cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.5861511.v1
title: Multivariate analyses to establish reference values for soils in Médio Paraíba, state of Rio de Janeiro, Brazil

description: ABSTRACT Quality Reference Values (QRVs) for potentially toxic elements are obtained from background levels in soils. However, this determination from mean values or percentiles is not appropriate given the variability in the natural distribution of these elements in soils. Therefore, the objective of this study was to propose a new methodology to establish the QRVs, using the Médio Paraíba region (RJ, Brazil) as an example, from groups of soils defined based on the pseudo-total levels of B, Ba, Co, Cr, Cu, Ni, Pb, and Zn through the use of multivariate analyses and discriminant functions. A total of 40 points, collected at depths of 0-20 and 20-40 cm, were used for the determination of pseudo-total contents, according to the EPA 3051A methodology. The samples were separated into three groups to better represent the variability of the soils of the region. The classification functions were obtained based on the variables Mn, Fe, and Mg. In general, the groups G1 and G2 presented lower values than the ones obtained when the sample universe was used, whereas G3 presented higher values. The QRVs obtained from the soil groups presented substantial differences that translate into advantages for the management of the contaminated areas of the region.
DOI: 10.6084/m9.figshare.5862078
title: Analysis of defects in coffee beans compared to biplots for simultaneous tables

description: ABSTRACT The demand for high quality coffee has become a consolidated criterion to achieve the best prices. Currently, cooperatives evaluate the coffee beans mainly through the particle size and the number of defects in the sample. This evaluation type generates counting data that originates contingency tables from different periods or groups involving the same variables in the row and column and there may be interest in knowing if two tables are related and how much are related. These are the so-called combined tables. Statistical analysis techniques normally employed do not include categorical data in the combined tables. The aim of this study was to evaluate the incidence of different types of defects in samples of large flat coffee beans in two different harvests through the construction of biplots. The decomposition theory in single simultaneous values of double entry contingency tables was used. The results of defect counting in beans of 24 coffee samples from southern Minas Gerais, Brazil, were evaluated in the 2014 and 2015 harvests. Moreover, the association among defect types, considered within different total defect proportions in the sample, was verified based on the percentage in 17/18 sieves. It was also evaluated the relative sums of squares from the similarity and dissimilarity among the harvests. It is concluded that the simultaneous analysis technique allows better visualizing the common behavior and alterations among different harvests, distinguishing the defect types associated with each harvest and among different proportions of large flat beans.
DOI: 10.6084/m9.figshare.5861163
title: Silicon as an attenuator of salt stress in Brachiaria brizantha ‘MG5’

description: ABSTRACT The aim of this study was to evaluate the effect of salt stress and silicon fertiliser on growth and nutritional value in Brachiaria brizantha ‘MG5’. The experimental design was completely randomised in a 4 x 5 x 3 factorial scheme with four replications; the treatments consisted of four concentrations of sodium chloride (0, 20, 40 and 60 mmol L-1), with five concentrations of silicon (0, 1, 2, 3 and 4 mmol L-1) in the nutrient solution, and three cutting periods (30, 60 and 90 days). The concentration of 4 mmol L-1 silicon minimised the detrimental effects of the sodium chloride on regrowth. However, the levels of silicon application were not sufficient to reduce the harmful effects of the sodium chloride on nutritional value or on dry-matter production in Brachiaria brizantha ‘MG5’.
DOI: 10.6084/m9.figshare.5861163.v1
title: Silicon as an attenuator of salt stress in Brachiaria brizantha ‘MG5’

description: ABSTRACT The aim of this study was to evaluate the effect of salt stress and silicon fertiliser on growth and nutritional value in Brachiaria brizantha ‘MG5’. The experimental design was completely randomised in a 4 x 5 x 3 factorial scheme with four replications; the treatments consisted of four concentrations of sodium chloride (0, 20, 40 and 60 mmol L-1), with five concentrations of silicon (0, 1, 2, 3 and 4 mmol L-1) in the nutrient solution, and three cutting periods (30, 60 and 90 days). The concentration of 4 mmol L-1 silicon minimised the detrimental effects of the sodium chloride on regrowth. However, the levels of silicon application were not sufficient to reduce the harmful effects of the sodium chloride on nutritional value or on dry-matter production in Brachiaria brizantha ‘MG5’.
DOI: 10.6084/m9.figshare.6125006
title: Inoculation efficiency of Azospirillum brasilense on economising nitrogen fertiliser in landrace popcorn

