Yield performance and leaf nutrient levels of coffee cultivars under different plant densities

Cultivares de cafeeiro (Coffea Arabica L.) adaptadas às regiões de cultivo, com população de plantas otimizada e adequado estado nutricional são premissas para a obtenção de produções elevadas de café. Estudou-se a produção trienal de café e o teor foliar de macronutrientes de cultivares de cafeeiro em função das densidades de plantio. Foram utilizados os cultivares Catuaí Amarelo (IAC 47), Obatã (IAC 1669-20), Acaiá (IAC 474-19) e Icatu Amarelo (IAC 2944) nas populações de 2.500 plantas ha-1 com duas plantas por cova; e, 5.000, 7.519 e 10.000 plantas ha-1 com uma planta por cova. As plantas foram adubadas de modo homogêneo, porém, sem calagem. À medida que a população de cafeeiros aumentou, a produtividade trienal de café aumentou, a produção de frutos por planta diminuiu e os teores foliares de fósforo (P), potássio (K) e enxofre (S) aumentaram. Nos cafeeiros sob adensamento encontrou-se igual ou maior teor de macronutrientes do que naqueles sob espaçamento convencional, sendo que os maiores teores foram observados nas cultivares de porte alto, e os menores, na cultivar Obatã, de porte baixo. Nos cafeeiros das covas com uma planta observou-se maior produção de café e menores concentrações de P, Ca e S do que naqueles das covas com duas plantas. No geral, os cultivares e as populações de cafeeiros estavam com teores de N e S acima dos limites de referência citados na literatura, mas com teores dos demais macronutrientes dentro da faixa adequada.

Vegetative and productive aspects of organically grown coffee cultivars under shaded and unshaded systems

Although Coffea arabica species has its origin in the African understories, there is great resistance on the part of the Brazilian producers for growing this species under agroforestry systems as they fear that shading reduces production. This study aimed at evaluating some vegetative traits and the productivity of organically grown coffee (Coffea arabica L.) cultivars under shaded and unshaded systems. Twelve treatments consisting of two cultivation systems (shaded and unshaded) and six coffee cultivars were arranged in randomized blocks with four replicates, in a split-plot scheme. Shading was provided by banana (Musa sp.) and coral bean plants (Erythrinaverna). Shading delayed fruit maturation. Late maturation cultivars, such as the Icatu and the Obatã, matured early in both cultivation systems, while medium and early maturation cultivars presented late maturation. Cultivation in the shaded system increased the leaf area and the number of lower branches, decreased the number of productive nodes per branch, and increased the distance between the nodes and the number of leaves present in the branches. Cultivation in the unshaded system presented greater number of plants with branch blight in relation to plants grown in the shade. The productivity of the cultivars was not different, at 30.0 processed bags per hectare in the shaded system, and 25.8 processed bags per hectare in the unshaded system. The most productive cultivars in the shaded system were the Tupi, the Obatã, and the Catuaí, while no differences between cultivars were obtained in the unshaded system.

Interactions in the Agrobacterium-soybean system and capability of some Brazilian soybean cultivars to produce somatic embryos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Criteria for peanut seed pre-conditioning for the tetrazolium test

The staining pattern of peanut (Arachis hypogaea L.) seeds with a tetrazolium solution was evaluated to determine the adequate conditions of seed quality evaluations. Three seed lots with different vigour levels and similar moisture content were pre-conditioned using the combination of five periods of time (4, 8, 12, 16 and 20 hours) and four temperatures (20, 25, 30 and 35 degrees C) and then exposed to a 1.0% tetrazolium solution for three hours. The moisture content levels of seeds conditioned for 8 hours at the temperatures of 25, 30 or 35 degrees C, for 12 hours at 20 or 25 degrees C and for 16 hours at 20 degrees C, were above 30%. In this range of moisture level, the staining in tetrazolium was clear and uniform, reflecting an appropriate conditioning of the seeds. However, under a practical point of view, the period of 16 hours at 20 degrees C showed to be the best option, since it allows to start the pre-conditioning an late afternoon of one day and submit the seeds for staining in the following morning.

Dry matter production of shoots and root density of two cultivars of Lablab purpureus (L.) Sweet

This experiment was conducted in green house conditions to evaluate the DM accumulation in the shoots and in the roots of two cultivars of Lablab purpureus (L.) Sweet. A 2x3 factorial (two cultivars and three evaluation dates) was conducted according to a randomized complete block design with four replications, being the cultivars Highworth and Rongai evaluated at 42, 56, and 70 days after seedling emergence (DASE). The results indicated that the cvs. Highworth and Rongai have the same pattern of DM accumulation in the shoots. In the upper layer of the soil (0-0.20 in) it was found 38.83% and 43.64% of the DM accumulated in the roots down to 2.00 in depth, in the cvs. Highworth and Rongai, respectively. In the deepest layer (1.80-2.00 in) it was found 3.02% and 1.5% of the DM accumulated in the roots of the cvs. Highworth and Rongai, respectively. The root density showed a striking decrease upper layer from the soil (0-0.2 m) down to the depth of 0.60 0.80 in (from 10.83 to 1.75 cm.cm(-3) in the cv. Highworth and from 10.76 to 1.28 cm.cm(-3) in the cv. Rongai). At the bottom layer (1.80-2.00 in) the root density values were 0.98 cm.cm(-3) and 0.59 cm.cm(-3), respectively for the cvs. Highworth and Rongai. The root/shoot ratios were similar in both cvs. and decreased from 42 to 70 DASE showing that the cvs. evaluated had the same dynamics of DM accumulation.

Structural organization in leaf blade and sheath of elephant-grass cultivars (Pennisetum purpureum Schum. - POACEAE).

