Scielo RSS <![CDATA[Scientia Agricola]]> vol. 75 num. 5 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[Crude glycerin in co-composting with laying hen manure reduces N losses]]> ABSTRACT: The composting of laying hen manure is an efficient way of treating waste and producing an organic fertilizer with excellent characteristics; however, the high N losses reduce its concentration in the resulting fertilizer. Associating this residue with crude glycerin (CG) promotes a better C:N ratio and contributes to higher N retention during composting, with improvements in solids reduction and production of organic fertilizer with higher concentration of this nutrient. We carried out this research considering the hypothesis that adding CG – a byproduct of biodiesel production – to laying hen waste composting provides better N retention in the fertilizer generated. Increasing CG doses (0, 3, 6, 9, and 12 % in relation to the fresh mass in the windrows) were added to the laying hen manure with windrows composted for 70 days. A reduction by 100 % in total and thermotolerant coliforms occurred at all levels of CG addition. The maximum reductions in total (TS) and volatile (VS) solids were 64 and 76 %, respectively, and occurred with the addition of 6 % CG. The windrows that did not receive CG had higher N losses during the process (32 %) while the highest N concentration in the compost was 5 % at 6 % CG. We identified that adding 6 % CG to the laying hen manure in co-composting increases the reductions in TS and VS and provides higher N retention, which improves the quality of the organic fertilizer. <![CDATA[Bioprospecting and selection of growth-promoting bacteria for <em>Cymbidium</em> sp. orchids]]> ABSTRACT: Inoculants containing bacteria which promote growth in plants can increase productivity and both the economic and the environmental cost in plant crop systems. Similarly, in the flower and ornamental plant sector, the use of diazotrophic bacteria is a promising approach for improving orchid propagation from tissue culture to the ex vitro environment. We isolated diazotrophic bacteria from the roots and leaves of Cymbidium sp. The isolates were used to inoculate Cymbidium sp. plantlets during acclimatization in the nursery. After 150 days, plants were collected and their morphological and nutritional characteristics assessed. Eight bacterial strains were isolated containing traits that promote plant growth: Bacillus thuringiensis, Burkholderia cepacia, Burkholderia gladioli, Herbaspirillum frisingense, Pseudomonas stutzeri, Rhizobium cellulosilyticum, Rhizobium radiobacter, and Stenotrophomonas maltophilia. The isolated Herbaspirillum frisingense and Stenotrophomonas maltophilia increased 26 % and 29 % in dry matter in Cymbidium sp. plants, respectively, compared to the control. In addition, H. frisingense led to higher contents of N and P, by 68 % and 28 %, respectively, than those found in the control plants. These isolates, therefore, have potential for application as biostimulants and biofertilizers to promote growth and development of Cymbidium sp. during acclimatization. <![CDATA[Screening a bacterium and its effect on the biological degumming of ramie and kenaf]]> ABSTRACT: Biological degumming is an eco-friendly, efficient, high-quality and low-cost method that has become the leading bast fiber degumming technology. However, bacterial strains with short degumming cycles, high gum removal rates and small fiber damage are few. To screen high quality microbial resources with bast-fiber biological degumming function, soil samples were collected from a continuously cultivated banana plantation and then used to be enriched by ramie and kenaf materials in turn. A selective pectin-degrading medium was used to screen for excellent bacteria. A dominant bacterial strain was identified by phenotypic and genotypic characteristics, and its biological degumming effects on ramie and kenaf were verified by a comprehensive evaluation system. Results showed that seven bacterial strains secreting pectinase were obtained and the largest hydrolysis circle with a diameter ratio H/C of 2.4 was produced by the bacterial strain hn1-1, which was preliminarily identified as the Bacillus cereus by colony morphological characteristics and 16S rDNA sequence (GenBank accession number: KX013542) cluster analysis. The fiber production of ramie and kenaf degummed by B. cereus hn1-1 for 10 h were 72 % and 76 %, the residual gum rates were 4 % and 5 %, respectively. These values satisfied the textile industry requirement of &lt; 6 % residual gum rate. Therefore, an effective biological degumming bacterium, B. cereus, was identified using a pectin-hydrolysis selective medium through a simple, economical, and time-saving method. Furthermore, the biological degumming technology by B. cereus for ramie and kenaf had a short cycle, ideal removal gum rate, and high-quality and productive fiber output. <![CDATA[Abscisic acid and ethephon treatments applied to ‘Verdejo’ white grapes affect the quality of wine in different ways]]> ABSTRACT: Exogenous ethephon and abscisic acid (ABA) treatments are used worldwide to improve the coloring of red table grapes, but there is little information about their impact on the quality of white grapes and wines. The aim of this work was to evaluate the effects of exogenous ethephon and ABA applications at veraison on the composition of ‘Verdejo’ white grapes, and on the quality of their wines. To attain this objective, a field trial was carried out in a ‘Verdejo’/110 Richter vineyard located in north-central Spain. Two levels of ethephon (0 and 1500 mg L−1) and ABA (0 and 800 mg L−1) were sprayed on clusters at veraison, in a factorial design for