Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2009
Abstract
European ash (Fraxinus excelsior), also known as common ash, occurs naturally inland in lower areas of southeastern Norway and along the southern coast of the country. It is important both as a forest and ornamental tree. During the last decade, dieback has become a disastrous disease on F. excelsior in many European countries. The anamorphic fungus Chalara fraxinea T. Kowalski (1), described for the first time from dying ash trees in Poland, is now considered the cause of ash dieback (2). In May of 2008, C. fraxinea was isolated from 1.5 m high diseased F. excelsior in a nursery in Østfold County in southeastern Norway. Symptoms included wilting, necrotic lesions around leaf scars and side branches, and discoloration of the wood. From symptomatic branches, small pieces (approximately 1 cm3) were excised in the transition area between healthy and discolored wood. After surface sterilization (10 s in 70% ethanol + 90 s in NaOCl), the pieces were air dried for 1 min in a safety cabinet, cut into smaller pieces, and placed on media. The fungus was isolated on potato dextrose agar (PDA) and water agar (WA). On PDA, the cultures were tomentose, light orange, and grew slowly (21 mm mean colony diameter after 2 weeks at room temperature). Typical morphological features of C. fraxinea developed in culture. Brownish phialides (14.8 to 30.0 [19.5] × 2.5 to 5.0 [4.1] μm, n = 50) first appeared in the center of the colonies on the agar plugs that had been transferred. The agar plugs were 21 days old when phialides were observed. Abundant sporulation occurred 3 days later. Conidia (phialospores) extruded apically from the phialides and formed droplets. Conidia measured 2.1 to 4.0 (3.0) × 1.4 to 1.9 (1.7) μm (n = 50). The first-formed conidia from each phialide were different in size and shape from the rest by being longer (6 μm, n = 10) and more narrow in the end that first appeared at the opening of the phialide. Internal transcribed spacer sequencing confirmed that the morphological identification was correct (Accession No. EU848544 in GenBank). A pathogenicity test was carried out in June of 2008 by carefully removing one leaf per plant on 10 to 25 cm high F. excelsior trees (18 trees) and placing agar plugs from a 31-day-old C. fraxinea culture (isolate number 10636) on the leaf scars and covering with Parafilm. After 46 days, isolations were carried out as described above from discolored wood that had developed underneath necrotic lesions in the bark and subsequently caused wilting of leaves. All the inoculated plants showed symptoms, and C. fraxinea was successfully reisolated. No symptoms were seen on uninoculated control plants (eight trees) that had received the same treatment except that sterile PDA agar plugs had been used.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Randi Therese Garmo Adam Dunstan Martin Adam Dunstan Martin Erling Thuen Øystein Havrevoll Håvard Steinshamn Egil Prestløkken Åshild T. Randby Åshild T. Randby Margrete Eknæs Andres Waldmann Olav ReksenAbstract
Progesterone profiles in Norwegian Red cows were categorized, and associations between the occurrence of irregularities in the profiles and the commencement of luteal activity were investigated. The cows were managed in 3 feeding trials from 1994 to 2001 and from 2005 to 2008 at the Norwegian University of Life Sciences. The cows were followed from calving, and the milk samples collected represented 502 lactations from 302 cows. Milk samples for progesterone analysis were taken 3 times weekly from 1994 throughout 1998 and from 2005 to 2008 and 2 times weekly from 1999 to 2001. Commencement of luteal activity was defined as the first day of 2 consecutive measurements of progesterone concentration >= 3 ng/mL not earlier than 10 d after calving. Delayed ovulation type I was defined as consistently low progesterone concentration, <3 ng/mL for >= 50 d postpartum. Delayed ovulation type II was defined as prolonged interluteal interval with milk progesterone measurements <3 ng/mL for >= 12 d between 2 luteal phases. Persistent corpus luteum (PCL) type I was defined as delayed luteolysis with milk progesterone >= 3 ng/mL for >= 19 d during the first estrous cycle postpartum. Persistent corpus luteum type II was defined as delayed luteolysis with milk progesterone >= 3 ng/mL for >= 19 d during subsequent estrous cycles before first artificial insemination. Delayed ovulation type I was present in 14.7%, delayed ovulation type II in 2.8%, PCL type I in 6.7%, and PCL type II in 3.3% of the profiles. Commencement of luteal activity was related to milk yield, parity, PCL type I, and the summated occurrence of PCL type I and II. The least squares means for the interval to commencement of luteal activity were 24.2 d when PCL type I and II were present and 29.5 d when PCL type I and II were absent. The likelihood of pregnancy to first service was not affected in cows with a history of PCL when artificial insemination was carried out at progesterone concentrations <3 ng/mL (i.e., during estrus); however, cows that had experienced PCL were more likely to be inseminated during a luteal phase. The occurrence of delayed ovulation and PCL in Norwegian Red cows was less than that reported in most other dairy populations.
Abstract
The CO2 uptake of the terrestrial biosphere (Gross Primary Productivity, GPP) plays a key role in the global carbon balance. This carbon flux cannot be determined directly on a global scale. Yet, the remotely sensed Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) is a valuable proxy for GPP. This study aims at characterizing global FAPAR dynamics on different temporal scales and extracting corresponding spatial structures. The time series were analyzed to uncover the presence and extent of trends, and to identify quasi-oscillatory patterns from intra- to interannual time scales....
Abstract
A catchment provides ecosystem data along with (relatively) simple, operationally defined boundaries. In addition runoff is an integrated measure of the hydrochemical ecosystem response, which can be represented by fluxes at the weir. Integration at the weir occurs first of all with respect to spatial scales. Almost all fluid output leaves a (tight) catchment at this point. Evaluation of the runoff dynamics (quantity and quality) is primarily concerned with temporal scales. The Lange Bramke catchment study with its four runoff series from forested catchments (spring and weir at Lange Bramke, weirs at Dicke Bramke and Steile Bramke) provides an exceptionally comprehensive data set. The following scales and processes can be considered, when interpreting temporal variations in runoff data: above the time scale of forest rotation (species composition, biomass accumulation, timber export, soil nutrient pools) at decadal time scales up to a full forest rotation of about 100-120 years (changes in forest growth rate, changes in deposition, climate change, insect outbreaks) at annual time scales (uptake, transpiration) at hourly to weekly time scales of hydrological events (precipitation, runoff, dilution effects of solvents).
Authors
Sekhar Udaya NagothuAbstract
The interdisciplinary study aims to contribute towards an increased knowledge base and dialogue between the stakeholders themselves and between researchers and stakeholders for addressing the impacts of climate change on rice farming in the Cauvery River Basin located in the peninsular part of India.
Authors
Aksel DøvingAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Two female and two male cultivars have previously been released as a result of clone evaluation at Bioforsk Nord Holt. The selection criteria were the number of pistils or stamens per flower, the number of flowers and the number of shoots per m2. Currently a new group of clones are being evaluated with the aim of finding new cultivars for release. The preliminary results on flowering and berry production show a strong variance in these traits. Over three years of registration, the number of produced flowers varied from under 100 for the weakest clone to more than 1000 for the best clone. The number of produced berries varied from 9 for the weakest clone to 242 for the best clone. The three clones that produced the most flowers all had very low berry production and deviated from the rest of the clones by having high numbers of flowers per harvested berry. New selection criteria will be considered before selection of new cultivars for release. In addition to the production traits, new selection criteria will most likely include berry contents, such as the levels of antioxidants.