description: ABSTRACT Nitrogen is one of the nutrients most demandedby popcorn, and one that most increases production costs. Considering these factors, the aim of this study was to evaluate the effectiveness of inoculatingpopcorn seeds with Azospirillum brasilense together with four levels of nitrogen fertiliser, and its contribution to characteristics related to production. The experiment was carried out in the experimental area of the Centre for Agrarian Sciences and Biodiversity of the Federal University of Cariri, in Crato, in the State of Ceará. Eight treatments were evaluated with four replications, using an experimental design of randomised blocks in a 2x4 factorial scheme corresponding to the presence and absence of inoculation, and to four doses of nitrogen as top dressing. The following characteristics were evaluated: plant height, height of ear insertion, number of plants, number of lodged plants, number of broken plants, number of poorly husked ears, ear diameter, ear length, number of ears, number of diseased ears, number of infested ears, grain productivity, ear weight, mean 100-grain weight, and expansion capacity. There were significant differences for most of the characteristics under evaluation, with an increase of 17.18% in the number of ears and 10.78% in grain productivity, reducing the top dressing to 50 kg ha-1 in the presence of A. brasiliensi. These results demonstrate the potential for economisingnitrogen fertiliser in popcorn production under the soil and climate conditions of the Cariri region of the State of Ceará.
DOI: 10.6084/m9.figshare.6125006.v1
title: Inoculation efficiency of Azospirillum brasilense on economising nitrogen fertiliser in landrace popcorn

description: ABSTRACT Nitrogen is one of the nutrients most demandedby popcorn, and one that most increases production costs. Considering these factors, the aim of this study was to evaluate the effectiveness of inoculatingpopcorn seeds with Azospirillum brasilense together with four levels of nitrogen fertiliser, and its contribution to characteristics related to production. The experiment was carried out in the experimental area of the Centre for Agrarian Sciences and Biodiversity of the Federal University of Cariri, in Crato, in the State of Ceará. Eight treatments were evaluated with four replications, using an experimental design of randomised blocks in a 2x4 factorial scheme corresponding to the presence and absence of inoculation, and to four doses of nitrogen as top dressing. The following characteristics were evaluated: plant height, height of ear insertion, number of plants, number of lodged plants, number of broken plants, number of poorly husked ears, ear diameter, ear length, number of ears, number of diseased ears, number of infested ears, grain productivity, ear weight, mean 100-grain weight, and expansion capacity. There were significant differences for most of the characteristics under evaluation, with an increase of 17.18% in the number of ears and 10.78% in grain productivity, reducing the top dressing to 50 kg ha-1 in the presence of A. brasiliensi. These results demonstrate the potential for economisingnitrogen fertiliser in popcorn production under the soil and climate conditions of the Cariri region of the State of Ceará.
DOI: 10.6084/m9.figshare.6124817
title: Physical quality of bauxite tailing after a decade of environmental recovery

description: ABSTRACT Tailings from bauxite washing produced in Porto Trombetas, Pará state, a Brazilian Amazon region, have chemical and physical characteristics limiting the development of plants, which hinders to revegetate the tanks where they are deposited. This study was carried out under field conditions, and aimed to assess the physical quality of these tailings after a decade of recovery practices. Three treatments were assessed: no application of inputs and planting of seedlings (T1) and two levels of fertilization, one with lower (T2) and other with higher (T3) doses of limestone and fertilizers associated with planting tree seedlings. After ten years of experimentation, penetration resistance (PR) and substrate moisture up to 60 cm depth were assessed and the least limiting water range (LLWR), water retention curve (WRC), and pore size distribution were determined and calculated. After a decade of environmental recovery, differences in physical characteristics were observed in the tailings due to different revegetation modes. Moisture in the substrate profile, LLWR, WRC, and pore size distribution were sensitive indicators to variations in substrate physical quality. Liming, fertilization, and planting of seedlings are necessary for revegetation and improvement of the physical quality of tailings. Treatment T3 was the best intervention identified so far for tank revegetation. The absence of fertilization and planting precludes revegetation even with sources of propagules nearby.
DOI: 10.6084/m9.figshare.6504413
title: Environmental variables influencing the expression of morphological characteristics in clones of the forage cactus

