Spanish Journal of Agricultural Research
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Surplus thermal energy model of greenhouses and coefficient analysis for effective utilization
No full textIf a greenhouse in the temperate and subtropical regions is maintained in a closed condition, the indoor temperature commonly exceeds that required for optimal plant growth, even in the cold season. This study considered this excess energy as surplus thermal energy (STE), which can be recovered, stored and used when heating is necessary. To use the STE economically and effectively, the amount of STE must be estimated before designing a utilization system. Therefore, this study proposed an STE model using energy balance equations for the three steps of the STE generation process. The coefficients in the model were determined by the results of previous research and experiments using the test greenhouse. The proposed STE model produced monthly errors of 17.9%, 10.4% and 7.4% for December, January and February, respectively. Furthermore, the effects of the coefficients on the model accuracy were revealed by the estimation error assessment and linear regression analysis through fixing dynamic coefficients. A sensitivity analysis of the model coefficients indicated that the coefficients have to be determined carefully. This study also provides effective ways to increase the amount of STE
Modelling the number of olive groves in Spanish municipalities
No full textThe univariate generalized Waring distribution (UGWD) is presented as a new model to describe the goodness of fit, applicable in the context of agriculture. In this paper, it was used to model the number of olive groves recorded in Spain in the 8,091 municipalities recorded in the 2009 Agricultural Census, according to which the production of oil olives accounted for 94% of total output, while that of table olives represented 6% (with an average of 44.84 and 4.06 holdings per Spanish municipality, respectively). UGWD is suitable for fitting this type of discrete data, with strong left-sided asymmetry. This novel use of UGWD can provide the foundation for future research in agriculture, with the advantage over other discrete distributions that enables the analyst to split the variance. After defining the distribution, we analysed various methods for fitting the parameters associated with it, namely estimation by maximum likelihood, estimation by the method of moments and a variant of the latter, estimation by the method of frequencies and moments. For oil olives, the chi-square goodness of fit test gives p-values of 0.9992, 0.9967 and 0.9977, respectively. However, a poor fit was obtained for the table olive distribution. Finally, the variance was split, following Irwin, into three components related to random factors, external factors and internal differences. For the distribution of the number of olive grove holdings, this splitting showed that random and external factors only account about 0.22% and 0.05%. Therefore, internal differences within municipalities play an important role in determining total variability
Culinary and sensory traits diversity in the Spanish Core Collection of common beans (Phaseolus vulgaris L.)
No full textThe Spanish National Plant Genetic Resource Center’s core collection of bean germplasm includes 202 accessions selected from more than 3000 accessions in function of passport data, seed phenotype, genetic background, and agronomic traits. To acquire more useful information about these accessions, we cultivated and characterized them for sensory and culinary traits. We found considerable variation for culinary and sensory traits of the cooked beans (mean coefficients of variation: 41% for the sensory traits and 40% for the culinary traits). The large dataset enabled us to study correlations between sensory and culinary traits and among these traits and geographic origin, seed color, and growth habit. Greater proportion of white in the seed coat correlated positively with brightness and negatively with mealiness (r=0.60, r=-0.60, p<0.001, respectively). Mealiness correlated negatively with seed-coat roughness and rate of water absorption (r=-0.60, r=-0.53, p<0.001, respectively). Materials of Andean origin had lower seed-coat brightness (p<0.01) and seed-coat roughness, and greater seed-coat perceptibility, mealiness, flavor, and aroma (p<0.001) than materials of Mesoamerican origin. Growth habit failed to correlate with culinary or sensory traits. Breeders can benefit from the information about this core collection available at www.crf.inia.es/crfesp/paginaprincipaljudia.asp
Short communication: Laboratory approach to the use of sulphur and kaolin as preventive control against Drosophila suzukii
