Nutritional evaluation of “Braquiarão” grass in association with “Aroeira” trees in a silvopastoral system

This study aimed at evaluating the influence of a silvopastoral system (SPS) composed of “Aroeira” trees (Myracrodruon urundeuva) on the nutritional value of Brachiaria brizantha cv. Marandu forage grass over the rainy season. The experiment was conducted in the SPS located in the “Cerrado” biome in Lagoa Santa County, Minas Gerais state, Brazil, in the agricultural year of 2004–2005. It was evaluated the influence of “Aroeira”, whose density in the area was 140 trees/ha, on the following parameters of the B. brizantha cv. Marandu forage grass: forage mass harvest above stubble height, morphogenic attributes, bromatological composition and nutritional value. The effects of “Aroeira” trees on the micro-climatic conditions were also evaluated. The experiment adopted a randomized block design with five blocks (cutting seasons), two treatments (a shaded pasture—B. brizantha cv. Marandu shaded by M. urundeuva—and a pasture in full sun—B. brizantha cv. Marandu in full sun), and three replicates. The tree component, composed of the tree species M. urundeuva in the experimental density adopted, increased dry matter and crude protein of the forage mass harvest above stubble height, without affecting the concentration of neutral detergent fibre or acid detergent fibre, thus causing dry matter and organic matter in vitro degradability as well as effective degradability of the forage grass to remain the same as those obtained in full sun. Therefore, the results of this study show the possibility of using trees and grass to increase both animal production and environmental services.     

Mono- and Multielement Sorption of Trace Metals on Oxidic Industrial By-products

Assessing multielement adsorption of trace metals on materials having potential to be used as soil amendments is an essential stage for the remediation success, as soil contamination rarely occurs with a single element. This study evaluated mono-/multielement adsorption of Zn, Cu, Cd, and Pb on aluminum (AMB) and iron mining by-products (IMB, used for comparison). Prior to adsorption, these products were characterized by X-ray diffraction, isoelectric point, infrared spectroscopy, scanning electron microscopy, and microwave furnace digestion. Sorption experiments comprised: (1) pH adjustment (5.5, 6.5, and natural suspension pH), (2) mono- and multielement adsorption, and (3) desorption. Rising pH from 5.5 to natural suspension values (9.5) increased monoelement adsorption of Zn, Cu, Cd, and Pb on AMB up to 3.8-, 1.4-, 6.2-, and 1.1-fold, whereas multielement adsorption was increased up to 17.3-, 2.0-, 20.3-, and 1.2-fold, respectively. Zinc and Cd were less adsorbed than Cu and Pb and more affected by competition. Multielement adsorption at 5.5 pH in AMB resulted in smaller adsorption of Zn (up to 4.6-fold), Cu (1.4-fold), Cd (3.3-fold), and Pb (1.1-fold) when compared with monoelement adsorption. The lower the pH, the smaller the adsorption and the higher the desorption. The AMB showed higher capacity to maintain the elements adsorbed than the IMB.     

Determination of the quality index of a Paleudult under sunflower culture and different management systems

Soil is an essential resource for life and its properties are susceptible to be modified by tillage systems. The impact of management practices on soil functions can be assessed through a soil quality index. It is interesting to assess soil quality in different soil types. Therefore, the aim of this study was to determine the soil quality index of a Paleudult under different management conditions and sunflower culture. The experiment was carried out in Botucatu (SP, Brazil), in an 11-year non-tilled area used for growing soybean and maize during summer and black oat or triticale in winter. Four management systems were considered: no-tillage with a hoe planter (NTh), no-tillage with a double-disk planter (NTd), reduced tillage (RT) and conventional tillage (CT). Soil samples were taken from the planting lines at harvest time. To determine the soil quality indices, following the methodology proposed by Karlen and Stott (1994), three main soil functions were assessed: soil capacity for root development, water storage capacity of the soil and nutrient supply capacity of the soil. The studied Paleudult was considered a soil with good quality under all the observed management systems. However, the soil quality indices varied between treatments being 0.64, 0.68, 0.86 and 0.79 under NTh, NTd, RT and CT, respectively. Physical attributes such as resistance to penetration and macroporosity increased the soil quality index in RT and CT compared to NTh and NTd. The soil quality indices obtained suggested that the evaluated soil is adequate for sunflower production under our study conditions. In view of the SQI values, RT is the most suitable management for this site since it preserves soil quality and provides an acceptable sunflower yield.     