description: ABSTRACT The environmental factors that affect the morphological characteristics of different genera of cacti are little known. The aim of this study therefore was to analyse the contribution of environmental variables to growth in cladodes and plant of forage cactus clones of the genera Nopalea and Opuntia. The data used in this study were obtained from an experiment conducted in Serra Talhada, Pernambuco, Brazil, between 2012 and 2013, where the clones 'IPA Sertânia' (Nopalea), 'Miúda' (Nopalea) and 'Orelha de Elefante Mexicana' (Opuntia) were submitted to different irrigation depths (2.5, 5.0 and 7.5 mm) and fixed irrigation intervals (7, 14 and 28 days). Morphological characteristics of the cladodes and plants and weather variables were obtained over time. Pearson's correlation, followed by multicollinearity, canonical and path analysis were applied. The minimum temperature, maximum and minimum relative humidity, wind speed and solar radiation were the variables that most affected growth in the cactus. The genus Opuntia showed less sensitivity to variations in air temperature compared to the genus Nopalea. The higher intensities of global solar radiation affected clones of the genus Nopalea more than the genus Opuntia. It can be concluded that there are different environmental requirements between forage cacti of the genera Nopalea and Opuntia.
DOI: 10.6084/m9.figshare.6504413.v1
title: Environmental variables influencing the expression of morphological characteristics in clones of the forage cactus

description: ABSTRACT The environmental factors that affect the morphological characteristics of different genera of cacti are little known. The aim of this study therefore was to analyse the contribution of environmental variables to growth in cladodes and plant of forage cactus clones of the genera Nopalea and Opuntia. The data used in this study were obtained from an experiment conducted in Serra Talhada, Pernambuco, Brazil, between 2012 and 2013, where the clones 'IPA Sertânia' (Nopalea), 'Miúda' (Nopalea) and 'Orelha de Elefante Mexicana' (Opuntia) were submitted to different irrigation depths (2.5, 5.0 and 7.5 mm) and fixed irrigation intervals (7, 14 and 28 days). Morphological characteristics of the cladodes and plants and weather variables were obtained over time. Pearson's correlation, followed by multicollinearity, canonical and path analysis were applied. The minimum temperature, maximum and minimum relative humidity, wind speed and solar radiation were the variables that most affected growth in the cactus. The genus Opuntia showed less sensitivity to variations in air temperature compared to the genus Nopalea. The higher intensities of global solar radiation affected clones of the genus Nopalea more than the genus Opuntia. It can be concluded that there are different environmental requirements between forage cacti of the genera Nopalea and Opuntia.
DOI: 10.6084/m9.figshare.6125315
title: Use of capacitive sensors with the instantaneous profile method to determine hydraulic conductivity

description: ABSTRACT Due to the need to monitor soil water tension continuously, the instantaneous profile method is considered laborious, requiring a lot of time, and especially manpower, to set up and maintain. The aim of this work was to evaluate the possibility of using capacitive sensors in place of tensiometers with the instantaneous profile method in an area of the Lower Acaraú Irrigated Perimeter. The experiment was carried out in a Eutrophic Red-Yellow Argisol. The sensors were installed 15, 30, 45 and 60 cm from the surface, and powered by photovoltaic panels, using a power manager to charge the battery and to supply power at night. Records from the capacitive sensors were collected every five minutes and stored on a data acquisition board. With the simultaneous measurement of soil moisture obtained by the sensors, and the total soil water potential from the soil water retention curve, it was possible to determine the hydraulic conductivity as a function of the volumetric water content for each period using the Richards equation. At the end of the experiment, the advantage of using capacitive sensors with the instantaneous profile method was confirmed as an alternative to using a tensiometer. The main advantages of using capacitive sensors were to make the method less laborious and to allow moisture readings at higher tensions in soils of a sandy texture.
DOI: 10.6084/m9.figshare.6125315.v1
title: Use of capacitive sensors with the instantaneous profile method to determine hydraulic conductivity

