RESUMEN
The intensive use of organochlorine in the past decades has resulted in contamination of soil worldwide. The phytotoxicity of two organochlorine pesticide, endosulfan sulfate and heptachlor, on the early growth stage of sweet corn (Zea mays), waxy corn (Zea mays) cowpea (Vigna sinensis), cucumber (Cucumis sativus) and water morning glory (Ipomoea aquatica) were studied. In the range of concentration found in Thai agricultural soil, 0.4 – 40 mg kg-1 of each pesticide, did not affect the percentage of seed germination. Heptachlor seemed to affect the shoot and root length of test plants more than endosulfan sulfate. The combined effect of both pesticides to corn seedling growth was tested. There was no significant effect on combined treatment of both pesticides to corn growth. The 0.4 – 40 mg kg-1 concentration of endosulfan sulfate and heptachlor did not produced significant effect on early growth of plants.