Laércio Couto

Padrão de qualidade de mudas de Trema micrantha (L.) Blume, produzidas sob diferentes períodos de sombreamento

This work aimed to verify the influence of the under shading period in the parameters employed to evaluate Trema micrantha (crindiuva) seedling quality pattern. The research was carried out using a randomized design, with four replications per treatment and 88 plants per replication. Three evaluations were performed at 90, 120 and 150 days after emergence. The following treatments were used in the evaluation: Evaluation I, 45, 60, 75 and 90; Evaluation II, 45, 60, 75, 90, 105 and 120 and Evaluation III, 45, 60, 75, 90, 105, 120, 135 and 150 days under shading with 48% of solar radiation retention, respectively. The morphological parameters of the seedlings, their relationships, and the Dickson quality index were evaluated. Seedlings developed under the longer shading periods presented higher shoot heights and leaf area but the lowest values for seedling quality, such as smaller stem diameter, root dry mass and the Dickson quality index. They also presented an increase in shoot height/stem diameter and shoot/root ratios. Period under shading did not affect significantly the parameters for leaf area, leaf dry mass, shoot and total. Seedlings showed better quality patterns at 120 days, when grown under 45 and 60 days under shading. The Dicksons quality index was the best and the most suitable parameter to evaluate the target seedling grown in a suspended nursery.

Produção forrageira de gramíneas cultivadas sob luminosidade reduzida

The objective of this work was to evaluate the influence of three levels of artificial shade (0, 30 and 60%) on dry matter production, nitrogen content and morphological characteristics of six forage grasses (Andropogon gayanus cv. Planaltina, Brachiaria brizantha cv. Marandu, B. decumbens, Melinis minutiflora, Panicum maximum cv. Vencedor and Setaria anceps cv. Kazungula). A randomized block design, with split plots and four replicates, was used; the shading levels were allotted to the plots and the species to the split plots. The results showed that shading affected the production of dry matter, the nitrogen content and the morphological characteristics of the evaluated species. The production of forage was differentially affected by the shade. The dry matter production of P. maximum cv. Vencedor was 19.72% higher, at moderate shade than in broad daylight. The forage production of S. anceps cv. Kazungula, however, was not affected by the shade. The dry matter production of other species decreased with the reduction of the light. In all species there was an increase of N content and reduction of the content of dry matter of the forage, which became juicier in the shade. The morphological characteristics did not show a standard behavior, which varied according to the studied specie.

Desempenho de seis gramíneas solteiras ou consorciadas com o Stylosanthes guianensis cv. Mineirão e eucalipto em sistema silvipastoril

A study was conducted in the Brazilian Cerrados to evaluate the performance of six tropical forage grasses (Brachiaria brizantha cv. Marandu, B. brizantha cv. MG-4, B. decumbens cv. Basilisk, Panicum maximum cv. Mombaça, Melinis minutiflora and Hyparrhenia rufa), associated or not with the tropical forage legume Stylosanthes guianensis cv. Mineirão, in a silvopastoral system with a clone of Eucalyptus sp. The forages were established in plots of 12 x 10 m, in the interrows of eucalypts, in a randomized block design with three replications. Ground cover, proportion of the legume and total dry matter availability in the understorey were evaluated one year after the establishment, under short time grazing. After two grazing cycles, there was reduction of the proportion of the legume in the mixture with all grasses, notably with the more aggressive ones (B. brizantha cv. Marandu and B. decumbens), where it practically disappeared. With the other grasses, however, the presence of the legume favored the productivity of the understorey. The grasses with the best productive performance were B. brizantha cv. Marandu, B. decumbens and P. maximum cv. Mombaça, the latter mainly when associated with the legume.RESUMO - Conduziu-se este estudo na regiao dos Cerrados de Minas Gerais, visando avaliar o desempenho de seis gramineas forrageiras (Brachiaria brizantha cv. Marandu, B. brizantha cv. MG-4, B. decumbens cv. Basilisk, Panicum maximum cv. Mombaca, Melinis minutiflora e Hyparrhenia rufa), consorciadas ou nao com a leguminosa Stylosanthes guianensis cv. Mineirao e Eucalyptus sp., em um sistema silvipastoril. As forrageiras foram estabelecidas em parcelas medindo 12 x 10 m, nas entrelinhas do eucalipto, em um delineamento experimental de blocos ao acaso, com tres repeticoes, e avaliadas quanto ao grau de cobertura do solo, % de leguminosa e disponibilidade de materia seca total no sub-bosque, um ano apos o estabelecimento, submetidas a pastejos de curta duracao. Apos dois ciclos de pastejo, houve reducao da proporcao da leguminosa no consorcio com todas as gramineas, sendo mais evidente com as mais agressivas (B. brizantha cv. Marandu e B. decumbens), onde ela quase desapareceu. Entretanto, a presenca do estilosantes Mineirao favoreceu a produtividade do sub-bosque, quando consorciado com as demais gramineas. O melhor desempenho produtivo foi obtido pelas gramineas B. brizantha cv. Marandu, B. decumbens e P. maximum cv. Mombaca; a ultima principalmente quando consorciada com o estilosantes Mineirao.

