Spanish Journal of Agricultural Research
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Association mapping for morphological traits relevant to registration of barley varieties
No full textElucidating marker-trait associations would have fruitful implications in distinctness, uniformity, and stability (DUS) tests of new varieties required for both variety registration and granting plant breeders’ rights. As the number of new varieties with narrow genetic bases increases, the necessity for deployment of molecular markers to complement morphological DUS traits gets particular attention. We used simple sequence repeats (SSRs) and sequence related amplification polymorphisms (SRAPs) markers in association mapping of morphological traits in a collection of 143 barley landraces and advanced breeding lines. This panel represented a diverse and uniform sample in terms of both quantitative and categorical traits whilst it was structurally partitioned by number of ear rows (six- and two-rowed) and seasonal growth habit (winter and spring types) characteristics. SSRs were more powerful compared with SRAPs in separating six- and two-rowed genotypes based on both model-based Bayesian and neighbor joining clustering methods. A number of associated SSR and SRAP markers were found for 15 out of 36 DUS traits after considering Bonferroni correction through linear models (GLM and MLM) and chi-square-based tests (SA and AAT). This is also the first report of association of awn roughness and grain color with molecular markers in barley. Moreover, SSR marker BMAC0113 appeared associated with time of ear emergence (TEE), confirming previous findings. These markers could be beneficial to complement and speed up DUS testing of new varieties, as well as for improving management of barley reference collections
A method to evaluate the perceived ease of use of human-machine interface in agricultural tractors equipped with Continuously Variable Transmission (CVT)
No full textAt the end of the 20th century the adoption of the Continuously Variable Transmission (CVT) was one of the disruptive technological advances in agricultural tractors. Several changes in the Human Machine Interface (HMI) of the tractor cab have been introduced to accommodate this technology. HMIs are known to raise issues about their ease of use; however, this topic has been under-investigated in the agricultural sector. The present study introduces a method to investigate the perceived ease of use of the HMI of agricultural tractors equipped with technological innovations. The HMI required to manage a CVT tractor was evaluated by sixteen tractor drivers (8 novices and 8 experts). During the first contact with the machine and after having performed two targeted tasks with the tractor, participants filled in a questionnaire about the ease of use of the controls and of the touch-screen display, and evaluated the general perception of ease of use, safety, quality and solidity of the machine. The trial pointed out some significant differences between novices and experts, thus confirming the validity of the proposed method. In particular, novice users showed some difficulties when interacting for the first time with the HMI of the CVT tractor working station, whereas experts did not report similar difficulties. Thus, expertise seems to play a role in determining the quality of the interaction with the HMI. Training interventions should be designed to help novices in increasing their expertise effectively, avoiding effort and errors and improving user’s comfort and system performance
Mode of inheritance of low-N tolerance adaptive traits in wheat (Triticum aestivum L.) under contrasting nitrogen environments
No full textBecause of essential economic and ecological concerns, there is increased interest worldwide in developing wheat cultivars that are more efficient in utilizing nitrogen (N) and better suited to N limitations. The objective of the present investigation was to get information on the type of gene action controlling the inheritance of wheat low-N tolerance traits in order to start a breeding program for improving such traits. Six parents of contrasting low-N tolerance were crossed in a diallel fashion. Evaluation of 6 parents, 15 F1crosses and 15 F2 crosses was done using a randomized complete block design with three replications under two levels of soil N, i.e. low-N (0 kg N/ha) and high-N (180 kg N/ha).The magnitude of dominance variance inF2's for all studied traits was much greater than that of additive variance under both high N and low N, suggesting that selection should be postponed to later segregating generations in order to eliminate masking effects of dominance variance and take advantage of the additive variance for the improvement of nitrogen use efficiency and grain yield traits. Narrow-sense heritability (h2n) in F2's was generally of higher magnitude under low-N than high-N, suggesting that it is better to practice selection for studied nitrogen efficiency and grain yield traits under low-N conditions to obtain higher values of selection gain
Development of an index based on ultrasonographic measurements for the objective appraisal of body condition in Andalusian horses
