Scielo RSS <![CDATA[Scientia Agricola]]> vol. 75 num. 1 lang. es <![CDATA[SciELO Logo]]> <![CDATA[Microenvironments in swine farrowing rooms: the thermal, lighting, and acoustic environments of sows and piglets]]> ABSTRACT: The present research hypothesized that the thermal, lighting and acoustic environments in commercial swine farrowing rooms vary over time and from crate to crate. This study was conducted on 27 replicates in two commercial farrowing rooms in North Central Indiana, each equipped with 60 farrowing crates. Temperature, relative humidity, light intensity, sound intensity, and air velocity were continuously monitored and estimated for each crate at the sow level, for 48 h post-farrowing, which is usually a critical period for piglet survivability. Average daily temperature for all the crates in Room 1 was 24.1 ± 2.0 °C, 1.0 °C lower (p &lt; 0.05) than in Room 2. Although the overall mean temperature was similar between rooms and seasons, frequency distribution diagrams revealed that the proportion of time spent within distinct limits of mean daily temperature ranged from 15.0 °C to 28.0 °C and varied substantially between rooms and seasons. Similar results were found for all variables measured in this study. Differences in temperature, relative humidity, light intensity, air velocity, and sound intensity in crates were as high as 9.6 °C, 57 %, 3,847.3 Lx, 0.87 m s–1, and 38.7 dBC, respectively, in the same farrowing room when measured at the same instant. The results of the present research indicate that aspects that go beyond the physical environment of the sows, such as thermal, lighting, and acoustic environment can vary substantially over time and between crates of automatically climate controlled farrowing rooms. These differences should be taken into consideration in production setting and research. <![CDATA[<em>In vitro</em> rumen fermentation and effect of protein fractions of canola meals on methane production]]> ABSTRACT: Canola provides oil for human consumption and a by-product from the extraction of its oil canola meal (CM), is used as a good quality protein and lipid supplement for ruminants. The aim of this study was to determine the chemical composition and fermentation profile associated with the potential for methane production of three types of CM: solvent-extracted CM of Brassica napus (CMBN), B. juncea (CMBJ) and cold press-extracted CM from B. napus (CPCM) used to feed ruminants. The protein content of canola meal ranged from 36 to 41 %. The acid and neutral detergent insoluble in nitrogen ranged from 1 to 2 % and 4 to 5 %, respectively. The lipid content of canola meal samples ranged from 2 % (CMBN, CMBJ) to 14 % (CPCM). In vitro, dry matter disappearance of CMBJ was higher than that of other types of CM at 4 h, 24 h and 48 h. Gas production from CMBJ was greater than that of CPCM and CMBN at 24 h and 48 h of incubation. CPCM produced lower methane than CMBJ at 48 h of incubation. CPCM produced a higher (p &lt; 0.05) molar proportion of propionate from 12 h to 48 h of incubation. In conclusion, this study found that CPCM could be a good source of protein (mainly PB2) and lipids in the feed of ruminants; it will decrease methane production and enhance propionate production. There was correlation between less methane production, and the content of lipids and PB2 in the three types of CM studied. <![CDATA[Cover crop rotations in no-till system: short-term CO<sub>2</sub> emissions and soybean yield]]> ABSTRACT: In addition to improving sustainability in cropping systems, the use of a spring and winter crop rotation system may be a viable option for mitigating soil CO2 emissions (ECO2). This study aimed to determine short-term ECO2 as affected by crop rotations and soil management over one soybean cycle in two no-till experiments, and to assess the soybean yields with the lowest ECO2. Two experiments were carried out in fall-winter as follows: i) triticale and sunflower were grown in Typic Rhodudalf (TR), and ii) ruzigrass, grain sorghum, and ruzigrass + grain sorghum were grown in Rhodic Hapludox (RH). In the spring, pearl millet, sunn hemp, and forage sorghum were grown in both experiments. In addition, in TR a fallow treatment was also applied in the spring. Soybean was grown every year in the summer, and ECO2 were recorded during the growing period. The average ECO2 was 0.58 and 0.84 g m2 h–1 with accumulated ECO2 of 5,268 and 7,813 kg ha–1 C-CO2 in TR and