Resumo em Inglês:

In grass conservation systems, drying in the field is an essential process upon which the quality and quantity of the material to be conserved is dependent on. In this study a Computational Fluid Dynamics (CFD) model, previously validated, was used to assess qualitatively and quantitatively the field drying process of cut grass under different weather conditions and structural specifications of the grass. The use of the CFD model depicts the climate heterogeneity in the grass area with a special focus on moisture distribution, influence of the weather conditions, in order to create the possibility of applying the model as a decision support tool for an enhanced treatment of the grass after cutting.

Resumo em Inglês:

Dry mass production and persistence of Panicum maximum pastures depends on nitrogen supply. Defoliation influences N uptake and allocation patterns yet its effects on plasticity of N dynamics in P. maximum have not been investigated. Stable isotopes of N (15N) were used in order to test the hypothesis that defoliation in terms of proportion of the leaf area removed effects N mobilisation, uptake and allocation patterns in P. maximum. The plants were initially cut weekly to a height of either 0.15 m or 0.30 m for seven weeks. Eight weeks after the first defoliation, all plants were defoliated for a final time to remove 0, 25, 50, 75 or 100 % of the area of each individual leaf blade of the main tiller. Root N uptake was reduced when all leaf area was removed, but more lenient defoliation improved N uptake due to a positive effect on specific N uptake. Young leaves, side tillers and roots were the main sinks for N from root uptake. Roots of P. maximum became a net source of N for mobilisation immediately after severe defoliation. Root uptake was the main source of N for new growth in P. maximum plants. Allocation pattern of mobilised N was different from that of N derived from root uptake. It was concluded that adaptation of P. maximum to defoliation is related to plasticity of N uptake, mobilisation and allocation, but changes in N dynamics did not offset negative impacts of complete defoliation of the plants.

Resumo em Inglês:

Effects of meteorological variables on crop production can be evaluated using various models. We have evaluated the ability of the Hybrid-Maize model to simulate growth, development and grain yield of maize (Zea mays L.) cultivated on the Loess Plateau, China, and applied it to assess effects of meteorological variations on the performance of maize under rain-fed and irrigated conditions. The model was calibrated and evaluated with data obtained from field experiments performed in 2007 and 2008, then applied to yield determinants using daily weather data for 2005-2009, in simulations under both rain-fed and irrigated conditions. The model accurately simulated Leaf Area Index , biomass, and soil water data from the field experiments in both years, with normalized percentage root mean square errors < 25 %. Gr.Y and yield components were also accurately simulated, with prediction deviations ranging from -2.3 % to 22.0 % for both years. According to the simulations, the maize potential productivity averaged 9.7 t ha-1 under rain-fed conditions and 11.53 t ha-1 under irrigated conditions, and the average rain-fed yield was 1.83 t ha-1 less than the average potential yield with irrigation. Soil moisture status analysis demonstrated that substantial potential yield may have been lost due to water stress under rain-fed conditions.

Resumo em Inglês:

Several biological phenomena have a behavior over time mathematically characterized by a strong increasing function in the early stages of development, then by a less pronounced growth, sometimes showing stability. The separation between these phases is very important to the researcher, since the maintenance of a less productive phase results in uneconomical activity. In this report we present methods of determining critical points in logistic functions that separate the early stages of growth from the asymptotic phase, with the aim of establishing a stopping critical point in the growth and on this basis determine differences in treatments. The logistic growth model is fitted to experimental data of imbibition of araribá seeds (Centrolobium tomentosum). To determine stopping critical points the following methods were used: i) accelerating growth function, ii) tangent at the inflection point, iii) segmented regression; iv) modified segmented regression; v) non-significant difference; and vi) non-significant difference by simulation. The analysis of variance of the abscissas and ordinates of the breakpoints was performed with the objective of comparing treatments and methods used to determine the critical points. The methods of segmented regression and of the tangent at the inflection point lead to early stopping points, in comparison with other methods, with proportions ordinate/asymptote lower than 0.90. The non-significant difference method by simulation had higher values of abscissas for stopping point, with an average proportion ordinate/asymptote equal to 0.986. An intermediate proportion of 0.908 was observed for the acceleration function method.

