Thorn apple (Datura stramonium L.) allelopathy on cowpeas (Vigna unguiculata L.) and wheat (Triticum aestivum L.) in Zimbabwe

Abstract

Datura stramonium extracts have allelopathic properties. The study was conducted to investigate the allelopathic effects of D. stramonium weed on seed germination, early seedling growth and dry biomass of crop plants (Triticum aestivum and Vigna unguiculata). Laboratory and greenhouse trials were arranged as completely randomised design and the field pot experiment was arranged as a randomised complete block design. Aqueous leaf extracts of D. stramonium at 2, 4, 6 and 8% concentrations were applied to determine their effects on seed germination, early seedling growth of crops under laboratory, field and greenhouse conditions. Distilled water (0%) acted as a control. Results from the study indicated that germination, shoot length and dry weight significantly decreased proportionally (p<0.001) as the concentration increased from 2 to 8%. The results showed that D. stramonium has allelopathic effects on wheat and cowpeas, hence cannot be used as a bio herbicide to control Tagetes minuta and Amaranthus hybridus on the selected crops since it is non selective to the crops studied. There is therefore need for further research on screening of arable crops against the allelopathic effects of D. stramonium. This will help to identify arable crops which are not negatively affected by allelochemicals from D. stramonium weed so that it can be used as a selective bio herbicide against other weeds.