Spanish Journal of Agricultural Research
Not a member yet
2067 research outputs found
Sort by
Physical and physiological quality of Jatropha curcas L. seeds at different maturity stages using image analysis
No full textAim of study: To assess the potential of automated X-ray image analysis to evaluate the physical characteristics of Jatropha curcas seeds, and to relate the parameters obtained with the physiological quality of the seeds harvested at different maturity stages.Area of study: Experimental area of Agronomy Department, Federal University of Viçosa (UFV), Brazil.Material and methods: The fruits were harvested from 20 plants, based on the external skin color (green, yellow, brownish-yellow and brown). The study was performed by automated and visual analysis of radiographic images of the seeds, in which measurements of tissue integrity, density and seed filling were performed. Seed dry matter, germination and seedling growth were also analysed.Main results: Variables obtained through automated analysis of radiographic images correlated significantly with all physiological variables (r > 0.9), as well as visual image evaluations (r > 0.75). The seeds extracted from green fruits presented lower tissue integrity and lower physiological quality. Radiographic analysis was efficient for monitoring J. curcas seed quality at different maturity stages. Morpho-anatomical parameters obtained from X-ray analysis were highly correlated with seed physiological attributes.Research highlights: It is important to develop and improve methodologies based on lower-cost techniques, such as X-ray analysis. In this context, we verified that X-ray images can be used for monitoring J. curcas seed filling and maturation. Radiographic images of seeds can be analyzed automatically with ImageJ software. Internal morphology and physical characteristics of seeds have relationship with their physiological quality
Soil carbon sequestration and stocks: short-term impact of maize succession to cover crops in Southern Brazil Inceptisol
No full textAim of study: To evaluate soil organic carbon (SOC) sequestration and stock over the succession of maize to winter cover crops under a short-term no-tillage system.Area of study: A subtropical area in Southern Brazil.Material and methods: The experiment was implemented in 2013. The treatments were: seven winter cover crops single cultivated (white-oats, black-oats, annual-ryegrass, canola, vetch, fodder-radish and red-clover); an intercropping (black-oats + vetch); and a fallow, with maize in succession. Soil samples were collected after four years of experimentation, up to 0.60 m depth, for SOC determination.Main results: SOC stocks at 0-0.6 m depth ranged from 96.2 to 107.8 t/ha. The SOC stocks (0-0.60 m depth) were higher under vetch and black-oats, with an expressive increase of 23 and 20% for C stocks in the 0.45-0.60 m layer, compared to fallow. Thus, SOC sequestration rates (0-0.60 m depth), with vetch and black oats, were 1.68 and 0.93 t/ha·yr, respectively.Research highlights: The establishment of a high-quality and high C input cover crops in the winter, as vetch or black-oats in succession to maize, are able to increase SOC stocks, even in the short term.
Effects of distillated myrtle (Myrtus communis L.) leaves’ intake on cull ewes’ body weight gain, carcass composition and meat quality
No full textAim of study: Cull ewes are characterized by poor body condition, low body weights and tough meat texture. This work aimed to investigate the effect of distillated myrtle leaves (MDL) intake on body weight (BW) gain; carcass characteristics and meat quality of Barbarine cull ewes.Area of study: Northwest of TunisiaMaterial and methods: 27 Barbarine ewes were assigned into 3 groups receiving 500 g of oat hay and 750 g of concentrate control group (C), while they were given concentrate and pellets, containing 87% MDL, as substitute to hay in MHay group; for MConc group, they were fed hay, concentrate and pellets containing 30% MDL in partial substitution to concentrate. At the end of the fattening period (90 days), ewes were slaughtered.Main results: The dry matter intake was higher (p<0.05) for MConc and C groups. The average daily gain was significantly higher for C and MConc than MHay groups (113 and 107 vs. 87 g, respectively). Ewes fed MHay and MConc had a significantly lower feed conversion rate than Control group (12.5 vs. 15.4). Dietary treatment had no significant effect on carcass joint’s weight and proportions. The dressing percentage and carcass tissue composition were similar for all groups. The ultimate pH, water cooking loss and color parameters values were unaffected by the type of diet.Research highlights: These findings revealed that MDL could substitute, in ewes feeding, up to 87% to hay or up to 30% to concentrate without negative effects on body weight, carcass characteristics and meat quality
Technical-economic viability of mechanized picking coffee (Coffea arabica L.) in up to three annual operations
