Allelopathy activity under laboratory, greenhouse and field conditions: A review

Weeds are one of the significant problems that impact agriculture production. Farmers have been using synthetic herbicides to control weed infestations in the field. However, the excessive usage of herbicides has led to various environmental concerns, including the emergence of herbicide resistant weeds. Allelopathy is an environment-friendly alternative that can control weeds. Here, we performed a systematic literature review to assess the potential and effects of allelopathy under laboratory, greenhouse and field conditions. Articles were collected by searching the SCOPUS database and guided by PRISMA. Of 371 studies identified, forty-three articles used allelopathy to control weeds under greenhouse and field conditions, with Poaceae being the prominent family studied as donor plants. Six articles reported up to 80% weed growth suppression when spraying allelopathy extract under greenhouse conditions, while mulch and soil incorporated with donor plants contributed over 50% suppression under field conditions. The findings revealed that 20 studies had conducted metabolite identification to determine the allelochemicals with phytotoxic activity against target plants. However, the mechanism of allelopathy was not thoroughly investigated. In conclusion, we found an increasing trend of allelopathy experiments conducted under greenhouse and field conditions. Furthermore, field trials should be included to validate laboratory data and to provide insight into allelochemical action and its relationship with the environment.