Silicon and manganese on rice resistance to blast

• Published in: Bragantia Vol. 71; no. 2; pp. 239 - 244
• Main Authors: Cacique, Isaías Severino, Domiciano, Gisele Pereira, Rodrigues, Fabrício Ávila, Vale, Francisco Xavier Ribeiro do
• Format: Journal Article
• Language: English
• Published: Instituto Agronômico de Campinas 2012
• Subjects: AGRICULTURE, MULTIDISCIPLINARY; Oryza sativa; Pyricularia oryzae; nutrição mineral; mancha foliar; leaf spot; mineral nutrition
• DOI: 10.1590/S0006-87052012000200013
• ISSN: 0006-8705; 1678-4499

Blast, caused by the fungus Pyricularia oryzae, is the most important fungal disease of rice. The effect of silicon (Si) and manganese (Mn), and their interaction, on rice resistance to blast was investigated. Rice plants (cultivar "Metica 1") were grown in hydroponic solution with 0 or 2 mmol L-1 of Si and with 0.5, 2.5, and 10 mmol L-1 of Mn. Sixty-day-old plants were inoculated with a conidial suspension of P. oryzae and the incubation period (IP), the number of lesions (NL) per cm² of leaf area, the lesion size (LS), and blast severity were evaluated. Blast severity was scored at 48, 72, 96, and 144 hours after inoculation and data were used to obtain the area under blast progress curve (AUBPC). Silicon concentration was significantly higher in leaf tissues of plants supplied with this element than on its absence, regardless of Mn rates. There was no significant difference in Si concentration among the Mn rates for both - Si and +Si treatments. The Mn concentration was significantly higher in the tissues of plants from the - Si treatment as compared to plants of the +Si treatment, but only at the rate of 10 mmol L-1 of Mn. There was a significant increase in Mn concentration as the rates of this micronutrient increased from 0.5 to 10 mmol L-1 regardless of the Si treatments. The IP significantly increased in the +Si treatment. The Mn rates had no effect on the IP regardless of the Si treatments. The NL was significantly lower in the presence of Si regardless of the Mn rates. The Mn rates had no effect on NL regardless of the Si treatments. The addition of Si to the nutrient solution significantly reduced both LS and AUBPC regardless of Mn rates. However, in the absence of Si, the values for LS and AUBPC were significantly lower at the Mn rate of 10 µmol L-1 as compared to the rate of 0.5 µmol L-1. Overall, the results from this study showed the potential of Si to decrease blast development on rice regardless of the foliar concentration of Mn. A brusone, causada pelo fungo Pyricularia oryzae, é a doença fúngica mais importante do arroz. O efeito do silício (Si), do manganês (Mn) e da interação deles na resistência do arroz à brusone foi investigado. Plantas de arroz da cultivar Metica 1 foram cultivadas em solução nutritiva contendo 0 ou 2 mmol L-1 de Si e 0,5, 2,5 e 10 mmol L-1 de Mn. Aos 60 dias, as plantas foram submetidas à inoculação com uma suspensão de conídios de P. oryzae e foram avaliados o período de incubação (PI), o número de lesões (NL) por cm² de área foliar, o tamanho de lesão (TL) e a severidade da brusone. A severidade da brusone foi avaliada às 48, 72, 96 e 144 horas após a inoculação e os dados foram usados para calcular a área abaixo da curva do progresso da brusone (AACPB). A concentração foliar de Si foi maior nas plantas supridas com Si. A concentração de Mn na solução nutritiva não interferiu na concentração de Si nas folhas das plantas de arroz. Houve aumento na concentração foliar de Mn à medida que a concentração desse micronutriente na solução nutritiva aumentou, independentemente da presença do Si. A presença de Si na solução nutritiva reduziu a concentração de Mn nas plantas cultivadas na dose de 10 mmol L-1 de Mn. O fornecimento de Si aumentou PI e reduziu o NL, o Tl e a AACPB. As doses de Mn não tiveram efeito no PI e no NL, independentemente da presença ou não do Si. Na ausência de Si, os valores do TL e da AACPB foram significativamente menores para a dose de 10 µmol L-1 de Mn em comparação com a dose de 0,5 µmol L-1 de Mn. Os resultados deste estudo reforçam o potencial do Si em reduzir o progresso da brusone em arroz independentemente da concentração foliar de Mn.