Acúmulo de silício em plantas de arroz do ecossistema de várzea submetido à aplicação de diferentes fontes

Abstract

( 3 ); ANTONIO NOLLA ( 4 ) RESUMO A baixa produtividade brasileira de arroz decorre, principalmente, da reduzida fertilidade do solo e alta suscetibilidade a algumas doenças. A adubação com silício pode ser uma alternativa no sentido de amenizar, sobretudo, o impacto das doenças sobre a produtividade. No intuito de identificar fontes eficientes quanto ao fornecimento de Si para a cultura do arroz, foi instalado um experimento em vasos, utilizando-se Neossolo Quartzarênico Órtico típico, em delineamento em blocos casualizados. As fontes de Si utilizadas foram siligran e silicon, nas formas granulada e pó, na dose de 200 mg kg -1 de Si. A curva de resposta a Si foi estabelecida pela aplicação de uma fonte-padrão (Wollastonita) nas doses de 0, 50, 100, 200, 400 mg kg -1 de Si, visando obter uma curva de resposta. Após a semeadura da cultivar de arroz Rio Formoso, avaliou-se a produção de massa seca da parte aérea, massa de panículas, produção de grãos, Si acumulado na planta e teores de Si no solo. A fonte-padrão Wollastonita apresentou comportamento linear, aumentando o Si disponível no solo e a absorção pelo arroz com o aumento das doses aplicadas. Os maiores aumentos, nos teores de Si na parte aérea, casca, Si acumulado e na massa seca total foram proporcionados pela Wollastonita. A fonte que proporcionou maior aumento na produtividade de grãos foi silicon na forma de pó. O extrator ácido acético extraiu maiores quantidade de Si do solo em relação ao cloreto de cálcio, superestimando os resultados.Palavras-chave: Oriza sativa, silicato de cálcio, adubação. ABSTRACT SOURCES AND ACCUMULATION OF SILICON IN PLANTS OF LOWLAND RICEThe low Brazilian productivity of rice is mainly because of the low soil fertility and high susceptibility to some diseases. The fertilization with silicon can be an alternative to decrease the impact of the diseases in the yield. To identify efficient silicon sources for rice, an experiment was installed in pots, using a Quartzipsamment soil, in randomized blocks. The silicon sources used were siligran and silicon, in the forms granulated and powder, in the dose of 200 mg kg -1 of Si. The curve of response to Si was established by application of a standard source (Wollastonite) in the doses of 0, 50, 100, 200, 400 mg kg -1 of Si, seeking to obtain a curve of response. The rice cultivar Rio formoso was sown and the production of dry mass of the aerial part, panicles mass, production of grains, plant tissue and soil Si content, were determined by the rice cycle. The standard source Wollastonite had linear behavior, increasing soil Si availability and its absorption by rice with the increase of the applied doses. The largest increases in the contents of Si in the aerial part, in the peel, and Si accumulated in the plant and Si in the dry total mass were produced by Wollastonite. The source that provided larger increase in the yield of grains was silicon in the powder form. The acetic acid extracted larger amount of Si of the soil than calcium chloride, overestimating the results.

Silicon fertilization improve yield and quality of rice and pearl millet in cerrado soils

“…These results are in agreement with experiments conducted in pots using 400 kg ha -1 Si (silicate) in flooding rice (RAMOS et al, 2008), and 500 kg ha -1 Si (wollastonite) in upland rice . Although increases on Si uptake by rice were linear up to 800 kg ha -1 Si, the maximum grain and shoot dry weight production was obtained in RQ with rates of 542 and 550 kg ha -1 Si, respectively ( Figure 3B and C).…”

“…This could be explained by the higher Si uptake by shoots compared to grains. Lower Si rates used in other studies provided only increases in Si uptake and grain, but not in shoot dry weight RAMOS et al, 2008). For the pearl millet, a lower rate (480 kg ha -1 ) provided the maximum shoot dry weight (Figure 3 B).…”

“…This is also evidenced by the lower Si content in both soils after harvesting the rice and pearl millet ( Figures 1C, 1 D, 2C, 2D). Si rates applications of 400 kg ha -1 Si, 500 kg ha -1 Si and 935 kg ha -1 Si have already increased grain weight RAMOS et al, 2008), shoot dry weight (PEREIRA et al, 2004) and grain yield (BARBOSA FILHO et al, 2004), respectively.…”

“…However, they focused on the evaluation of the acidity correction and Ca, Mg, and Si supply under field conditions (BARBOSA FILHO et al, 2001;KORNDÖRFER et al,2001;CARVALHO-PUPPATTO et al,2003) and pots (PEREIRA et al,2004;KORNDORFER et al, 1999;CAMARGO et al, 2007b) and only a few studies (RAMOS et al, 2008) have evaluated the benefits of Si supply for the rice crops on its uptake, yield and quality without the additional effects (increasing on pH and Ca and Mg content in soils) of silicate applied in tropical soils. The Ca and Mg levels in soil had to be used in the same quantities when different silicate rates were applied in soil, as already done in incubation studies of Si sources and rates (CAMARGO et al, 2007a;PEREIRA et al, , 2010.…”

Helicônia "Golden Torch": produtividade e qualidade pós-colheita sob diferentes fontes e doses de silício

“…Para isto é necessário que as rochas silicatadas sejam extraídas, trituradas e moídas para aumentar sua superfície de contato, solubilidade e disponibilidade (Oliveira et al, 2007;Ramos et al, 2008).…”