Análise de crescimento e anatomia foliar da planta medicinal Ageratum conyzoides L. (Asteraceae) cultivada em diferentes substratos

Ageratum conyzoides L. (Asteraceae) é uma espécie herbácea que ocorre em áreas de cerrado e, por se tratar de planta medicinal, é cultivada em escala familiar. O objetivo deste trabalho foi estudar possíveis alterações no desenvolvimento das plantas quando cultivadas em solos com texturas diferentes (solo de cerrado, franco arenoso ou solo de terra roxa, muito argiloso). Foram analisados aos 40, 70 e 90 dias, o comprimento do caule e da raiz, massa seca da parte aérea (caule e folhas) e das raízes, número de folhas e área foliar; além de parâmetros anatômicos foliares, como a densidade de tricomas. Os resultados mostraram que os comprimentos do caule e da raiz aumentaram no decorrer do experimento, independentemente do substrato (com exceção do comprimento da raiz de plantas cultivadas em solo de terra roxa). Porém, o comprimento do caule foi sempre maior nas plantas cultivadas em solo de cerrado, enquanto o comprimento da raiz foi significativamente maior somente aos 90 dias de cultivo neste solo. As biomassas secas da raiz e do caule também foram maiores nas plantas cultivadas em solo de cerrado por 70 e 90 dias, respectivamente. A massa seca foliar foi maior nas plantas cultivadas em solo de cerrado a partir dos 70 dias de experimento. Esse aumento foi devido ao maior número de folhas produzidas e a maior área foliar dessas plantas. No geral, a anatomia foliar não diferiu, porém o número de tricomas glandulares foi maior nas plantas cultivadas em solo de cerrado. Os resultados indicaram que esta espécie tem melhor desenvolvimento quando cultivada em solo mais arenoso.

Estudo preliminar sobre a diagnose foliar do sorgo sacarino

Têm sido obtidos bons resultados para a diagnose foliar do sorgo granífero quando é amostrada uma folha da altura mediana da planta, na época do emborrachamento. No presente trabalho, foi feita amostragem semelhante em plantas de duas variedades de sorgo sacarino (Brandes e Rio), cultivadas em dois solos (Latossolo Roxo e Latossolo Vermelho-Escuro textura média), onde foram aplicados três níveis de N, P e K, e cultivadas em solução nº 1 de Hoagland e Arnon em três níveis de diluição. Os resultados obtidos permitiram concluir que, em condições de casa de vegetação, com solução nutritiva, poderiam ser considerados normais para o sorgo sacarino os seguintes teores médios de nutrientes nas folhas medianas da planta, na época do emborrachamento: 3,20% de N, 0,80 a 0,95% de P, 2,60 a 3,10% de K, 0,45 a 0,65% de Ca, 0,45 a 0,52% de Mg, 9 a 10 ppm de Cu e 48 a 54 ppm de Mn. A amostragem utilizada para a diagnose foliar parece detectar apenas grandes diferenças nos teores de nutrientes no substrato, não se mostrando, porém suficientemente sensível nas condições de campo.

Phosphite determination in fertilizers after online sequential sample preparation in a flow injection system

A flow injection spectrophotometric system is proposed for phosphite determination in fertilizers by the molybdenum blue method after the processing of each sample two times on-line without and with an oxidizing step. The flow system was designed to add sulfuric acid or permanganate solutions alternately into the system by simply displacing the injector-commutator from one resting position to another, allowing the determination of phosphate and total phosphate, respectively. The concentration of phosphite is obtained then by difference between the two measurents. The influence of flow rates, sample volume, and dimension of flow line connecting the injector-commutator to the main analytical channel was evaluated. The proposed method was applied to phosphite determination in commercial liquid fertilizers. Results obtained with the proposed FIA system were not statistically different from those obtained by titrimetry at the 95% confidence level. In addition, recoveries within 94 and 100% of spiked fertilizers were found. The relative standard deviation (n = 12) related to the phosphite-converted-phosphate peak alone was <= 3.5% for 800 mg L-1 P (phoshite) solution. Precision due to the differences of total phosphate and phosphate was 1.1% for 10 mg L-1 P (phosphate) + 3000 mg L-1 P (phosphite) solution. The sampling rate was calculated as 15 determinations per hour, and the reagent consumption was about 6.3 mg of KMnO4, 200 mg of (NH4)(6)Mo7O24 center dot 4H(2)O, and 40 mg of ascorbic acid per measurement.

