Roberto Wagner Cavalcanti Raposo

Yield components and morphogenesis of Aruana grass in response to nitrogen supply

Areas with Aruana grass (Panicum maximum Jacq.) in Brazilian pastures, especially those used by sheep, have expanded due to yield and morphological characteristics of this grass that are favorable to these animals. Nevertheless, the knowledge concerning yield attributes of this grass in relation to nitrogen fertilization is very limited. The objective of this research was to evaluate yield and physiological attributes in this forage grass when grown in nutrient solutions containing N rates. The experiment was carried out in a greenhouse with plastic pots containing ground quartz as substrate, during the Spring season. Six N rates in the solution (14, 112, 210, 294, 378, and 462 mg L-1), with 70% N-NO3- and 30% N-NH4+ were tested. Experimental units were set up in a completely randomized block design, with four replications. Plants were harvested at 35 days after the seedlings were transplanted to the pots and again at 28 days after the first harvest. After the second harvest, the roots were taken from the substrate. In both growing periods, dry matter yield for plant tops and roots, leaf area, number of expanded green leaves, number of tillers, leaf appearance rate, and phyllochron were significantly affected by the N rates, and the data were adjusted to a second-order model. Aruana grass required high rates of N to show maximum response in those variables.

Influência de doses de fósforo no fluxo difusivo em solos de Alagoas

The effect of distinct doses of phosphorus was evaluated on the diffusion of this element in soil samples from the State of Alagoas. The experiment was performed in the laboratory of the Centro de Ciencias Agrarias of the Federal University of Alagoas, Rio Largo, AL. The soils were classified as a compacted Yellow Latossol, Grey Argissoil, Fluvic Neosoil, Quartzanic Neossoil and ortic Chromic Luvissoil. Chemical, physical and mineralogical analyses had been made. The determination of the remaining P was made in the equilibrium solution. The maximum capacity of adsorption was determined through the remaining phosphorus, using PVC rings which were used as diffusion chambers. The doses of phosphorus had been equivalent to 0, 10, 20 and 30% of the maximum capacity of adsorption. The evaluation of the diffusive flow of phosphorus in the soils was carried out through papers of anionic exchange, using filter-papers saturated with the iron oxide. The experiment was constituted of a factorial arrangement (6 x 4), corresponding to six soils and four doses of phosphorus. The most sandy soils and the largest dose always showed the largest diffusive fluxes of phosphorus.

Desenvolvimento e qualidade nutricional de mudas de mangabeiras cultivadas em substratos contendo fibra de coco e adubação fosfatada

In order to produce good quality seedlings it is necessary to use a mixture that presents appropriate physical, chemical and biological properties, which supplies the necessary conditions for the germination and the seedlings establishment. This experiment was carried out at the Agricultural Sciences Center, Paraiba Federal University (Brazil), whose objective was to evaluate the growth and the mineral composition of Hancornia speciosa seedlings in substrata composed by concentrations of coconut fiber from 0% to 40%, manure bovine from 0% to 25%, soil from 25% to 70%, sand 15% and triple superphosphate between 0 and 11 g dm-3. The soil and coconut fiber had beneficial effects on the H. speciosa seedlings with the increase of its concentrations in the mixture. The addition of the manure and the doses of triple superphosphate provoked a decrease in the matter and in the foliate area in the H. speciosa seedlings. There was an increase of the nutrients content in the seedlings in which there was an increase of the manure concentration in the mixture. It is recommended to use the concentrations of 14% of manure, 56% of soil, 15% of coconut fiber, 15% of sand and 4 g dm-3 of triple superphosphate, for the maximum estimated values of growth and nutritional composition.

Acid phosphatase activity and leaf phosphorus content in soybean cultivars

A adubacao fosfatada corresponde a fracao mais onerosa do custo de producao da cultura da soja. A obtencao de cultivares de soja eficientes na absorcao e utilizacao de fosforo (P) em condicao de media disponibilidade deste nutriente pode contribuir para aumentar o potencial produtivo da cultura. Trinta e dois cultivares de soja [Glycine max (L.) Merr.], de ciclo precoce, semiprecoce, semitardio e tardio, recomendados para o cerrado, foram cultivados em Latossolo Vermelho-Amarelo distrofico tipico, do cerrado, objetivando avaliar a atividade da fosfatase acida, concentracao de P na folha diagnostico e biomassa da parte aerea. Ocorreram diferencas entre os cultivares dentro de todos os ciclos de maturacao na atividade da fosfatase acida e na biomassa da parte aerea. Cultivares de ciclos semitardio e tardio apresentaram diferencas significativas quanto a concentracao de fosforo na folha diagnostico. A atividade da fosfatase acida correlacionou-se positivamente com a biomassa da parte aerea nos cultivares dos ciclos semiprecoce (r = 0,46) e tardio (r = 0,47) e, negativamente (r = -0,40), com a concentracao de P na folha-diagnostico, nos cultivares do ciclo tardio. A ocorrencia de cultivares de soja com alta e baixa atividade da fosfatase acida dentro do mesmo ciclo de maturacao sinalizam a existencia de diferentes mecanismos envolvidos na mobilizacao de P no solo e remobilizacao interna deste nutriente na planta entre os grupos de cultivares.

