Regina Maria Quintão Lana

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.

Variabilidade espacial de atributos químicos do solo em áreas sob sistema plantio convencional

SUMMARY : SPATIAL VARIABILITY OF SOIL CHEMICAL ATTRIBUTES INAREAS MANAGED UNDER CONVENTIONAL TILLAGE The spatial variability of soil chemical attributes was evaluated in a commercialplantation under conventional soil tillage in Uberlândia, state of Minas Gerais, Brazil, in2004. The sampling grid was the Santa Rosa Farm, where the soil is classified as veryclayey Red Latosol (680 g kg -1 clay). The objective was to evaluate the spatial distributionand dependence of the soil chemical attributes in a plantation under conventional soiltillage. For this purpose, soil data were collected from a grid of 121 sampling points in the0–0.2 m layer, spaced 50 m apart, and analyzed by means of geostatistics. The followingsoil attributes were assessed: soil pH water ; phosphorus and available potassium; calcium,magnesium and exchangeable aluminum; H + Al; boron; copper; iron, manganese; zinc;sulphur and organic matter. The values of base saturation (V %), total CEC (T) and sum ofbases (SB) were also computed. The data were evaluated by descriptive statistics andspatial dependence analysis, through the adjustment of semivariograms. The variationcoefficient (CV) of most attributes was high; the highest one was found for phosphorus(73.51 %) and the lowest for soil pH

Variabilidade espacial do pH, teores de matéria orgânica e micronutrientes em profundidades de amostragem num Latossolo Vermelho sob semeadura direta

The space variability of the indexes of fertility of the soil increases with the no-till system, being verified differences in the nutrients contents of a superficial layer of the soil in relation to the other lower layer. Therefore, it requires the definition of new sampling procedures to contemplate those alterations. The study was aimed at evaluating the spatial variability of the pH, organic matter and micronutrients (B, Cu, Fe, Mn and Zn) in a Acrustox loamy texture, cultivated since 1995 under no till system. The soil was sampled in regular intervals of 50m, in regular mesh of 121 points, in three depths (0-10cm, 10-20cm and 0-20cm). The data evaluated by descriptive statistics and geostatistics, based on semivariograms adjustment. Larger contents of organic matter, Mn and Zn were verified in the first 10cm of the soil, whereas contrary behaviors were observed for Fe. The highest variabilities were found for B and the lowest for pH in water. For the attributes that presented spatial dependence, this was classified as moderate or strong. Most of the data was adjusted to the semivariograms of exponential model, folloed by the spherical model. Only the variable zinc, in the depth of 0-20cm, did not present spatial dependence. The results obtained results should be considered in the definition of plans of soil sampling and management fertilization of the studied area by the analysis of range and horizontal and vertical variability of the chemical attributes evaluated.

Efeito de doses de torta de filtro e modo de aplicação sobre a produtividade e qualidade tecnológica da soqueira de cana-de-açúcar

A expansao do setor sucroalcooleiro aumenta areas de plantio, assim como volumes de residuos (como a torta de filtro) que podem ser utilizados na agricultura como fonte de nutrientes, reduzindo a contaminacao ambiental e os custos com adubacao, entretanto, faltam informacoes sobre modos de aplicacao. Nesse contexto, conduziu-se este trabalho, com o objetivo de avaliar doses de torta de filtro e modos de aplicacao (superficial na linha e incorporado na entrelinha) sobre as variaveis tecnologicas e produtividade da cana soca. O experimento foi instalado em soqueira de cana-de-acucar (SP 81-3250), cultivada em solo de textura argilosa, localizado no municipio de Goianesia/GO. O delineamento experimental utilizado foi em blocos ao acaso (DBC), com onze tratamentos e 5 repeticoes, em esquema fatorial 5 X 2 + 1 que correspondem a 5 doses crescentes de torta de filtro (0, 10, 20, 40 e 80 t ha-1), combinadas a 2 modos de aplicacao (na linha superficial e na entre linha incorporada) e um tratamento adicional correspondente a adubacao mineral da Usina Jalles Machado S.A.. A aplicacao de torta de filtro na cana-soca na dose de 70 t ha-1 proporcionou a maior producao de colmos de cana-de-acucar, independentemente do modo de aplicacao.