description: ABSTRACT Due to the need to monitor soil water tension continuously, the instantaneous profile method is considered laborious, requiring a lot of time, and especially manpower, to set up and maintain. The aim of this work was to evaluate the possibility of using capacitive sensors in place of tensiometers with the instantaneous profile method in an area of the Lower Acaraú Irrigated Perimeter. The experiment was carried out in a Eutrophic Red-Yellow Argisol. The sensors were installed 15, 30, 45 and 60 cm from the surface, and powered by photovoltaic panels, using a power manager to charge the battery and to supply power at night. Records from the capacitive sensors were collected every five minutes and stored on a data acquisition board. With the simultaneous measurement of soil moisture obtained by the sensors, and the total soil water potential from the soil water retention curve, it was possible to determine the hydraulic conductivity as a function of the volumetric water content for each period using the Richards equation. At the end of the experiment, the advantage of using capacitive sensors with the instantaneous profile method was confirmed as an alternative to using a tensiometer. The main advantages of using capacitive sensors were to make the method less laborious and to allow moisture readings at higher tensions in soils of a sandy texture.
DOI: 10.6084/m9.figshare.6503708
title: Performance of broiler chickens reared at two stocking densities and coir litter with different height

description: ABSTRACT The objective of this study was to evaluate the performance of broiler chickens reared at two stocking densities and coir litter with different height. A total of 522 one-day male chicks were distributed in a completely randomized design in a 3×2 factorial arrangement, with three litter height (5, 10 and 15 cm) and two densities (10 and 13 birds/m2), with six triplicates. The experimental period lasted 42 days, evaluating pH and litter moisture; performance; carcass traits; bone quality; and intensities of breast, hock and footpad lesions in the birds. Regarding the effect of density, a significant influence was observed only on performance, wherein the birds reared at the density of 13 birds/m2 showed lower intake and weight gain and better feed conversion than those reared at the density of 10 birds/m2. Irrespective of the rearing density and litter height, the hock and footpad lesions were frequent, and with severe intensity. It is concluded that coir with 5 cm height can be used to housing up to 13 birds/m2; however, the high rate of hock and footpad lesions makes the use of coir in the evaluated form unfeasible.
DOI: 10.6084/m9.figshare.6503708.v1
title: Performance of broiler chickens reared at two stocking densities and coir litter with different height

description: ABSTRACT The objective of this study was to evaluate the performance of broiler chickens reared at two stocking densities and coir litter with different height. A total of 522 one-day male chicks were distributed in a completely randomized design in a 3×2 factorial arrangement, with three litter height (5, 10 and 15 cm) and two densities (10 and 13 birds/m2), with six triplicates. The experimental period lasted 42 days, evaluating pH and litter moisture; performance; carcass traits; bone quality; and intensities of breast, hock and footpad lesions in the birds. Regarding the effect of density, a significant influence was observed only on performance, wherein the birds reared at the density of 13 birds/m2 showed lower intake and weight gain and better feed conversion than those reared at the density of 10 birds/m2. Irrespective of the rearing density and litter height, the hock and footpad lesions were frequent, and with severe intensity. It is concluded that coir with 5 cm height can be used to housing up to 13 birds/m2; however, the high rate of hock and footpad lesions makes the use of coir in the evaluated form unfeasible.
DOI: 10.6084/m9.figshare.6504035
title: Culture of Nile tilapia in a biofloc system with different sources of carbon

