Phytosociological survey and allelopathic effects of some weed species extracts on seed germination and seedling growth of maize (Zea mays L.) and pepper (Capsicum annuum L.)

Abstract

Allelopathy is an important agricultural practice that has gained attention in sustainable agriculture management. A weed survey was carried out in irrigation fields of Katcha and Gbako Local Government Areas of Niger State, and a laboratory experiment was conducted in the Department of Crop Production Laboratory, Federal University of Technology, Minna, Nigeria to assess the allelopathic effect of Siam weed (Chromolaena odorata.), Giant thatching grass (Hyparrhenia rufa.), Kodo millet (Paspalum scrobiculatum.), Pigweed (Portulaca oleracea.), Bermuda grass (Cynodon dactylon.) on germination and seedling growth of maize and pepper. The result of the weed survey revealed that twenty-nine weeds were found existing in the fields surveyed and nine were identified as the most dominant and important weed species, namely Cyperus rotundus, Setaria pumila, Digitaria horizontalis, Brachiaria deflexa, Senna obtusifolia, Ageratum conyzoides, Cynodon dactylon, Phyllanthus niruri and Eragrotis sp. Among the weed species, the aqueous extract of Portulaca oleraceae showed more phytotoxic effect which reduced germination percentage in maize by 64 %, plumule length by 83.1% and radicle length by 93.1% respectively, over the control. Similarly, P. oleraceae aqueous extract reduced the same parameters by 100% over the control in pepper. It is clear from this study that aqueous extract of P. oleraceae exerted a stronger inhibitory effect on the germination and seedling growth of maize and pepper than the other weed species, and should be considered important in these crops