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.

Variabilidade entre genótipos de feijoeiro na eficiência no uso do fósforo

The use of the genetic variability in common bean (Phaseolus vulgaris L.) for its efficiency in the absorption and use of phosphorus arises as an alternative to avoid the deficiency of this element in Cerrado soils. Aiming at detecting such efficiencies, an experiment was carried out in a greenhouse at the Federal University of Uberlândia-MG, from July to August 1997. The experimental design was of complete randomized blocks with four replications, on an 8 x 2 factorial scheme. Eight genotypes of common bean (BAT 477, Carioca MG, Emgopa 201, Jalo Precoce, Perola, Rosinha, Roxo e Xamego) and two levels of P2O5 (24 and 120mg dm-3) were evaluated. The production of dry mass of shoots and roots of genotypes, content of phosphorus in shoots and roots; root:shoot ratio and the efficiency in the use of the phosphorus (a value), were determined at 45 days after germination. The genotypes were classified in four groups: efficient and responsive, not efficient and responsive, efficient and not responsive and not efficient and not responsive. The genotypes were classified as efficient in the absorption and use of phosphorus BAT 477, Jalo Precoce and Roxo and the genotypes Carioca MG, Jalo Precoce , Perola e Roxo were classified as responsive.

Fontes, doses e modos de aplicação de fósforo na recuperação de pastagem com brachiaria

Objetivando-se avaliar diferentes fontes, doses e metodos de aplicacao de fosforo na recuperacao da Brachiaria decumbens, um experimento foi conduzido na Fazenda Caminho das Pedras, municipio de Uberlândia-MG, em Latossolo Vermelho distrofico, textura media, entre novembro de 2003 e abril de 2004. Os tratamentos constaram de tres fontes de fosforo (Superfosfato Triplo, Termofosfato magnesiano e hiperfosfato de Gafsa) nas dosagens de 0; 50; 100 e 150 kg ha-1 de P2O5, com manejo incorporado e nao incorporado, em tres repeticoes, no delineamento de blocos casualizados. Foram utilizadas parcelas de 2,0 x 5,0 m, as quais foram adubadas uniformemente com 330 kg ha-1 de N e 220 kg ha-1 K2O, na forma de ureia + sulfato de amonio e cloreto de potassio, respectivamente. Foi avaliada a produtividade da Brachiaria em tres cortes da parte aerea, em um intervalo de 30 dias entre os cortes. A aplicacao de fosforo com diferentes fontes e doses promoveu incremento na produtividade da Brachiaria, porem nao houve diferenca comparando-se os metodos de aplicacao. A maior resposta foi obtida com 150 kg ha-1 de P2O5, na forma de superfosfato triplo com produtividade media de 2997 kg ha-1 de MS por corte, e a menor produtividade ocorreu no tratamento com 50 kg ha-1 de P2O5 na forma de hiperfosfato de Gafsa. Houve aumento na porcentagem do fosforo foliar e do fosforo no solo, com aumento da dose em todas as fontes, em ambos extratores. Na avaliacao dos extratores, o Mehlich-1 apresentou maior extracao na fonte hiperfosfato de Gafsa, contrariando os resultados de producao.

O cultivo protegido de hortaliças em Uberlândia-MG

The situation of the protected cultivation in Uberlândia-MG is described and the causes that led many producers to lack of success in this system are discussed. A questionnaire was applied to the vegetable producers that produced and those that are producing under protected cultivation, being observed the main information related to the production, from the installation to the commercialization of the cultivated products. We identified that the protected cultivation in Uberlândia began in 1990/1991. Two years later, approximately 84% of the producers had abandoned this activity. The lack of cultivars and adapted hybrids to the region; the scarce information about commercialization and manuring of the soil; the lack of technical attendance to the producer; the beginning of the activity without doing market research; the lack of adapted handling of the protected atmosphere; high cost of the installation; the absence of differentiated prices for products obtained from protected cultivation; the absence of governmental incentive; lack of professional experience of the beginners in this agribusiness; lack of project and economic planning of the production, were the reasons that motivated the farmers to stop the protected cultivation in Uberlândia. This research stand out, also, the need of new information about the handling in the protected cultivation in this city.