Desempenho no armazenamento de sementes de milho tratadas com inseticidas

Abstract

The maize seed treatment, aiming to control soil pests and shoot tissue in the early stages of crop establishment, is becoming increasingly common practice in Brazil. Although effective in pest control, some products may cause phytotoxicity in seeds, immediately after treatment or during the storage period. This work aims to study the quality performance of maize seed lots, presenting different levels of initial vigor, submitted to chemical treatment with insecticides and stored for different periods of time, under controlled conditions of temperature and relative humidity. Before treatment, two seed lots were selected: one of high initial vigor, with a result of 95% in cold test; and another of medium vigor, with a result of 85% in cold test. The seeds were treated, according to manufacturer’s recommendations of, with the products thiamethoxam, thiamethoxam + fipronil and a conventional treatment, and stored in climate-controlled environment with temperature of 10 ° C and relative air humidity of 50%. The physiological seed quality was evaluated by the germination test, cold test and field emergency immediately after chemical treatment and after each three months of storage. The experiment was conducted in a completely randomized design (CRD) in subdivided plots with four replications. It was observed that the initial seed vigor is essential to reduce disposal of insecticide treated lots, due to the low physiological quality, during storage period. The results show also that lots of high initial vigor, treated with thiamethoxam and thiamethoxam + fipronil preserve physiological quality for up to 12 months, while the lots with medium vigor, treated with thiamethoxam preserve the quality for only six months, and treated with thiamethoxam + fipronil, do not tolerate storage after treatment.