Effect of growing media and fertilizers on the early growth of Aechmea fasciata Bak

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of doses of fungicides and plant resistance activators on the control of Rhizoctonia foliar blight of soybean, and on Rhizoctonia solani AG1-IA in vitro development

Rhizoctonia foliar blight (RFB) of soybean [Glycine max (L.) Merrill] occurs in many tropical and subtropical regions, causing yield reductions of up to 70% and in Brazil, up to 60%. The disease is caused by Rhizoetonia solani AG1-IA and AG1-IB, and by AG2-3 in Japan. RFB occurs in the North, Northeast and Mid-west regions of Brazil. Chemical control remains the only effective method of controlling RFB, but its efficiency depends upon environmental conditions. In this study, 18 fungicides, salicylic acid (SA) and acibenzolar-s-methyl (ASM) were evaluated on R. solani AG1-IA in vitro, by mycelial growth rating and estimating effective concentration for 50% (EC 50) and 90% (EC 90) inhibition of mycelial growth, and in vivo by reduction of disease severity on soybean plants in greenhouse conditions. Mycelial growth was strongly inhibited by the fungicides pyraclostrobin + boscalid and fludioxonil. Preventive fungicide applications were the most effective. Strobilurins were more efficient both in preventive and curative applications. Best results with plant resistance activators were obtained with SA (2.5 mM) sprayed at 20 d before inoculation and with ASM (12.5 mg a.i. l(-1)) 10 d before inoculation. (c) 2005 Elsevier Ltd. All rights reserved.

Adubação foliar. I. Épocas de aplicação de fósforo na cultura da soja

The search for new alternatives in order to increase soybeans productivity has been constant objective of researchers and farmers. The crop responses to phosphorus application in the soil are well defined, being this nutrient very important on its development and yield. The leaf fertilization on this crop appears as a new rationale option, mainly when the plant nutrient levels are low. So, this work aimed to study the effect of phosphorus leaf fertilization, applied at different plant stage, including: V5, R1, R4, V5 + R1, V5 + R4, R1 + R4, V5 + R1 + R4, V5 + R1 + R4 + R6 and test plot. The experiment was installed in a soybeans crop, Monarca cultivar, at Palmital Farm, Ijaci county, Minas Gerais state, Brazil, using a totally randomized design, with 9 treatments and 3 replications. The chelate Quimifol P30 in liquid form with 30% of the nutrient soluble in CNA + water in the, with doses of 21. ha(-1), was utilized as phosphorus source, using the applications performed with a constant pressure CO(2)-nebulizer. The different epochs of phosphorous application significantly altered the grains yield, proportioning significant increases, up to 16% for the V5, V5 + R1, V5 + R4, V5 + R1 + R4, V5 + R1 + R4 + R6 epochs, when compared to the test plot, clearly expressing the positive effect of these applications at V5 stage. The plant height, first legume insertion, and lodging index characteristics were not significantly altered by the different epochs evaluated. It was observed significant response for the nutrient leaf amounts only in the case of K and Zn indices, exclusively in the V5 + R4, and in the V5, V5 + R1 and V5 + R1 + R4 + R6 treatments, respectively.

