Spanish Journal of Agricultural Research
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Evaluation of agronomic and fruit quality traits of fig tree varieties (Ficus carica L.) grown in Mediterranean conditions
No full textIn this work, the agronomic behaviour and fruit quality of ten varieties of common fig were evaluated for the establishment of new commercial orchards destined for fresh consumption. The following traits were measured: annual yield, cumulative yield, trunk cross sectional area (TCSA) and yield efficiency of each variety, as well as weight, width, total soluble solids (TSS), pH, titratable acidity (TA) and maturation index (MI) of brebas and figs. The results show that ‘Banane’ and ‘Brown Turkey’ were the earliest to enter into production, and ‘Banane’ showed the highest annual yield in the 7th green (2014), with 76 kg/tree, followed by ‘Brown Turkey’ (57.6 kg/tree), ‘Cuello Dama Blanco’ (52 kg/tree) and ‘Colar Elche’ (39 kg/tree). On the other hand, 'Cuello Dama Blanco' and 'De Rey' exhibited the better organoleptic traits, with TSS and MI values ranged from 18.7 ºBrix and 203.3 MI (‘Cuello Dama Blanco’) to 20.4 ºBrix and 187.1 MI (‘De Rey’) for brebas and from 21.4 ºBrix and 278.7 (‘Cuello Dama Blanco’) to 23.3 ºBrix and 255.6 (‘De Rey’) for figs. This study will allow the fruit grower to select the most interesting and appropriate range of varieties based on market needs taking into account the ripening season (early, middle or late) and fruit colour (green, purple or black)
Development of a model to calculate the overall heat transfer coefficient of greenhouse covers
No full textA Building Energy Simulation (BES) model based on TRNSYS, was developed to investigate the overall heat transfer coefficient (U-value) of greenhouse covers including polyethylene (PE), polycarbonate (PC), polyvinyl chloride (PVC), and horticultural glass (HG). This was used to determine the influences of inside-to-outside temperature difference, wind speed, and night sky radiation on the U-values of these materials. The model was calibrated using published values of the inside and outside convective heat transfer coefficients. Validation of the model was demonstrated by the agreement between the computed and experimental results for a single-layer PE film. The results from the BES model showed significant changes in U-value in response to variations in weather parameters and the use of single or double layer greenhouse covers. It was found that the U-value of PC, PVC, and HG was 9%, 4%, and 15% lower, respectively, than that for PE. In addition, by using double glazing a 34% reduction in heat loss was noted. For the given temperature U-value increases as wind speed increases. The slopes at the temperature differences of 20, 30, 40, and 50 °C, were approximately 0.3, 0.5, 0.7, and 0.9, respectively. The results agree with those put forward by other researchers. Hence, the presented model is reliable and can play a valuable role in future work on greenhouse energy modelling
Vicia narbonensis-Avena strigosa mixture, a viable alternative in rainfed cropping systems under Mediterranean conditions
No full textThe demand of vegetable protein for animal feed and the need to diversify the crop rotation in rainfed Mediterranean climates has led to study the viability as new forage crop of the Vicia narbonensis-Avena strigosa mixture. Therefore, a 3-year field trial was conducted at two different and representative locations of the area to evaluate the capacity of both species to form a balanced mixture and to define its potential for high yield and forage quality. Different seeding ratios (65:35, 50:50 and 35:65) were compared with their pure stands and the standard mixture Avena sativa-Vicia sativa (65:35). Forage mixtures establishment and growth varied according to the environmental conditions with a negative influence of a dry year 1 for legumes (<300 mm) and a wet year 2 for oats (>630 mm). However, competition ratio indicated that there were not significant differences between mixed treatments, displaying intermediate ground coverage values, dry matter yield and crude protein regarding pure stands. Higher dry matter yield than control mixture in addition to similar crude protein, acid-detergent fibre, neutral-detergent fibre and digestible dry matter values, were produced at 35:65 in dry years and 65:35 and 50:50 in rainy years with loamy and clay soils, respectively. The appropriate development of both species in the mixture at different soil and rainfall conditions, as well as a good yield often higher than control mixture and a great forage quality, confirm to the narbon bean-black oat mixture as a viable and profitable crop alternative in rainfed cropping systems under Mediterranean conditions
Farmer preference for improved corn seeds in Chiapas, Mexico: A choice experiment approach
No full textAppropriate technologies must be developed for adoption of improved seeds based on the farmers’ preferences and needs. Our research identified the farmers’ willingness to pay (WTP) as a key determinant for selecting the improved varieties of maize seeds and landraces in Chiapas, Mexico. This work also analyzed the farmers’ observed heterogeneity on the basis of their socio-economic characteristics. Data were collected using a semi-structured questionnaire from 200 farmers. A proportional choice experiment approach was applied using a proportional choice variable, where farmers were asked to state the percentage of preference for different alternative varieties in a choice set. The generalized multinomial logit model in WTP-space approach was used. The results suggest that the improved seed varieties are preferred over the Creole alternatives, thereby ensuring higher yields, resistance to diseases, and larger ear size. For the preference heterogeneity analyses, a latent class model was applied. Three types of farmers were identified: innovators (60.5%), transition farmers (29.4%), and conservative farmers (10%). An understanding of farmers’ preferences is useful in designing agricultural policies and creating pricing and marketing strategies for the dissemination of quality seeds
Comparison of how different feed phosphates affect performance, bone mineralization and phosphorus retention in broilers
