Janice Guedes de Carvalho

Efeito da aplicação de silício em plantas de milho no desenvolvimento biológico da lagarta-do-cartucho Spodoptera frugiperda (J.E.Smith) (Lepidoptera: Noctuidae)

The effect of the application of silicon to corn plants on the development of the fall armyworm Spodoptera frugiperda (J.E. Smith) was evaluated. Silicon treatment consisted in applying 3.2 ml of a sodium silicate solution [25-28% (w/v) SiO2] plus 96.8 ml of water into the soil at 5, 10, 15, 20 and 25 days after emergence of corn plants kept in pots. Another group of plants were grown free of silicon. Larvae were fed on leaves obtained from silicon treated plants and their mortality at the end of the 2nd larval instar, length of the larval and pupal period, and pupal weight were compared to those of larvae fed on normal leaves. No effect of silicon was observed on the length of larval and pupal phase, pupal weight and mortality of pupae. However, increased mortality and cannibalism were registered in groups of fall armyworm at the end of the 2nd instar and greater mortality of the larvae was seen at the 2nd and 6th instars fed on silicon-treated corn plant leaves in comparison with the control. The jaws mandibles of fall armyworm at the 6th instar showed marked wear on the incisor region when in contact with leaves with higher silicon content. Silicon application can make fall armyworm feeding difficult, causing higher mortality and cannibalism, thus increasing plant resistance to this species.

Efeito do silício na resistência do sorgo (Sorghum bicolor) ao pulgão-verde Schizaphis graminum (Rond.) (Homoptera: Aphididae)

The objetive was to evaluate the effect of silicon as a resistence inducer of sorghum plant to the greenbug Schizaphis graminum (Rond.). Preference tests were conducted using two sorghum genotypes, a suscetible and a resistent one, with and without silicon application. In a free choice test, the adult aphids were released into the center of an arena made up of four leaf disks. In a no choice test, the aphids were confined on sections of leaves. The silicon affected both by reducing the preference and reproduction of the greenbug.

Fitotoxidez de cádmio para Eucalyptus maculata e E. urophylla em solução nutritiva

The effects of increasing concentration of Cd in nutrient solution on growth, mineral uptake and phytotoxicity symptoms in Eucalyptus maculata and E. urophylla seedlings were studied under greenhouse conditions. Seedlings were kept for five weeks in 2 L pots containing Clarks nutrient solution amended with 0, 45, 90, 135 and 180 mM as CdSO4. After one week of exposure to Cd treatments seedlings of E. maculata exhibited nerval reddish spots, interveinal leaf chlorosis, leaf necrosis, drought and root darkening, whereas E. urophylla showed additionally apical dieback and leaf fall. The critical dose to reduce shoot dry matter by 10% was low; 2.4 mM and 1.5 mM of Cd to E. maculata and E. urophylla, respectively, while toxicity critical concentration in the shoots were 14.5 and 10.8 mg kg-1 dry matter for these species, respectively.These results indicate that E. maculata is probably less sensitive to Cd than E. urophylla. It was also found that Cd reduced translocation of Cu by 24 and 43% as compared to control in E. maculata and E. urophylla, whereas translocation of Fe was reduced from 36% on average for the two species in the control to 12% at 180 mM of Cd. Shoot concentrations of Ca and Mg was also reduced in both species, reaching levels below those considered adequate for E. urophylla. Increasing concentration of Cd in nutrient solution reduced Ca and Mg contents in shoots of species, reaching Mg contents below those of the range considered suitable for E. urophylla. Relationships of Cd phytotoxicity in Eucalyptus with Cu and Fe translocation as well as with Mg foliar contents were shown.

