Gaspar Henrique Korndörfer

Silicon nutrition and sugarcane production: A review 1

Abstract Silicon (Si) is one of the most abundant elements found in the earths crust, but is mostly inert and only slightly soluble. Agriculture activity tends to remove large quantities of Si from soil. Sugarcane is known to absorb more Si than any other mineral nutrient, accumulating approximately 380 kg ha−1 of Si, in a 12‐month‐old crop. Sugarcane (plant growth and development) responses to silicon fertilization have been documented in some areas of the world, and applications on commercial fields are routine in certain areas. The reason for this plant response or yield increase is not fully understood, but several mechanisms have been proposed. Some studies indicate that sugarcane yield responses to silicon may be associated with induced resistance to biotic and abiotic stresses, such as disease and pest resistance, Al, Mn, and Fe toxicity alleviation, increased P availability, reduced lodging, improved leaf and stalk erectness, freeze resistance, and improvement in plant water economy. This review ...

Effect of Silicon and Host Resistance on Sheath Blight Development in Rice

Rice cultivars high in partial resistance (Jasmine, LSBR-5), moderately susceptible (Drew and Kaybonnet), and susceptible (Lemont and Labelle) to sheath blight were grown in a silicon-deficient Histosol with and without calcium silicate slag. The treatment with silicon increased the concentration of this element in plant tissue by 80%over all experiments. Fertilization with silicon significantly reduced the severity of sheath blight, and the total area under the vertical lesion extension progress curve on moderately susceptible and susceptible cultivars compared to those cultivars high in partial resistance without silicon. The percentage of infected tillers was significantly reduced by 82, 42, 28, 41, 26, and 17%respectively for Jasmine, LSBR-5, Drew, Kaybonnet, Lemont, and Labelle, when silicon was applied, over all experiments. Dry matter accumulation was significantly greater with added silicon. In the absence of disease, silicon enhanced dry matter accumulation by 15%over the control, whereas silicon more than doubled the mean dry matter accumulation in infected plants. The application of silicon to complement host resistance to sheath blight appears to be an effective strategy for disease management in rice, especially when the soil is low or limiting in plant-available silicon.

CALIBRATION OF SOIL AND PLANT SILICON ANALYSIS FOR RICE PRODUCTION

Calibration of field crop response to nutrient availability is the bases for making a fertilizer recommendation from soil and tissue analyses. The purpose of this study was to evaluate and summarize results from a series of experiments on silicon (Si) fertilization of rice in the Everglades Agriculture Area. Twenty-eight rice field experiments were conducted from 1992 through 1996. The experiments consisted of 2 to 5 rates of calcium silicate applied to soils (Histosols) of varying Si soil-test values. Soil samples were taken before planting and analyzed for acetic acid (0.5 mol L−1) extractable Si. Straw samples were collected at harvest and analyzed for total Si. Grain yield was determined. The “critical” levels for Si in the soil (point below which response to Si fertilizer is expected) calculated by the Cate & Nelson procedure was 19 mg Si L−1 soil. The amount of silicon to correct Si deficiency in the soil and to obtain optimum rice yield was 1500, 1120 and 0 kg ha−1 for low (<6 mg L−1), medium (6 to 24 mg L−1), and high (>24 mg L−1) level of soil Si, respectively. Silicon in the straw was classified as high when Si concentration was >34 g kg−1, medium when in between 17 and 34, and low when <17 g kg−1 (3.4 and 1.7%, respectively). *Florida Agricultural Experiment Station Journal Series No. R-06752.

Influence of silicon on sheath blight of rice in Brazil

The effect of silicon (Si) on sheath blight (Rhizoctonia solani K . uhn) of rice was studied under greenhouse conditions. The predominant commercial rice cultivars ‘BR-IRGA409’, ‘Metica-1’, ‘EPA GRI-109’, ‘Rio Formoso’, ‘Java ! and ‘CICA-8’, were grown in pots containing low-Si soil amended with 0, 0.48, 0.96, 1.44 or 1.92 g Si pot � 1 . Plants were inoculated at the maximum tillering stage. For all cultivars, Si concentration in straw increased more than 60% as the rates of Si increased from 0 to 1.92 g pot � 1 . Incubation period of R. solani was slightly prolonged with increasing Si rates and ranged from 53 to 64 h depending upon the cultivar. Total number of sheath blight lesions, total area under the relative lesion extension progress curve, severity of sheath blight, and the highest relative lesion height on the main tiller decreased by 37%, 40%, 52% and 24%, respectively, as the rate of Si increased from 0 to 1.92 g pot � 1 . Silicon may offer a viable method to control sheath blight in areas where soil is deficient in Si and