No full textThe objective of this work was to evaluate the comparative P bio-avalability of different sources of phosphate based on their effects on animal performance, bones mineralization and mineral retention in broilers. To achieve this goal, two experiments were conducted. In Experiment 1, twenty diets were prepared including five different phosphorus sources, either mono-calcium phosphate (MCP) or 4 different batches of di-calcium phosphate, to supplement non phytic P (NPP) levels at 3.0, 3.5, 4.0 and 4.5 g/kg in the diets. In Experiment 2, three treatments were used: the low MCP diet was deficient in NPP (3.1 g/kg for the starter phase and 2.8 g/kg for the grower phase); the high MCP diet and the high TCP (tri-calcium phosphate) diet included adequate levels of NPP (4.4-4.7 g/kg for the starter phase and 4.2-4.3 g/kg for the grower phase). Phytase was not added to experimental diets. Results of Exp. 1 indicated that an increase of NPP in the diet from 3.0 to 4.0 g/kg increased weight gain and feed intake between d 1 and d 21 (Trial 1). Alternatively, tibia weight and ash percentage at d 21 responded up to the level of 4.5 g/kg and showed significant difference with birds of the 4.0 g/kg NPP group. In Trial 2, chickens fed with the high MCP and TCP had improved growth performances and bone mineralization. No differences were observed on the P availability among different mineral P sources. A level of 4.5 g/kg, NPP is recommended when phytase is not included to maximize both performance and bone mineralization in broiler chickens up to d 21
Crop insurance demand in wheat production: focusing on yield gaps and asymmetric information
No full textAnalysis of yield gaps were conducted in the context of crop insurance and used to build an indicator of asymmetric information. The possible influence of asymmetric information in the decision of Spanish wheat producers to contract insurance was additionally evaluated. The analysis includes simulated yield using a validated crop model, CERES-Wheat previously selected among others, whose suitability to estimate actual risk when no historical data are available was assessed. Results suggest that the accuracy in setting the insured yield is decisive in farmers’ willingness to contract crop insurance under the wider coverage. Historical insurance data, when available, provide a more robust technical basis to evaluate and calibrate insurance parameters than simulated data, using crop models. Nevertheless, the use of crop models might be useful in designing new insurance packages when no historical data is available or to evaluate scenarios of expected changes. In that case, it is suggested that yield gaps be estimated and considered when using simulated attainable yields
Physiological changes of pepper accessions in response to salinity and water stress
No full textNew sources of water stress and salinity tolerances are needed for crops grown in marginal lands. Pepper is considered one of the most important crops in the world. Many varieties belong to the genus Capsicum spp., and display wide variability in tolerance/sensitivity terms in response to drought and salinity stress. The objective was to screen seven salt/drought-tolerant pepper accessions to breed new cultivars that could overcome abiotic stresses, or be used as new crops in land with water and salinity stress. Fast and effective physiological traits were measured to achieve the objective. The present study showed wide variability of the seven pepper accessions in response to both stresses. Photosynthesis, stomatal conductance and transpiration reduced mainly under salinity due to stomatal and non-stomatal (Na+ accumulation) constraints and, to a lesser extent, in the accessions grown under water stress. A positive relationship between CO2 fixation and fresh weight generation was observed for both stresses. Decreases in Ys and YW and increased proline were observed only when accessions were grown under salinity. However, these factors were not enough to alleviate salt effects and an inverse relation was noted between plant salt tolerance and proline accumulation. Under water stress, A31 was the least affected and A34 showed the best tolerance to salinity in terms of photosynthesis and biomass
Genetic diversity of the Northern Morocco goat population assessed with microsatellite markers
No full textThe main goal of this work was to study the genetic diversity of the Northern Morocco goat population through the analysis of 19 microsatellites in 144 animals from 61 herds. To detect a possible population structure, three distinct geographic subpopulations were characterized as a function of climate and environmental influences. Most of the markers were highly polymorphic, and the results revealed considerable genetic variation across the studied loci. A total of 204 alleles were detected, with an average number of 10.7 per locus. The PIC average was 0.728, and four microsatellites showed a significant deviation (p< 0.05) from Hardy-Weinberg Equilibrium. Analysis of molecular variance (AMOVA) indicated that only 0.5% of the variation corresponded to differences among subpopulations, and 99.5% corresponded to differences among individuals. Factorial correspondence analysis showed intense admixtures across the putative subpopulations, and the subdivision related to geographical or environmental adaptation was undetectable. The Northern Morocco goat population presented high genetic diversity and a lack of population structure. The main reason for these findings is the absence of the breed concept (reproductively closed population), resulting in uncontrolled crossbreeding with exotic breeds and other local goats
Risk factors associated with honey bee colony loss in apiaries in Galicia, NW Spain
No full textA cross-sectional study was carried out in Galicia, NW Spain, in order to estimate the magnitude of honey bee colony losses and to identify potential risk factors involved. A total of 99 samples from 99 apiaries were collected in spring using simple random sampling. According to international guidelines, the apiaries were classified as affected by colony loss or asymptomatic. Each sample consisted of worker bees, brood and comb-stored pollen. All worker bees and brood samples were analysed individually in order to detect the main honey bee pathogens. Moreover, the presence of residues of the most prevalent agrotoxic insecticides and acaricides was assessed in comb-stored pollen. The general characteristics of the apiaries and sanitary information regarding previous years was evaluated through questionnaires, while the vegetation surrounding the apiaries sampled was assessed by palynological analysis of comb-stored pollen. The colony loss prevalence was 53.5% (CI95%=43.2-63.9) and Nosema ceranae was found to be the only risk factor strongly associated with colony loss. The decision tree also pointed out the impact of the Varroa mite presence while variables such as apiary size, the incorrect application of Varroa mite treatments, and the presence of Acarapis woodi and Kashmir bee virus (KBV) were identified as possible co-factors