Inferring phenotypic causal structure among farrowing and weaning traits in pigs

Direct selection for litter size or weight at weaning in pigs is often hindered by external interventions such as cross‐fostering. The objective of this study was to infer the causal structure among phenotypes of reproductive traits in pigs to enable subsequent direct selection for these traits. Examined traits included: number born alive (NBA), litter size on day 21 (LS21), and litter weight on day 21 (LW21). The study included 6,240 litters from 1,673 Landrace dams and 5,393 litters from 1,484 Large White dams. The inductive causation (IC) algorithm was used to infer the causal structure, which was then fitted to a structural equation model (SEM) to estimate causal coefficients and genetic parameters. Based on the IC algorithm and temporal and biological information, the causal structure among traits was identified as: NBA → LS21 → LW21 and NBA → LW21. Owing to the causal effect of NBA on LS21 and LW21, the genetic, permanent environmental, and residual variances of LS21 and LW21were much lower in the SEM than in the multiple‐trait model for both breeds. Given the strong effect of NBA on LS21 and LW21, the SEM and causal information might assist with selective breeding for LS21 and LW21 when cross‐fostering occurs.     

Effect of seed phosphorus concentration on nodulation and growth of three common bean cultivars

Abstract

An experiment was conducted in the greenhouse to evaluate the effects of seed phosphorus (P) concentration on growth, nodulation, and nitrogen (N) and P accumulation of three common bean (Phaseolus vulgaris L.) cultivars. Seeds were produced under low or high soil P levels, and soaked, or not, in 200 mM KH₂PO₄ solution. The experiment had a 3×3×2×2 factorial block design: three cultivars (ICA Col 10103, Carioca and Honduras 35), three levels of applied P (15, 30 and 45 mg P kg^?1 soil), two native seed P concentrations, and two seed soaking treatments. Plants were harvested at flowering. Soaked seeds increased the number, dry mass and P content of nodules, but did not affect plant growth. Plants originated from seeds with high native P concentration presented higher shoot dry mass and nodule number and mass at every soil P level, and were less responsive to increased soil P supply, than plants from low seed P. In plants from seeds with high P, soil P levels did not alter significantly root dry mass, while in plants from seeds with low P bean cultivars expressed wider differences in root dry mass. The genotypic variability of nodulation was influenced by soil P levels and seed P concentration. Both higher soil or seed P supply enhanced N and P accumulation in shoots. These results indicate that a high seed P concentration produces plants less dependent on soil P supply, and can enhance nodulation and N₂ fixation of common bean. Seed P supply affected the cultivar performance, and should be considered in evaluation of bean genotypes.     

EFFECT OF DELAYED EMERGENCE ON CORN (ZEA MAYS L.) GRAIN YIELD

Uneven crop stands result in a reduction in corn yield production. This study was conducted to determine the effect of delayed emergence on corn yields and the effect of nitrogen (N) applications to compensate for yield reductions. The design used was a randomized complete block, with 4 sequences of delayed planting (0,4,7,and 10 days after planting) and 3 rates of nitrogen fertilizer (0, 40, 80 kg N ha^?1). At maturity, individual plants were tagged in sets of three and hand harvested. Corn ears were shelled, and yield per plant calculated. Grain yield of the delayed plant compared to that of the neighbors was reduced by 27, 8, 20 and 12 kg ha^?1day^?1 for 2007 LCB1, 2007 LCB2, 2010 LCB1 and 2010 LCB2, respectively. Over locations and years, the mean grain yield decrease of the delayed plant versus neighboring plants for each day delay was 122 kg ha^?1.     

