Allelopathic Effects of Para grass (Brachiaria mutica (Forssk.) Stapf) on Seed Germination and Growth of Tainan 9 Peanut

Abstract

The study on allelopathic effects of para grass on the seed germination and seedling growth of Tainan 9 peanut was carried out from May, 2018 to September 2019. It aims at investigating the efficacy of 4 solvents; hexane, dichloromethane, methanol and distilled water in extracting the crude yields of allelopathic materials from both shoot and root of para grass. The highest crude extract yield was obtained by methanol at 8.78 and 6.65 % respectively. Results of the study on inhibitory effect of each crude extract with varying concentrations on seed germination and seedling growth of Tainan 9 showed that methanolic extraction expressed the highest inhibitory effects on seed germination and seedling growth. The reduction in germination percentages of peanut as affected by the para grass extracted with methanol hexane, dichloromethane, and distilled water were 38.75, 40.37, 50.62 and 51.00% respectively. Regardless of the extraction solvent, all concentrations of para grass extracts from root showed significantly higher inhibitory effect on seed germination and seedling growth than extracts from shoot. At the concentration 15 mg/ml, the para grass crude extract could inhibit seed germination, shoot length, root length and % dry weight by 47.96, 51.98, 50.27 และ 3.02% respectively. However, methanol crude extraction exhibited the strongest inhibitory effect on seed germination, shoot length, root length and % dry weight of peanut at 77.50, 81.31, 79.95 and 5.03 % respectively. Results suggested that para grass extracts contained allelopathic compounds which could inhibit seed germination and seedling growth of peanut. Due to the high extract yield obtained and severe inhibitory effect of para grass, methanol should be used as an extraction solvent if needed.