Allelopathic potential of wheat and canola residues on germination and initial growth of some crops and weeds in laboratory condition

Allelopathic potential of aqueous extracts of wheat and rapeseed on rice, maize, sunflower, common amaranth and cockspur grass was studied. Plants foliage were dried at 60 °C, grounded and used for plant extractions preparation in concentrations of 1, 2.5, 5.0, 7.5, and 10% w/v ratios. Experiment was carried as completely randomized block design with three replications. The aqueous extracts caused significant inhibitory effect on germination, radicle and hypocotyl elongation in receptor plants. The inhibitory effect of wheat and rapeseed aqueous extracts was proportional and higher concentrations 5-10% had the strong inhibitory effect whereas stimulatory effect was observed in some cases of lower concentrations of 1-2.5%. Also, inhibitory effects were much pronounced in radicle elongation rather than hypocotyl growth. Also, inhibitory of canola was greater than wheat on germination indices. Negative allelopathic effects on common amaranth growth were greater than on cockspur grass. On the whole, wheat and canola residues had allelopathic potential on studied plants. Therefore, it is giving them this advantage in mixed cropping and crop rotation to control weeds and possibly fighting with plant pathogens. Hence, these plants can be a good candidate to study and produce bio-herbicides and pesticides as one of the important goals of sustainable agriculture.