Efeito do silício no controle da cercosporiose em três variedades de cafeeiro

A cercosporiose do cafeeiro (Coffea arabica), causada por Cercospora coffeicola, e uma das mais importantes doencas na fase de viveiro. O objetivo desse trabalho foi avaliar o efeito da aplicacao de silicio (1 g de CaSiO3 incorporada em 1 kg do substrato utilizado para encher os tubetes) no controle dessa doenca em tres variedades de cafeeiro (catuai, mundo novo e icatu) e, determinar quais os possiveis fatores de resistencia associados. As plantas com dois pares de folhas foram inoculadas com suspensao de 1,4 x 104 conidios de C. coffeicola por ml. Aos sete meses apos a inoculacao avaliaram-se a porcentagem de folhas lesionadas e o numero total de lesoes por planta. Apos essa avaliacao, retiraram-se amostras das folhas para o estudo em Microscopia Eletronica de Varredura (MEV) e Microanalise de Raios-X (MAX). As plantas da variedade catuai tratadas com silicato, tiveram reducao de 63,2% nas folhas lesionadas e de 43% no total de lesoes por planta, em relacao a testemunha. A MAX e o mapeamento para Si indicaram distribuicao uniforme do elemento em toda a superficie abaxial das folhas de cafeeiro nas tres variedades tratadas. Nas folhas das plantas nao tratadas, o Si foi raramente encontrado. Nas imagens de MEV tambem foi observada camada de cera bem desenvolvida na superficie inferior das folhas originarias de todas as plantas tratadas, sendo esta mais espessa em catuai e rara ou ausente nas nao tratadas.

Características anatômicas de mudas de morangueiro micropropagadas com diferentes fontes de silício

O objetivo deste trabalho foi avaliar o efeito de diferentes fontes de silicio, utilizadas na micropropagacao, nas caracteristicas anatomicas de mudas de morangueiro (Fragaria x ananassa). Foram utilizados propagulos da cv. Oso Grande cultivados em meio Murashige e Skoog (MS), acrescido de 30 gL-1 de sacarose, 6 gL-1 de agar e 1 mgL-1 de 6-benzilaminopurina. Os tratamentos consistiram da adicao ao meio MS dos silicatos de calcio, de sodio e de potassio, na dosagem de 1 gL-1. O tratamento testemunha foi o meio MS sem fonte de silicio. Odelineamento experimental foi o inteiramente ao acaso, com dez repeticoes. Os propagulos foram mantidos por 45 dias em sala de crescimento, em condicoes controladas. Avaliaram-se caracteristicas fitotecnicas e anatomicas dos propagulos in vitro. Verificou-se que o aumento da massa de materia fresca e seca dos propagulos de morangueiro ocorreu na presenca de silicato de sodio. Asuplementacao do meio de cultura com silicio proporcionou maior teor de clorofila. Aadicao de silicato de sodio ao meio MS resultou em aumento da espessura dos tecidos do limbo foliar e da deposicao de cera epicuticular e na formacao de deposito de silicio nas celulas.

Adubação com potássio e nitrogênio em três cíclos de produção da bananeira cv. prata-anã

Nitrogen, after potassium, is the chemical element most required by banana crop. This work evaluated the effect of nitrogen and potassium fertilization on irrigated banana crop (Prata-Ana, AAB) yield. Five rates of N (0 , 200 , 400 , 800 and 1600 kg ha-1 year-1) and five rates of K2O (0; 200; 400; 800 and 1600 kg ha-1 year-1), in a (5x5) factorial design were studied. The data were obtained during three yield cycles (second, third and four cycles), on an eutrofic Red-Yellow latosol, sandy-clay, in the North of Minas Gerais State, Brazil. The content of Mn have increased in the leaves with the increased amount of N applied in the soil. The banana yield reduced with the rise of the Mn content in the leaves, on the second and third cycle. The maximum yield was obtained with the application of 962,5 kg of K2O ha-1year-1, on the fourth cycle. No interaction between N and K was found.

Incidência e severidade da cercosporiose do cafeeiro em função do suprimento de potássio e cálcio em solução nutritiva

An experiment was carried out at UFLA to evaluate the incidence and severity of the brown eye spot caused by Cercospora coffeicola in coffee (Coffea arabica) seedlings, in relation to different dosages of K and Ca in nutrient solution. The experimental design was completely randomized with 16 treatments, three replicates and two plants per replicate. Treatments were displayed in a 4 x 4 factorial scheme, with four levels of K (1, 3, 5 and 7 mmol/l) and four levels of Ca (2, 4, 6 and 8 mmol/l). The seedlings were inoculated, every week, for three months, with a conidial suspension of C. coffeicola of 15,000 conidia/ml. Total leaf area, total number of leaves and total injury number were obtained from seven evaluations made every fortnight. After the final evaluations, coffee seedlings were collected, the injured leaf area and the dry matter weight determined. The K x Ca interaction influenced total injury, total number of leaves and percentage of injured leaf area under the disease progress curve. The dosages of K reduced the total dry matter, the total leaf area and the area under the disease incidence progress curve, while the dosages of Ca influenced the total leaf area and the area under the disease incidence progress curve.

