Resumo em Inglês:

ABSTRACT: Crop coefficient (Kc) is the ratio between crop evapotranspiration (ETc) and reference evapotranspiration (ETo), representing the phenological effects on crop water consumption. Kc is fundamental to estimating ETc by agrometeorological methods. This research study aimed to determine Kc and ETc values for Guinea grass (Megathyrsus maximus cv. Mombaça) and Bermuda grass (Cynodon spp.), both single cropped for one year and overseeded with black oat (Avena strigosa) and ryegrass (Lolium multiflorum) during fall/winter. The experiment in the field comprised four plots, two for each tropical forage, with and without overseeding. At the center of each plot, there was a weighing lysimeter with an automated system for data collection. ETc was measured daily over four seasons following the lysimetric method; ETo was calculated using the Penman-Monteith equation. ETc and ETo values were used to estimate Kc values. The single cropped Guinea grass showed the highest values for ETc, with mean ETc and Kc of 3.99 mm d–1 and 1.07, respectively. The single cropped Bermuda grass showed ETc and Kc values of 3.57 mm d–1 and 0.96, respectively. The results of paired t-testing for Kc showed no significant differences (p = 0.05) between single cropped and intercropped for both Guinea grass and Cynodon spp. During winter, intercropped Guinea grass did not show an ETc significantly higher than single cropped Guinea grass, with mean Kc values 0.98 for intercropped and 1.10 for single cropped. Similarly, Bermuda grass did not show significant differences between mean Kc values for intercropped (1.02) and single cropped (1.00).

Resumo em Inglês:

ABSTRACT: Interest in improving feed efficiency of cattle has been increasing. The residual feed intake (RFI), the most commonly used measurement of feed efficiency, is expensive and can only be used in a small number of animals. The Kleiber Index has also been proposed to measure RFI. In this study, we estimated genetic parameters for the Kleiber Index average daily weight gain and adjusted weights to obtain a more comprehensive understanding of potential responses to selection and support the development of breeding strategies. Genetic analyses were conducted on animal records from a data file with 36,505 animals recorded by ABCZ (Brazilian Association of Zebu Breeders). Restricted maximum likelihood estimates of genetic parameters were computed with Wombat software. Heritabilities ranged from 0.24 to 0.22 for adjusted weights, from 0.12 to 0.26 for Kleiber Indexes and from 0.15 to 0.22 for average daily gains. Correlations between traits ranged from -0.06 to 0.99. Results indicated that Kleiber Indexes at different ages do not constitute a viable solution for the selection of bulls and cows for Brazilian Brahman populations in terms of feeding efficiency.

Resumo em Inglês:

ABSTRACT: Gossypol easily pairs with lysine side chains and enzymes involved in the cellular growth process. The effect of gossypol (a compound present in cotton co-products) in ruminant metabolism and meat quality is not yet clear. This study was undertaken in order to evaluate the effects of cotton co-products in lamb muscle proteome. Twenty-four Santa Inês ram lambs, 5-months old (20.6 ± 1.9 kg), were randomly assigned to four treatments: control (without cottonseed), whole cottonseed, cottonseed meal and high oil cottonseed meal. At 95 days into the experiment, lambs were slaughtered and samples from Longissimus dorsi were collected. Proteins were extracted and analyzed by 2-D electrophoresis. Spots showing a significant effect from the treatment (the “treatment effect”) and present in more than 90 % of the samples were identified using mass spectrometry. Cotton co-products decreased the abundance of aldehyde and malate dehydrogenases, creatine kinase M-type and Adenosine triphosphate (ATP) synthase. They also increased four proteins related to muscle contraction. Thus, feeding cotton co-products to lambs changed the abundance of important muscle proteins. A cotton co-product diet induced a negative impact on the energy supply of muscle cells and, consequently, the abundance of ATP dependent proteins (contractile apparatus) increased, probably in order to offset and maintain muscle function. These proteomic changes can promote our understanding of alterations in the sensorial properties of meat due to cotton co-product diets in further investigations.

Resumo em Inglês:

ABSTRACT: Although water deficit and iron deficiency chlorosis are common environmental stresses in the Mediterranean area, few data are reported in the literature on their effects on vineyards, when acting simultaneously. The main objective of this research was to study the combined effects of iron deficiency and water status on vigor, yield and fruit composition in rainfed vineyards. Moreover, the investigation aimed to evaluate the feasibility of using foliar chlorophyll content (Chl) and predawn leaf water potential (LWP), measured at veraison, to assess potential quality of grapes in the framework of precision viticulture. For this, 24 non-irrigated ‘Tempranillo’ vineyard subzones were monitored in Ribera del Duero (North-Central Spain) during three consecutive seasons (2011-2013). The analysis of variance and principal component analysis showed that malic acid concentrations of the must were impacted only by Chl, whereas total soluble solids and total acidity were mainly modified by LWP. Both water and iron status reduced yield and berry weight and had additive effects on extractable anthocyanin content in grapes, total polyphenol index and color density of the must. In all seasons, the ratio Chl/LWP had a better predicting value for quality parameters of these grapes than leaf area index, Chl or LWP individually. The present work demonstrates the potential interest of physiological indexes combining water status and foliar chlorosis as indicators of grape phenolic potential in rainfed vineyards affected by iron deficiency.