Resumo em Inglês:

Fish consumption per capita in Brazil is relatively modest when compared to other animal proteins. This study analyses the influence of protein prices, other food prices and population income on the fish demand in Brazil. First, the problem of fish supply in Brazil is characterized. It is followed by reviews of the relevant economic theory and methods of Almost Ideal Demand System - AIDS and their elasticity calculations. A descriptive analysis of fish demand in Brazil using the microdata called "Pesquisa de Orçamento Familiar" (Familiar Budget Research) - POF 2002-2003 is presented. Finally, demand functions and their elasticities are calculated for two different cases: one considering five groups of animal proteins (Chicken; Milk and Eggs; Fish; Processed Proteins and Red Meat) and other with seven groups of food categories (Cereals; Vegetables and Fruits; Milky and Eggs; Oils and Condiments; Fish; Other processed foods; and Meats). The main results are: per capita consumption of fish (4.6 kg per inhabitant per year) is low in Brazil because few households consume fish. When only households with fish consumption are considered, the per capita consumption would be higher: 27.2 kg per inhabitant per year. The fish consumption in the North-East Region is concentrated in the low-income class. In the Center-South Region, the fish consumption is lower and concentrated in the intermediate income classes. The main substitutes for fish are the processed proteins and not the traditional types of meat, such as chicken and red meat.

Resumo em Inglês:

Sugar snap pea (Pisum sativum L. var. macrocarpon Ser.) is an edible-podded sweet pea that is being considered as a new totally mechanized crop to supply raw material to the agri-food industry of the Ebro Valley (Northern Spain). It is of great interest from an agronomic and commercial standpoint but neither its agronomic behaviour nor its adaptation to the area are known. The objective of this study was to determine the effect of sowing date and seed density on the growth and yield of the sugar snap pea at industrial scale. Six randomized blocks experiments with four replicates were conducted on irrigated land in Villafranca (Navarra, Spain) in 1998, 1999, and 2000. Three experiments for testing sowing dates (Mar., Apr., and May) and another three for seed densities (from 75 to 150 plants m-2) were performed. Phenological development, thermal integral and qualitative and quantitative yield controls were performed. Sugar snap pea required 960 ºC d-1 (Tb = 3 ºC) from sowing to harvest. The early sowings gave more biomass, but yield was similar. However, Harvest Index and crop morphology varied. The sowing densities had similar yields sowing that sugar snap pea has a bigger adaptation availability. Sugar snap peas can be satisfactorily cultivated at industrial scale in the zone with sowings between Mar. and May and with seeding densities between 75 and 150 plants m-2.

Resumo em Inglês:

Olive (Olea europaea L.) production in the world has been made by using many cultivars, and the genetic uniformity of commercial cultivars is important for standard olive oil and table olive production. The genetic variation among and within commonly cultivated olive cultivars in Turkey was analyzed using SSR markers. A total of 135 leaf samples were collected from 11 commonly cultivated olive cultivars from 11 provinces in four geographical regions of Turkey. Seven SSR primer pairs generated 46 SSR markers, and the number of SSR markers per primer pair ranged from 4 (UDO-14) to 9 (GAPU-89) with an average of 6.57. This high level of SSR polymorphism suggests that olive production in Turkey has been made using genetically diverse olive cultivars and this high level of genetic variation is probably due to the location of Turkey in the center of the origin of olive. The UPGMA dendrogram, developed to visualize the estimated genetic relationships among the 135 samples, demonstrated that the clustering of olive cultivars was not based on geographical regions of cultivation. Presence of genetic variation was detected within a nationwide grown Turkish olive cultivar, called 'Gemlik'. Olive growers successfully discriminated olive cultivars with distinct morphological and pomological characters. However, there was some confusion about the identification of cultivars with similar phenotypic traits. To prevent misidentification of olive cultivars and to minimize intra-cultivar variation, certified propagation materials which were characterized using DNA based molecular markers should be used during the establishment of new olive orchards.

Resumo em Inglês:

Lipids have been used in ruminant feed to replace high amounts of grain for increasing the diet energy density, performance and meat quality. This study evaluated the qualitative characteristics of meat from feedlot heifers fed with sources of lipid supplements. Twenty-one crossbred heifers (1/4Nelore × 1/4Santa Gertrudis × 1/2Braunvieh) were used. Each heifer received 60 % forage with a base of corn silage and 40 % concentrate, resulting in 5.8 % lipid content in the total diet. The following sources of lipids were used: soybeans, protected fat and soybean oil. There were no differences on physical characteristics of meat samples from heifers fed with the lipid sources. Soybeans increased the concentration of linoleic acid, content of polyunsaturated fatty acid and activity of the Δ9-desaturase C16 enzyme in the Longissimus muscle. The use of soybean oil in the diet increased the oleic acid, monounsaturated fatty acid, total cis- and trans-fatty acids (C18:0) and the activity of the Δ9-desaturase C16 enzyme in the subcutaneous fat. Diets with soybean grain had greater deposition of linoleic and linolenic acids than diets with fat protected and greater presence of these essential fatty acids are associated to a better composition and meat quality.