Effect of Equilibrium Solution Ionic Strength on the Adsorption of Zn,Cu, Cd,Pb, As,and P on Aluminum Mining By-Product

Adsorption onto powdered activated carbon (PAC) is a promising option to remove organic micro-pollutants (OMP) from drinking water sources or wastewater. Since this treatment option requires continuous PAC dosing, sufficient contact time and subsequent separation of the PAC, the integration into existing process chains is challenging. In the present investigation, the pre-loading of a deep bed filter with PAC used as fixed bed adsorber was investigated. The retention and distribution of an exemplary PAC in a pumice rapid filter were determined. Gravimetry combined with combustion of the PAC at 550 °C was applied to differentiate between PAC and filter material residues and revealed comparably high PAC immobilization in the upper third of the pumice filter. Comparative adsorption experiments in batch with suspended PAC and continuous filtration tests with immobilized PAC showed advantageous results for immobilized PAC with regard to the removal of OMP and the sum parameters dissolved organic carbon and UV light absorption at 254 nm wavelength. The results indicate that a conventional rapid filter together with PAC can be effectively utilized as fixed bed adsorption filter.     

Ineffectiveness of pruning to control citrus huanglongbing caused by <Emphasis Type="Italic">Candidatus</Emphasis> Liberibacter americanus

The huanglongbing (HLB) disease of citrus trees, caused by Candidatus Liberibacter asiaticus and Ca. Liberibacter americanus, was first reported in Brazil in March, 2004. The presence of the disease has caused serious concerns among growers. Pruning experiments were conducted to determine if removal of symptomatic branches or the entire canopy (decapitation) would eliminate infected tissues and save HLB-affected trees. Pruning was done in five blocks on a total of 592 3- to 16 year-old ‘Valência’, ‘Hamlin’ or ‘Pêra’ sweet orange trees showing no symptoms or with two levels of symptom severity. Ten decapitated trees per block were caged and all trees were treated with insecticides to control the psyllid vector, Diaphorina citri. Mottled leaves reappeared on most symptomatic (69.2%) as well on some asymptomatic (7.6%) pruned trees, regardless of age, variety, and pruning procedure. Presence of the pathogen (Ca. Liberibacter americanus) in all symptomatic trees was confirmed by PCR. In general, the greater the symptom severity before pruning the lower the percentage of trees that remained asymptomatic after pruning.     

Lippia alba (Verbenaceae) hydrolate as sedative of tambaqui (Colossoma macropomum) juveniles in simulated transport conditions

Lippia alba hydrolate (LAH) is produced as a secondary product in essential oil extraction. The objective of this study was to evaluate the use of LAH in a simulation of the transport of tambaqui (Colossoma macropomum) juveniles. A series of 17 hr simulations were performed using load densities of 30, 60 and 90 juveniles per L and four LAH concentrations of 0.4%, 1%, 2% and 5%, with a control of just water. Fish survival, temperature, dissolved oxygen, conductivity, pH, ammonia excretion, alkalinity water hardness and net Na⁺, K⁺, Cl^‐ fluxes, were all evaluated before and after the transport simulations. Mucous cell densities in the gills were also determined microscopically, post simulation. The results showed that addition of 5% LAH achieved better survival during the simulation than the water control. Dissolved oxygen was significantly lower with an increased load density. Also, conductivity, NH₄ excretion and net ionic fluxes (K⁺ and Cl^?) were lower with 5% LAH, although mainly where higher load densities were tested. Mucous cell density was lower in LAH concentrations of 2% and 5%, again with higher load densities. In view of these findings, it is suggested that 5% LAH is an effective sedative for use in the transport of tambaqui, mainly with high load densities. This work is the first study of LAH and highlights its potential applications in aquaculture management.