Different temperatures on mycelial growth of Corynespora cassiicola isolates causal agent of soybean target spot.

Soybean target spot caused by Corynespora cassiicola is a common disease in Brazil. The aim of this study was to evaluate different temperatures on mycelial growth of C. cassiicola isolates obtained from three soybean growing regions in Brazil. Isolates from São Paulo, Paraná and Mato Grosso states were provided by Embrapa Soja. The isolates studied were MT13, PR21, MT29, MT67, SP70, PR27, PR28, PR06, PR02 and MT04. Mycelium plug of 0.5 cm in diameter of each isolated were transferred to PDA media. The plates were incubated in BOD at 10°C, 15°C, 20°C, 23°C, 25°C, 27°C and 30°C temperatures with 12 hours photoperiod. The experimental design was randomized, with 10 isolates, 7 temperatures and 5 replicates. The assessments were made by daily measurements of mycelial growth. Mycelial growth curves were established over time for each temperature using linear regression (Y= A+BX, where Y is the mycelial growth, X is time, A is the intercept and B mycelial growth rate). A mycelial growth curve was set with the ?B? values as a function of temperature for beta generalized equation: Y = B1 ((B2-X)^B4) ((B3-X)^B5, where Y is the mycelial growth rate, X the temperature and the parameters B2 and B3 represent the minimum and maximum temperatures, respectively. The isolates grew at all temperatures studied, except PR21 isolated which did not grow at 10ºC and 30ºC temperature. The increase of temperature caused greater mycelial growth however MT13, PR 27, SP70 and PR02 showed a decrease in mycelial growth at 30ºC temperature. The minimum and maximum temperature estimated by the generalized beta function was between 7,2 ºC and 32,5ºC respectively

Influência da temperatura e da luz na esporulação e germinação de basidiosporos de Thanatephorus cucumeris, agente da mancha areolada da seringueira.

Resumo apresentado no XXI Congresso Brasileiro de Fitopatologia, Salvador, 1988. Resumo 051

Tillage system effect on the epidemic of soybean brown spot.

Six field experiments were carried out during the summers of 1997 to 2003 to evaluate disease progress of soybean brown spot caused by Septoria glycines considering two tillage systems, conventional and no-tillage (wheat was cultivated during winter in all plots). Two logistic models were fitted to the disease progress data: (i) a logistic model with constant disease progress rate r [y=1/(1+(1/y0-1)exp(-rt)), where y0 is the initial disease level at time t=0] and (ii) a logistic model with an exponentially increasing progress rate r(t)=r0 ebt [y=1/(1+(1/y0-1) exp(r0/b(1-ebt))), where r0 is the initial progress rate at time t=0, b the rate increasing parameter, and y0 again the initial disease level]. The logistic model with constant rate underestimated disease incidence on the first disease assessment in nine out of twelve epidemics. The logistic model with an increasing rate gave a better fit to all disease progress curves (R2 between 0.90 and 0.99; no pattern in the residuals). According to this model, y0 was in most cases (four out of six) significantly smaller in the plots with no-tillage compared with conventional tillage, but no differences were detected in the initial rate parameter r0 and the rate increasing parameter b (with one exception). It is proposed that these results are due to higher susceptibility of old leaflets compared with young leaflets, as demonstrated by artificial inoculation: In four laboratory experiments the mean brown spot severity was 16.7 % on old leaflets but only 3.9 % on young leaflets

O vírus da queima do broto da soja no Brasil: etiologia, epidemiologia e controle.

Caracteristicas do virus; Modo de transmissao; Sintomas; Epidemiologia e controle; Distribuicao no Brasil e plantas hospedeiras; Danos e controle.bitstream/item/60659/1/Documentos-85.pd

O método potenciométrico na determinação do H+ trocável em solos

For the determination of exchangeable hydrogen ion in soils, the authors of the presente work made the extraction with normal calcium acetate solution that may have an initial pH between 7 and 8 without altering the amount of hydrogen ion extracted. The extraction was made by shaking 5,0 grams of air dry soil with 100 ml of normal calcium acetate solution, the pH of wich was ascertained to 7,0, 7,5 and 8,0 with acetic acid, in 250 mil conical flasks for 30 minutes in a Wagner shaker (30-40 rpm). The contents of the flasks were then, filtered. A 50 ml aliquot of each of the leachate was titrated with a 0,020 N NaOH solution and the volumes consumed sodium hydroxide were ploted against pH. The titration curves thus obtained showed to be straight lines between pH 8 and 9 and parallel to the curve obtained by the titration of the blank. Two ways of locating the end point of the titration showed to be possible: the use of a pHmeter or titrimeter or the use of phenolphtalein as indicator. When using a pH meter or a titrimeter, the end point may rest in any point between pH 8 and 9, and the volume of sodium hydroxide consumed is found by comparison with a similar curve obtained by the titration of the blank. When using phenolphtalein the calcium acetate solution must have a pH below 8

