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181.
Two tomato scions (cvs. ‘Raf’ and ‘Gorety’) were grafted on three different rootstocks: S. torvum, ‘Beaufort’ (Lycopersicum esculentum × Lycopersicum hirsutum) and intermediate grafting of eggplant ‘Cristal’ between tomato and S. torvum (double graft). Plants were grown in Mediterranean greenhouse conditions. The response to grafting was measured through growth parameters, Fv/Fm and leaf macronutrients analysis, and it was compared with non-grafted plants. The scions grafted on S. torvum in simple and double graft showed lower fresh and dry weight of leaves, number of commercial fruits, plant height, Fv/Fm and decreased their capacity to absorb several nutrients resulting in a lower mineral concentration in scions leaves, as a result of a thickened graft union. On the other hand, both scions showed a good response when grafted on the rootstock ‘Beaufort’, with which growth parameters, yield and photosynthetic capacity were similar to non-grafted plants.  相似文献   
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183.
Changes in alleles frequencies of marker loci linked to yield quantitative trait loci (QTL) were studied in 188 barley entries (landraces, old and modern cultivars) grown in six trials representing low and high yielding conditions in Spain (2004) and Syria (2004, 2005). A genome wise association analysis was performed per trial, using 811 DArT® markers of known map position. At the first stage of analysis, spatially adjusted genotypic means were created per trial by fitting mixed models. At the second stage, single QTL models were fitted with correction for population substructure, using regression models. Finally, multiple QTL models were constructed by backward selection from a regression model containing all significant markers from the single QTL analyses. In addition to the association analyses per trial, genotype by environment interaction was investigated across the six trials. Landraces seemed best adapted to low yielding environments, while old and modern entries adapted better to high yielding environments. The number of QTL and the magnitude of their effects were comparable for low and high input conditions. However, none of the QTL were found within a given bin at any chromosome in more than two of the six trials. Changes in allele frequencies of marker loci close to QTL for grain yield in landraces, old and modern barley cultivars could be attributed to selection exercised in breeding, suggesting that modern breeding may have increased frequencies of marker alleles close to QTL that favour production particularly under high yield potential environments. Moreover, these results also indicate that there may be scope for improving yield under low input systems, as breeding so far has hardly changed allele frequencies at marker loci close to QTL for low yielding conditions.  相似文献   
184.
Bioeconomic models consist of the use of mathematics to model the behaviour of biological systems conditioned by biological, environmental, economic and technical factors. At present, market competitiveness in aquaculture is growing steadily and the amount of data that producers have to manage is increasing. In this context, bioeconomic models are a crucial tool for improving the efficiency of decision-making processes. This paper reviews the literature on bioeconomic modelling in aquaculture from 2004 to 2015. In order to find the papers reviewed in the present study, an exhaustive online search was conducted in various databases that contain papers published in the most relevant journals in this area of research. After identifying the application of these models to aquaculture throughout the last decade, an analysis was developed for the papers published in the three main research areas: aquaculture management, economic viability and risk management. The last section presents a discussion about the types of relationships modelled, the data used, the estimation techniques, and the limitations and challenges within this discipline that would improve knowledge about aquaculture management.  相似文献   
185.
An amalgam of empirical data from laboratory and field studies is needed to build robust, theoretical models of climate impacts that can provide science‐based advice for sustainable management of fish and shellfish resources. Using a semi‐systematic literature review, Gap Analysis and multilevel meta‐analysis, we assessed the status of empirical knowledge on the direct effects of climate change on 37 high‐value species targeted by European fisheries and aquaculture sectors operating in marine and freshwater regions. Knowledge on potential climate change‐related drivers (single or combined) on several responses (vital rates) across four categories (exploitation sector, region, life stage, species), was considerably unbalanced as well as biased, including a low number of studies (a) examining the interaction of abiotic factors, (b) offering opportunities to assess local adaptation, (c) targeting lower‐value species. The meta‐analysis revealed that projected warming would increase mean growth rates in fish and mollusks and significantly elevate metabolic rates in fish. Decreased levels of dissolved oxygen depressed rates of growth and metabolism across coherent species groups (e.g., small pelagics, etc.) while expected declines in pH reduced growth in most species groups and increased mortality in bivalves. The meta‐analytical results were influenced by the study design and moderators (e.g., life stage, season). Although meta‐analytic tools have become increasingly popular, when performed on the limited available data, these analyses cannot grasp relevant population effects, even in species with a long history of study. We recommend actions to overcome these shortcomings and improve mechanistic (cause‐and‐effect) projections of climate impacts on fish and shellfish.  相似文献   
186.
  • 1. The objectives of the present study were to describe and analyse the composition and structure of aquatic Coleoptera and Hemiptera assemblages in three coastal lagoons of north‐western Spain during a one year cycle, in order to evaluate their relative adequacy to provide information about the conservation value of lagoonal habitats and sites. The lagoons are designated as Special Areas of Conservation (SAC) under the European Union Habitats Directive and two of them are also protected by the Ramsar Agreement. Several abiotic variables, including salinity, were recorded at the time of sampling.
  • 2. In total, 67 species (52 Coleoptera and 15 Hemiptera) and 6568 adult individuals (2664 Coleoptera and 3904 Hemiptera) were collected. In all pair‐wise comparisons Kendall's coefficients of concordance between lagoons were higher for Hemiptera than for Coleoptera, indicating that Hemiptera assemblages were more similar across sites.
