Detection of Toxoplasma gondii DNA in Fresh and Frozen Semen from Rams in Brazil

The aim of this study was to estimate the prevalence of genomic DNA of Toxoplasma gondii in semen samples from commercial rams in artificial insemination centres in Brazil, as well as in fresh semen from rams in the northeast of Brazil. In total, 108 semen samples were obtained from artificial insemination centres, and genomic DNA of T. gondii was detected in 24 of 108 (22.2%). The prevalence of antibodies anti‐Toxoplasma gondii among sheep on rural properties was 9.2% (10/109), and 100% of the semen samples of these animals were positive in the PCR for T. gondii DNA. The molecular identity was confirmed through sequencing, which indicated 99.9% similarity with the T. gondii DNA sequences stored in the GenBank. This study reports the first occurrence of T. gondii DNA in the semen of rams, which came from artificial insemination centres in Brazil, as well as the occurrence of T. gondii DNA in the fresh semen of naturally infected rams in the northeast of Brazil.     

Rice Drying,Storage and Processing: Effects of Post-Harvest Operations on Grain Quality

Various post-harvest processes of rice are commonly employed, especially during the off-season, to ensure its consumption feasibility, which often affect the grain quality. Different forms of drying, storage and processing of rice are evaluated to identify their effects on grain quality. Microwave drying has emerged as an alternative to the widely-used intermittent-drying and fixed-bed-dryer methods of drying paddy rice. Control of drying-air temperatures (between 40 °C and 60 °C) according to the rice variety can improve quality, especially for exotic varieties. Keeping stored grain in hygroscopic balance, with water content between 11% to 15%, at temperatures between 16 °C and 20 °C and with intergranular relative humidity near 60%, allows 12 months of storage in a controlled environment without significant deterioration. Other innovations, notably the application of artificial refrigeration to grain stored in bulk in vertical cylindrical silos and the use of impermeable packaging for storage, ensure the conservation of grain mass. The different stages and equipments used to obtain polished, brown and parboiled rice result in significant changes in the nutritional value of rice because of the removal of the outermost layers of the grains. Polishing reduces the nutritional value and physical homogeneity of rice. Brown rice retains more bioactive compounds and nutrients because it does not lose the outer layer of the grains in the polishing processes. Parboiled rice, although less nutritious than brown rice, has better grain integrity and milling yield and less loss of nutrients than white rice.     

Geostatistical analysis of the spatial variation of the berry borer and leaf miner in a coffee agroecosystem

The advent of geostatistics and geographical information systems has made it possible to analyze complex spatial patterns of ecological phenomena over large areas in applied insect ecology and pest management. The objective of this study was to use geostatistics to characterize the spatial structure and map the spatial variation of damage caused by the berry borer (Hypothenemus hampei) and leaf miner (Leucoptera coffeella) in a coffee agroecosystem planted with the cultivar Catuai Vermelho IAC-99. Infestations of berry borer and leaf miner were evaluated in fruits and leaves, respectively. The pests were monitored at 67 georeferenced points in an area of 6.6 ha in 2005, 2006 and 2007. Variograms estimated by the method of moments (MoM) and residual maximum likelihood REML were compared. The latter were generally better in terms of the kriging error coefficients. Spherical variograms estimated by REML for berry borer infestation in fruits had ranges of spatial dependence of 34.62–118.4 m and for the leaf miner they were 53.93–133.7 m. For models fitted by weighted ordinary least squares (OLS) to the MoM experimental variogram, the ranges varied between 37.22 and 68.67 m for the berry borer and 100 and 155.4 m for leaf miner infestation. The variogram model parameters were used with the data for ordinary kriging to map the spatial variation of coffee pests for different monitoring periods. If there was no suitable variogram, inverse distance weighting was used to map the variation. The maps enabled visualization of the intensity of infestation of the insect pests for the different periods evaluated.     

Seed potato minituber production in an aeroponic system under tropical conditions: electrical conductivity and plant density

Abstract

Most seed potatoes in Brazil are produced in beds, pots or boxes containing substrate, but the yields are low. Aeroponic systems are one strategy for increasing the yield. However, the concentration of nutrient solutions, managed by varying the electrical conductivity (EC), is of upmost importance and can alter plant responses. Plant density is another important factor for obtaining high yields. The objective of this study was thus to determine the effect of nutrient-solution EC and plant density on plant and seed potato production in aeroponic system. The experimental design was a randomized block with a split-plot design and four replicates, with plots for EC and subplots for plant density. Two potato cultivars were tested. The best ECs for “Agata” and “Asterix” were 2.1 and 1.7?dS?m^?1, respectively. The highest plant density (100 plants m^?2) for both cultivars produced the highest minituber yield and economic feasibility.     