A precipitação do estrôncio na forma de cromato em meio amoniacal e hidroalcoolico

This paper describes the data obtained concerning qualitative and quantitative analyses of the precipitate formed when to a solution containing strontium ion are added potassium dichromate, ammonium hydroxide and 95 per cent alcohol. Three replications of standard solution containing 1.8, 4..4, 8.8, 13.7, 27.5, 41.2, and 50.5 mg of strontium were treated with potassium dichromate and then, with constant stirring 95 per cent of alcohol and ammonium hydroxide. The precipitate was allowed to stend for two hours and afterward was centrifuged, washed with 95 per cent alcohol dried at 80ºC for 14-16 hours and weighed. Qualitative analysis of the precipitate showed potassium and ammonium ions, besides strontium and chromate. The relationships between the weight of strontium and the weight of the precipitate obtained is given by the regression line expressed by the equation: Y = 5.48 + 0,84, where X, is the weight of strontium in milligram Y, is the weight of the precipitate in milligram The value 4, 58 for the B parameter of the regression equation and the qualitative and quantitative analysis of the precipitate, suggested that its composition must be quite different from the simple strontium chromate SrCr0(4). The data allow to admit the following probable composition: 6 SrCrO4 . (NH4)2CrO4 . 6K2CrO4O presente trabalho relata os dados relativos a análise qualitativa e quantitativa do precipitado, que se forma quando se adiciona a uma solução contendo estrôncio, dicromato de potássio, em meio amoniacal e hidroalcoólico. Em lugar de se formar cromato de estrôncio simples, SrCrO4, forma-se um cromato que além do estrôncio, contém os ions amônio e potássio. Soluções padrões contendo desde 1, 8 até 50,5 mg de estrôncio, foram tratadas com solução de dicromato de potássio 2 normal, amoníaco e solução hidroalcoólica com 95% de álcool absoluto. O precipitado foi pesado e a equação de regressão que relaciona o peso do estrôncio colocado e o peso do precipitado obtido, e a seguinte: Y = 4,58 X + 0, 84, onde: X é o pêso em miligramas, do estrôncio colocado Y é o pêso em miligramas, do precipitado A composição provável do precipitado parece ser 6 SrCrO4 (NH4)2 CrO4. 6K2CrO

Determinação polarografica do zinco em plantas, após a sua separação em resina trocadora de íons