three consecutive seasons. Ethephon and ABA had additive effects, decreasing titratable acidity and increasing pH of the must, which could be exploited by accelerating the grape ripening process in cold-climate zones. Nevertheless, each growth regulator affected the composition and sensory analysis of the wines differently. Ethephon treatments produced wines with lower concentration of acids and better flavor quality than those made from untreated plants, while wines with ABA applications tended to have a higher ethanol concentration and poorer aroma quality than controls. The wines submitted to treatments with ethephon obtained the best overall evaluation in the sensory analysis throughout the trial. <![CDATA[Repeatability coefficients and genetic gains in table grape progenies for the Brazilian semi-arid region]]> ABSTRACT: Table grape stands out among the main fruit-bearing plants of irrigated agriculture in the São Francisco Valley region of Brazil. This study estimated repeatability and heritability coefficients and predicted genetic gains in order to select superior genotypes in grape progenies from controlled hybridizations using the Restricted Maximum Likelihood/Best Linear Unbiased Prediction (REML/BLUP) methodology. Individual plants were evaluated for the variables of production (kg per plant), number of bunches, bunch weight (g), berry diameter (mm), and soluble solids content (°Brix). We evaluated 194 hybrids from 30 crosses between Vitis vinifera and interspecific hybrids in Juazeiro, Bahia State, Brazil, over four growing seasons. Repeatability coefficients, ranging from 0.164 for soluble solids content to 0.72 for berry diameter, were estimated with accuracy values higher than 80 % for all variables, except for soluble solids content (66 %). The 30 best individuals classified for each variable exhibited genetic gains and their new estimated mean values were higher than the overall mean of the population in all variables. Regarding production and number of bunches per plant as the main variables, 15 genotypes were selected simultaneously for both variables. Among which, hybrids CPATSA 15.05, 15.06, 15.06T, and 23.103 stand out because they have trace seeds and should be selected for the following steps of genetic breeding to develop new table grape cultivars for the Brazilian semiarid region. <![CDATA[Compressibility and water availability in Albaqualf soils under different deployment times in no-tillage]]> ABSTRACT: The southern Brazilian lowlands have been historically used for flooded rice cultivation. Over time, heavy machinery and intensive tillage practices have resulted in soil structure disruption, soil compaction, higher production costs and lower agricultural profitability. This study aimed to evaluate the effect of different deployment times of no-tillage (NT). Soil properties including bulk density (BD), compression index (CI), preconsolidation pressure (σp), bulk density at preconsolidation pressure (BDσp), degree of compactness (DC), soil water retention curve (SWRC), plant available water (PAW) and total organic carbon (TOC) content were evaluated using a 30-yr non-cultivated field (NC), adjacent to the experimental plots as a control. The BD, σp, BDσp and DC decreased in response to NT adoption time while the soil water holding capacity increased, allowing for higher PAW. Results from this study demonstrated the positive effects of NT on the overall quality of soils. <![CDATA[Efficiency of garden waste compost teas on tomato growth and its suppressiveness against soilborne pathogens]]> ABSTRACT: The use of compost teas is of great interest to sustainable agriculture. Aerated compost tea (ACT) and aerated vermicompost tea (AVT) originating from garden waste have been analytically characterized and tested in vitro and in vivo on tomato plants to determine their suppressive effect on Rhizoctonia solani and Fusarium oxysporum f. sp. lycopersici. The nitrogen (N, 3840 ppm) and potassium superoxide (K2O, 5800 ppm) contents were relevant in ACT. Both ACT and AVT were shown to contain indoleacetic acid IAA (80 - 20 mg L−1), salicylic acid (5.85 - 1.33 ng L−1) and humic acids (190 - 140 mg L−1). Direct confrontation assays against the pathogens showed that ACT had a high suppressive effect on F. oxysporum f. sp. lycopersici (relative growth of the pathogen [RG]: 12 %) and AVT had a high suppressive effect on R. solani (RG: 18 %). These suppressive effects have been confirmed by tests performed in vitro and on potted tomato plants. Results of plants growth assays showed that both teas can be applied, in their concentrated forms, to the growth medium. The analysis of the growth effect of the teas on tomato plants clearly indicated that both ACT and AVT, when applied weekly, produce a positive effect on shoot and root dry weight (dry weights were tripled), chlorophyll content and stem diameter compared to untreated plants. These results support the use of ACT and AVT as potential alternatives to the application of synthetic fungicides, and as plant promoters in crop production, for attaining environmental sustainability for farming and food safety. <![CDATA[Mineralogy, magnetic susceptibility and geochemistry of Fe-rich Oxisols developed from several parent materials]]> ABSTRACT: Fe-rich Oxisols on mafic rocks in Brazil generally have high magnetic susceptibility with high contents of some trace elements. These are taxonomically similar soils; however, differences in magnetic and geochemical properties may affect agricultural or environmental usability and subsequent management. This study investigated the pedogenesis of Fe-rich Oxisols from various parent materials and evaluated the lithogenetic influence on magnetic