Effect of Nitrogen and Potassium Fertilization on Banana Plants Cultivated in the Humid Tropical Amazon

Banana (Musa spp.) is widely cultivated in tropical regions because of their economic importance for the local market as the source of food for the regional population. In the Amazon region, the banana crop was cultivated in the river basin before the 90th decade of the last century, but after the black sigatoka (Mycosphaerella fijiensis) and the increases of the bacteria wilt (Raostonia solanarum), the crops migrated to upper land soils with low natural fertility where there was no influence of floods for natural fertilization from the regional rivers. Nitrogen (N) and potassium (K) have been the foremost nutrient required by the banana trees and the aim of this study was to evaluate during two growing periods, the influence of the N and dipotassium oxide (K₂O) fertilization in yield and nutritional status of banana. The experimental design was a completely randomized blocks in a factorial 3 × 4 scheme with three replicates. The treatments were three N rates (0, 267, and 533 kg ha^?1) and four K₂O rates (200, 800, 1,600, and 2,400 kg ha^?1). The field plots had seven plants where the useful area had only five plants spaced 3 m × 2 m. The foliar N and sulfur (S) content were significantly influenced by the N rates, while foliar K, magnesium (Mg), and copper (Cu) were significant under the K₂O rates. The N, K₂O, and N × K₂O interaction interfered the foliar zinc (Zn) content. In both crop cycles, the bunch biomass and banana yield were not influenced by the N and K₂O rates.     

Modelling black Sigatoka epidemics with seasonal dispersal of Mycosphaerella fijiensis ascospores over a banana plantation in the Ribeira Valley,São Paulo,Brazil

Knowing the patterns of Black Sigatoka development is essential to propose adequate disease management practices and evaluate their effects, which can be achieved through temporal analysis by integrating the evolving interactions of the pathosystem components, expressed by data on cumulative incidence and severity, and summarizing these data in a disease progress curve. Airborne spores are essential components for the progression of an epidemic in the context of a specific pathosystem. In this perspective, the spore count is an essential approach to assess and model an epidemic. This study evaluated the temporal dynamics of Black Sigatoka in a banana plantation in the Ribeira Valley, state of São Paulo, Brazil, while simultaneously performing a year-long evaluation of fungal spore aerobiology. The disease was intense during the rainy season, but the leaf emergence rate was high enough for quickly inverting the severity peak (between 169 and 197 days of evaluation). After that, the disease severity raised until reach the higher rates (around the score 7 out of 8). The disease progress curve of Black Sigatoka showed peaks of extreme severity, one in the rainy and another in the dry season, with high levels of ascospores in the air. The ascospore concentration and the severity of the disease correlated significantly on the same day of sampling and 15 days after ascospore sampling, corresponding to the average latency period of the disease in the region. The patterns of the disease progress curve in both peaks fitted the monomolecular model, with higher rates of disease increase in the rainy season.

     

The effects of foliar spray application of silicon on plant damage levels and components of larval biology of the pest butterfly Chlosyne lacinia saundersii (Nymphalidae)

We investigated sunflower leaf palatability to Chlosyne lacinia saundersii Doubleday & Hewitson (Lepidoptera: Nymphalidae) in plants treated with silicon (Si) and subjected to mechanical injury. We also examined the effects of those treatments on plant development. The experimental study was carried out as a completely randomized design, consisting of the six treatments (10 replicates each): (1) control, (2) plants mechanically injured, (3) Si applied around the plant stem (Si drench), (4) Si drench + injured, (5) Si drench + foliar spray, and (6) Si drench + foliar spray + injured. Si drench + injured significantly reduced the percentage of caterpillar-injured leaves (CIL), leaf area consumed (LAC), and caterpillar weight (CW), leading to increased caterpillar mortality. The only intrinsic plant characteristic affected by the treatments was Si content (SiC), which was higher in plants treated with either Si drench + foliar spray or Si drench + foliar spray + injured. Negative correlations were observed between SiC and the variables CIL, LAC and CW, whereas positive correlations were observed between CIL and LAC, CIL and CW, and LAC and CW. The treatment strategy of Si combined with artificial mechanical injury affects leaf palatability and development of C. lacinia saundersii, conferring resistance to sunflower plants as a function of Si accumulation, although it did not increase crop vegetative variables.     

