Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2011
Forfattere
Ricardo HolgadoSammendrag
In 1955 the potato cyst nematode was recorded for the first time in Agder. This detection produced the initial legislation of PCN control, and was implemented based on the statutory regulation of 1916. Since 1956 PCN was given quarantine status in infested agricultural land and home gardens. Official controls of certified seed potatoes started in 1939. Each year about 3000 soil samples are analyzed for PCN to clear areas for certified seed potato production. These areas are so far free of PCN. The total acreage with seed potatoes in 2009 was 813.7 Ha. Extensive surveys started in 1955; and were carried uninterrupted until the end of the 1990ties. These surveys included producing potato agricultural land and home gardens. In 2009 a new national survey program for the principal potato districts has started, the surveys is aimed to update the PCN occurrence. The surveys will continue during the subsequently years until all major potato areas will be cover. Statutory regulations for PCN from 1956-2010 to Support to Norwegian Food Safety Authority The regulations have without doubt contributed in preventing PCN infestations in the seed potato areas, and probably also prevented further spreading of wPCN and virulent yPCN as each the find has been placed under quarantine. Permanent grass as a statutory regulation in home garden plots may have contributed to reduce the spread of wPCN to commercial fields. The regulations have most probably made possible the early reduction in use of chemical fumigants, organophosphates or carbamate nematicides. These chemicals have not been used since the early 1970s. The domestic production of seed potato has been kept free of PCN by frequent inspections and analyses for more than 50 years. The fact that farmers are not allowed to import seed potatoes adds to the level of security. New project Studies on the biology of potato cyst nematodes (Globodera spp.) under Nordic conditions for improving management and regulation in Norway. Major goal is to increase the scientific basis for amending the management system for PCN, Globodera spp under Nordic conditions.
Forfattere
Ricardo Holgado Christer MagnussonSammendrag
In Norway PCN was recorded in 1955. This resulted in extensive surveys and implementation of statutory rules. Regular surveys until the 1990s revealed PCN to occur in 6406 properties. The first statutory regulation for PCN appeared in 1956, and prohibited the introduction and spread of PCN with soil and plant materials. Before the early 1970:ties control strategies included the use of nematicides (fumigants, organophosphates and carbamate) and resistant potato cultivars. The distribution of species and pathotypes is of crucial importance for mangement. The yellow species Globodera rostochiensis (yPCN) occurs in the pathotypes Ro1, Ro2, and Ro3, while the white species G. pallida (wPCN) has been detected in the pathotypes Pa1, Pa2 and Pa3. The most common pathotype Ro1 constitutes 98% of total finds. Recently the detections of wPCN and yPCN Ro3 in ware potato fields have increased. Today non-virulent G. rostochiensis is managed with crop rotations using non-host crops and alternating susceptible and resistant potato. The use of certified seed potato is important. Detection of G. pallida or virulent G. rostochiensis results in statutory regulation (at least 40-years ban on growing potato). Generally Norwegian potato cultivars have the resistance gen, Gro-1 (H1) from Solanum tuberosum ssp. andigena. In Norway great emphasis has been placed on documenting freedom of PCN in areas for certified seed potatoes. In 2009 a national survey of ware potato land was initiated. The use of early potato and Solanum sisymbriifolium as trap crops, and the significance of micro-organisms antagonistic to PCN are considered in current research. Norwegian regulations have prevented PCN infestations in the seed potato areas, and reduced spread of wPCN and virulent yPCN. A better prognosis of rates of decline in PCN numbers and infectivity in fields could allow for a reduction in the quarantine period and improve the economy of farmers and enterprises.
Forfattere
Ricardo Holgado Christer MagnussonSammendrag
Cyst nematodes, Heterodera spp. are known world-wide as parasites of cereals and grasses. Norwegian surveys have revealed that nematodes belonging to the H. avenae complex occur throughout the country; our studies have combined morphology, protein variability (IEF), bio-tests and internal transcribed spacers (ITS3 and ITS5) for the identification of Heterodera populations. Our results showed some divergences between techniques in species identity of some of the studied populations H. avenae is the most common species followed by H. filipjevi (Holgado et al., 2009).. Several populations of H. filipjevi west did not reproduce in oat differentials. In this case both the morphology and protein patterns rather indicated these populations to belong to H. pratensis. In this study a population from Brekstad differed from all other populations in its morphology, and the protein pattern was close to H. mani. This population was collected from barley, and in the pathotype test it was virulent on several barley cultivars. Mathews, 1971reported that H. mani did not reproduce on cereals while (Cook, 1982) indicates that some barley cultivars can serve as hosts. Surprisingly the ITS studies indicated the Brekstad population to be close to H. avenae. This population is in many ways strikingly different from H. avenae, and this result may indicate a need to revise the present gene library of H. avenae. It also demonstrates the need for using several techniques in species identification. In our study the least degree of divergent results on nematode identity is between morphology and IEF.
