Luiz Antônio Zanão Júnior

Produção da alface em função do uso de diferentes fontes de fósforo em solo de Cerrado

The lettuce (Lactuca sativa L.) is a very demanding crop for phosphorus, being little tolerant to the soil acidity. The response of the lettuce crop to sources of soluble and reactive phosphorus fertilizer of slow solubility was evaluated in the presence of liming. . The experimental design consisted of a randomizing complete block design with six treatments (single superphosphate, thermalphosphate magnesium, triple superphosphate, Fosmag, Arad phosphate rock and control without phosphorus), in four replications, conducted in a Typic Acrustox. P suppression, yield and plant diameter indicate, as well as all other variables related to plant growth, the importance of P for the lettuce development. Significant responses to different P sources were also observed for fresh and dry matter production of aerial part, fresh mass of roots and level of P in the soil. Best responses in decreasing order were obtained for Fosmag, triple superphosphate, single superphosphate, thermalphosphate magnesium and Arad phosphate rock match sources. Fosmag and triple superphosphate were equivalent for production of root dry mass and diameter of the aerial part. Adjusting soil acidity, the accumulated level of P in leaves was higher when Fosmag, triple superphosphate and simple superphosphate were used as sources of P.

Variabilidade espacial dos teores de macronutrientes em latossolos sob sistema plantio direto

A eficacia dos planos de amostragem do solo pode ser aumentada se for conhecida e considerada a variabilidade espacial de seus atributos, e, para isso, devem ser estudados os fatores que a determinam. O objetivo deste trabalho foi avaliar a variabilidade espacial dos teores de macronutrientes P, K, Ca, Mg e S em dois Latossolos, um muito argiloso e outro de textura media, cultivados com manejo semelhante, ha oito anos sob sistema plantio direto. A coleta das amostras do solo foi realizada em intervalos regulares de 50 m, totalizando 121 pontos, em duas camadas (0-10 e 10-20 cm). Os dados foram avaliados por estatistica descritiva e geoestatistica, com base no ajuste de semivariogramas. Verificou-se que a dependencia espacial varia conforme o elemento, a textura do solo e a profundidade de coleta da amostra. Assim, o Latossolo de textura media, de maneira geral, apresentou maior variabilidade espacial para os teores dos nutrientes em relacao ao de textura muito argilosa. A camada de 0-10 cm, nos dois Latossolos, proporcionou maior variabilidade espacial para os teores dos nutrientes avaliados. A analise de dependencia espacial mostrou que, nos dois solos e nas duas camadas, a maioria dos nutrientes estudados apresentou moderada correlacao espacial. Os modelos de semivariogramas ajustados foram o exponencial e o esferico, sendo o primeiro em maior quantidade. Maiores teores de todos os macronutrientes avaliados foram verificados nos primeiros 10 cm do solo. Os valores de alcance da dependencia espacial foram menores no Latossolo de textura media, variando de 9 a 29 m; no de textura muito argilosa eles variaram de 31 a 399 m. Se for adotada a geoestatistica no esquema de amostragem, o numero de amostras a serem coletadas sera menor no Latossolo de textura muito argilosa, devido aos maiores valores do alcance apresentados por todas as variaveis.

Variabilidade espacial de atributos químicos em diferentes profundidades em um Latossolo em sistema de plantio direto

Spatial variability of chemical attributes at different depths in an Oxisol under no-till system The study of spatial variability of soil chemical attributes is an important step in precision agriculture. The objective of this study was to evaluate the spatial variability at two depths (0-10 and 10-20 cm) of the pH in water, base saturation, and levels of organic matter and micronutrients (B, Cu, Fe, Mn and Zn) in an Oxisol, medium texture, under no-tillage system for eight years. Soil sample collection was performed at regular intervals of 50 m in a regular grid of 121 points. Data were analyzed by descriptive statistics and geostatistics based on the adjustment of semivariograms. Higher levels of organic matter, Zn and Mn were recorded in the first 10 cm of soil. The greatest variability was found for B and the lowest for pH in water. Most of the data fit the model of Gaussian semivariogram. The values of range were different as a function of the sampling depth and greater at the depth 010 cm. If a geostatistical sampling scheme is used, the number of samples to be collected will be different for the two depths and among the evaluated attributes.

