Adsorption, leaching and phytotoxicity of some herbicides as single and mixtures to some crops

The study investigated adsorption, leaching potential, and phytotoxicity of alachlor, bromacil, and diuron on melon, Molokhia, and wheat in Gaza strip. Plant height was used to estimate growth inhibition (phytotoxicity). Growth inhibition data were regressed versus concentrations of corresponding herbicide to estimate EC₅₀ value. The lowest EC₅₀ value indicates the highest phytotoxicity. Adsorption results indicated that alachlor, bromacil and diuron have different shapes. Leaching potentials indicated that alachlor totally disappeared from the top 5 cm and accumulated at a deeper depth whereas bromacil and diuron accumulated in the top 8 cm of soil layer with a decreasing intensity at deeper depth. Phytotoxicity tests showed that diuron has the lowest EC₅₀ values on melon (1.64) and Molokhia (0.15) whereas bromacil has the lowest one on wheat (0.08), values are in (mg/kg soil). Results of binary mixtures showed that the mixture contained alachlor and diuron was the most toxic to melon, whereas mixture contained alachlor and bromacil was the most toxic to Molokhia and wheat. Tertiary mixture (alachlor + bromacil + diuron) was more toxic on Molokhia than melon and wheat, EC₅₀ values were 3.02, 32.174, and 633.9 TU/kg soil on Molokhia, melon, and wheat respectively. An interesting outcome of the study is that Molokhia was the most sensitive plant and binary mixtures showed synergistic phytotoxicity.