Crescimento e absorção de nutrientes por mudas de freijó (Cordia goeldiana huber) em função de doses de fósforo e de zinco

The objective of this work was to study the influence of the zinc-phosphorus relationship on the growth, content and accumulation of nutrients in Brazilian walnut (Cordia goeldiana Huber). Samples of Dark-Red Latosol, 0 - 20 cm depth, from the campus of the Federal University of Lavras, with 1 mg P (Mehlich 1) and 0.9 mg Zn per dm3 soil. The experiment was arranged in a complete randomized factorial design 4 x 3, with 4 P doses (0; 150; 300 and 450 mg dm-3) and 3 Zn doses (0; 5 and 10 mg dm-3), with 4 repetitions. At 12 months after planting, plants were harvested, and dry matter of shoots, roots and leaves were ground separately for chemical analysis. Phosphorus application promoted increase in seedling growth and in the contents and accumulation of P in the different plant parts, but caused reduction in leaf zinc contents. The zinc-phosphorus interaction caused reduction in the zinc content in the roots, when in the presence of the different zinc doses. The zinc doses provided increases in both the level and content of zinc in the leaves and roots and reduced P contents in the leaves and shoots. The effect on the other macronutrients varied with the plant part.

Efeito de fontes de silício na incidência e na severidade da antracnose do feijoeiro

ABSTRACTEffects of silicon sources on the incidence and severity of the common beans anthracnose Three e xperiments were performed to study the influence of the silicon on the reduction of the common bean ( Phaseolumvulgaris ) anthracnose. The first experiment involved a plant fertilized with calcium silicate and different inoculumconcentrations of the Colletotrichum lindemuthianum (0, 10 3 , 10 4 , 5x10 4 , 10 5 , 5x10 5 and 10 6 conidia/ml). In theconcentration 10 6 conidia/ml the difference b etween calcium silicate and calcium oxide was evaluated for effects on thedisease. The second experiment evaluated the influence of sodium and calcium silicate on the reduction of the anthracnose.In the third experiment, the scanning electron microscopy (SEM) and X-ray micro-analysis (EDAX) were used to study theeffect of the silicon on the plant resistance mechanism. Five evaluations of the incidence, severity and leaf area were done, i nthe first and second experiment. Disease evaluation was made using area under disease progress curve for incidence (AUDPCI)and severity (AUDPCS) and healthy leaf area duration (HAD). Inoculum concentration was found to increase the AUDPCIand AUDP CS. In contrast, the HAD had decreased. Fertilization of plants with calcium silicate significantly reduced the AUDPCIand AUDPCS, when compared to inoculated control and fertilized plants by calcium oxide (CaO) with higher inoculumconcentration. On the second trial, the application of sodium silicate on the leaves of the bean plant reduced AUDPCS by62,4% when compared to control. When the treated leaves were scanned with SEM and EDAX was performed, although thesilicon had reduced the disease, no accumulation of an external silicon barrier was observed with application of the element.

Intensidade da cercosporiose em mudas de cafeeiro em função de fontes e doses de silício

ABSTRACTEffect of silicon doses and sources on the intensity of the brown eye spot of coffee seedlings The objective of this work was to evaluate the effect of calcium and sodium silicate on the intensity of brown eyespot ( Cercospora coffeicola ) in coffee ( Coffea arabica ) seedlings (Catuai IAC 99) by using doses (0; 0.32; 0.63 and 1.26g of SiO 2 .kg -1 ) of substrate. Five evaluations were done by counting the number of diseased plants, number of leaves withlesions, number of lesions per leaf and total number of lesions per plant. The concentration of macro, micronutrients,silicon and lignin in the leaves was determined at the end of the experiment. The lowest area under the disease progresscurve of the total number of lesions was observed with 0.84 g.kg -1 of sodium silicate. Diseased plants were found to havea linear decrease of area under the disease progress curve and an increase in the concentration of lignin up to the dose of0.52 g.kg -1 of sodium silicate. The increase of sodium silicate and dose application into the soil up to 0.53 g.kg decreasedthe concentration of SiO