Aplicação de nitrogênio no solo e pulverização foliar com ácido giberélico e uréia em Setaria anceps Stapf cv. Kazungula

O objetivo do experimento foi verificar o efeito do nitrogénio no solo, parcelado de diferentes formas e aplicado durante o período de "verão", combinado com pulverização foliar de ureia e/ou ácido giberélico, sobre a produção e qualidade de Setaria anceps Stapf cv. Kazungula. O nitrogênio (60 kg/ha/ano) foi aplicado segundo quatro formas de parcelamento: Testemunha (sem nitrogênio), N20M40 (20 kg/ha de N em novembro + 40 kg/ha de N em março), N30M30 (30 kg/ha de N em novembro + 30 kg/ha de N em março), F20M40 (20 kg/ha de N em fevereiro + 40 kg/ha de N em março). No início do período de "inverno" foram aplicados os quatro tipos de pulverizações foliares: Testemunha (sem ácido giberélico ou uréia), uréia a 2%, ácido giberélico a 50 ppm e uréia a 2% + ácido giberélico a 50 ppm. Os resultados revelaram que o parcelamento do nitrogénio no solo não influiu no aumento da produção de matéria seca do capim setária no período de "verão", apesar de proporcionar um incremento da mesma no corte de "inverno". Observou-se, ainda, uma boa distribuição da produção de matéria seca entre "verão" e "inverno", apresentando essa última estação 34,52% da produção total anual, em média. Os diferentes tipos de pulverização não influíram significativamente sobre a produção de matéria seca e a composição química bromatológica da forrageira no período de "inverno".

Spectrophotometric determination of phosphite in fertilizers in a flow injection system with online sample preparation

A flow injection system with online sample preparation is proposed for the determination of phosphite in liquid fertilizers by spectrophotometry. After loop-based injection, phosphite is oxidized by an acidic permanganate solution (1.0 10(-2) mol L-1 KMnO4 + 1.0 mol L-1 H2SO4) in a heated reactor (50 degreesC). The phosphate generated is then determined by the molybdenum blue method. Influence of flow rates, temperature, and concentration and order of addition of reagents, sample volume, and reactor configuration for the blue complex formation on recorded signals were investigated. The pow system was applied to phosphite determination in commercial samples of liquid fertilizers. The proposed system handles about 80 samples per hour [0.05-0.40% (w/v) H3PO3; R = 0,9998], consuming about 80 muL sample, 1 mg KMnO4, 25 mg (NH)(6)Mo7O24, and Ia mg ascorbic acid per determination. Results are precise [relative standard deviation less than or equal to 3.5% for 0.1% (w/v) H3PO3, n = 12] and in agreement with those obtained by gravimetry at 95% confidence level. (C) 2000 John Wiley & Sons, Inc.

Direct determination of phosphite in fertilizers by flow-injection amperometry

A sensor based on graphite electrode modified with palladium-platinum-palladium film is proposed for phosphite determination by flow-injection amperometry. The modified electrode was prepared by a sequential cathodic deposition of Pd, Pt and Pd on a graphite electrode from 0.5% m/v PdCl2 + 28% m/v NH4OH and 2% m/v H2PtCl6 + 10% v/v H2SO4 solutions. After suitable conditioning, the electrode showed catalytic activity for phosphite oxidation when 0. 15 V was applied. The proposed system handles approximately 50 samples per hour (0.0.1 - 0.05 mol L-1 Na-2 HPO3; R-2 = 0.9997), consuming ca. 70 mu L of sample per determination. The limit of detection and amperometric sensibility were 5 X 10(-4) mol L-1 and 1.5 mA L mol(-1), respectively. The proposed method was applied to analysis of fertilizer samples without pre-treatment. Results are in agreement with those obtained by spectrophotometry and titrimetry at 95% confidence level and good recoveries (96-109%) of spiked samples were found. Relative standard deviation (n=12) of a 0.01 mol L-1 Na2HPO3 sample was 2%. The useful lifetime of modified electrode was around 220 determinations. For routine purposes it means that this electrode can be continuously used for 5 hours.

