Doses, fontes e épocas de aplicação de Zn: efeito na germinação, potencial fisiológico de sementes e produtividade de arroz irrigado por inundação

Abstract

This work aimed evaluate the effect of rates, sources and times of zinc (Zn) application on germination, seed physiological potential and flooded irrigated rice grain yield. The experimental design used was completely randomized: in laboratory experiment was used a factorial scheme 6 x 2 and four replications. Six Zn rates: 0, 50, 100, 200, 400 e 800 g ha-¹ and two Zn sources: zinc sulphate heptahydrate (ZnSO₄.7H₂O) and zinc chloride (ZnCl₂). After seed treatment were evaluated germination, seedling length, seedling dry matter, cold test, accelerated aging and seedling emergence. In field, was used a factorial scheme 7 x 3 x 2, with three replicates consisting of 7 L soil each. Were used seven Zn rates: 0, 50, 100, 200, 400, 800 e 1600 g ha-¹ ; three application times: in seed, vegetative stage (V₄), vegetative stage (V₁₁); with ZnSO₄.7H₂O and ZnCl₂. In harvest were evaluated panicle number, shoot dry mass, 100 grains mass and rice grain yield. The rice seeds treatment with Zn do not change germination and seedling emergence. Among the parameters to assess rice seeds physiological potential, seedlings dry mass and germination at low temperature are benefited when using the ZnSO₄.7H₂O. Rice seeds treatment with ZnCl₂ provides higher grain yield compared to ZnSO₄.7H₂O. The Zn application by seed treatment and spraying in V₁₁ stadium promote higher rice grain yield in relation to V₄ stage.