Results 1 - 10 of 188
Results 1 - 10 of 188. Search took: 0.016 seconds
|Sort by: date | relevance|
[en] The present study evaluated the effect of different associations between coulters and fertilizer furrow openers on soil disturbance, furrow depth and width, according to forward speed. The study was conducted on a farm in Santa Maria (Brazil/RS), in soil classified as sandy loam Ultisol. The experiment consisted of 24 combinations of treatments with three replications in a 2×3×4 factorial experiment. The combinations were formed by the interaction of the factors including: two types of furrow openers (hoe and double-disc), three types of coulters (no-coulter, smooth and offset fluted) and four levels of forward speed (1.11, 1.67, 2.22 and 2.78 m/s). Soil elevation and soil disturbance area profiles were obtained with the use of a micro profilometer, and disturbance values were calculated with the aid of computer software program Auto Cad. The disturbance area was not affected by speed; it was greater when using the hoe opener, and in association with the offset fluted coulter. Speed was inversely proportional to the depth of the furrows made by the hoe opener. Furthermore, the hoe caused the greatest furrow width (0.26 m) in comparison with the double-disc (0.24 m). The use of different coulters associated with furrow openers increased this variable (0.23 m for the no-coulter condition, 0.25 m with smooth and 0.26 m with offset fluted). The use of coulters combined with furrow openers reduces soil swelling, in approximately 8% for the smooth and 20% for the offset fluted. (Author)
[en] Hydrological droughts are a major risk for irrigated agriculture in many regions of the world. The aim of this article is to propose an insurance tool to help irrigators manage the risk of water scarcity in the framework of the Spanish Crop Insurance System (SCIS). Only the United States Insurance System provides this type of coverage, but has very restrictive conditions. To determine the type of insurance scheme that better fits with the SCIS and to the Spanish irrigated agriculture, an expert panel was held with the participation of all stakeholders involved in crop insurance. Following the expert panel conclusions, an hydrological drought index insurance (HDII) addressed to irrigation districts (ID) is proposed. It would compensate water deficits suffered in the whole ID. We detail the conditions that the ID should fulfill to be eligible for HDII. HDII is applied to the Bardenas Irrigation District V (ID-V) in Spain, and the hedging effectiveness of the instrument is analyzed comparing ID-V’s gross margins with and without the insurance contract. Results suggest that the proposed insurance scheme could provide an effective means of reducing farmers’ vulnerability to water shortages and there is no major impediment for it to be included as a new line in the SCIS. This type of insurance can be generalized to any ID fulfilling the conditions mentioned in this paper. (Author)
[en] Haplotypes from sequencing data may improve the prediction accuracy in genomic evaluations as haplotypes are in stronger linkage disequilibrium with quantitative trait loci than markers from SNP chips. This study focuses first, on the creation of haplotypes in a population sample of 450 Holstein animals, with full-sequence data from the 1000 bull genomes project; and second, on incorporating them into the whole genome prediction model. In total, 38,319,258 SNPs (and indels) from Next Generation Sequencing were included in the analysis. After filtering variants with minor allele frequency (MAF< 0.025) 13,912,326 SNPs were available for the haplotypes extraction with findhap.f90. The number of SNPs in the haploblocks was on average 924 SNP (166,552 bp). Unique haplotypes were around 97% in all chromosomes and were ignored leaving 153,428 haplotypes. Estimated haplotypes had a large contribution to the total variance of genomic estimated breeding values for kilogram of protein, Global Type Index, Somatic Cell Score and Days Open (between 32 and 99.9%). Haploblocks containing haplotypes with large effects were selected by filtering for each trait, haplotypes whose effect was larger/lower than the mean plus/minus 3 times the standard deviation (SD) and 1 SD above the mean of the haplotypes effect distribution. Results showed that filtering by 3 SD would not be enough to capture a large proportion of genetic variance, whereas filtering by 1 SD could be useful but model convergence should be considered. Additionally, sequence haplotypes were able to capture additional genetic variance to the polygenic effect for traits undergoing lower selection intensity like fertility and health traits.