Mancha-foliar-de-Phyllosticta em gengibre. caracterização cultural do patógeno e efeito de tratamentos químicos no controle da doença em Morretes, Estado do Paraná

The objectives of this work were to determine the micelial growth curve of the pathogen and the sensitivity to some fungicides potencially efficient to disease control. The optimum temperature range for micelial growth of Phyllosticta sp, was between 25 and 27.5 degrees C. The maximum and minimum temperatures for micelial growth were 32.5 degrees C and 10 degrees C. Temperatures of 5 and 35 degrees C completely inhibited the growth of the isolates. Total inhibition of the micelial growth was observed with captan and mancozeb (1000 mg a.i./ml) and triadimenol (100 mg a.i./ml). Partial reduction of the micelial growth was observed with iprodione, methyl tiofanate and chlorothalonil until 1.000 mg/ml. The chemical control of PLS was studied in a commercial area of ginger ''Gigante'', in Morretes, PR, where 18 sprays were carried out, with a break of 7 to 10 days, from December to April. The highest reduction of the area under the disease progress curve standardized (AUDPCs) was observed with the spray of chlorothalonil. With the application of dithianon, cupper oxychloride, folpet, mancozeb and captan it was observed AUDPCs between 15.05 and 18.61 lesions/leaf. Iprodione, benomyl, triadimenol and methyl tiofanate did not control the disease (AUDPCs between 20.03 and 25.04 lesions/leaf). The AUDPCs in the check plot was 35.88 lesions/leaf. There was no significant difference of vigor and of ginger yield between fungicide treatments. The cupper oxichloride was phytotoxic to ginger.

The azomethine-H modified colorimetric method of boron determination at fertilizers.

The present work studied the azomethine-H colorimetric method for boron determination to fertilizers analysis applications. The reagent azomethine-H needs lights conditions of reaction that, jointed to the big sensibility and specificity, diffused its use in boron's dosage in many materials. The most suitable experimental parameters were established for such colorimetry, and analysis conditions: standard curve between 0,200 e 2,25 mg. L(-1) boron, in maximum absorption at 415nm, I cm cell and reading between 30 and 90 minutes standing after the final homogenization of the boron's solution in analyse and with dye reactive (azomethine If 0,90 % m/v solution at buffer ammonium acetate 1,82 mol . L(-1) - potassium acetate 0,10 mol . L(-1) - acetic acid 1,67 mol . L(-1)-EDTA 2,7 . 10(-2) mol . L(-1)-NTA 2,1.10(-2) mol . L(-1) pH 5,5). Statistics analysis of the results didn't present big differences when the same results were got by the colorimetric method offered and by the potentiometric, from AOAG, whatever in manufactured fertilizers or in lab sintetized fertilizers.

Application of Polysaccharide Hydrogels in Adsorption and Controlled-Extended Release of Fertilizers Processes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Adubação organomineral e biofertilização líquida na produção de frutos de pinheira ( Annona squamosa L.) no submédio São Francisco, Brasil