Silicon sources for rice crop

Although silicon is not an essential nutrient, its application is beneficial for plant growth and development. To evaluate silicon sources in relation to agronomic efficiency and economic viability in rice crops (Oryza sativa L.), a greenhouse experiment was conducted, Quartzipsamment soil, in a completely randomized experimental design (n = 4). Treatments were 12 silicon sources and a control. Silicon was applied at the rate of 125 kg Si ha-1. Data were compared to a standard response curve for Si using the standard source Wollastonite at rates of 0, 125, 250, 375, and 500 kg Si ha-1. All treatments received CaCO3 and MgCO3 to balance pH, Ca and Mg. One hundred and fifty days after sowing, evaluations on dry matter yield in the above-ground part of plants, grain yield, and Si contents in the soil and plant tissues were performed. Wollastonite had linear response, increasing silicon in the soil and plants with increasing application rates. Differences between silicon sources in relation to Si uptake were observed. Phosphate slag provided the highest Si uptake, followed by Wollastonite and electric furnace silicates which however, did not show differed among themselves. The highest Si accumulation in grain was observed for stainless steel, which significantly differed from the control, silicate clay, Wollastonite, and AF2 (blast furnace of the company 2) slag. Silicate clay showed the lowest Si accumulation in grain and did not differ from the control, AF2 slag, AF1 slag, schist ash, schist, and LD4 (furnace steel type LD of the company 4) slag.

Effect of Rice Growth Stages and Silicon on Sheath Blight Development

ABSTRACT The objective of this study was to determine the effect of silicon (Si) and rice growth stages on tissue susceptibility to sheath blight (Rhizoctonia solani Kühn) under controlled conditions. Rice plants (cv. Rio Formoso) were grown in pots containing low-Si soil amended with Si at 0, 0.48, 0.96, 1.44, and 1.92 g pot(-1) and inoculated with R. solani at the following days after emergence: 45 (four-leaf stage), 65 (eight-leaf stage), 85 (tillering), 117 (booting), and 130 (panicle exsertion). For plants inoculated with R. solani at all growth stages, Si concentration in straw increased as rate of Si increased from 0 to 1.92 g pot(-1). Concentration of calcium in the straw did not differ among plant growth stages. Although incubation period was not affected by the amount of Si added to the soil, this variable was shorter at booting and panicle exsertion stages. As the rates of Si increased in the soil, the total number of sheath blight lesions on sheaths and total area under the relative lesion extension curve decreased at all plant growth stages. The severity of sheath blight was lower at booting and panicle exsertion stages as the rates of Si increased in the soil. In general, plants grown in Si-nonamended pots and inoculated with R. solani were more vulnerable to infection at all growth stages, but especially at 45 days after emergence. Plant dry weights for inoculated plants increased as the Si rates increased from 0 to 1.92 g pot(-1). The greatest dry weight increases occurred for plants inoculated at booting and panicle exsertion stages. Si fertilization is a promising method for controlling sheath blight in areas where soil is Si deficient and when cultivars that exhibit an acceptable level of resistance to sheath blight are not available for commercial use.

Volatilização de N-NH3 na cultura de milho: I. efeito da irrigação e substituição parcial da uréia por sulfato de amônio

A field experiment was carried out on a dark-red latosol (Oxisol) of the Centro de Pesquisas Novartis-Seeds, in Uberlândia, State of Minas Gerais, Brazil. The objective of this study was to evaluate the effects of irrigation, side-dressed application of urea, and urea partially substituted by ammonium sulphate on losses of NH3-N by volatilization in corn crop. The fertilizers were applied at 25 and 36 days after planting. The treatments, arranged in randomized complete block design, were: (i) control, (ii) urea, with irrigation before the two applications, (iii) urea, with irrigation after the two applications, (iv) urea + ammonium sulphate (rate N:S = 2.1:1) at the first application, and only urea at the second application, with irrigation before the applications, and (v) with irrigation after applications. Nine samples of volatilized NH3-N were taken, using semi-open static collectors, which were installed after the first N application, at intervals of 4 to 5 days. With irrigation after N application the NH3-N gaseous losses were 40.6% for urea and 23.0% for urea with partial substitution by ammonium sulphate. With irrigation before N application the NH3-N gaseous losses were 42.8 and 38.6%, respectively. Even though the N losses did not show significant differences among the treatments, the partial substitution of urea by ammonium sulphate was positive when the irrigation was performed after the N application. This treatment also showed the largest stalk diameter, the greatest plant high and the highest leaf-N concentration. At harvest, only the fertilized treatments increased yield compared to the control. The relationship between NH3-N volatilized and corn yield established by an inverse linear regression showed that 19.3 kg-1 of grains were lost per every kilogram of volatilized nitrogen.

