Effects of Selected Crops on Germination and Growth of Bidens pilosa and other Weeds

A screen house pot study was done at Uganda National Crops Resources Research Institute, Namulonge in Uganda during September-December 2021. Profiled metabolites from 5-donor plants; Mucuna pruriens, L. (Mc), Cymbopogon nardus L. (C), Desmodium uncinatum Jacq. DC. (D), (Zea mays, L. (Mz) and New Rice for Africa 1 (NERICA 1) were Terpenoids and Phenols. NERICA 1 (R) is a cross of Oryza sativa and Oryza glaberrima. C produced 10 terpenoids + 1 ester, R and D each released 6 Terpenoids + 3 Phenols. Mc produced 2 Terpenoids + 4 Phenols and 5 Terpenoids + 4 Phenols were profiled from Mz. Completely randomised block design were adopted with 3 replicates and eight combinations of 3 leaf+stem+root powders namely; Mc+D+C, Mz+Mc+C, RDC, Mc+D+C, Mz+R+Mc, Mz+D+Mc, R+Mc+C and Mz+R+C, mixed with 1.5 kg soil (15, 30 and 45 %, w/w). Controls had no powders. Mixtures were placed in plastic pots and 20 seeds of Biden pilosa L. were sown in each pot. Every 2 days, 200 ml of water was applied to all treatments for 60 days. Mz+Mc controlled B. pilosa and volunteer weeds relative to R+C and C+D. Weed germination and biomass reduced with increased powder doses. Volunteer monocot weeds were more inhibited than dicots. High potential exists for functional allelopathy using allelochemicals in the donor plants to develop bio-herbicides.