description: ABSTRACT The aim of this work was to evaluate the effects of using different sources of organic carbon on water quality, growth performance and the acceptability of Nile tilapia (Oreochromis niloticus) fillets grown in a biofloc system. The experiment was carried out over 145 days at the Aquaculture Station of the Federal Rural University of Pernambuco, Brazil. Fish of 72.6 ± 6.83 g were stored (35 fish m-3) in 19 circular tanks (800 L) in a completely randomised experimental design with three treatments, including as a source of carbon, sugar (SUG), liquid molasses (MOL) and molasses powder (MOP), each with five replications, and one control treatment (CTL) without bioflocs, with four replications. Dissolved oxygen concentrations were significantly higher (P≤0.05) in the tanks with no bioflocs due to the absence of bacterial biomass. Total ammoniacal nitrogen (TAN) showed a statistical difference (P≤0.05) between the SUG treatment and the other treatments with bioflocs, having the lowest concentration of 2.53 mg L-1. Survival was greater than 80%, with no statistical difference between treatments (P&gt;0.05); productivity varied from 9.72 (SUG) to 14.22 kg m-3 (CTL) (P≤0.05). Water consumption in the tanks with bioflocs was 11.8 times lower than in the control (CTL). The tilapia fillets from the bioflocs with sugar were preferred by the evaluators, with a score of 7.77 (like moderately to like very much). The carbon sources used (molasses and sugar) can be employed in the culture of O. niloticus tilapia in bioflocs with no damage to the culture water or to productivity.
DOI: 10.6084/m9.figshare.6504035.v1
title: Culture of Nile tilapia in a biofloc system with different sources of carbon

description: ABSTRACT The aim of this work was to evaluate the effects of using different sources of organic carbon on water quality, growth performance and the acceptability of Nile tilapia (Oreochromis niloticus) fillets grown in a biofloc system. The experiment was carried out over 145 days at the Aquaculture Station of the Federal Rural University of Pernambuco, Brazil. Fish of 72.6 ± 6.83 g were stored (35 fish m-3) in 19 circular tanks (800 L) in a completely randomised experimental design with three treatments, including as a source of carbon, sugar (SUG), liquid molasses (MOL) and molasses powder (MOP), each with five replications, and one control treatment (CTL) without bioflocs, with four replications. Dissolved oxygen concentrations were significantly higher (P≤0.05) in the tanks with no bioflocs due to the absence of bacterial biomass. Total ammoniacal nitrogen (TAN) showed a statistical difference (P≤0.05) between the SUG treatment and the other treatments with bioflocs, having the lowest concentration of 2.53 mg L-1. Survival was greater than 80%, with no statistical difference between treatments (P&gt;0.05); productivity varied from 9.72 (SUG) to 14.22 kg m-3 (CTL) (P≤0.05). Water consumption in the tanks with bioflocs was 11.8 times lower than in the control (CTL). The tilapia fillets from the bioflocs with sugar were preferred by the evaluators, with a score of 7.77 (like moderately to like very much). The carbon sources used (molasses and sugar) can be employed in the culture of O. niloticus tilapia in bioflocs with no damage to the culture water or to productivity.
DOI: 10.6084/m9.figshare.7186544.v1
title: Costs, viability and risks of organic tomato production in a protected environment

description: ABSTRACT The aim of this research was to evaluate the agro-economic performance of two table-tomato cultivars (Santa Clara and Siluet), under organic cultivation and in a protected environment. Through the analysis of production costs, economic viability and project risk, it was sought to generate a proposal for agricultural profitability having less socio-environmental impact on family farming. To achieve that, the Operating and Total Production Costs, Net Present Value (NPV) and Internal Rate of Return (IRR) were calculated. A sensitivity analysis and economic risk analysis were then carried out. Both cultivars under consideration presented satisfactory economic indicators for the period being analysed. Judging by the criterion of Net Present Value, almost all discount rates (except for the rates of 10 and 12% for the Santa Clara cultivar) were found to be economically viable, with internal rates of return higher than the annual rate of 6%, the minimum rate of financial attractiveness considered. The sensitivity analysis revealed that price received and productivity have the greatest interference on project profitability, followed by packaging and labour costs. The estimated economic risk was relatively low, with a probability of obtaining a negative NPV of 30.31% in the case of the 'Santa Clara', and 4.48% for the 'Siluet'. It is therefore concluded that the organic production of 'Siluet' and 'Santa Clara' tomatoes under protected cultivation is an economically viable activity, with emphasis on the agro-economic superiority of the Siluet cultivar.