RH, respectively. Sunn hemp, when compared to pearl millet, resulted in lower ECO2 by up to 12 % and an increase in soybean yield of 9% in TR. In RH, under the winter crop Ruzigrazz+Sorghum, ECO2 were lower by 17%, although with the same soybean yield. Soil moisture and N content of crop residues are the main drivers of ECO2 and soil clay content seems to play an important role in ECO2 that is worthy of further studies. In conclusion, sunn hemp in crop rotation may be utilized to mitigate ECO2 and improve soybean yield. <![CDATA[Potentiality of <em>Melastoma malabathricum</em> as Phytoremediators of soil contaminated with sewage sludge]]> ABSTRACT: Heavy metal pollution of the soil environment has become a major source of concern and continues to pose serious health problems to both humans and ecological systems worldwide. Phytoremediation is a biological treatment whereby plants are used to remove pollutant from the environment. An experiment was conducted to evaluate the potential of Melastoma malabathricum as a phytoremediator to absorb heavy metals from soil contaminated with sewage sludge. Melastoma malabathricum seedlings were planted on six different growth media: T0 - Control (100 % soil), T1 (80 % soil + 20 % sewage sludge), T2 (60 % soil + 40 % sewage sludge), T3 (40 % soil + 60 % sewage sludge), T4 (20 % soil + 80 % sewage sludge) and T5 (100 % sludge). There were differences found in both growth parameters and plant biomass. The highest growth performance such as plant height and number of leaves was found in T3. Iron was highly accumulated in the roots, Cu in the stems in T3, while Pb was accumulated in leaves in T5. The results showed the lowest Translocation Factor (TF) and highest Bioconcentration Factor (BCF) values in relation to the following elements: Cu, Fe, Mn, Pb and Zn. Melastoma malabathricum roots are able to uptake and translocate the elements into the plant's shoots. Therefore, it can be considered a good accumulator plant due to its capability of concentrating contaminants in aerial tissue. Melastoma malabathricum were thus found to be suitable for absorbing heavy metals in contaminated soils, and this species can also be considered an effective phtyoremediator of contaminated soil and mitigator of soil pollution. <![CDATA[Intraspecific tetraploid hybrids of <em>Paspalum notatum</em>: agronomic evaluation of segregating progeny]]> ABSTRACT: For many decades, animal production in southern Brazil has been based on native forage grasses. Paspalum notatum Flügge (bahiagrass) is one of the most frequently used native grass in southern Brazil. The native germplasm of P. notatum is tetraploid and displays apomictic reproduction; hence, chromosome doubling of sexual diploid accessions is required to facilitate hybridization. The main goal of this study was to evaluate forage production and other agronomical evaluation of P. notatum intraspecific hybrids in order to obtain new varieties that could be registered and/or protected and launched as new cultivars in the future. Three tetraploid sexual genotypes were crossed with the ecotypes Bagual and André da Rocha. Biomass production (leaf, stem, and inflorescence fractions), plant growth habit, plant height, number of tillers, and frost damage were evaluated in the resulting hybrids. The general combining ability (GCA) and specific combining ability (SCA) were calculated for the six families generated. We evaluated 196 hybrids and the most productive yielded 42 % more total dry mass than the most productive parent (ecotype Bagual), and Bagual production was seven-fold higher than that of cultivar ‘Pensacola’. The highest GCA values were observed for Bagual and Q4205. No correlation was observed between leaf coloration and the frost effect or regrowth in the following winter. Similarly, no correlation between plant growth habit and dry mass production was observed. The reproduction mode of the most productive hybrids are currently being analyzed in larger plots to identify apomictic and sexual genotypes for future registration and protection. <![CDATA[Molecular characterization of GSyV-1 and GLRaV-3 and prevalence of grapevine viruses in a grape-growing area]]> ABSTRACT: The aims of this study were to determine the prevalence of viruses in 119 samples from 32 grapevine cultivars, collected from nine vineyards in a specific grape-growing area in southeastern Brazil, perform a partial molecular characterization of 14 isolates of Grapevine