susceptibility and trace elements contents. Soil samples were collected from Bw horizons in 13 Rhodic Oxisols and a Typic Oxisol developed from several parent materials in Minas Gerais State, Brazil. Soils were analyzed by X-ray diffractometry (XRD) and magnetometry. Soil chemical analyses consisted of sulfuric and total (tri-acid) digestions and selective Fe oxides dissolutions and statistical correlations were determined. Fe-rich Oxisols presented a typical mineralogical composition of highly weathered soils with structural stability. The results confirm the difficulty to identify accurately magnetic minerals in different grain sizes using XRD. However, coarse fractions still exert dominant influence on the magnetic properties of the Fe-rich Rhodic Oxisols. In addition, coarse fractions probably contribute to the enrichment of superparamagnetic particles for the clay fraction. Although highly weathered, Fe-rich Oxisols may have their geochemical attributes still controlled by the parent material, where trace elements seem to be correlated with the magnetic minerals in the coarse fractions. Thus, the natural replacement of some trace elements from soil-solution equilibrium reactions during plant development could be more effective in soils with higher magnetic particles concentrations in the coarse fractions. <![CDATA[Soil microbial and chemical properties influenced by continuous cropping of banana]]> ABSTRACT: The impacts of continuous cropping of banana on soil microbiological and biochemical properties are little understood. In this study, we evaluated the variations in soil bacterial community abundance and diversity, microbial biomass carbon (MBC) and nitrogen (MBN) as well as soil enzyme activities involved in C, N and P cycles as affected by continuous cropping of banana. An initial increase in bacterial 16S rRNA copy and soil microbial biomass was observed in the second cropping and then decreased until the fourth cropping. The diversity of bacterial community showed a continuous decrease throughout the experiment. In addition, continuous cropping of banana caused shifts in bacterial community composition and structures. Soil urease and invertase exhibited the highest activities in the second cropping and then decreased gradually from the second to the fourth cropping. The phosphatase activity showed a gradual increase from the first to the third cropping. The bacterial 16S rRNA copy was positively correlated with the contents of MBN and urease activities. The results indicated that continuous cropping of banana was responsible for the disturbance of the bacterial community and that the effect on enzyme activity varies depending on the type of soil enzyme. <![CDATA[Common resistance to Fusarium head blight in Brazilian wheat cultivars]]> ABSTRACT: Mycotoxin levels in Fusarium head blight (FHB) infections can be difficult to quantify. The relationship between mycotoxin and disease is not consistent and it is not clear if wheatpathogen interaction is of significance in regions where more than one Fusarium species with distinct trichothecene production ability co-exists. This study aimed to investigate whether a set of eight Brazilian wheat genotypes, varying in resistance according to classification by the breeder, exhibit a common or differential resistance to Fusarium graminearum (Fgra) (deoxynivalenolproducing) and Fusarium meridionale (nivalenol-producing) (Fmer) using full-spike and central spikelet inoculation (type II resistance). Fgra was generally more aggressive than Fmer based on the percentage of diseased spikes (99 and 84 %, respectively) and number of diseased spikelets (mean 2.8 and 2.0, respectively) below the central spikelet. The genotype-pathogen species interaction was not significant, but there were differences between the genotypes, with BRS 194 and BRS 327 being the least and most resistant, respectively, based on severity ratings. The incidence of Fusarium-damaged kernel (FDK, %) was not affected by species, but two genotypes (BRS Parrudo and BRS 327) showed a lower incidence of FDK. There were substantial variations in the accumulation of deoxynivalenol and nivalenol among the genotypes, reaching maxima of 691.2 µg g−1 and 355.2 µg g−1, respectively, suggesting that Fgra is a more potent producer of trichothecene. Our data confirm prior resistance classifications by the breeders and suggest that the use of a single highly aggressive Fgra isolate may be sufficient for effective screening for FHB resistance. However, further studies are needed to elucidate the accumulation of resistance to trichothecene. <![CDATA[Good Manufacturing Practices, Hazard Analysis and Critical Control Point plan proposal for distilleries of cachaça]]> ABSTRACT: Cachaça poses many quality (appearance, taste, consumer acceptability) and safety hazards (chemical, metal, and microbiological contaminations during the process). In this work, an effort is made for the quality and safety analysis of cachaça, by describing and outlining the potential hazards in every step of the process. This study revealed that the critical control points (CCPs) involved in Good Manufacturing Practices (GMP) to prevent cachaça safety hazards are the stages of sugarcane growing, sugarcane harvesting, fermentation, distillation, and aging process. The most significant factors for both CCPs and critical points (CPs) that should be controlled are determined. The implementation of the Hazard Analysis and Critical Control Point (HACCP) system in small distilleries of cachaça has been very helpful to provide the required safety for domestic consumers and boost cachaça exportations. Therefore, the main objective of the cachaça industry is to achieve production consistency.