Silicon and manganese on rice resistance to blast

Abstract

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 cm 2 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.Key words: Oryza sativa, Pyricularia oryzae, leaf spot, mineral nutrition. Silício e manganês na resistência do arroz à brusoneResumo 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 cm 2 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 ...

Combined Effects of Soil Silicon and Host Plant Resistance on Planthoppers, Blast and Bacterial Blight in Tropical Rice

“…Our results corroborate previous studies that showed soil silicon to reduce the severity of blast diseases and bacterial blight in rice [ 21 , 32 , 76 , 77 , 78 , 79 , 80 ]. Applications of silicon nanoparticles to foliage have also been shown to effectively reduce (by 70%) blast disease in rice [ 81 ].…”

“…Furthermore, in our experiments, although the effects of soil silicon were small compared to the relatively large effects of host resistance in reducing the severity of blast and bacterial blight; nevertheless, soil silicon added to the resistance, particularly against the more virulent strain of bacterial blight, and thereby improved seedling growth. Similar effects of silicon in reducing disease severity have been documented across a range of rice pathogens [ 8 , 15 , 21 , 22 , 32 , 79 , 80 , 81 , 82 , 87 ].…”

Priming effect of root-applied silicon on the enhancement of induced resistance to the root-knot nematode Meloidogyne graminicola in rice

“…The role of silicon(Si) in conferring plant resistance to both abiotic and biotic stress has received increased attention [ 7 , 11 , 30 , 40 , 53 ]. Several studies have demonstrated that soil-applied Si can induce systemic defenses against different pathogens in many plants.…”

“…Root-applied Si significantly increased the activity of phenylalanine ammonia-lyase in cucumber and decreased the powdery mildew disease index [ 30 ]. The addition of Si to the nutrient solution significantly reduced both lesion size and area under the blast progress curve in rice [ 7 ]. Amendment of plants with calcium silicate remarkably reduced the number of root galls and eggs of various species of Meloidogyne in bean, tomato and coffee [ 13 ].…”

Difference in blast development in upland rice grown on an Andosol vs a Ferralsol

“…Mn content appeared to be adequate or high. The role of elements in affecting rice blast susceptibility such as Mn or P are difficult to interpret; the literature is mixed in that these elements have been reported to either increase or decrease blast susceptibility (Datnoff et al, 2007;Cacique et al, 2012).…”