[en] Interest in the preservation of endangered breeds such as the Blanca Andaluza goat, has increased and some steps should be therefore taken to ensure it. The study was designed to determine the seasonal reproductive pattern of Blanca Andaluza bucks, and whether this affects the quality of their semen and its freezability over the year. Seven bucks were used and their body weight, testicular weight, plasma testosterone concentration and fresh sperm quality determined every week. The collected sperm was cryopreserved and stored; it was then thawed and the same sperm quality variables measured every fortnight. High plasma testosterone concentrations were recorded during the summer and autumn, and low concentrations were recorded during winter and spring (p<0.001). No differences were seen between seasons in terms of the percentage of bucks ejaculating, the percentage of active bucks, or ejaculate volume. However, the sperm concentration, the total number of sperm per ejaculate, and the values for most fresh sperm variables were lower during the winter period (at least p<0.05). After freezing-thawing, the quality of winter-collected sperm was better, in some respects, than that of summer-collected sperm (at least p<0.05). These results reveal that Blanca Andaluza bucks show seasonal reproductive activity in terms of their plasma testosterone concentration, but no clear change in their sexual behaviour between seasons was observed. The values of fresh sperm variables also vary over the year, reaching their lowest during winter. However, after freezing-thawing, winter-collected sperm is of overall better quality than sperm collected during the summer. (Author)
[en] Shortage of irrigation water at critical growth stages of maize is limiting its production worldwide. Breeding drought-tolerant cultivars is one possible solution while identification of potential genotypes is crucial for genetic improvement. To assess genetic variation for seedling-stage drought tolerance, we tested 40 inbred lines in a completely randomized design under glasshouse conditions. From these, two contrasting inbred lines were used to develop six basic generations (P1, P2, F1, F2, BC1F1, BC2F2). These populations were then evaluated in a triplicated factorial randomized complete block design under non-stressed and drought-stressed conditions. For statistical analyses, a nested block design was employed to ignore the replication effects. Significant differences (p=0.01) were recorded among the genotypes for investigated seedling-traits. Absolute values of fresh root length, fresh root weight, and dry root weight lead to select two genotypes, one tolerant (WFTMS) and one susceptible (Q66). Estimates of heritability, genetic advance, and genotypic correlation coefficients were higher and significant for most of the seedling-traits. Generation variance analysis revealed additive gene action. Narrow-sense heritability [F2 = 65; F8 = 79] revealed the same results. Generation mean analysis signified additive genetic effects in the inheritance of cob girth, non-additive for plant height, grains per ear row and grain yield per plant, and environmental for ear leaf area, cob length, grain rows per ear, biomass per plant, and 100-grain weight under drought-stressed conditions. For conferring drought-tolerance in maize, breeders can adopt the recombinant breeding strategy to pyramid the desirable genes. (Author)
[en] Virgin olive oil is a key ingredient of the renowned Mediterranean diet. In this context, the main objective of this study was to estimate and decompose productivity change for Protected Designations of Origin (PDOs) in the Spanish virgin olive oil sector for the period 2008-2013. To this end, we introduced a Luenberger-type indicator based on a specific weighted additive model in Data Envelopment Analysis (DEA), which, in contrast to previous studies, captured all sources of inefficiency and avoided infeasibilities. Regarding the results, we found a reduction in productivity, in average terms, in the first periods analyzed (-0.12 and -1.65), followed by an improvement (0.79 and 0.54), that in the last period analyzed (2012-2013), however, returned to adverse figures (-0.47). In Spain, where foreign competition is weak, the most productive PDOs were those with an important number of oil mills and packaging/marketing companies such as “Montes de Toledo” and “Siurana”; productivity changes were mainly the consequence of downwards and upwards of the frontier of the technology over time. These changes were explained, to a certain extent, by the evolution of the economic crisis; and the productivity of the sector declined, in general, from 2008 to 2010, improving thereafter except for the last registered period, 2012-2013, where expectations for market recovery exceeded actual sales. (Author)
[en] Female mules are considered as infertile; however, they could be used as recipients in interspecific embryo transfer. This study reports for the first time how it is possible to obtain the birth of a live Andalusian donkey foal after transfer a donkey embryo to a non-cycling mule. Two non-cycling mules were used as recipients, oestradiol benzoate was administered when donors showed oestrus and long-acting progesterone after ovulation. The mules also received long-acting progesterone every 7 days until 120 days of gestation. One embryo was collected from the two donor jennies and transferred to one of the mules after 5 days of progesterone treatment. Pregnancy was established and maintained after embryo transfer. The pregnant mule carried to term and delivered a live donkey foal after 375 days of pregnancy. In conclusion, non-cycling mules treated with oestradiol benzoate and long-acting progesterone can be successfully used as recipients of donkey embryos, which open new ways for the conservation of endangered donkey species.
