Isolation of herbicidal compounds from Melia azedarach L. to control Rumex dentatus L. in wheat
Isolation of herbicidal compounds from Melia azedarach L. to control Rumex dentatus L. in wheat
- Author(s) Muhammad Akbar, Arshad Javaid, Tayyaba Khalil and Muhammad Sajjad Iqbal
- Year: 2022
- Month: March
- Volume: 55
- Pages: 163-176
In field studies, we evaluated the herbicidal effects of Melia azedarach L. leaf extract against a weed Rumex dentatus L. and wheat (Triticum aestivum L.) crop. We isolated and identified a bioactive constituent in the methanolic extract of M. azedarach leaves with column chromatography and Gas Chromatography Mass Spectrometry (GC-MS). The leaf extract of M. azedarach at 10 % (w/v) concentration significantly reduced the R. dentatus weed biomass up to 65.24 % and subsequently increased the wheat yield by 41.4 %. While, the leaf extract of M. azedarach at 10 % concentration + Bromoxynil (70 g a.i.) + MCPA (70 g a.i) significantly reduced the R. dentatus weed biomass up to 96.77 %, with an increase of 67.6 % in wheat yield. In lab. study, 11 purified fractions (1, 2, 3, …, 11) from methanolic leaf extract of M. azedarach were tested for their herbicidal activity on leaf discs of R. dentatus. Fraction 7 showed the highest herbicidal activity and was identified as a-selinene through GC-MS analysis. It showed herbicidal activity against R. dentatus at 0.5 mg mL-1 concentration, but was not harmful to wheat. In lab bioassays, 2,4-D [2,4-dichlorophenoxyacetic acid] was used a reference compound that caused necrosis in R. dentatus at a concentration of 0.25 mg mL-1. This study concluded that the a-selinene identified from M. azedarach may be developed as natural herbicide to avoid the harmful effects of synthetic herbicides. Besides, structure of a-selinene can be used as an analogue to synthesize commercial herbicides. To further improve the herbicidal activity of this compound, its derivatives need to be investigated.
