and compete. The present study aims to evaluate the allelopathic potential of N. glauca aqueous extracts from leaves, flowers, and twigs on Acacia gerrardi seed germination and seedling growth. Petri dishes containing extracts from N. glauca parts with different concentrations were incubated in a growth chamber. The results indicated that extracts and concentrations negatively impact seed germination and hypocotyl. Relative to the control, the leaf extract with concentrations of 60 and 100 g/L reduced the seed germination rate by 81.11% and 93.33%, respectively. Flower extracts of similar concentrations decreased germination by 81.91 and 92.55%, while the twig extracts declined germination by 79.56 and 95.69%, respectively. The leaf, flower, and twig extracts (100 g/L) decreased hypocotyl radicle by 76.54, 78.05, and 65.75%, respectively. Overall, the concentrations of 20, 60, and 100 g/L showed the lowest growth indices. Generally, aqueous extracts, particularly 100 g/L, impacted the germination and protrusion of A. gerrardii hypocotyl. In conclusion, our study draws attention to the harmful impact of N. glauca on A. gerrardii regeneration.