Syrah virus 1 (GSyV-1) and Grapevine leafroll-associated virus 3 (GLRaV-3) and assess the coat protein genetic variability of these viruses. The detection of viruses was implemented by real-time RT-PCR (reverse transcription polymerase chain reaction) aiming to detect seven viruses and one viroid. With the exception of the Grapevine Cabernet Sauvignon reovirus (GCSV), the viruses and viroid that were evaluated were widespread in the sampled areas, often in high prevalence and multiple infections, ranging from 15 % up to 76 %. Eight isolates of GSyV-1 and six of GLRaV-3, partially characterized by complete coat protein gene nucleotide sequencing and a variability study showed nucleotide identities ranging from 91 % to 99 % (GSyV-1) and from 98 % to 100 % (GLRaV-3) among themselves, respectively. Comparisons between conventional and real-time RT-PCR detections were implemented for GSyV-1 and GLRaV-3 infections. Analysis of genetic variability indicated molecular differences between GSyV-1 and GLRaV-3 isolates and negative selection acting on the coat protein gene of both viruses. This is the first report of GSyV-1 in commercial vineyards in Brazil. The survey revealed widespread infections of seven important pathogens in one prominent Brazilian grape-producing region implying contaminated grapevine cuttings in the spread of disease. <![CDATA[Automatically controlled deficit irrigation of lettuce in “organic potponics”]]> ABSTRACT: Concerns with water crisis involve all sectors of society and irrigated agriculture remains the main water consumer. This study evaluated an agricultural production system for lettuce cultivation in greenhouse, “organic potponics”, to economize water and manure use, using a Simplified Irrigation Controller (SIC), based on soil matric potential monitoring. Five irrigation volumes were evaluated in pots with 4.8 L, fertilized with 200 g of vermicompost. One of the volumes was controlled with the SIC. The other volumes represented 130, 80, 60 and 33 % of that controlled by the SIC and all treatments received water at the same time. Shoot fresh weight, head diameter and stomatal conductance (gs) increased linearly with irrigation volumes. For shoot dry weight, number of leaves and water use efficiency (WUE), the regression was quadratic with maximum values at 126, 114 and 83 %, respectively. Leaf relative water content did not show variation among treatments and changes in some fluorescence parameters (Reo/RC, Sm, N and φR0) were much more remarkable to drought compared with the FV/ FM ratio, one of the most commonly used stress indicators. The data indicated a tradeoff between WUE and plant growth thus the economic values of water and lettuce should be taken into account to indicate the best SIC irrigation volume. Organic potponics is promising and should be further improved to save on water, labor and fertilizer use. <![CDATA[A hydropedological approach to a mountainous Clayey Humic Dystrudept in the Mantiqueira Range, southeastern Brazil]]> ABSTRACT: The Mantiqueira Range region is one of the most important headwaters in southeastern Brazil. In this context, the relationship between pedology and hydrology has been debated and analyzed in recent years, contributing to the creation of a multidisciplinary science call hydropedology. Therefore, the aim of this study was to evaluate the hydropedological properties of a mountainous Clayey Humic Dystrudept in the Mantiqueira Range region, in the state of Minas Gerais, Brazil, comparing two land-uses, native forest and pasture. The hydraulic conductivity results demonstrated that native forest (MFO) has a strong influence on this parameter, offering conditions for movement of water in the soil that are more adequate in this profile than in pasture. These results were supported by pore size distribution analyses which showed that soil from native forest has a greater amount of macropores than soil from pasture as well as greater connectivity between the macropores. In general, the MFO site had greater S index values than the micro-catchment taken from pasture, offering favorable physical conditions for the formation of preferential flowpaths in the soil profile and, therefore, better conditions for groundwater recharge. Soil erosion and water quality results confirmed the importance of native forest areas in the interaction between interception of the direct impact of intense precipitation on the soil surface, and hydropedological attributes, such as saturated hydraulic conductivity and porosity. <![CDATA[How accurate are pedotransfer functions for bulk density for Brazilian soils?]]