Phytotoxicity of the Herbicides; Alachlor, Bromacil and Diuron and their Mixtures to Wheat, Watermelon, and Molokhia Plants in Gaza Strip, Palestine

Abstract

This study aimed at investigating phytotoxicity of the herbicides: alachlor, bromacil, diuron, and their mixtures to wheat (Triticum spp), watermelon(Citrulus lanatus) and molokhia (Corchorus Olitorius L.) plants inGaza strip. The study indicates that phytotoxicity for herbicides on plants decreases the growth of the plants that were exposed to a different concentration of herbicides. This experiment was conducted in pots under controlled conditions for two weeks and then they were harvested. The biomass was used as an indicator for determination of growth inhibition. The phytotoxicity of selected herbicides was determined through the percentage of growth inhibition and was estimated by the toxic units of these used herbicides. These herbicides were used either individually or in a mixture of binary or tertiary. It has been found that the effect of the phytotoxicity of these herbicides and their mixtures on plants is varied from one herbicide to another. However, these variations may be referred to the difference concentration and EC50 for each herbicide. It was found that EC50 for alachlor, bromacil and diuron were: 11.37, 4.77, 1.64 respectively on melon, 0.33, 0.29, 0.15 respectively on molokhia, and 0.11, 0.08, 0.24 respectively on wheat. In the binary mixture tests, The EC50 of (alachlor and bromacil), (alachlor and diuron), and (bromacil and diuron) was 12.21, 5.84, 10.22 for melon, 0.982, 925.4, 38.1 for molokhia, and 0.673, 1.34, 0.644 for wheat. In tertiary mixture tests EC50 of (alachlor, bromacil and diuron) the result was 633.9 for melon, 3.02 for molokhia and 32.174 for wheat. EC50 was estimated by using the linear regression equation and it was found that the effect of the remaining herbicides on the plants growth for the individual experiments is more clearly compared with the experiment of the herbicides mixture. The individual herbicides test proved that the diuron is more toxic than both alachlor and bromacil. Other effects may be caused by interaction between two herbicides or more and it may be additive, synergistic or antagonistic.