This study aimed to investigate the effect of silicon (Si) on the reduction of brown spot severity (BSS), caused by Bipolaris oryzae, and grain discoloration in several rice genotypes. An experiment was conducted in a greenhouse where eight genotypes were evaluated for their response to Si rates and decrease on BSS. The relationship between Si rates and BSS was linear negative. Additionally, a field experiment was conducted including forty-eight genotypes which were grown in upland conditions and evaluated for their response to Si rates and reduction on grain discoloration. The relationship between Si rates and grain discoloration was quadratic negative. Weight of filled grains per panicle increased as the Si rates in the soil increased. Genotypic differences for Si concentration in husk were evident for both non-amended and Si-amended plots. While the Si concentration in husk increased to all genotypes, there was no relationship between grain discoloration and Si concentration in husk for plants from non-amended and Si-amended plots. The genotype CAN-7024 with the highest resistance to leaf brown spot also showed the lowest grain discoloration in comparison to the genotypes Casado and Caqui.
In Brazil, upland rice is cultivated mainly on cerrado soils, which, due to their highly weathered degree, present low pH, low base saturation and low ratio of Si oxides of Fe and Al. A greenhouse experiment was conducted to evaluate the response of upland rice to calcium silicate as well as its effect on correcting soil acidity. The treatments consisted of six levels of SiO2 (0; 125; 250; 375; 500 and 625 mg kg-1 of soil) as of wallastonite, Wansil-10 (50% of SiO2, 44 of CaO and 1.48 of MgO) and three upland rice cultivars (Caiapo, Carajas, and Confiança).The experimental design was completely randomized with four replications. Rice response to SiO2 was linear, showing significant positive correlation with Si and Ca content of soil, derived from application of calcium silicate. The application of SiO2 also increased the pH, exchangeable Ca and Mg and soluble Si in the soil.
No Brasil, o arroz de sequeiro é cultivado predominantemente em solos de cerrado, os quais, em razão do seu avançado grau de intemperização, apresentam baixos valores de pH, baixa saturação por bases e baixa relação Si/óxidos de Fe e Al. Assim, realizou-se um experimento em casa de vegetação, com objetivo de avaliar o efeito do silicato de cálcio no rendimento de grãos do arroz de sequeiro, bem como seu efeito corretivo na acidez do solo. Os tratamentos consistiram de seis doses de SiO2 (0; 125; 250; 375; 500 e 625 mg kg-1 de solo), na forma de volastonita Vansil-10 (50% de SiO2, 44 de CaO e 1,48 de MgO), e três cultivares de arroz de sequeiro (Caiapó, Carajás e Confiança), dispostos em delineamento inteiramente casualizado com quatro repetições. O rendimento de grãos aumentou de forma linear com a fertilização silicatada, mostrando correlação significativa e positiva com os teores de Si e Ca no solo, derivados da aplicação do silicato de cálcio. A aplicação de SiO2 aumentou o pH e os teores de Ca, Mg trocáveis e Si solúvel no solo.