Allelopathic weed control techniques

From the report «Environment friendly (allelopathic extract) weed control techniques in wheat crop», from Imtiaz khan and Muhammad Ishfaq Khan, published at Revista Mexicana de Ciencias Agrícolas.

Use of chemicals as a sole weed management tool has proved harming due to the development of resistance in weeds and their adverse effects on the environment. Ground water, ponds, lakes and rivers are affected by herbicide pollution. The herbicides that find their way into rivers, streams and lakes end up poisoning the marine life and have an adverse effect on the fishing industry.

Exploitation of allelopathy is a natural and environment-friendly technique having potential to be a unique tool for weed management and sustainable agriculture. Although derived from plants, allelochemicals may be more biodegradable than traditional herbicides but may also have undesirable effects on non-target species, necessitating ecological studies before widespread use. So in field studies, the phytotoxic effects of organic weed extracts were determined on the weeds and wheat crop.

Ethanol or CHCl3 (trichloromethane or chloroform) extracts of toothpick weed (Ammi visnaga L.) and field bindweed (Convolvulus arvensis L.) were applied at 1 000 and 500 ppm on the weeds and wheat crop. One month after wheat sowing.


The CHCl3 extract of field bindweed at 1 000 ppm and toothpick weed at 500 ppm drastically reduced the weeds population (33.67 weeds/m2 each than 101 weeds/m2 in untreated control) but increased the wheat grain yield. The CHCl3 extract of bindweed applied at 500 ppm gave maximum wheat yield (1.2 t/ha), while toothpick weed extract in the same solvent and applied at 1 000 ppm gave wheat yield of 1.1 t/ha.

The both organic extracts of weed species Ammi visnaga and Convolvulus arvensis in Ethanol and CHCl3 were phytotoxic to weeds, but did not any adverse effect on wheat crop. Such natural products are needed to be exploited for sustainability in the agro-ecosystems and which also reduce pollution due to different chemical herbicides used for weed control. The selectivity contemplated between wheat and weeds offers a window for their selective use in wheat crop.

Judicious control measures for noxious weeds of allelopathic extracts are recommended to be adopted for harvesting better quantity and quality of wheat and also avoid the air pollution as well.