No full textBody condition scoring (BCS) is an indirect measure of the level of subcutaneous fat; however, by measuring the subcutaneous fat thicknesses (SFT), the precision of the degree of fatness assessment is improved. The aims were: 1) to develop an alternative body fat scoring index (BFSI) based on ultrasonographic measurements; 2) to assess the agreement between BCS and the new index applied to Andalusian horses; 3) to adjust the BCS cut-off values (if necessary) for overweight and obesity in this breed. One hundred and sixty-six Andalusian horses were included in this cross sectional study. On each horse, BCS, body fat percentage (BF%) and ultrasonography of SFT at localized deposits were evaluated. According to BFSI five possible body categories were established. Only one horse (0.6%) was classified as emaciated, 9.0% as thin, 74.7% as normal, 11.4% as overweight and 4.2% as obese. Despite higher BCS and SFT values were observed compared to other breeds, most of the horses evaluated presented a normal body condition under the new BFSI. BCS and BFSI were significantly associated (p<0.001), however, the concordance was low (weighted Cohen’s kappa coefficient, 0.262 ± 0.071; p=0.004). Using BFSI, obese horses had significantly greater BF% than the rest of categories (p<0.001). BCS showed a good diagnostic accuracy for detection overweight (AUC = 0.759 ± 0.055; p<0.001) and obese (AUC = 0.878 ± 0.050; p=0.001) horses; redefining the cut-off values for overweight and obesity condition as 7.5/9 and 8.5/9 respectively in Andalusian horses
Machine learning applied to the prediction of citrus production
No full textAn in-depth knowledge about variables affecting production is required in order to predict global production and take decisions in agriculture. Machine learning is a technique used in agricultural planning and precision agriculture. This work (i) studies the effectiveness of machine learning techniques for predicting orchards production; and (ii) variables affecting this production were also identified. Data from 964 orchards of lemon, mandarin, and orange in Corrientes, Argentina are analysed. Graphic and analytical descriptive statistics, correlation coefficients, principal component analysis and Biplot were performed. Production was predicted via M5-Prime, a model regression tree constructor which produces a classification based on piecewise linear functions. For all the species studied, the most informative variable was the trees’ age; in mandarin and orange orchards, age was followed by between and within row distances; irrigation also affected mandarin production. Also, the performance of M5-Prime in the prediction of production is adequate, as shown when measured with correlation coefficients (~0.8) and relative mean absolute error (~0.1). These results show that M5-Prime is an appropriate method to classify citrus orchards according to production and, in addition, it allows for identifying the most informative variables affecting production by tree
Alpha-tocopherol improves frozen-thawed sperm quality by reducing hydrogen peroxide during cryopreservation of bull semen
No full textThis study was conducted to investigate the effects of different levels of α-tocopherol in cryopreservation media on the bull sperm quality after thawing. Semen samples were collected from six Holstein bulls using artificial vagina twice a week. Semen samples were pooled to eliminate individual differences and then divided into four equal parts for freezing with extenders containing different concentrations of α-tocopherol according to experimental groups as follows: 0 (control), 1.2 mM (E1), 2.4 mM (E2) and 4.8 mM (E4). Motion characteristics, viability, plasma membrane functionality, lipid peroxidation and H2O2 status were determined after thawing. Results showed that malondialdehyde (MDA) concentration was significantly lower in E4 (6.1±0.6 nmol/mL) than E1 and E2 extenders (8.1±0.6 nmol/mL and 8±0.6 nmol/mL, respectively). Also, the lowest significant concentration of H2O2 was observed in E4 (3.2±0.13 nmol/mL) compared to E1 (4 ±0.1 nmol/mL), E2 (5.3± 0.1 nmol/mL) and control (6.7±0.1 nmol/mL). Moreover, E2 and E4 produced the highest significant motility (74.2±1.6%, 75.9±1.6%), viability (78.2±1.8%, 76.1±1.8%) and membrane functionality (73±1.6%, 70.5±1.6%) compared to other groups. It can be concluded that α-tocopherol at the concentration of 4.8 mM can be an efficient antioxidant additive in Bioxcell extender for cryopreservation of bull semen
Relationship between birth order, birth weight, colostrum intake, acquisition of passive immunity and pre-weaning mortality of piglets
No full textThis study investigates the relation between birth order (BO), birth weight (BW0), colostrum intake (CI), level of passive immunity and pre-weaning mortality of piglets. The animals used were 551 cross-bred piglets [Piétrain × (Large-White × Landrace)] born from 40 sows. Colostrum immunoglobulins G (IgG) determinations were made from 17 sows. Colostrum samples were obtained at birth of the first piglet then at 3, 6, 12, 24, and 36 h later, and on the first-two and the last-two piglets born. Serum IgG determinations from 68 piglets were made at 2d of age and at weaning. Individual CI was estimated from body weight gain. Relative birth order (RBO) and BW0 within-litter were weakly (R2<0.05) but positively correlated (p<0.01). Colostrum intake of piglets was independent from RBO (p>0.10) but increased by 26 ± 1.6 g per 100 g increase in BW0 (p<0.001). Serum IgG concentrations of the last two born piglets were 29.5% lower (p<0.01) than the first two born at 2 d of age, and 25% (p<0.05) at weaning. They were also lower at weaning than at 2 d of age (p<0.001). Serum IgG concentrations of piglets at weaning and at 2 d of age were positively correlated (R2=0.50, p<0.001). Within-litter, CI explained 11% (p<0.01) of the variation observed in piglets’ IgG at 2d of age. Mortality of piglets was irrespective of RBO (p>0.10). It was concluded that despite last-born piglets obtained less passive immunity than first-born, they were not at higher risk of dying before weaning. Major causes of mortality were low birth weight and insufficient colostrum (energy) intake