Cu e Zn na cultura do sorgo cultivado em três classes de solos: I. Crescimento vegetativo e produção

The micronutrients copper and zinc are important for good vegetative growth and for grain formation in cereals. An experiment was carried out aiming to evaluate the effect of copper and zinc application upon growth attributes of sorghum and upon its grain yield. A randomized block experimental design was used, with a combination of five doses of copper (0, 0.26, 0.90, 1.54 and 1.80 mg kg-1) and five doses of zinc (0, 0.32, 1.1, 1.88 and 2.2 mg kg-1) combined by Box Central Composite design, resulting in nine treatments which were applied in three soil classes (Latosol, Alfisol and Entisol), with three replications. Ninety six days after sowing, growth attributes and sorghum yield were determined. The copper application increased leaf area, stem diameter, panicle length and diameter, dry matter yield and grain yield, however the same results were not observed for zinc application. The foliar concentrations of copper and zinc presented negative interactions between the applied doses. Alfisol was the soil most influenced by nutrient application.

Resposta do arroz em casa de vegetação a fontes de micronutrientes de diferentes granulometria e solubilidade

A granulometria e a solubilidade do fertilizante podem resultar em maior ou menor efeito da adubacao. O objetivo deste trabalho foi comparar o efeito de um produto comercial granulado e moido de micronutrientes, com uma mistura de igual composicao feita com materiais pro-analise. O delineamento experimental foi o inteiramente casualizado, utilizando tres produtos com micronutrientes e quatro doses de cada mistura (0, 14, 28 e 56 mg dm-3), com quatro repeticoes. A maior producao de graos e obtida com a aplicacao do produto comercial em po. A melhor correlacao entre os materiais e teor na planta ocorre em razao do zinco.

Resposta do milho a doses de fósforo

An experiment was conducted in a greenhouse of the Centro de Ciencias Agrarias, Universidade Federal de Alagoas - Rio Largo/AL, aiming to evaluate the effect of different doses of P recommended by the maximum adsortion capacity of phosphorus - CMAP (%), on content of P and the production of mass of dry matter in corn. The soils were classified as cohesive Yellow Latosol, Gray Argisol, Fluvic Neosol, Quartzarenic Neosol, ortic Chromic Luvisol and palic Chromic Luvisol. Soil samples were taken for physical, chemical and mineralogical analyses. The experiment was arranged in a factorial design (6 x 4) corresponding to the 6 soils and the 4 doses of P (0, 10, 20 and 30% of the CMAP), in a randomized block design. The determination of the remenecent P was made in a equilibrium solution. The CMAP was determined through the remenecent phosphorus. As experimental units, plastic pots were used with the capacity of 10 dm3 containing 7 dm3 of soil. The mass of dry matter of the aerial part of the plant presented better result in the palic Chromic Luvisol, with the dose of 10% of the CMAP and the Fluvic Neosol provided the highest content of phosphorus in the plant with the dose of 30% of the CMAP.

Cu e Zn na cultura do sorgo cultivado em três classes de solos: II. Composição mineral

The micronutrients copper and zinc have important functions in vegeatable metabolism, but studies about micronutrient needs for sorghum are scarce. Aiming to evaluate the effect of copper and zinc application in nutritional attributes of sorghum an experiment was carried out in a randomized block experimental design with a combination of five doses of copper (0, 0.26, 0.90, 1.54 and 1.80 mg kg-1) and five doses of zinc (0, 0.32, 1.1, 1.88 and 2.2 mg kg-1) combined by Box Central Composite design, resulting in nine treatments, which were applied in three soil classes (Latosol, Alfisol and Entisol), with three replications. Ninety six days after sowing, nutrients contents and accumulation and protein contents were determined. The copper application increased nitrogen, phosphorus, potassium and copper contents and crude protein content in grains, however, the same results were not observed for zinc application. Alfisol was the soil most responsive to the application of nutrients.

ÍNDICES DE ARIDEZ APLICADOS AO SEMI-ÁRIDO PARAIBANO: DE MARTONNE, LANG, MEYER, CCD E XEROTÉRMICO (GAUSSEN)

POLLINATOR FORAGING STRATEGY IN Galactia peduncularis (BENTH.) TAUB. (LEGUMINOSAE: PAPILIONOIDEA) IN THE PARQUE ESTADUAL DA SERRA DE CALDAS NOVAS BRAZIL The way the animals look for food is an important characteristic of their behavior. The optimal foraging theory is based on the existence of a balance between costs and benefits of these behavioral decisions. The present study aimed to evaluate the behavior of the pollinator in response to increased availability of floral resources. The experiment was conducted in a recently burned Cerrado area (Campo rupestre) in the State Park of Serra de Caldas Novas , located in the municipalities of Caldas Novas and Rio Quente Brazil. The species chosen to test our hypothesis was Galactia peduncularis (Benth.) Taub. (Leguminosae: Papilionoidea). 17 pairs of specimens were selected with a number of flowers, and the individuals of each pair were spaced by about 2m. In these pairs, one of them was considered the focal, and the other, the isolated. To test possible differences in pollination between isolated plants and focus, we performed two randomization tests: a test binary (TB), where all pairs were analyzed and verified the number of times where the focus on the individual floral visits were higher than the number of visits in isolated. According to the data analyzed, floral visitors preferred to use plants that could provide a greater amount of floral resources so that the number of visitors varied positively with the increment of flowers. Plants with many flowers can provide a greater amount of food in one location so that visitors do not need to flower around for long distances in search of meeting their energy needs.