> ABSTRACT: The aim of this study was to evaluate the performance of pedotransfer functions (PTFs) available in the literature to estimate soil bulk density (ρb) in different regions of Brazil, using different metrics. The predictive capacity of 25 PTFs was evaluated using the mean absolute error (MAE), mean error (ME), root mean squared error (RMSE), coefficient of determination (R2) and the regression error characteristic (REC) curve. The models performed differently when comparing observed and estimated ρb values. In general, the PTFs showed a performance close to the mean value of the bulk density data, considered as the simplest possible estimation of an attribute and used as a parameter to compare the performance of existing models (null model). The models developed by Benites et al. (2007) (BEN-C) and by Manrique and Jones (1991) (M&amp;J-B) presented the best results. The separation of data into two layers according to depth (0-10 cm and 10-30 cm) demonstrated better performance in the 10-30 cm layer. The REC curve allowed for a simple and visual evaluation of the PTFs. <![CDATA[Initial root length in wheat is highly correlated with acid soil tolerance in the field]]> ABSTRACT: In acid soils, toxic aluminum ions inhibit plant root growth. In order to discriminate aluminum (Al) tolerance, trustful screening techniques are required. In this study, 20 wheat cultivars, showing different levels of Al tolerance, were evaluated in a short-term soil experiment to access their relative root length (RRL). Moreover, the alleles of two important genes (TaALMT1 and TaMATE1B) for Al tolerance in wheat were discriminated. Both of these genes encode membrane transporters responsible for the efflux of organic acids by the root apices that are thought to confer tolerance by chelating Al. Genotypes showing TaALMT1 alleles V and VI and an insertion at the TaMATE1B promoter were among the ones showing greater RRL. Mechanisms of Al tolerance, which are not associated with organic acid efflux, can be potentially present in two cultivars showing greater RRL among the ones carrying inferior TaALMT1 and TaMATE1B alleles. The RRL data were highly correlated with wheat performance in acid soil at three developmental stages, tillering (r = −0.93, p &lt; 0.001), silking (r = −0.91, p &lt; 0.001) and maturation (r = −0.90, p &lt; 0.001), as well as with the classification index of aluminum toxicity in the field (r = −0.92, p &lt; 0.001). Since the RRL was obtained after only six days of growth and it is highly correlated with plant performance in acid soil under field conditions, the short-term experiment detailed here is an efficient and rapid method for reliable screening of wheat Al tolerance. <![CDATA[Local food: benefits and failings due to modern agriculture]]> ABSTRACT: This paper aims to examine the issue raised by the consumption of locally produced food in all its various aspects, and in particular, addresses how this practice contributes to local and global sustainability. It analyzes the different definitions of local food, the strategies used, the implications of the distance traveled in the transportation of food to the consumer's table – food miles, the relationships between local food consumption and sustainability, farming practices that reduce carbon emissions, contribution of urban agriculture to local food, local trading of food produced by rural farmers, as well as a number of relationships between the consumption of local food and human nutrition and health, local food protection and the ability to support local food production for humanitarian actions in disaster situations. The promotion of “local food” is a complex problem covering environmental issues, the economy and health. Transportation is not the only factor that determines how efficient it is to consume local food. Often, the technologies used for agricultural production are those most responsible for the degree of sustainability in the production and supply of food to the population. Local production does not always mean lower emissions of greenhouse gases. In general, the consumption of local foods, produced in ways adapted to the local environment using technologies with an ecological basis, is something beneficial and salutary for the environment, economy and society in general.