Resumo em Inglês:

ABSTRACT: Raspberry (Rubus idaeus L.) is an economically important crop and its cultivation has been expanded across temperate and subtropical regions of Brazil. Growing raspberries under plastic cover has becoming more common worldwide. This study investigated the effect of plastic cover on productive and morphological performance of primocane-fruiting raspberry cultivars, in southern Brazil. The experiment was arranged in a 3 × 2 × 2 factorial design, with three raspberry cultivars, ‘Heritage’; ‘Fallgold’ and ‘Alemãzinha’; two cultivation systems, presence and absence of plastic cover; and two production cycles, fall and spring. We measured days from transplanting to flowering and harvesting. Plants were evaluated for dry mass of pruning, plant height, stem diameter, plant leaf area, fruit production, number of fruits, fruit weight, fruit longitudinal and transversal diameter, and harvesting period. Plastic cover reduced incident radiation on the canopy by 17 %. Cultivar ‘Heritage’ is early ripening in the fall cycle. The management under plastic cover prolonged the harvesting period of raspberries in the fall productive cycle for the cultivar ‘Heritage’ and, in spring, for cultivars ‘Alemãzinha’ and ‘Fallgold’. In the spring cycle, plants increased their leaf area, fruit production and number of fruits. The cultivar ‘Alemãzinha’ performed better in the spring cycle when managed under plastic cover and was more productive, with a longer productive cycle and larger fruits.

Resumo em Inglês:

ABSTRACT: Asian citrus psyllid, Diaphorina citri, is considered the most important citrus pest worldwide, as it transmits Huanglongbing – serious citrus disease. New efficient and sustainable strategies to control this pest have been investigated and the use of entomopathogenic fungi has become a promising alternative. The objective of this study was to evaluate the effects of adjuvants a) Tween 80 at 0.01 % (v/v); b) Silwet L77 at 0.025 % (v/v) and c) KBRAdj at 0.075 % (v/v) on adhesion, germination and pathogenicity of Isaria fumosorosea ESALQ-1296(5 × 106 conidia mL–1). Female adults of D. citri used in this experiment were sprayed on Citrus limonia seedlings. The sprayed insects were analyzed through scanning electron microscopy (SEM) to identify the most susceptible integument regions for fungus attachment and the effect of adjuvants used. In the pathogenicity test, adjuvants Silwet L77 and KBRAdj presented a higher efficiency than Tween 80. Fungi adhered predominantly to the ventral posterior (abdomen) region in comparison with the dorsal anterior (thorax) region. In addition, adjuvants Silwet L77 and KBRAdj presented faster germination (< 48 h) of I. fumosorosea spores when compared to Tween 80 (> 72 h). Conidial germination in the dorsal part of the thorax of the insects was observed only with adjuvant KBRAdj 72 h post inoculation.

Resumo em Inglês:

ABSTRACT: Tolerance to acid soil is an important trait of Eucalyptus and Pinus species introduced into commercial forestry plantations in tropical ecosystems. The objective of this study was to evaluate the effect of the exchangeable Al on growth of the seedlings of two species and one hybrid of Eucalyptus and two species of Pinus. We also wanted to identify the role of the root cation exchangeable capacity (CEC) on Al tolerance. The experiment was conducted under controlled conditions in a greenhouse. The soil used was collected from the top layer of a red yellow Oxisol, from the Brazilian savanna region. The treatments consisted of different rates of P and the presence or absence of liming with CaCO3 and MgCO3. The species of Eucalyptus and Pinus showed no growth differences between the treatments. For all species, a higher density of fine roots was found in treatments with lower levels of bases and a higher Al exchangeable concentration. The Pinus species had a higher root CEC than the Eucalyptus species, which had a lower leaf Al concentration. Al concentration in the fine roots was 50 fold greater than in the leaves of all species. Similar to Al, concentrations of Fe, Cu and Zn in the roots were significantly higher than in the leaves in all species. In contrast, higher Mn concentration was found in the leaf tissue. This may lead species of Eucalyptus and Pinus to be more susceptible to Mn than to Al toxicity.

Resumo em Inglês:

ABSTRACT: Management systems to improve soil quality are essential for agricultural and environmental sustainability. We assessed the quality of soil management systems applied to a subtropical Acrisol in terms of the carbon management index (CMI), the stratification ratio for total organic carbon (SR-TOC) and light fraction of organic matter (SR-LF). In addition, we examined their relationship to chemical, physical and biological soil quality indicators, as well as to maize yield. The study was conducted on a long-term experiment (18 years) in southern Brazil involving two different systems [no tillage (NT) and conventional tillage (CT)], two cropping systems [black oat/maize (O/M) and black oat + vetch/maize + cowpea (OV/MC)] and two nitrogen fertilizer rates for maize (0 and 180 kg ha–1). Based on the three indices, the best managements for soil quality comprised NT (50-212 % better than CT), legume cover crops (10-47 % better than O/M) and N fertilization (8-33 % better than no fertilizer). All three indices proved accurate to assess the impact of soil management systems, especially SR-LF, which showed increased sensitivity and close relationships with chemical, physical and biological soil quality indicators. On the other hand, a poor relationship was observed between soil C indices and maize yield, which was improved only by legume cover crops and N fertilization. The results showed that the association of no-till system to an abundant supply of crop residues is key to ensure high soil quality and crop yields in humid subtropical regions.