The organic production systems based on natural processes do not allow the use of synthetic fertilizers with a high solubility, so it is required the use of technologies in accordance with the organic production legislation in order to make the technical, economical and environmental sustainable activities viable. To evaluate the effects of the usage of mineral and organic natural fertilizers, associated with liquid biofertilizers (BLE= enriched liquid biofertilizer and BF= leaf biofertilizers) on the production of the sugar apple fruit crop Annona squamosa L., replacing totally the chemical fertilizers, used by conventional farming systems, a nine year old orchard was driven in the irrigated plot n degrees 1295, irrigated project Nilo Coelho, district of Petrolina - PE. The experiment was carried out from September 2005 to February 2006. The experimental design was done through randomized blocks with eight treatments and four replications in plots of three plants each, with 96 plants in total. The treatments were the following: T(1) - plants with no fertilizer; T(2) - 60 g de N + 32 g de P(2)O(5) + 48 g de K(2)O; T(3) - 90g de N + 32 g de P(2)O(5) + 48 g de K(2)O; T(4) - 30 g de N + 32 g de P(2)O(5) + 48 g de K(2)O + 15 L de BLE + BF a 5 %; T(5) - 60g de N + 32 g de P(2)O(5) + 48 g de K(2)O + 30 L de BLE + BF a 5 %; T(6)- 90g de N + 32 g de P(2)O(5) + 48 g de K(2)O + 45 L de BLE + BF a 5 %; T(7) - 120g de N + 32 g de P(2)O(5) + 48 g de K(2)O + 60 L de BLE + BF a 5 %; T(8) - 150 g de N + 32 g de P(2)O(5) + 48 g de K(2)O + 75 L de BLE + BF a 5 % The fruit growth analyses (diameter and average length), total yield, productivity, average fruit weight, average number of fruits, fresh weight of the skin and pulp and dry weight of the fruits were used to evaluate the experiment. The results were relevant to the total production, fresh weight of the skin and dry weight of the fruits. The use of organominerals associated with liquid fertilizers increased significantly the productivity in values ranging from 10.44% (T(5) = 1.98 t ha(-1)) to 24.52 % (T(7) = 12.34 %). The treatment T(3) stood out (90g de N + 32g de P(2)O(5) + 48g de K(2)O) with a higher production than the control. The fruit weight increased in the fertilized treatments, with values increasing from treatment (T(2) = 5.26 %) to the treatment (T(7) = 12.34 %) in relation to the control. The fruit development was characterized by an average growth increase of 82 % in length and 84 % in diameter until the 56(th) day, with a sigmoidal growth pattern.

Relação entre o fluxo luminoso interceptado em diferentes épocas no índice de área foliar de diferentes forrageiras

The objective was to evaluate the leaf area index of six different grasses. The experiment was installed at the Instituto Federal de Tecnologia e Educacao of Uberaba, using a randomized block design with split plots in time. The plots were sown: Brachiaria decumbens cv. Basilisk, Brachiaria brizantha cv. Marandu, Panicum maximum cv. Mombasa, Panicum maximum cv. Tanzania, Brachiaria brizantha cv. Xaraes, Cynodon dactylon hb. Tifton and the plots, ten seasons of evaluation in 10 x 6 factorial arrangement with four replications. Rates of leaf area of each forage at different times of year were evaluated. Compared to other forage species, Panicum maximum had a higher leaf area index when subjected to periodic fertilization and irrigation. Only in the late fall Brachiaria Xaraes IAF had increased, but did not differ significantly from the others.

Effect of constituents of the foliar wax of Didymopanax vinosum on the foraging activity of the leaf-cutting ant Atta sexdens rubropilosa

Leaf epicuticular waxes may affect substrate selection by leaf-cutting ants, and host recognition by several phytophagous insects. The influence of the crude epicuticular wax of Didymopanax vinosum E. March. (Araliaceae), and its major constituents lupeol and free primary alcohols, on substrate selection by the leaf-cutting ant Atta sexdens rubropilosa Forel, was investigated. Two ant colonies were used in laboratory bioassays. Corn flakes (zea) were impregnated with chloroform solutions of the substances being tested and fed to the adults. One of the colonies gave results, in most of the tests, not significantly different from the controls. The other colony, however, discriminated against the crude wax, a strong deterrent effect being observed from the first of a series of eight trials. The same colony was able to discriminate against lupeol after the second trial. The fraction of primary n-alcohols (22% C28, 66% C30 and 12% C32) deterred feeding only after the fifth trial. The results demonstrate that some constituents of epicuticular waxes may deter the foraging activity of A. sexdens rubropilosa, depending, however, on the colony under observation. It is suggested that lupeol, of the foliar wax of D. vinosum, is an important deterrent to leaf-cutting ants, although with less pronounced effects than those observed in tests with the crude wax.