[en] In a laboratory study we investigated the contact and barrier efficacy of different natural substances (wood ash, sawdust, hydrated lime, and diatomaceous earth) against slugs of the genus Arion, an important agricultural pest. Natural substances were tested individually and in combination with each other. The experiment was carried out in plastic petri dishes and in glass insectaria. Moistened tampons and fresh leaves of lettuce were placed into both experimental arenas. The slugs were starved for 48 hours prior to the experiment. Six categories of behaviour were identified for slugs in the presence of the natural substances: (1) slug survived the experiment, (2) slug died during the experiment, (3) slug crossed the barrier, (4) slug did not cross the barrier, (5) slug fed on the lettuce, and (6) slug did not feed on the lettuce. The effect of different treatments (natural substances) was significant. The results of our study have shown that hydrated lime had the best contact efficacy on slugs (the mortality of slugs was 100%), both individually and in combination with other substances. The treatments with hydrated lime also proved to be the most efficient barrier preventing slugs from feeding on lettuce. Hydrated lime shows great potential in Arion control in our investigation; however, further research is needed to investigate the practical value (how to avoid the problem when the substance becomes wet), safety and economics of hydrated lime used in this way. (Author)
[en] Weeds and non-cultivated plants have a great impact on abundance and diversity of beneficial arthropods in agriculture. The main aim of this work was to study the influence of the ecological infrastructure (meadows and weedy margins) on the arthropod composition in vineyard surrounding landscape. Research was carried out from May to October during three years. Sampling took place in the ecological infrastructure of three differently managed vineyards (organic, integrated and extensive). Three zones were chosen in each vineyard (3 m, 10 m, and 30 m from the edge of the vineyard). Samples were taken using a standardised sweep net method. In total, we captured 6032 spiders and 1309 insects belonging to 4 orders and 10 families. Arthropod fauna was numerically dominated by Aranea (82.1%); among insects, Coleoptera was the most abundant taxonomic group (10.6%); Neuroptera showed the lowest value (0.88%). Significant differences were found between sites and zones. Organic vineyard showed the highest abundance of arthropods (92.41% were spiders) and in the integrated vineyard there was a 23% of insects. Both the highest abundance of arthropods and the highest Shannon Index value (2.46) was found 3 m away from the edge of the vineyard. Results showed that spiders were the dominant arthropods and ladybugs the dominant insects. Weedy strips near the edge of the vineyard contained a high number of insects and spiders. Our results support the importance of weedy margins in enhancing the population of arthropods as well as in biodiversity promotion. Well-managed field margins could play important role in biological control of vineyard pests. (Author)
[en] This study compared the effects of a proportionate spray volume (PSV) adjustment model and a fixed model (300 L/ha) on the infestation of processing tomato with potato late blight (Phytophthora infestans (Mont.) de Bary) (PLB) and azoxystrobin and chlorothalonil residues in fruits in three consecutive seasons. The fungicides were applied in alternating system with or without two spreader adjuvants. The proportionate spray volume adjustment model was based on the number of leaves on plants and spray volume index. The modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was optimized and validated for extraction of azoxystrobin and chlorothalonil residue. Gas chromatography with a nitrogen and phosphorus detector and an electron capture detector were used for the analysis of fungicides. The results showed that higher fungicidal residues were connected with lower infestation of tomato with PLB. PSV adjustment model resulted in lower infestation of tomato than the fixed model (300 L/ha) when fungicides were applied at half the dose without adjuvants. Higher expected spray interception into the tomato canopy with the PSV system was recognized as the reasons of better control of PLB. The spreader adjuvants did not have positive effect on the biological efficacy of spray volume application systems. The results suggest that PSV adjustment model can be used to determine the spray volume for fungicide application for processing tomato crop. (Author)