Forfattere
Ricardo HolgadoSammendrag
Cyst nematodes, Heterodera spp. are known world-wide as parasites of cereals and grasses. Norwegian surveys have revealed that nematodes belonging to the H. avenae complex occur throughout the country; our studies have combined morphology, protein variability (IEF), bio-tests and internal transcribed spacers (ITS3 and ITS5) for the identification of Heterodera populations. Our results showed some divergences between techniques in species identity of some of the studied populations H. avenae is the most common species followed by H. filipjevi (Holgado et al., 2009).. Several populations of H. filipjevi west did not reproduce in oat differentials. In this case both the morphology and protein patterns rather indicated these populations to belong to H. pratensis. In this study a population from Brekstad differed from all other populations in its morphology, and the protein pattern was close to H. mani. This population was collected from barley, and in the pathotype test it was virulent on several barley cultivars. Mathews, 1971reported that H. mani did not reproduce on cereals while (Cook, 1982) indicates that some barley cultivars can serve as hosts. Surprisingly the ITS studies indicated the Brekstad population to be close to H. avenae. This population is in many ways strikingly different from H. avenae, and this result may indicate a need to revise the present gene library of H. avenae. It also demonstrates the need for using several techniques in species identification. In our study the least degree of divergent results on nematode identity is between morphology and IEF.
Sammendrag
The objective of this study is to explore and evaluate multifunctionality of dairy farming systems.Both current and potential new farming systems are examined using a model that combines ideas from mathematical programming and multi-criteria analysis. The first step is identifying variables with importance for multifunctionality. The different combinations of these variables are then examined using an algorithm that steps through the different combinations and generates a set of farmingsystems that are compared using multi-criteria analysis. This approach makes it possible to compare different farming systems with respect to several criteria. Examples of criteria are net farm income, labour input, N loss from soil, and ecological impacts. The ecological impacts of a farming system are quantified as an index using expert opinion. Sensitivity analysis will be used to examine how the weight assigned to each criterion affects the choice of farming system. The sensitivity analysis can thus provide valuable insight into how the preferences and values of individual farmers and stakeholders influence their perception of the “optimal” farming system. The model is flexible, new aspectsof multifunctionality can easily be integrated, and the model can be scaled up from the farm to the landscape or regional level.
Sammendrag
Specific PCR primers were developed for identifying two post harvest pathogens, Mycocentrospora acerina and Fibularhizoctonia carotae, which cause liquorice rot and crater rot respectively, during prolonged low temperature storage of carrots. The methods allow routine detection of less than 0.3 pg of M. acerina DNA and less than 0.03 pg F. carotae DNA, even in the presence of large excess of plant or soil DNA. Standard PCR and quantitative PCR gave similar results and either method could be used in a practical situation. Experiments were carried out testing these methods on different types of carrot tissue- and soil- samples. Soil was sampled before sowing, and soil adhering to the roots or root tissue was sampled at different times during the growing season or at harvest. Soil adhering to the carrots at harvest had the best predictive ability for liquorice rot development during storage (R2predicted 74.9 % using standard PCR), but samples taken during the growing season also gave reasonably good predictive ability values. PCR data from soil samples taken in the spring were not as good as a predictor for thisdisease. A dense sampling strategy using 20 m between sampling points generally gave better orrelation between PCR data and disease data than using 40 m between the sampling points. Use of the developed methods in an IPM strategy for liquorice rot is discussed. For crater rot the correlation between PCR data and disease data was generally poor for all types of samples. These results are discussed in relation to the biology of F.carotae.
Sammendrag
Strawberry production in high plastic tunnels is becoming popular for the advantages of extended production and reduced disease problems. However, this production system creates favorable conditions for several pests, including the two-spotted spider mite (Tetranychus urticae) and for some diseases, of which powdery mildew (Podosphaera aphanis) is the most important. Preliminary laboratory experiments were conducted to study: (1) the preference of T. urticae to mildew infected vs. healthy strawberry leaves, and (2) the impact of powdery mildew on T. urticae egg production and predation of the predatory mite Phytoseiulus persimilis. Five days after the mite release, the total number of T. urticae eggs and nymphs found on healthy leaf discs were two times higher than on leaf discs with powdery mildew, predatory mites or both. In the preference experiment, a significant number of T. urticae moved to healthy strawberry leaf discs and settled there for the whole period of the experiment. The results indicated that T. urticae did not thrive on strawberry leaves heavily infested with powdery mildew, and that powdery mildew seemed to reduce the predation efficiency of P. persimilis. Therefore, it may be economical and efficient to control powdery mildew before releasing P. persimilis to control the spider mites.
