Allelopathic Potential of Sorghum Residue in Biological Control of Weeds in Cowpea Cropping System

 

Ajayi, Oyinlola A, Akinola, M.O And Awodoyin, R.O

 

Full Length Research Paper I Published February,2017

 

Journal of Physical Science and Environmental Studies Vol. 3 (2), pp. 18-24

ABSTRACT

The global concern about the risks associated with the use of synthetic herbicides in controlling weeds in agroecosystems coupled with the limitation of other methods of weed control had necessitated the need for concerted efforts on promoting alternatives to synthetic herbicides. The study intended to evaluate the allelopathic potentials of Sorghum bicolor residue in biological control of weeds in cowpea cropping system. The experiment was laid out in Randomized Complete Block Design (RCBD) with plot size of 3 x 3 m with three replicates. Different concentrations (20, 10.0, 7.5 and 5.0% w/v) of the aqueous extracts of Sorghum residue were applied immediately after planting and at 21 and 35 DAP at the rate of 20 l/ha. For comparisons, glyphosate, hand weeding and weedy plots maintained as checks. The reduction in total weed density at 65 days after planting (DAP) obtained with the application of 20 and 10% (w/v) aqueous extract was 67.62 and 47.11% decrease, respectively, while the weed control efficiency (WCE) was 81.22 and 71.57%, respectively. Maximum grain yield was obtained with the application of 20% (w/v) aqueous extract with 80.68% increase in relation to the weedy check while the application of glyphosate (synthetic herbicide) and hand weeding resulted in 58.09 and 58.92% increase, respectively. The bioactive substances detected in the aqueous Sorghum bicolor were phenols, flavonoids, tannin, saponnin and alkaloids. Thus, Sorghum residue extract is recommended for weed control in cowpea cropping system.

Key words: Agroecosystems, Allelopathic, Sorghum residue, Weed and Herbicides.

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