Journal of Research in Weed Science

Abstract The aim of the present work is to evaluate the herbicidal activity allelopathic extracts of sorghum plants (Sorghum bicolor L.) on wheat and accompanied weeds namely wild oat and canary grass under local conditions in Egypt. The biocidal activity of the aqueous and methanolic extracts of sorghum was compared with two of the most common herbicides used on wheat i.e. diclofop-methyl and clodinafop-propargyl. Application of the tested materials was carried out by using three concentrations of sorghum extracts (5, 10 and 20%) and the recommended dose of each diclofop-methyl (750 ml/fed) and clodinafop-propargyl (140 gm/fed) under laboratory, green house and semi field conditions. The herbicidal and phytotoxic effects of both biochemical agents and conventional herbicides were carried out by measuring germination percentage, seedling shoots and root length, dry weight, chlorophyll content, plant height, plant numbers, spike length and spike weight of the treated wheat. The obtained results indicated that there is no adverse effect of the tested extracts against the measured parameters of productivity and yield of wheat. At the same time promising herbicidal activity of aqueous and methanolic extracts of sorghum was revealed against wild oat and canary grass in particular with aqueous extract of sorghum at concentration of 20%.

Abstract The objective of this work is to evaluate the allelopathic effects of the aqueous and methanolic extract of rice straw (Oryza sativa L.) on wheat (Triticum aestivum L.) and wheat weeds, including wild oat (Avena fatual L.) andcanary grass (phalaris minor). Three concentrations (5, 10 and 20%) of each aqueous and methanolic extract as well as the recommended dose of chemical herbicide clodinafop propargyl (140 g/ fed) and diclofop-methyl (750 ml/fed) were used on the tested plants as a post-emergence treatments. Response of the treated plants were measured by using 7 parameters includes: germination %, seedling shoots and root length, dry weight, chlorophyll content, plant height, plant number and spike length and weight of treated wheat. Data of each parameter were discussed separately. Generally, treatments with higher concentrations (20% rice straw aqueous and methanolic extract) showed negative effects on wheat weeds at the same time cause increasing the wheat productivity. However, rice straw methanolic extracts showed suppressive effect on wheat seed. Comparing the efficacy of the straw extract with the tested conventional herbicides, the obtained data showed that clodinafop propargyl and diclofop-methyl were the most effective against the time tested weeds as it severely reduced the weed population and other tested parameters.