O presente trabalho relata os dados obtidos na determinaçao do zinco em plantas segundo uma nova técnica. Esta nova técnica consistiu em se aliar a separação do zinco de outros interferentes, através do emprego de uma coluna de resina trocadora de anions, ao método polarografico da dosagem do citado elemento. A amostra de planta (1, 000g) foi incinerada em copo de Pyrex a 450-5009C durante 90 minutos e o zinco foi extraido da cinza com solução de HC1 2N. A separação do zinco de outros elementos interferentes foi feita pela passagem da solução através da resina trocadora de anions, Amberlite, IRA-401. Após a eluiçao do zinco da coluna, a solução obtida foi levada ao polarografo registrador. (Sargent, modelo XXI) para a determinação, Trabalhando-se com um conjunto de 10 (dez) a 12 (doze) colunas de resina, pode-se executar 10 (dez) a 12 (doze) determinações num periodo de 6 (seis) horas.This paper deals with the polarographic determination of zinc in plants after its separation with an anion exchange resin column. One gram of plant was ashed in a 20 ml beaker at 4505009C for 90-100 minutes. The solution of plant ash in 2N hydrochloric acid was passed through the column formed by a resin bed (Amerlite IRA-401) of 9 cm of length, which adsorbed zinc in the form of an anion an allowed to pass all the interfering ions. Twenty ml of 0,125 N sodium nitrate solution was used to elute the zinc and the effluent was dried in silica dish in vapour bath. Ten ml of 0, 35 N ammonium hydroxide with 0, 0125 % of gelatin, were added to the dish and the solution was stirred in order to dissolve the zinc. Three to five ml of solution were transferred to one special cell of the Sargent Visible Recording Polarograph Model XXI and the polarogram were obtained with the dropping mercury electrode and the stationary pool of mercury as the second electrode. Some of the obtained data are presented: PLANT Micrograms of zinc Micrograms %Recuperation added to the sample of zinc found (average) Coffee (leaves) 0,0 9,2 Coffee (leaves) 0,0 9,2 Coffee (leaves) 0,0 9,2 Coffee (leaves) 20,0 29,2 Coffee (leaves) 20,0 30,4 101,4 Coffee (leaves) 20,0 29,2 Sweet Clover (aerial part) 0,0 22,4 Sweet Clover (aerial part) 0,0 22,4 Sweet Clover (aerial part) 0,0 21,2 Sweet Clover (aerial part) 20,0 42,4 Sweet Clover (aerial part) 20,0 43,6 101,9 Sweet Clover (aerial part) 20,0 42,4 Sugar Cane (leaves) 0,0 12,0 Sugar Cane (leaves) 0,0 12,0 Sugar Cane (leaves) 0,0 10,8 Sugar Cane (leaves) 20,0 31,8 Sugar Cane (leaves) 20,0 31,8 100,6 Sugar Cane (leaves) 20,0 31,8 With the proposed method it is possible to analyse ten to twelve plant samples in six hours

A separação do Cálcio de Estroncio mediante o emprego de Resina Trocadora de Íons e de Estroncio Radioativo Sr-89

O presente trabalho relata os dados obtidos na separação do estrôncio do cálcio, pelo uso de uma solução de NH4- EDTA, com pH entre os valores 4,8 e 5,3, passando através de uma coluna de resina trocadora de cátions. Assim, 200 ml de uma solução a 2,5% de NH4- EDTA com pH = 4,8 e contendo 0,36 mg de estrôncio e 199,2 mg de cálcio (o que dá uma relação de 1 de Sr para 553 de Ca) foram passados através de uma coluna de 25 a 28 ml de resina trocadora de cátions Amberlite IR - 120 (H+) prèviamente preparada. O estrôncio ficou retido na coluna e o cálcio continuou na solução que passou. Depois de passar solução de NH4- EDTA com pH 5,3 e solução de HCl de 0,25 a 0,75 N, o estrôncio foi eluido com solução 3N de HCl. Como empregou-se estrôncio radioativo Sr-89, esse ion foi determinado por radiometria, para se conhecer a eficiência da separação. O cálcio foi determinado pelo método permanganométrico em solução de NH4- EDTA após a eliminação do agente quelante. Os dados obtidos mostraram que houve uma separação muito eficiente, indicada pela porcentagem de recuperação do estrôncio qu efoi de 97,7, 97,0 e 98,6% ao passo que a recuperação do cálcio foi de 100,0, 99,9 e 99,7%.A simple, rapid and efficient method of separation of strontion from calcium can be perfomed by using a solution of 2.5% NH4- EDTA, with pH adjusted to 4.80 to dissolve those cations. After, the solution is passed through a 25-28 ml column of the Amberlite 1R-120 (4+) cation exchange resin. Strontinum is quantitatively retained on the resin, while calcium passes through. After removal of ammonium ions with 0.25 to 0.75 normal solution of HC1, the strontium is eluted with 3 normal solution of HCl. The method was used to separate strontium and calcium from prepared strontinum-calcium mixture containing 0.36 mg of Sr with radioactive strontinum Sr-89 and 199.2 mg of Ca. The recovery of strontinum was 97.7, 97.0, and 98.6% in three replications and the recovery of calcium was 100.0, 99.9 and 99.7%. The strontinum was determined radiometrically with the "1000" Scaler, model SC-33, Tracerlab, Inc

Cálcio e fósforo no leite da região de Piracicaba

Twelve samples of fluid milk delivered by "Laticínios Piracicaba Ltda." for public consumption, from March 25 do August 7, 1959, were analysed to determine its calcium and phosphorus content per 100 ml. A slight variation was observed. Calcium varied from 119 to 136 mg and phosphorus from 83 to 91 mg. These results are comparable to the ones obtained in other countries, showing that calcium and phosphorus content in cow milk is almost invariable