Danos mecânicos e tratamento químico na qualidade de sementes de milho armazenadas

Abstract

The current system of seed production is highly mechanized and these operations can contribute to product quality loss due to the incidence of mechanical damages, making the seeds more susceptible to attack by pests and to the infestation by pathogenic fungi. Using healthy seeds is a requirement for the obtainment of good yields and the chemical treatment can be an alternative to minimize the effect of mechanical damages and their consequences. The objective of this work was to study the effect of the chemical treatment and the storage on quality of maize seeds with mechanical damages. The work was developed at the Central Laboratory of Seeds Analyses, in Lavras – MG. It was used only one hybrid, from crop 2013/2014 provided by the Seed Care Institute. Initially, seeds were analyzed through X-ray test for the obtainment of three lots; seeds with damages, seeds without damages, and seeds without separation. Following, the lots were evaluated according the physiological quality, sanity and enzymatic analyzes. It was performed a chemical treatment with the insecticide Maxim Advanced ® and the fungicide Cruiser ® , and the treated and non-treated seeds were re-evaluated, before the storage and at 90 days of storage. It can be conclude that the chemical treatment of maize seeds with the fungicide is efficient in the control of pathogens, like Fusarium sp.. The performance of seeds with internal and external damages can be maintained for 90 days when treated with fungicides and insecticides and stored in environment condition. The isoenzymatic patterns of catalase (CAT), superoxide dismutase (SOD), malate dehydrogenase (MDH) and alcohol dehydrogenase (ADH), confirmed the higher deterioration of non-treated seeds during the storage in comparison to those seeds that were treated. The mechanical damages found in seeds contribute to the reduction of viability and vigor of maize seeds.