Qualidade de sementes e grãos de arroz irrigado em função da aplicação de fungicida, época de colheita e período de armazenamento

Abstract

Protection of irrigated rice plants using fungicides is growing every year as observation of fungal diseases is increasing. Higher occurrence of disease is observed when seeding is conducted after the recommended period. Success of rice yield depends on several steps since the implantation of the culture until harvest, being the last a very important step especially for physical and physiological rice quality. Rice production cycle will be only completed with grains and seeds storage, which consists in preserving physiological seed quality for new crops or grain quality for consumption and industrialization. The research was conducted using three field experiments in crop season 2008/09, with the intention of characterizing the response of different rice genotypes to fungicides application with a formulated mixture of propiconazole + trifloxystrobin applied at different developmental stages in a late seeding crop (Chapter I), quality of grain and seeds with different harvest moisture according to the fungicide application moment for different cultivars (Chapter II) and the behavior of grain and seeds to storage in controlled condition of temperature and humidity and in normal conditions (Chapter III). Experiments were conducted in a lowland area of the Crop Department of the Federal University of Santa Maria (UFSM). Each experiment was constituted by a suitable factorial scheme. Use of fungicide in different irrigated rice genotypes late sown showed to be efficient to high productivity. Harvest conducted with rice grain moisture under the recommended by researches demonstrated reduction of physical and physiological rice quality. There was less reduction in quality when two fungicide applications were performed. Increasing seed storage time caused reduction in physiological seed quality independently of storage in controlled condition or in normal conditions. Use of fungicide reduced the intensity of seed deterioration and incidence of fungus associated to seeds. Percentage of whole grain increased with storage time.