Effect of sulfur source and rates on yield and yield components of soybean in subtropical soils

Abstract

The supply of sulfur (S) fertilizers, such as phosphogypsum, to new agricultural frontiers has been hindered by the high cost of freight. However, this problem could be resolved by utilizing deposits of rock in the affected regions. Accordingly, a greenhouse study was designed to evaluate the effect of S source and rate on soybean yield. Five S rates (0, 50, 100, and 200?mg kg^?1) and five S sources (S-phosphogypsum, S-Niquelândia rock, S-Araripina rock, S-Grajaú rock, and S-Sulfurgran [90% S0?+?10% bentonite]) were applied to soybean grown in two soil types (Typic Ultisol and Typic Oxisol), which differ in clay content. Regardless of soil type, the application of P-phosphogypsum resulted in a higher grain yield. However, application of the other S sources also improved grain yield as well as total dry weight; S application, in general, improved soybean yield components (number of grains per pod, number of pods per pot, and weight of pods per pot), photosynthetic rate, chlorophyll content, and the S levels of leaves and grains as well as the available sulfate (SO₄^2-) levels in the soil. Therefore, for soybean grown in Typic Ultisol and Typic Oxisol, different S sources effectively improve a variety of variables that ultimately improve grain yield.     

Interaction of Glyphosate with Zinc for the Yield,Photosynthesis, Soil Fertility and Nutritional Status of Soybean

Application of glyphosate herbicide in genetically modified (GM) soybean [Glycine max (L.) Merrill] in soils with low zinc (Zn) concentration may interfere in the uptake of this and other nutrients, with negative impact on productivity. Thus, an experiment was conducted in greenhouse conditions on Ustoxix Quatzipsamment soil to investigate the effects of the interaction of glyphosate with Zn for the yield, photosynthesis, soil fertility and nutritional status of soybean. The treatments consisted of two soybean varieties [BRS 133 (conventional—NGM) and its essentially derived transgenic line BRS 245RR (GM) with and without glyphosate application] and five Zn rates (0, 5, 10, 20 and 40 mg kg^?1, source zinc sulfate (ZnSO₄)), with four replicates. Except for the copper (Cu) and iron (Fe) concentrations, the introduction of the herbicide-resistant gene is the predominant factor reducing nutrient uptake, photosynthetic (A) rate, stomatal conductance (Gs), leaf chlorophyll and ureide concentrations. The administration of Zn rates lowered the leaf phosphorus (P) concentration, and there was significant increase in Zn concentration in the soil and in the plant. Except for the 20 mg kg^?1 of Zn rate, the use of the herbicide did not affect the shoot dry weight (SDW) and seed yield, and on average, the maximum seed yield was obtained with Zn concentrations of 26.4 and 18.7 mg kg^?1 extracted by Mehlich 1 and diethylenetriaminepentaacetic acid-triethanolamine (DTPA-TEA), respectively.     

Bioavailability of Nutrients in Seeds from Tropical and Subtropical Soybean Varieties

The selection of varieties or species of plants with higher nutrient uptake efficiency and nutrient concentration for biofortification of food crops is a key tool to reduce malnutrition. Soybean (Glycine max L. Merr) is one of the most important food crops, because it is consumed directly or indirectly, in the form of seeds, processed (milk and/or derivatives), or used as a protein component of animal feed worldwide. In order to select plants with higher nutrients concentration in seeds, 24 soybean varieties for tropical and subtropical conditions and different general features were assessed. There was great variability in photosynthesis rate, chlorophyll content, seed yield (SY), and concentration and uptake of nutrients by seeds between the varieties. Not genetically modified (NGM) crops showed higher nitrogen (N), cooper (Cu), and manganese (Mn) concentration and higher N, potassium (K), Cu, iron (Fe), Mn, and zinc (Zn) uptake, while for genetically modified (GM) crops only calcium (Ca) concentrations were higher. Varieties BRS 284 and BMX Magna RR showed the highest nutrients concentrations in the group with the highest nutrient efficiency. The genetic variability observed among the varieties regarding uptake and translocation of nutrients into seeds allows selecting more promising materials to be used in the biofortification of nutrients in soybean seeds.