Yield and shelf life of chrysanthemum in response to the silicon application

O crisântemo de vaso e uma das principais flores produzidas em ambiente protegido. O silicio tem promovido melhorias tanto no aspecto quantitativo quanto no qualitativo quando fornecido a algumas especies ornamentais produzidas nestas condicoes. Assim, o objetivo desse trabalho foi avaliar a resposta a aplicacao de silicio de tres cultivares de crisântemo cultivadas em vaso. O experimento foi conduzido em casa de vegetacao da Universidade Federal de Vicosa. Os tratamentos foram dispostos em esquema fatorial 3x2 (tres cultivares de crisântemo: Coral Charm, White Reagan e Indianapolis e duas doses de silicio aplicadas no substrato: 0 e 800 mg kg-1) com seis repeticoes, em delineamento inteiramente casualizado. Foram avaliados o diâmetro dos botoes e das hastes florais; comprimento das hastes florais; altura da planta; producao de materia seca de raizes, folhas, caule, inflorescencias e parte aerea; numero total de inflorescencias; diâmetro da inflorescencia mais aberta; teor de Si nos tecidos foliares; ciclo e longevidade floral. A cultivar White Reagan produziu o maior numero de inflorescencias (29,17) por vaso e mostrou ser mais precoce (85,83 dias). Nao houve interacao negativa entre Si, Ca e K e nao foi constatado efeito do silicio na producao e na longevidade das inflorescencias de crisântemo. Houve aumento nos teores deste elemento nas folhas com a aplicacao do metasilicato de potassio.

Doses de nitrogênio na produção de couve-da-Malásia

E recomendavel que a introducao de uma cultura em uma regiao passe por avaliacoes previas que demonstrem a produtividade das plantas nas condicoes edafo-climaticas do local, bem como suas exigencias nutricionais. Isto vem sendo feito com Brassica chinensis var. parachinensis, introduzida no Brasil, municipio de Uberlândia, em 1992. Avaliou-se o efeito de doses de nitrogenio na produtividade e na acumulacao de nutrientes na parte aerea das plantas, em experimento em delineamento de blocos casualizados, com cinco tratamentos incluindo quatro doses de N (105; 210; 315 e 420 kg ha-1) e a testemunha sem N, e quatro repeticoes. O nitrogenio foi aplicado parceladamente, sendo 30% da respectiva dose na semeadura, 35% aos 15 e 35% aos 30 dias apos a semeadura. Foram avaliados massa fresca e seca da parte aerea e das raizes, numero de folhas, diâmetro do caule e acumulacao de N, P, K, Ca, Mg, S, B, Cu, Fe, Mn e Zn pela parte aerea de plantas cultivadas em casa de vegetacao, em vasos de 5 dm3 contendo Latossolo Vermelho Distrofico tipico. A couve-da-Malasia respondeu significativamente a aplicacao de nitrogenio, sendo o maior crescimento, a maior produtividade e absorcao de nutrientes registrados na dose de 210 kg ha-1, exceto o N, Mn e Zn que aumentaram linearmente.

Produção de rosas influenciada pela aplicação de doses de silício no substrato

The use of Si in the cultivation of pot-grown ornamental species in greenhouse has increased the output and quality of the final product. The objective of this study was to evaluate yield and nutrient uptake of two rose cultivars grown in pots under Si application to the substrate. The treatments, arranged in a 2 x 5 factorial design, consisted of two rose cultivars (Yellow Terrazza® and Red White Terrazza®) and five Si doses (0.0; 0.25; 0.50; 0.75 e 1.00 g kg-1), and evaluated in a randomized block design with four replications. The plant height, cycle, yield, diameter, floral longevity, concentration and amounts foliar Si, macro- and micronutrients were evaluated. Analysis of variance was performed adjusting regression equations for the effect of Si doses. Silicon applied to the substrate improved the output and quality of the roses grown in pots in greenhouse, although the plant response varied with the Si rates. To obtain 90 % of the maximum production of flowers dry matter the Si rates were of 0.43 and 0.22 g kg-1 for the Yellow Terrazza® and Red White Terrazza®, respectively. Negative effects of the element were however observed at rates of 0.86 and 0.55 g kg-1 Si and upwards for Yellow Terrazza® and Red White Terrazza®, respectively. The foliar Si contents increased according to the Si rate applied to the substrate.