Resumo em Inglês:

ABSTRACT: Mechanical sugarcane harvesting increases soil compaction due to the intense traffic of agricultural machinery, reducing longevity of sugarcane crops. In order to mitigate the harmful effects caused by agricultural traffic on the soil structure in sugarcane fields, this study evaluated impacts of mechanical sugarcane harvesting on traffic lane under two soil tillage systems based on load bearing capacity models. The experiment was carried out in the region of Piracicaba, state of São Paulo, Brazil, on a Rhodic Nitisol, under conventional tillage (CT) and deep strip-tillage (DST). For CT soil tillage was applied to the entire area with a heavy disk harrow, at operating depths from 0.20 to 0.30 m followed by a leveling harrow at a depth of 0.15 m. For DST, soil tillage was performed in part of the area at a depth of 0.80 m, forming strip beds for sugarcane planting, while the traffic lanes were not disturbed. Undisturbed soil samples from traffic lanes were used in the uniaxial compression test to quantify preconsolidation pressure and to model the soil load bearing capacity. The surface layer (0.00-0.10 m) was most susceptible to compaction, regardless of the tillage system (CT or DST) used. In the DST, the traffic lane maintained the previous soil stress history and presented higher load bearing capacity (LBC) than the traffic lane in the CT. As in CT the soil was tilled, the stress history was discontinued. This larger LBC in DTS minimized the impacts of the sugarcane harvest. Under CT, additional soil compaction due to mechanical sugarcane harvesting in the traffic lane was observed after the second sugarcane harvest. There was a reduction in load bearing capacity from 165 kPa to 68 kPa under CT and from 230 kPa to 108 kPa under DST, from the first to the second harvest at surface layer. Water content at mechanical harvesting was the most relevant factor to maximize impacts on the soil structure in traffic lanes, for both tillage systems.

Resumo em Inglês:

ABSTRACT: Soil management systems exert different effects on soil attributes, especially on the organic matter content, and, consequently, the soil aggregation. The aim of this study was to evaluate the impact of different land uses practiced by quilombola family farmers on water stable aggregates, glomalin and organic carbon in soil aggregates. Soil samples were collected at depths of 0-10 and 10-20 cm from areas cultivated under the following management systems: 1) conventional corn plantation (MA), 2) cultivation of citrus trees intercropped with annual crops (AC) (a conservationist approach), 3) pasture of Brachiaria (Urochloa spp.) (PA), and, as reference, an area of the Cerrado (CR) free of any anthropogenic interference. The studied areas were evaluated in a completely randomized design, with five replications, in a subplot scheme. The plots were the management systems and the subplots the depths. Soil macro-aggregates were predominant at both depths and the aggregate stability indices were higher than 90 % for all management systems. Total organic carbon in the two aggregate classes (micro and macro-aggregates) correlated with the MWD (mean weight-diameter), but not with the easily extractable glomalin (EEG) related soil protein. Soil micro and macro-aggregates, EEG and MWD discriminated management systems and are important soil quality indicators. The carbon content in both micro-aggregates (C-MIC) and macro-aggregates (C-MAC) of the intercropped system (AC) was higher than in the CR. The soil attributes that best separated the areas were C-MIC, MWD and EEG in macro-aggregates for the depth of 0-10 cm, and EEG in micro-aggregates, together with MWD and C-MAC for the depth of 10-20 cm.

Resumo em Inglês:

ABSTRACT: Crude glycerol is a major by-product of biodiesel production and is an economical additive feed for ruminants. However, residual methanol in crude glycerol can be harmful to animal health. Several methods exist for quantifying methanol residues in biodiesel, yet few have been described that identify the methanol level in crude glycerol. We propose a method for determining the methanol level in crude glycerol destined for animal feed. Crude glycerol was extracted from the headspace and quantified by gas chromatography using a flame ionization detector (GC-FID). The method was linear up to 0.5 % of methanol. The limits of detection (LOD) and quantification (LOQ) were 0.015 and 0.031 %, respectively. No significant matrix effects were observed. Precision was 2 % at the 0.05 and 0.5 % levels. The average percentage of recovery was 90 %. Three analyzed samples of crude glycerol had methanol residues of 0.027-7.802 %. Furthermore, this methanol quantification method may be externally or internally calibrated using a GC manual injector. A reduction of at least 20 % in running time was obtained with good resolution between the peaks. Thus, this method can be applied to determine the methanol level in crude glycerol according to the upper limits for animal feed (5,000 ppm) and for human consumption (150 ppm). Finally, this method is useful for the quality control of crude glycerol intended for use in animal feed, enabling the alternative use of this by-product to add value to the biodiesel production chain.