No full textDrosophila suzukii (Matsumura, 1931) is an invasive pest from South East Asia that was detected for the first time in Southern Europe in 2008. This species can damage a wide range of soft-skinned fruits crops affecting ripening fruits and causing important economic losses. Since the exclusive use of chemical insecticides for controlling D. suzukii may prompt the appearance of resistance and environmental pollution, alternative methods compatible with sustainable management are required. In this study, commercial formulations of powdered sulphur and kaolin were tested as a preventive method applied to blueberry fruits under laboratory conditions. In no-choice assay, powdered sulphur had a significant effect on oviposition and adult emergency with reductions of 76% and 77%, respectively. In addition, sulphur displayed a significant toxicity on males and lethal effect with over 40% adult mortality seven days after exposure. The choice assay confirmed and improved the powdered sulphur effects, with reductions of 98% and 96% in oviposition and adult emergence, respectively. In contrast, kaolin produced no significant reduction in infestation and adult mortality during no-choice and choice assays. These outcomes suggest that preventive use of powdered sulphur could be considered for sustainable control of D. suzukii in some berry crops
Effects of the amplitude and frequency of salinity fluctuations on antioxidant responses in juvenile tongue sole, Cynoglossus semilaevis
No full textTo understand the tolerance of tongue sole, Cynoglossus semilaevis, to varying salinities, the effects of the amplitude (2, 4, 6 and 8 g/L) and frequency (2, 4 and 8 days) of salinity fluctuations on the activities of antioxidant responses, including acidic phosphatase (ACP), alkaline phosphatase (AKP), catalase (CAT) and superoxide dismutase (SOD) from antioxidant system in liver, muscle, gills and kidney, were investigated in this study. The results showed that the antioxidant responses of tongue sole were highly tissue-specific during the varying salinity fluctuations. In all tissues, ACP and AKP activity was found to be highest at moderate salinity fluctuations compared to the control, low and high salinity treatments (p<0.05). SOD and CAT activities had significant effect due to salinity fluctuations in all tissues (p<0.05), except in hepatic and renal tissues. Variations in branchial SOD activity proved that salinity fluctuations had greater impact on tongue sole at moderate and high fluctuating salinities compared to the control and low fluctuating salinities, whereas the branchial CAT activities showed contrasting trend. Further, cortisol levels were significantly affected in lower and higher salinity fluctuations. However, plasma cortisol levels remained low in moderate salinity fluctuations and control (p<0.05). Taken together, the results indicated that salinity fluctuations could effectively stimulate and enhance the antioxidant enzyme activity in the liver, kidney, gills and muscle of the juvenile tongue sole, thus effectively eliminating the excessive reactive oxygen species and minimizing the body damage in tongue sole or could be for any other euryhaline teleosts
Cyclic use of saline and non-saline water to increase water use efficiency and soil sustainability on drip irrigated maize in a semi-arid region
No full textUse of saline water for irrigation is a strategy to mitigate water shortage. The objective of this study was to investigate the impact of the cyclic and constant use of saline and non-saline water on drip irrigated maize yield and irrigation water use efficiency (IWUE). Nine field treatments were laid out based on alternative irrigation management of non-saline and saline water combinations. The treatments were: two salinity levels of 3.5 and 5.7 dS/m and freshwater (0.4 dS/m) application in every one, three and five saline water application (1:1, 3:1 and 5:1, respectively). Results showed that the 1:1 combination management was the best in terms of crop yield and IWUE. In this treatment, salt concentration at the end of growing season was not significantly changed compared to its initial condition. If off-season precipitation or leaching was available, the 3:1 and 5:1 treatments were appropriated. Highest and lowest values of IWUE were 15.3 and 8.7 kg/m3 for the 1:1 management using water salinity of 3.5 dS/m and the treatment of constant irrigation with water salinity of 5.7 dS/m, respectively. Under low off-season precipitations, artificial leaching is essential for land sustainability in most treatments
Effect of the spray volume adjustment model on the efficiency of fungicides and residues in processing tomato
No full textThis 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
Changes in productivity in the virgin olive oil sector: An application to Protected Designations of Origin in Spain
No full textVirgin 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