Forfattere
Bente Kirkhus Britt I.F. Henriksen Aina Lundon G.I. Borge J-E Haugen G. VogtSammendrag
Camelina is an underexploited oilseed crop that may be well suitable for cropping innorthern areas. The oil is particularly high in the omega-3 fatty acid alpha-linolenic acid (C18:3n-3). The aim of the present study was to evaluate the potential for secure production of high quality edible oil from organically grown camelina (Camelina sativa L. Crantz), focusing on the effects ofenvironmental parameters on oil content, fatty acid composition and contents of phytosterols and tocopherols. Field experiments with pre-crop barley were conducted in the growing seasons 2007, 2008 and 2009. Trials were fully randomized with two levels of Nitrogen (N) fertilization, 0 and 120 kg total Nha-1, and two levels of Sulphur (S) fertilization, 0 and 20 kg total S ha-1. Additional experiments were performed in 2009 in order to evaluate the effects of replacing pre-crop barley with pre-crop pea. Crude oils were obtained by usinga pilot press and the fatty acid composition and contents of phytosterols and tocopherols were analyzed by GC-MS and LC-MS. The results showed significantseasonal variations in the contents of fatty acids, tocopherols andphytosterols. Furthermore, significant effects of N-fertilization were observed, with increased contents of C18:3n-3, erucic acid (C22:1) and γ-tocopherol at the highest level of N-fertilization. Pea compared to barley as pre-crop also increased the content of C18:3n-3. There were no effects of S-fertilization. Principal component analysis revealed positive correlations between the contents of C18:3, C22:1, γ-tocopherol and phytosterols, in particular brassicasterol. In conclusion, camelina seems to be well suitable for organic cropping. The oil quality was influenced by season and N-fertilization, still, the variation in nutrient content was small.
Forfattere
Jack D´Arcy E. Dunaevskaya Richard Fitzgerald Jim W. Treasurer Oddvar Ottesen Julie Maguire Celine Rebours Nina Zhuravleva Åsbjørn KarlsenSammendrag
The use of wrasse (F. Labridae) as biological cleaner-fish in the control of salmon lice has been demonstrated in a number of studies and they are successfully used on a large scale, with over two million wrasse being caught and stocked annually, in commercial salmon farms in Norway. Increasingly, efforts are being made to produce commercial stocks of wrasse for use on farms and an EU Northern Periphery Project entitled "Ecofish" has been established to develop the technologies for spawning and rearing the most promising cleaner fish, ballan wrasse, in captivity with dedicated production hatcheries will be established in Ireland, Norway and Scotland. This project will also look into the management of ballan wrasse in salmon cages in order to achieve the effective removal of lice. As part of the Ecofish work programme, this study examined the embryonic development of Ballan wrasse using material from a series of spawnings in Ireland and Norway. The overall development from fertilization to hatch was monitored and recorded and a standardized series of developmental stages are assigned, from zygote through cleavage, blastulation, gastrulation, segmentation to hatching: each with specific morphological landmarks. This standardization and the synchronization of the developmental stages will facilitate future studies with the species as we may be better able to compare the development rate of different geographic stocks and under different environmental conditions. The developing embryo was also staged at three different incubation temperatures; 10.5oC, 12.9 oC, and 16.5 oC with 50% hatched occurring at 171, 121 ands 96 hours post fertilisation respectively.
Forfattere
Jr. I Delalibera V.W. Wekesa Karin Westrum V. Duarte da Silveira T. Rodrigues de Castro S.S. Nilsen Ingeborg KlingenSammendrag
The mite-pathogenic fungus Neozygites floridana and N. tanajoae are important natural enemies of spider mites and are good candidates for microbial control. To be able to succeed in using Neozygites for the microbial control of spider mites we need to understand the factors that affect a Neozygites epidemic development. Studies have therefore been conducted with Brazilian and Norwegian isolates of these fungi to reveal the effect of abiotic (temperature, rainfall, humidity, light, pesticides) and biotic factors (host plant, presence of predators) on the fungal performance and epizootic development in cassava green mite, tomato red spider mite and twospotted spider mite populations. For Brazilian isolates, rainfalls do not seem to have an apparent impact on disease progression. Microclimatic humidity seems, however, to be a critical factor. When placed on microscope slides, these two fungi only sporulate at RH≥95%, while N. floridana-killed cadavers of the twospotted spider mite placed within the boundary layer of the abaxial side of a leaf sporulated also at 90% RH. The temperature optimum of Brazilian and Norwegian isolates varies and Brazilian isolates can sporulate at temperatures as low as 13°C but the highest production of capilliconidia occurs at 21-25°C. A Norwegian N. floridana isolate tested produces the highest numbers of primary conidia at 13°C and 18°C while 23°C resulted in a lower production. Our studies also show that performance of different N. floridana isolates may vary with light duration and intensity. In integrated pest management systems, Neozygites needs to be compatible with chemical pesticides. Our studies show, however, that several fungicides affect N. floridana negatively. Our studies have also shown that performance of Neozygites vary with host plants.