Emprego de um modelo de crescimento e produção em povoamentos desbastados de eucalipto

The objective of the present study was to evaluate the applicability of the Clutter model in thinned eucalypt stands. The study was developed with data from the Copener Florestal, Bahia Pulp Enterprise, located in the municipality of Alagoinhas, Bahia, Brazil. Data came from a thinning experiment established in eucalypt stands using a randomized block design with four treatments and three repetitions, each one in a different place, totaling 48 plots with a mean area of 2,600 m2 each. The plots were measured at 27, 40, 50, 58, 61 and 76 months of age, and the thinning was carried out at 58 months. For model adjustment, a system of simultaneous equations was used with stand information such as basal area, volume, age and site index. From the model adjustment, a yield table with variable density was built, and the technical cutting age was determined for various thinning intensities. Simulations were carried out with the yield table. It was concluded that the Clutter model was efficient to predict the present and future yields of the thinned eucalypt stands, showing its usefulness in the analysis of alternative managements, such as the technical cutting age determination for various site indexes and thinning intensities.

Avaliação de um modelo de distribuição diamétrica ajustado para povoamentos de tectona grandis submetidos a desbaste

The objective of this study was to evaluate, under the biological point of view, a diametric distribution model. Another objective was to evaluate the efficiency of the percentage of entries method to determine the technical age for the first and second thinning in teak (Tectona grandis L. f.) stands. This evaluation was carried out by comparing the technical thinning ages obtained by the percentage of entries method, the diametric distributions projected for future ages and the behavior of the remaining distribution, after some thinning simulations, with the expected logical tendency. It was be concluded that the proposed diametric distribution model generates estimates which follow a logical tendency, biologically speaking and that the percentage of entries method is suitable to determine the technical age of the first and second thinning.

Occurrence of Euplatypus parallelus, Euplatypus sp. (col.: Euplatypodidae) and Xyleborus affinis (col.: Scolytidae) in Pinus sp. in Ribas do Rio Pardo, Mato Grosso do Sul, Brazil

Wood borer species of the families Euplatypodidae and Scolytidae were observed attacking trees of Pinus sp. in the Municipality of Ribas do Rio Pardo, state of Mato Grosso do Sul, Brazil, in March 2000. This plantation had been previously burned in an accidental fire in January 2000, causing the trees to become partially or totally unhealthy, rendering them more susceptible to attack of these pests. Galleries of these wood borers were opened with a chisel to observe parameters such as their direction and form of these galleries. Species observed as wood borers of Pinus sp. were Euplatypus parallelus, Euplatypus sp. (Coleoptera: Euplatypodidae) and Xyleborus affinis (Coleoptera: Scolytidae).