Pulling back the curtain on 'behind the border' trade costs: The case of EU-US agri-food trade
No full textWith the rise of anti-free-trade sentiment on both sides of the Atlantic, there is a growing urgency by trade negotiators to conclude the Trans-Atlantic Trade and Investment Partnership (TTIP) negotiations. The harmonisation of non-tariff restrictions is a key component of the talks, whilst global modelling databases typically lack a price compatible representation of these measures, which lends a degree of bias to ex-ante modelling assessments. In the gravity literature, there is (limited) evidence of non-tariff ad-valorem equivalent (AVE) estimates of agriculture and food, although disaggregated agri-food activities and/or bilateral EU-US route specific estimates are still in relatively short supply. Using panel data, this study consolidates both of these issues, whilst also proposing an ‘indirect’ gravity method as a basis upon which to provide econometric non-tariff AVE estimates compatible with the degree of sectoral concordance typically found in global modelling databases. On a general note, the results revealed the presence of significant behind the border trade costs on both sides of the Atlantic, which exceed their tariff counterparts. Using simple aggregated averages, our estimates are comparable with ‘direct’ gravity method studies. Furthermore, rigorous qualitative and quantitative comparisons on a sector-by-sector basis showed that a number of bilateral non-tariff AVEs are also found to be plausible, although in some cases, with recourse to relevant policy documents and expert opinion, it is debatable whether the EU or the US is more restrictive. Further work could focus on refining the sector specificity of each gravity equation to improve the model's predictive capacity
Within-field distribution of the damson-hop aphid Phorodon humuli (Schrank) (Hemiptera: Aphididae) and natural enemies on hops in Spain
No full textA field trial was performed in a hop yard throughout 2002, 2003 and 2004 in order to determine the within-field distribution of Phorodon humuli (Schrank) (Hemiptera: Aphididae) and its natural enemies. The distribution of P. humuli was directly affected by the position of the hop plants in the garden, with significantly higher concentrations of aphids (p=0.0122 in 2002 and p=0.0006 in 2003) observed along the edge. However, in 2004 the plants located on the marginal plots had similar populations to those on the more inner plots. This can be explained by a higher wind speed which made it more difficult to land on edge plants first. The hop aphid’s main natural enemy was Coccinella septempunctata (Coleoptera: Coccinellidae), whose population was greatest where the aphids were most abundant with a significantly greater number of eggs (p=0.0230) and adults (p=0.0245) in 2003. Lacewing eggs were also frequently observed, with a significantly higher population (p=0.0221 in 2003 and p=0.0046 in 2004) where the aphid numbers were high. The number of winged aphids was greatest towards the margins of the garden in 2003. It is argued that the spatial distribution of the hop aphid and its natural enemies could be used to plan a sampling program and to estimate the population densities of these insects for use in integrated pest management programs
Discounting in agro-industrial complex. A methodological proposal for risk premium
No full textThe estimation of the discount rate is decisive for a reliable economic valuation. The discount rate has to be adjusted for the risks related to the company, the sector which the company has its market, and the risks related to the investment project. We present a proposal to incorporate the risk premium to the discount rate. The novelty of the methodology is that difference risk groups according to activity as a factor to adjust the cost of capital to companies. The study applies the methodology to the Agro-Industrial Complex (AIC) in Spain. The AIC is formed by industries that add value to farming production. This sector’s economic success demands financial management techniques that assess risk. The conventional method responds neither to the heterogeneity of the economic activities that make up the AIC, nor to differentiating risk by groups. The proposed methodology distinguishes activity groups in accordance with the NACE (National Code of Economic Activities) and uses net profitability variability to distinguish the risk in each group. Our results demonstrate the various levels of risk per group. The results show that among all the groups that form the AIC there are wide differences between levels of risk; thus, the risk neutral groups present risk levels on the order of 150 times lower than the groups extreme risk levels