No full textAim of study: Unavailability, coupled with the burden of labor for agricultural services nowadays, has made the mechanization process of harvesting of fallen coffee (Coffea arabica L.) essential. Although this operation has essential importance, it is often not monitored and executed in search of extreme quality. Considering the search for higher profits, this study aimed to analyze the performance of a coffee picker in three passes in an area in order to collect and process all the material and its economic viability.Area of study: The experiment was carried out in July 2017 in the Brazilian Cerrado, in the municipality of Presidente Olegário, Minas Gerais, Brazil, at Fazenda Gaúcha/Café.Material and methods: The amount of gathered coffee was equivalent to 600 kg ha−1 of processed coffee. The data from 2017 were used to analyze the economic viability of the picking operation. Treatments were distributed in split-blocks with three passes of the picking machine. The analyzed variables were picking and cleaning efficiency, picking losses, and percentage of vegetal and mineral impurities.Main results: Coffee losses reached the minimum level in the third pass. However, the harvesting operation could be carried out at most twice in the same area from the economic point of view under the evaluated conditions.Research highlights: Mechanized picking of coffee can be performed at most twice in the same area, providing a positive economic return
Nitrogen mineralization of legume residues: interactions between species, temperature and placement in soil
No full textAim of study: To assess the interactive effects of legume species, residue placement and temperature on the net nitrogen (N) mineralization dynamics in a sandy loam soil.Area of study: Northern PortugalMaterial and methods: Cowpea (Vigna unguiculata L. Walp), faba bean (Vicia faba L.) and pea (Pisum sativum L.) residues were incorporated or applied to the soil surface at typical field yields in Europe and incubated in aerobic conditions for up to 240 days, either at 10ºC or 20ºC. Initial chemical characteristics of the soil and residues were determined. Net N mineralization was estimated at eight time intervals.Main results: Cowpea residues caused no negative changes in soil mineral N contents and were able to release the equivalent of 21-45 kg N ha-1 in 240 days. Net N immobilization (up to 17 kg N ha-1) was observed throughout most of the trial in soil with faba bean and pea residues. Differences in mineralization patterns could be attributed to the higher quality (lower carbon to nitrogen (C:N) ratios) of cowpea. Surface placement increased net N mineralized by as much as 18 kg N ha-1. The sensitivity of N mineralization to changes in temperature and residue placement varied with legume species, likely due to effects associated with differences in C:N ratios.Research highlights: Adding cowpea residues to soil is suitable when high N availability is immediately required. Faba bean or pea residues are better suited for conservation of soil N for later release
Greenhouse application of light-drone imaging technology for assessing weeds severity occurring on baby-leaf red lettuce beds approaching fresh-cutting
No full textAim of study: For baby-leaf lettuces greenhouse cultivations the absence of weeds is a mandatory quality requirement. One of the most promising and innovative technologies in weed research, is the use of Unmanned Aerial Vehicles (or drones) equipped with acquisition systems. The aim of this study was to provide an estimation of the exact weed amount on baby-sized red lettuce beds using a light drone equipped with an RGB microcamera.Area of study: Trials were performed at specialized organic farm site in Eboli (Salerno, Italy), under polyethylene multi-tunnel greenhouse.Material and methods: The RGB images acquired were processed with specific algorithms distinguishing weeds from crop yields, estimating the weeds covered surface and the severity of weed contamination in terms of biomass. A regression between the percentage of the surface covered by weed (with respect to the image total surface) and the weight of weed (with respect to the total harvested biomass) was calculated.Main results: The regression between the total cover values of the 25 calibration images and the total weight measured report a significant linear correlation. Digital monitoring was able to capture with accuracy the highly variable weed coverage that, among the different grids positioned under real cultivation conditions, was in the range 0-16.4% of the total cultivated one.Research highlights: In a precision weed management context, with the aim of improving management and decreasing the use of pesticides, this study provided an estimation of the exact weed amount on baby-sized red lettuce beds using a light drone
The predictive power of farmers’ risk attitude measures elicited by experimental methods
No full textAim of study: Farmers’ behavior is shaped by their individual attitudes towards risk. Consequently, an understanding of the heterogeneous risk attitudes among farmers is key to predicting their decision-making. Therefore, there is a need for reliable methods to assess individuals’ risk attitudes. The main objective of this paper was to contribute to the existing literature about the external validity of risk attitude measures obtained with diverse experimental methods.Area of study: Irrigated agriculture in a Mediterranean climate region.Material and methods: Two different experimental methods widely applied in the agricultural sector were used to elicit farmers’ risk attitudes in a sample of irrigators in southern Spain: the Eckel and Grossman lottery-choice task and a self-assessment general risk question. We evaluated the explanatory power of both measures for the farming risk borne by farmers, using an approach based on dispersion measures of farming returns.Main results: Results revealed stability across these elicitation methods, but the study yielded no evidence of statistical correlation with the farming risk actually borne by farmers, suggesting that it may not be advisable to use these methods for directly predicting farmers’ decision-making in modeling exercises.Research highlights: The most relevant innovation of this paper was the validation approach followed, based on measures assessing the overall level of farming risk borne by individual producers, and the complementary analyses controlling for key variables that could affect farmer risk-taking
