Adaptações no teste de germinação para sementes de arroz tratadas com fungicidas e inseticidas

Abstract

Rice (Oryza sativa family Poaceae) is an annual grass adapted to aquatic environments. It is an important agricultural crop classified in the group of plants C-3. Rio Grande do Sul is the Brazilian largest rice producer. It is important to use high quality seeds in order to maximize the productive potential. Chemical treatment is a technique widely used by seed producers. However, the germination test is standardized for untreated seeds. The objectives of this work were to evaluate different registered chemicals for the treatment of rice seeds, in the substrates indicated by the Rules for Seed Analysis (RAS) and in alternative substrates, also considering the possible effects of storage on the treated seeds and, evaluate the use of these alternative substrates in batches with different seed quality levels and different rice cultivars and also by assessing isoenzymatic analyzes. The rice seeds were treated in a specific machine, and the products used according to the manufacturer's recommendations. The treated seeds were sown on the substrates described by RAS (paper and sand) and on alternative substrates (vermiculite between paper and sand between paper). The experimental design used for all studies was completely randomized, in a factorial scheme, according to the objective of each experiment. The variables analyzed were first germination count, germination, abnormal seedlings, dead seeds, seedling length and seedling isoenzyme activity. The results shows that sand and vermiculite between paper are methodological adjustments that prove to be efficient for the germination test in treated rice seeds; sand and vermiculite between paper are viable for chemically treated rice seeds, for both high-quality and low-quality seeds; the substrate paper + sand and paper + vermiculite were effective in the germination test in treated rice seeds for all cultivars tested; the seedlings germinated in the substrate sand + germitest paper have a greater total length and evaluating the different isoenzymes systems it was found, in general, that the addition of sand in the germitest paper was effective for the expression of isoenzymes.