Elephant-grass is known as a great feed to dairy and beef cattle at tropical regions. Its agricultural aspects have been very observed. However, its botanical, mainly anatomical characteristics, are few studied. The objective of this work was to investigate the anatomical changes occurred in leaves (leaf blades and sheaths) of three elephant-grass cultivars (Pennisetum purpureum Schum. cultivar Roxo, EMPASC 307 Testo and EMPASC 309 Areia) at three stages of physiological maturity (4, 8 and 16 weeks after sprouting). In general, the three cultivars presented similar anatomy. A unique feature, the presence of aerenchyma was found in the leaf sheath of all three cultivars, at the second harvest (a weeks).

Partial purification, heat stability and kinetic characterization of the pectinmethylesterase from Brazilian guava, Paluma cultivars

Pectinmethylesterase (PME) was extracted from guava fruit (Psidium guajava L.), cultivar Paluma, by 70% ammonium sulphate saturation and partially purified by gel filtration on Sephadex G100. Gel filtration showed PME isoenzymes with different values of molecular mass. Two samples were examined: concPME (70% saturation by ammonium sulphate) and Iso4 PME (one of the isoforms from gel filtration with the greatest specific activity). Optimum pH of the enzyme (for both samples) was 8.5 and optimum temperature ranged from 75 and 85 degrees C. The optimum sodium chloride concentration was 0.15 M. The K-M and V-max ranged from 0.32 to 0.23 mg m1(-1) and 244 to 53.2 mu mol/min, respectively, for concPME and Iso4PME. The activation energies (E-a) were 64.5 and 103 kJ/mol, respectively, for concPME and Iso4PME. Guava PME, cv Paluma, is a very thermostable enzyme, showing great heat stability at all temperatures studied. (c) 2005 Elsevier Ltd. All rights reserved.

Peanut seed tegument is affected by liming and drying method

Calcium plays a fundamental role in cell division and growth, and is an important constituent of the cell wall. An increase in Ca concentration in the tegument of peanut (Arachis hypogea L.) seeds in response to lime application can affect its structure. The tegument structure can also be affected by the drying method of the seeds. The effects of lime application and drying methods as affecting the peanut seed tegument structure were studied in seeds from a field experiment conducted in Sao Manuel, São Paulo, Brazil. Peanut (cv. Botutatu, Valencia Type) was grown in presence or absence of 2.1 Mg ha(-1) of lime and dried in an oven, in shade and in the field. The tegument anatomical features were described and its structure was analysed. Pectic substances, lipidic reserves and starch accumulation were studied. The peanut tegument exhibited well differentiated exotesta, mesotesta and endotesta rich in pectates and covered by a cuticle. Tannin was not observed but there was lipid accumulation in mature teguments. Lignin was observed in the vascular bundles. Lime increased the tegument thickness and decreased the central cavity mainly in the exotesta cells when the period of seed drying was shortened. The effect of drying method upon the tegument was more noticeable in seeds grown without lime. It can be inferred that liming increased the resistance of the tegument.

Stem anatomy of Pennisetum purpureum schum. (Poaceae) cultivars

Elephant-grass is known like a great feed to dairy and beef cattle al tropical regions. Its agricultural aspects have been very observed. However, its botanical, mainly anatomical characteristics are few studied. The objective of this work was to investigate the anatomical changes occurred in stems of three elephant-grass cultivars (ROXO, EMPASC 307 TESTO and EMPASC 309 AREIA) at three stages of plant development (4, 8 and 16 weeks after sprouting). The anatomical features were similar among cultivars. When stems were young (4 weeks), a disorganization of vascular bundles were detected. However, at 8 weeks stage the were organized as a definitive form. Was observed a magnified of lignification as the stems age, mainly caused by the increased of bundles sheaths that surrounds all vascular bundles.

Root-system of peanuts as affected by phosphorus fertilization

There have been some responses of peanut roots to phosphorus. An experiment was carried out to study peanut root growth and distribution as related to P in the soil. The cultivars Tatu, Oira and Tup4 and the lines FCA 170 and FCA 265 were grown with or without P fertilization with 80 kg P2O5/ha, as triple superphosphate. The fertilizer was applied in the seed furrows. There was higher P contents in the 0-10 cm layer of the soil 36 days after P application. At 66 and 98 days after application, P contents of the soil were increased by fertilization down to 15 cm. There was no response of peanut roots to P fertilization. Oira showed the highest root lenght density and Tatu the lowert. There was a root concentration the first 15 cm of the soil. Oira with the largest root system showed the lowest P absorption, and Tatu, with the smallest root system absorbed as much P as the others.

Use of reduced concentrations of tetrazolium solutions for the evaluation of the viability of peanut seed lots

The possibility of reducing the concentration of the working solution used in the tetrazolium test for peanut seeds (Arachis hypogaea L.) with or without seedcoats was studied. Tetrazolium solutions of different concentrations (0.05%, 0.075% and 0.1%) were tested at the temperatures of 35 and 40 degrees C, for determining the time needed for the seeds to reach proper staining. The efficiency of the selected treatments in evaluating the viability potential of the seeds was determined by comparing the results of the tetrazolium tests with those obtained by standard germination (using sand and rolled paper towel as substrata) and seedling emergence in the field tests. Staining the seeds without seedcoat in 0.05% tetrazolium solution for three hours at 40 degrees C yielded efficient results. on the other hand, reduced concentrations can be employed in the staining process of seeds with seedcoat; however, this method requires a higher consumption of tetrazolium salt, longer staining time as well as a higher ability and availability of time for embryo evaluation, since the cross-cutting of seeds is much more difficult in the presence of the seedcoat and the occurrence of damage to the outer surface of the cotyledons cannot be determined.

Fruit maturation as a parameter for selection of sweet orange cultivars in Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)