Allelopathic effect of different solvent extracts of Turnera subulata Sm. leaves against selected plants and weed

Nor Atirah Mohd Aridi1, Nornasuha Yusoff1, Muhd Arif Shaffiq Sahrir1, Mohd Fahmi Abu Bakar1 and Tse-Seng Chuah2
1 University Sultan Zainal Abidin, Faculty of Bioresources and Food Industry, Besut Campus, 22200 Besut, Terengganu, Malaysia
2 University Teknologi MARA Perlis Branch, Faculty of Plantation and Agrotechnology, Arau Campus, 02600 Arau, Perlis, Malaysia


Nor Atirah, M. A., Yusoff, N., Shaffiq, S.M.A., Mohd Fahmi, A. B. & Chuah, T. S.  (2023). Allelopathic effect of different solvent extracts of Turnera subulata Sm. leaves against selected plants and weed. Bulg. J. Agric. Sci., 29 (3), 490–500

Allelopathy had been identified as an alternative in minimize the dependency of herbicide in controlling weed. There has been limited research performed on Turnera subulata Sm., despite the exploration of allelopathy in the Passifloraceae family. In this research, the allelopathic effect of T. subulata leaf extracts was investigated on bioassay species of mustard, wheat grass, and weedy rice under laboratory conditions using various solvents, including water, methanol, ethyl acetate, and hexane. The experiments were conducted in different concentrations; 0.1, 1, 10, 50, and 100 mg/ml leaf extracts in five replicates. The total phenolic and flavonoid compounds of both leaf extracts were also determined. T. subulata leaf extracts significantly reduced the growth of bioassay species at 50 and 100 mg/ml.  At 100 mg/ml, off-white Turnera aqueous extract suppressed the most in root length of mustard, followed by the yellow Turnera, with 92% and 89% of inhibition, respectively, compared to the control. Aqueous extracts had the strongest inhibitory effect on the root growth of all species. The degree of phytotoxic activity of different solvent extracts on both yellow and off-white T. subulata can be classified in the order of decreasing inhibition as follows: water > methanol > ethyl acetate > hexane. When evaluated at 0.1 and 1.0 mg/ml of all solvents, there was a substantial stimulatory effect on the root and shoot growth of the bioassay species. The allelopathic activities of T. subulata leaf extract greatly depended on extract concentrations, bioassay species, and solvent types. These findings can be used as a benchmark for future weed management strategies.

Keywords: Turnera subulata Sm.; Allelopathy; Solvent Extract; Total Flavonoid Content; Total Phenolic Content

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