Volatilização de N-NH3 na cultura de milho:: II. avaliação de fontes sólidas e fluidas em sistema de plantio direto e convencional

Foram desenvolvidos dois experimentos em campo, em sistema de plantio direto (SPD) sobre cobertura de aveia-preta, em latossolo vermelho-escuro, distrofico, argiloso, e em sistema de plantio convencional (SPC), apos cultivo de soja, em latossolo vermelho-amarelo distrofico arenoso, no Centro de Pesquisa Novartis-Seeds e na Fazenda Sta. Teresinha, Uberlândia (MG) respectivamente. O estudo objetivou avaliar as perdas por volatilizacao de N-NH3 da cobertura nitrogenada na cultura de milho com cerca de 100 kg ha-1 de N, de cinco fontes nitrogenadas em ambos os sistemas de plantio. As fontes nitrogenadas - sulfato de amonio, nitrato de amonio, ureia e duas solucoes nitrogenadas constituidas de ureia + nitrato de amonio (uran) e ureia + nitrato de amonio + sulfato de amonio (sulfuran) - foram aplicadas na superficie e incorporadas no meio da entrelinha. Apos a aplicacao da cobertura, instalaram-se, ao acaso, tres coletores do tipo semi-aberto estatico, por tratamento, sendo efetuadas seis amostragens de N-NH3 volatilizado, em intervalos de quatro a cinco dias. No SPD, as perdas acumuladas de N-NH3 provenientes das fontes ureia, uran e sulfuran aplicadas na superficie foram, respectivamente, de 78,0; 37,2 e 26,9% do N aplicado. No SPC, as perdas mais significativas foram de ureia (30,7%) e uran (9,7%). O nitrato de amonio e o sulfato de amonio apresentaram perdas inferiores a 15,0% do N aplicado a superficie. A correlacao das perdas por volatilizacao de N-NH3 e a produtividade dos dois experimentos mostraram um ajuste linear negativo, de tal forma que no SPD houve uma queda de producao de 13,3 kg de graos e no SPC, de 11,8 kg de graos para cada quilograma de N volatilizado.

Potassium Silicate as Foliar Spray and Rice Blast Control

ABSTRACT Silicon (Si) is known as a “beneficial element” for plants. The direct and indirect benefits of the element for crops (especially grasses) are related to resistance to diseases, pests, and drought. Since most studies were done with fertilizers applied to the soil, new studies on the efficacy of silicon absorption through the leaves are required. The effect of silicon absorption through the leaves on rice blast (Pyricularia oryzae) control was studied using potassium silicate (K2SiO3) in different doses (0, 1, 2, 4, 8, or 16 g L− 1 Si), number of sprayings at two solution pHs. Rice (Oryza sativa), cultivar ‘Metica 1’ (susceptible to blast), was grown in pots in a completely randomized experimental design. Silicate was applied beginning at the 22nd day after emergence (DAE). The pathogen was inoculated on the 25th DAE. Disease incidence was evaluated ten days after inoculation. Potassium silicate pulverization on the leaves did not increase Si absorption or accumulation by the plant; however, there was a reduction on blast incidence. The greatest reduction on blast incidence was observed at 4 g Si L− 1, regardless of solution pH.

Silicon accumulation and water deficit tolerance in Brachiaria grasses

The beneficial effects of silicon (Si) fertilization have been observed for several plant species, especially when submitted to stress, either biotic or abiotic. Among the possible reasons for the greater adaptability and resistance of brachiaria grass in areas of low fertility soils in Brazilian savanna, stands its capacity of absorbing and accumulating Si in aerial parts. To evaluate the effect of Si on dry matter yield of Brachiaria decumbens Stapf and Brachiaria brizantha Hochst, grown under two soil moisture regimes, a trial was set up in a completely randomized design factorial scheme (5 × 2 × 2), with five Si rates: (0; 242; 484; 968 and 1,452 kg ha-1), two soil water tensions (60% and 80% of field capacity) and the two brachiaria species. The experiment was installed in a greenhouse, using one of the most representative soils in the region under cerrado, Typic Haplustox. Both brachiaria species can be considered Si-accumulating plants, since they present high Si contents in their aerial parts. Application of Si to the soil increased the contents of this element in both grass species but did not change their tolerance to water deficit, and did not affect dry matter yield.