Efficacy of invasive alien plants in controlling Arionidae slugs
No full textAim of study: To develop an alternative slug control method, we explored the use of plant material from seven invasive plant species against Arion slugs.Area of study: The experiments were performed at the University of Ljubljana (Slovenia).Material and methods: In laboratory (exp. A-C) and semi-field studies (exp. D), we investigated the contact and barrier efficacy of plant material (powder or liquid formulation) of seven invasive plant species (Japanese knotweed, bohemian knotweed, Canadian goldenrod, giant goldenrod, staghorn sumac, tree of heaven, and false indigo) against Arion slugs. In order to test a contact efficacy of the substance (exp. A), slugs were rolled in a plant material powder. In exp. B, powder made from a plant material was used as a barrier for slugs. Antifeedant effect of the slugs was tested in exp. C, where lettuce leaves were treated with a liquid formulation of a plant material. In exp. D, all above mentioned techniques were used in a semi-field trial.Main results: The results of our studies showed that the plant material of staghorn sumac, giant goldenrod, and Japanese knotweed showed the strongest anti-feedant and barrier effects against the slugs. In the semi-field trial, only 7% of the plants treated with giant goldenrod plant material were attacked by slugs.Research highlights: A contact efficacy of plant powders against Arion slugs was not confirmed in our investigation. Furthermore, several plant powders (goldenrods, staghorn sumac) showed good barrier efficacy. A semi-field trial showed that plant material (giant goldenrod) could represent an alternative solution in slug control
Evapotranspiration and components of corn (Zea mays L.) under micro irrigation systems in a semi-arid environment
No full textAim of study: This work summarizes the influence of surface drip irrigation (DI) and subsurface drip irrigation (SDI) systems on corn growth indices and actual evapotranspiration (ETc-act) and its components of plant transpiration (Tp) and soil evaporation (E).Area of study: Karaj, IranMaterial and methods: The experimental soil was loamy. The corn ETc-act of each mini-lysimeter was measured based on the water balance method. The E was measured using two mini-lysimeters and Tp was estimated from the difference between ETc-act and E.Main results: The resulting data showed that the ETc-act was lower under SDI (384.8 mm) than under DI (423.4 mm). The Kcb-m for the corn increased after sowing and peaked during the mid-season stage, with an average value of 0.47, a minimum value of 0.0 and maximum value of 1.52 under DI and 0.53, 0.0 and 1.74 respectively, under SDI. For Ke-m, the average, minimum and maximum values were 0.33, 0.20 and 0.58 under DI and 0.23, 0.15 and 0.46 respectively, under SDI. The biomass yield was much higher under SDI (81.90 ton/ha) than under DI (63.21 ton/ha). Less E and more Tp occurred under SDI than under DI. SDI achived superior WUE (8.32 kg/m3) compared with DI.Research highlights: SDI was superior to DI based on biomass yield, corn height, stem diameter, and leaf area index which contributed to more favorable soil moisture conditions and low weed incidence; Thus, the SDI system is more productive and would better increase WUE than the DI system
Is GNSS real-time positioning a reliable option to validate erosion studies at olive grove environments?
No full textAim of study: Soil degradation in agricultural areas is a widespread problem. In this framework, a data validation methodology is presented, including a study of the spatial resolution of Global Navigation Satellite System (GNSS) measurements, the calculation of erosion/deposition models, and the contribution of dual frequency and low-cost single frequency GNSS receivers.Area of study: A test olive grove in SE Spain.Material and methods: The study is based on three observation campaigns, between 2016 and 2018, using different GNSS receivers and working modes. The comparison between different surveys provide the volumetric variation over the analyzed period.Main results: Considering the dual-frequency receiver, there was no statistically significant difference between the means and the variances from 1.5 m and from 4.5 m data resolution at the 0.05 significance level. In order to estimate vertical differences from successive GNSS campaigns a differential digital elevation approach was applied. Although the differences depended on the zone of the test area and they changed along the monitoring period, the erosion rate could be catalogued as very low. The dual-frequency receiver satisfied the vertical centimetric precision limits for high accurate Digital Elevation Model (DEM), making it a reliable and accurate option to validate erosion studies in small areas.Research highlights: The results have allowed the characterization of multi-annual spatial redistribution of the topsoil at local scale, being of great help to design future prevention actions for the “tillage erosion” in olive grove environments. However, more tests are needed to guarantee the feasibility of low-cost receivers