SOIL-APPLIED SILICON DECREASES SEVERITY OF WHEAT SPOT BLOTCH ON SILICON-DEFICIENT SOILS

Spot bloth caused by Bipolaris sorokiniana is an important wheat desease mainly in hot and humid regions. The aim of this study was to evaluate the response of wheat to different sources and modes of Si application, as related to the severity of wheat spot blotch and plant growth, in two Si-deficient Latosols (Oxisols). An greenhouse experiment was arranged in a 2 x 5 factorial completely randomized design, with eight replications. The treatments consisted of two soils (Yellow Latosol and Red Latosol) and five Si supply modes (no Si application; Si applied as calcium silicate and monosilicic acid to the soil; and Si applied as potassium silicate or monosilicic acid to wheat leaves). No significant differences were observed between the two soils. When Si was applied to the soil, regardless the Si source, the disease incubation period, the shoot dry matter yield and the Si content in leaves were greater. Additionally, the final spot blotch severity was lower and the area under the spot blotch disease progress curve and the leaf insertion angle in the plant were smaller. Results of Si foliar application were similar to those observed in the control plants.

Yield and Nutrient Uptake of Common Bean Cultivars as Affected by Plant Population and Growing Season

Brazil’s production of common bean is insufficient to supply the domestic market. Factors such as plant density, cultivar, growing season, and nutrient uptake affect bean yield, suggesting the need for more studies to optimize bean production. The objective of this work was to evaluate the effect of plant density on seed yield components and nutrient uptake of two common bean cultivars grown in two different seasons. Field experiments were carried out at the IAPAR experimental site in Santa Tereza do Oeste, Parana, Brazil in the wet and dry season using five planting densities: 6, 8, 10, 12, and 14 plants m-1. The experimental design was randomized blocks with four replications and two bean cultivars of different growth types. The cultivars used were ‘IPR Curio’ (type I) and ‘IPR Tangara’ (type II), both have erect plant architecture and belong to the Carioca group. Obtained data underwent analysis of variance and regression. Macronutrient uptake was not affected by crop density probably due to nutrient availability and compensatory growth of the crop. High crop density per linear meter decreased the number of seeds and pods per plant but did not affect the first pod height or yield in both cultivars and seasons.

Leaf anatomy and gas exchange of ornamental sunflower in response to silicon application

Silicon applied to substrate for greenhouse cultivation of ornamental pot plants can improve the yield and quality of the ornamental product; however, the possible anatomical and physiological changes caused by Si have to be assessed. Therefore, the objective of this study was to evaluate gas exchange rates and leaf anatomy of ornamental sunflower ‘Sunbright’ grown on a substrate amended with Si. The experiment was conducted in a greenhouse, and the treatments consisted of sunflower plants cultivated in pots containing 600 g substrate fertilized with Si at rates of 0, 0.25, 0.50, 0.75, and 1.00 g kg. The treatments were arranged in randomized complete block design and four replications. Samples from the middle region of leaf blades in the sixth pair from the apex were collected and analyzed morphometrically. Epidermal trichomes were analyzed using diaphanization and scanning electron microscopy with energy-dispersive X-ray spectroscopy. The following traits were determined: leaf blade thickness, palisade and spongy parenchyma thickness, mesophyll thickness, and abaxial and adaxial epidermis thickness. Net photosynthesis, stomatal conductance and transpiration rates were determined in the fifth leaf at the beginning of the flowering stage by an infrared gas analyzer. The data were subjected to ANOVA and regression analyses. The results indicate that the ornamental sunflower ‘Sunbright’ accumulates Si in leaf trichomes, and that leaf thickness is not affected by Si application to the substrate; however, transpiration rates decrease while net photosynthesis rate and stomatal conductance increase in response to Si application.

Adubação do arroz com silício e manganês em um Latossolo Vermelho

The objective of this research was to study the biomass production, plant architecture and Si and Mn uptake in rice plants cultivated in a Acrustox fertilized with silicon and manganese. The experiment was carried out in a greenhouse using a 2x5 factorial (0 and 1000mg dm-3 Si x 0, 4, 12, 16 and 20mg dm-3 Mn) with four replications, in a randomized block design. The application of Si to the soil resulted in a smaller leaf insertion angle, a greater Si content in the leaves and roots and biomass production. Moreover, Si caused the decrease content of Mn in leaves and its increase in roots. With the rising dose of Mn, there was an increase in the content of this element in soil, roots and leaves, regardless of the Si application and reduction in biomass production of rice in the larger doses only when the Si was not added to the soil.