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.
2016
Sammendrag
Ventilation management and the tuber maturity at harvest are essential factors in maintaining potato quality during long-term storage. The aim of this study was to examine the effect of ventilation strategy on storage quality of potato tubers with three different maturity levels at harvest. Two potato cultivars, Saturna and Asterix, were stored in small-scale experimental stores and large-scale commercial stores. Both storage categories were ventilated by both low continuous air rates (natural ventilation) and intermittent high air rates (forced ventilation). The different maturity levels were obtained by a combination of pre-sprouting strategy, planting date and level of nitrogen fertilization of the seed tubers, where pre-sprouting, early planting date and low amount of nitrogen resulted in the most mature tubers. Storage quality parameters investigated during and after long-term storage (6 months in small-scale and 4 months in large-scale stores) included weight loss, respiration, dry matter, sucrose, glucose/fructose content and fry colour. In average over three years natural ventilation resulted in higher weight losses in small- and large-scale stores (1.36 and 3.93%), lower content of reducing sugars (glucose + fructose) in large-scale stores (2.35 mg g 1) and lighter fry colour than did forced ventilation. Immature potatoes had higher weight losses (4.16%), higher respiration rates (1.68 mg CO2 kg 1 h 1) and lower dry matter content (22.3–22.5%) than more mature potatoes. This study show that both maturity and ventilation strategy affects storage quality of potatoes as measured by weight loss, sugar content and fry colour.
Forfattere
Hugh Cross Ed Biffin Kor-Jent Van Dijk Andrew Lowe Michelle WaycottSammendrag
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Forfattere
Frode VeggelandSammendrag
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Sammendrag
The density and diversity of springtails (Collembola) in the upper soil layer (0–3.8 cm) were studied in a perennial grass-clover ley in NW Norway during April–June 2012. The study was part of a field experiment comparing yields and soil characteristics after application of non-digested slurry (NS) versus anaerobically digested slurry (DS) from dairy cows. In total for three sampling dates, 39 species of springtails were identified. In the Control plots receiving no manure, the density level was around 30 000 individuals (ind.) m−2 throughout the whole season. Three days after slurry application (40 t ha−1), the density of springtails had dropped significantly; from 55 214 to 7410 ind. m−2 in the NS treatment and from 41 914 to 10 260 ind. m−2 in the DS treatment. After 7 weeks the densities had increased again to 54% and 38% of the initial levels in NS and DS treatments, respectively. The springtails were divided into two ecological groups based on morphology and colour. The epigeic group comprised surface-dwelling species with eye organs and pigmentation. The endogeic group comprised soil-dwelling species lacking eye organs and pigmentation, and generally with shorter extremities than those found in the epigeic group. The negative effect of manure application on density was more severe and long-lasting in the epigeic than in the endogeic group. This effect was similar for both manure types. One species (Parisotoma notabilis) comprised 50% of the epigeic population, while three Mesaphorura spp. and Stanaphorura lubbocki comprised half the endogeic population. In general, the community structure, described by the relative abundance of each species, was more affected by manure application in the epigeic than in the endogeic group. Hence, slurry application seemed to affect surface-dwelling species more negatively than soil- dwelling species, even within the small sampling depth used here. The density of endogeic species seemed to recover faster than the density of the epigeic species. A simplified classification of epigeic and endogeic springtails, based on the presence or absence of pigmentation and eyes, may be useful in studies of soil springtails where identification of the actual species is not the primary purpose.
Sammendrag
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Forfattere
Nicholas ClarkeSammendrag
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Forfattere
Nicholas ClarkeSammendrag
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Forfattere
Nicholas ClarkeSammendrag
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Sammendrag
The effect of fertility status and temperature conditions during floral induction on flowering, berry yield,and weight and drupelet numbers of individual berries were studied in ‘Glen Ample’ raspberries grownunder controlled conditions. Withdrawal of normal fertilization prior to and at various stages duringfloral induction did not affect yield and berry size, but marginally advanced flowering and fruit ripening.The successive stages of floral initiation and differentiation were studied and identified by scanning elec-tron microscopy of the uppermost lateral buds of plants grown for six weeks under naturally decreasingautumn photoperiods at temperatures of 9, 15 and 21◦C. Low temperature advanced floral initiation, andadvanced and enhanced flowering and berry yield in the following season. However, at variance fromearlier studies, the plants eventually initiated flower primordia even at 21◦C. Marginal low temperatureand short day conditions during the last days before the temperature treatments were started on 17September might possibly have reduced the subsequent induction requirements enough to explain thisunexpected result. Correlation analyses revealed an over-all positive correlation between fruit weightand drupelet numbers (r = 0.568, P = 0.01). In berries from the early harvests, the number of drupelets perberry increased with decreasing temperature, while the numbers converged to the same level regardlessof temperature in the later harvests. Based on the progress of the floral initiation process at the vari-ous temperatures, we interpret this to mean that only the early initiated flowers, that gave rise to theearly maturing berries, were differentiated during the actual period of controlled temperature exposure,whereas the remaining flowers were differentiated afterwards when all plants were exposed to identicallow temperature conditions. Increased femaleness under optimal floral induction conditions is in agree-ment with results in both monoecious and dioecious plants and circumstantial evidence suggest that,in the raspberry, this might be mediated by changes in gibberellin activity which acts as a male sexualhormone in plants and is known to inhibit growth cessation and floral initiation in raspberry.
Sammendrag
The European plum cultivar 'Opal', widely grown in Scandinavia, frequently initiates too many flowers and set too many fruits. If excess fruitlets remain on the trees until harvest, the crop consists of small, unmarketable fruits of low fruit quality and return bloom will be reduced. The current study investigated effects of different crop loads established at blossom and fruitlet stages on yield, fruit quality and return bloom. For two seasons starting in 2008 on mature 'Opal'/'St. Julien A' trees, two crop loads 50 and 25% flowers reduced were established at full bloom and at 10-12 mm fruitlet size and compared with an un-thinned control treatment. Treatments were applied on single whole trees in a randomized complete block design with six replications. Spindle trees spaced at 3.0×5.0 m were selected for uniformity in growth habit, flowering intensity and trunk cross sectional area. Final fruit set varied from 63% on the control trees to 18% when thinned at bloom. Yield was negatively correlated with the fruit set response. Thinning at the fruitlet stage resulted in smaller fruits at the same crop level compared to flower thinning. Fruit quality parameters characterized by bright yellow skin background colour, red surface colour and the concentrations of soluble solids increased significantly as the crop load was reduced. Other fruit quality parameters like percentage acidity were not significantly different and did not show a clear response to the thinning. Return bloom was promoted most when trees were thinned at bloom the year before.