Response of Tomato to Metribuzin

Abstract

Metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazine-5(4H) one] injured and reduced growth of tomato (Lycopersicon esculentumMill.) but did not inhibit germination or emergence of several other species. In cucumber (Cucumis sativusL.), metribuzin did not have a specific site of uptake, being equally toxic when placed in the root, shoot, or seed zone. Tomato was more susceptible to metribuzin when the plants were grown under high humidity, high temperature, maintained under low light intensities before spraying, had their leaves rubbed with glass wool, or had a surfactant in the spray solution. The increased toxicity under low light was not overcome by exogenous sucrose. About 4% of the available metribuzin was absorbed by tomato leaves or roots and was translocated in the xylem. Tomato plants 13 cm in height were less susceptible to metribuzin injury than 8-cm high plants.