  • 3. Most species recorded had a wide Palearctic distribution and only three species of water beetles could be considered endemic to Iberia: Hydroporus vagepictus, Hydroporus vespertinus and Hydrochus angusi. Similarly, the species collected had a widespread distribution in the Iberian Peninsula as the only species considered to be rare taxa at this scale were Hydrochus angusi and Cymbiodyta marginella among the Coleoptera and Sigara scotti and Notonecta glauca glauca among the Hemiptera.
  • 4. The results do not support the idea of distinct aquatic insect assemblages for coastal lagoons in the Iberian Peninsula. Comparisons of the numbers of interior (non‐coastal) and coastal provinces of the Iberian Peninsula where the species had been recorded showed they had been recorded in a larger proportion of interior provinces.
  • 5. Salinity seemed to reduce species richness in both groups while the results of a canonical correspondence analysis (CCA) showed that the majority of species responded negatively to salinity.
  • 6. This study suggests that species richness and rarity of aquatic insect assemblages may underestimate the conservation value of lagoonal habitats because their net contribution to catchment biodiversity is likely to be low.
Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
187.
Shoot apices from six diploid potato genotypes for polyploidisation were treated with oryzalin and colchicine solutions at different concentrations and incubation times. In addition to chimeric plants, diploids, one octoploid and completely ploidy doubled plants (4x) were regenerated in these experiments. Tetraploid plants were obtained for three of the six genotypes treated with oryzalin, and no tetraploid plants were obtained after colchicine treatments of any of the genotypes. The best result of 43% tetraploid plants was achieved using 28.8 μM oryzalin and 24 h of incubation with the L37 genotype. Moreover, we determined that doubled plants should not be selected on the basis of a single measurement and require additional ploidy checks in successive clonal generations. Some L37 plants that were initially identified as tetraploids by flow cytometry produced diploid or mixoploid plants in the next clonal generation. Morphological characters of doubled L37 plants were compared with the original genotype. The PVY resistance present in a parental clone was maintained in all regenerants and significant differences among ploidy variants were found for some quantitative characters. Molecular AFLP analyses did not show any differences among genotypes. Since polyploidizing substances may produce a large proportion of chimeric plants, we applied a method to increase the number of tetraploid plants. Callus culture of chimeric leaf explants was performed on regeneration medium and tetraploid shoots were obtained in four of the six genotypes tested. The best result of 40% tetraploid plants was achieved with explants from the L37 genotype. This method was successful in producing additional tetraploid genotypes from mixoploid plants obtained after oryzalin treatments.  相似文献   
188.
Modelling growth as a function of feeding rate (FR) could be one of the most important tools for fish farms, because this knowledge allows growth to be maximized, or the feed conversion ratio (FCR) to be minimized, thereby improving profits. All growth models should include the three principal variables involved in growth: initial body weight, temperature and feeding rate. The thermal‐unit growth coefficient (TGC) already includes water temperature variation and initial body weight. Studying variation in TGC for fish fed the same diet, but at several feeding rates provides interesting information for modelling. Six different trials were conducted where gilthead sea bream of several different initial weights (24, 38, 50, 110, 220 or 289 g) were fed increasing amounts, and growth and the conversion index response were measured. The TGC response was modelled as a function of FR, and both asymptotic and quadratic responses were examined. The asymptotic model, TGC × 1000 = 2.037*(1?e (?0.8*(FR?0.22)), had an adjusted R2 value of 96.18, whereas the quadratic model, TGC × 1000 = ?0.381 + 1,715 × FR?0,382 × FR2, had an adjusted R2 value of 96.42. Simulations of the FCR and the economical profitability index (EPI) were conducted to provide tools for maximizing efficiency and profitability, and the results suggest that these tools will be useful for future investigations.  相似文献   
189.
Mini- and microsatellite sequences have proven to be excellent tools for the differentiation of strains and populations in several protozoan parasites due to their high variability. In the present work we have searched the genome of the tick-transmitted bovine hemoprotozoon Babesia bovis for tandem repeats (TRs) that could be useful for a multilocus typing system. Hundred and nineteen sequences were shortlisted and tested in five common B. bovis reference isolates originating from distinct geographic locations of North and South America: Texas, USA (T2Bo), Mexico (RAD and Mo7), and Santa Fe and Salta, Argentina (R1A and S2P, respectively). Satellite sequences were PCR-amplified using specific primers, separated by polyacrylamide gel electrophoresis, visualized by silver staining and sized. Fourteen TR sequences could be reliably amplified in all isolates and displayed length polymorphism. All primers used were specific for B. bovis and did not amplify genomic DNA from the bovine host or from Babesia bigemina, the principal co-infecting bovine parasite in the Americas, allowing their future use in field surveys. The 14 satellite markers identified are distributed throughout the four chromosomes of B. bovis as follows: chromosome 1 (n = 3), chromosome 2 (n = 2), chromosome 3 (n = 5), and chromosome 4 (n = 4). Within the five B. bovis isolates we identified nine satellite marker loci with two alleles, three with three alleles, one with four and another with five alleles. In comparison to Theileria parva, a bovine hemoprotozoan that pertains to the same piroplasmida order and owns a genome of similar size, the number of polymorphic TRs and the average number of alleles per TR locus seem to be significantly reduced in the B. bovis genome. Furthermore, the ratio of micro- to minisatellites in both B. bovis and T. parva is considerably lower than in other eukaryotes, as confirmed by bioinformatic analysis. The multilocus genotype of the five B. bovis isolates was assessed and the genetic distance between each other determined followed by cluster analysis based on neighbor joining. The resulting phenogram showed that B. bovis isolates segregated into three clusters according to their geographic origin. The presented marker system is suitable to explore various parameters of B. bovis populations such as genetic diversity, infection dynamics and their structure under different epidemiological situations, which are of crucial importance for improved control strategies.  相似文献   
190.
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