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.
2005
Sammendrag
Various needle discolorations, often due to lack of uptake of certain nutrients are frequently observed in nordmann fir (Abies nordmanniana) in Norwegian Christmas tree plantations. Most common are the yellow to necrotic needle tips on older needles caused by magnesium (Mg) deficiency (confirmed by chemical analysis of foliage). Even though chemical analysis of soil samples show that Mg is present in sufficient amount, various soil factors may cause Mg-deficiency; too high or too low pH, excess potassium (K) or too wet or too dry conditions. Antagonism, causing imbalance in nutrient uptake, can lead to negative effects. High pH may give Ca2+/Mg2+ antagonism, too low pH NH4+/Mg2+ antagonism, and abundant K K+/Mg2+ antagonism. During wet conditions K+ and other monovalent cations may leave the colloids to regain equilibrium between liquid and solid material. Then Mg2+ may easily bind to the free spaces on the colloids, and thereby becomes unavailable for the plants. If the soil is very dry there may not be enough liquid for the nutrients to be dissolved, and thus uptake inhibited. Nordmann fir is mainly grown in the southwestern coastal region of Norway since the climate there is fairly mild and suitable for this plant species. The yearly rainfall is high in that region, so a main cause for Mg deficiency on nordmann fir is probably related to wet soil conditions. Uptake of Mg after foliage application has proved to be ineffective due to the wax layer on the fir needles. However application on young needles and shoots has been reported by the Norwegian extension service to be successful. K deficiency also results in discoloration of older needles, but symptoms can easily be distinguished from Mg deficiency. Both deficiencies results in yellowing of the needles, but different from K deficiency, the base remains green on needles suffering from Mg deficiency. Both Mg and K are very mobile nutrients in plants, and they are therefore easily translocated from older to younger needles. Samples with yellow discoloration of the youngest needles have been observed to be low in iron (Fe) and manganese (Mn), especially when the trees have grown in soil with high pH. Both nutrients are nearly immobile in plants after they have been transported to the cells, and they are therefore not available for the young shoots. Nitrogen (N) deficiency is seen as a uniform, pale green discolouration of both young and old needles.
Sammendrag
Næringsmangel kan føra til redusert vekst og dårlegare vinterherding, prydverdi og motstandskraft mot ulike skadegjerarar. Ofte er ikkje grunngjødsling nok til å få fram fine tre. Då må ein inn med supplerande gjødsling med ulike næringsstoff. På grunn av vokslag på eldre nåler, vert effektivt opptak av bladgjødsel hindra. Generelt bør difor alle former for bladgjødsling gjennomførast om våren i strekkingsperioden til dei nye skota. I denne perioden er skota mjuke og svært utsette for skade, så ein må vera varsam. I denne artikkelen vert det gitt ei tilråding om grunngjødsling og sett fokusert på symptom på ulike mangelsjukdomar og dei tiltaka som vert tilrådde av Pyntegrøntringen.
Forfattere
Øystein Johnsen Carl Gunnar Fossdal Nina Elisabeth Nagy Jørgen A.B. Mølmann OG Dæhlen Tore SkrøppaSammendrag
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Sammendrag
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Sammendrag
Covering sweet cherry trees (Prunus avium L.) with plastic prior to harvest is used to prevent fruit cracking. The most commonly used covering system in Norway is a frame of wooden poles, which support a three-wire system. Removable plastic sheets lying as a flat roof above the trees are connected to the wires. Covering for 3 weeks prior to harvest reduced fungal fruit decay from 10 to 1% and from 50 to 10% in two years, respectively. Important fungal diseases causing fruit decay in Norway are brown rot, gray mold, bitter rot and Mucor rot. By covering the trees for five to six weeks prior to harvest (commercial practice is three to four weeks), one to two fungicide applications could be omitted. If the trees were covered all the time from flowering to harvest, all fungicide applications could be omitted without any increase in fruit decay. Extended periods of covering did not lower fruit quality. Sweet cherries are most susceptible to fruit decaying fungi during flowering and towards harvest. In a series of experiments, fruits were covered at those two periods and left uncovered during the less susceptible green fruit phase (ca. 5 weeks). Covering could replace fungicide sprays without any increase in fruit decay, but leaving out fungicide sprays on uncovered green fruits increased the amount of brown rot in three of four experiments. From numerous experiments we will conclude that use of rain protective cover is a powerful alternative to fungicide applications in sweet cherry.
2004
Sammendrag
Sweet cherry trees sometimes suffer from dieback symptoms under Scandinavian growing conditions. Some combinations of cultivars and rootstocks are more susceptible to this than others. The graft union between a rootstock and a scion is a junction between two different tissues. Differences in tissue development in the union may provide a mechanistic explanation of inhibiting transport of water and nutritional substances and likely inhibit growth of the scion. In order to investigate the relationship between growth and the amount of functional xylem tissue of potted sweet cherry trees, an experiment was conducted during 2002-2003. One year old field budded and bench grafted (from green house) sweet cherry trees of the cultivars Van, Ulster and Lapins in all combinations of the three rootstocks Prunus avium seedling, Colt and Gisela 5 were grown in pots for two growing seasons. After shoot extension had terminated when trees were in full leaf the second year, the total growth of the different parts of the trees and the quantification of functional area using safranin staining were conducted. The total mass production (tree dry weight, the length of two year old wood and number of leaves) was significant larger in the budded trees. Similarly the trunk cross sectional area was significant larger 10 cm above and in the middle of the graft union, but not 10 cm below. The Colt trees were the most vigorous followed by the seedling and Gisela 5. Small differences between the different cultivars were registered. Xylem staining with aqueous safranin combined with quantitative image analysis showed that the rootstock stem had a higher proportion of stained tissue than the scion stem. Sections taken in the middle of the graft tissue and above showed that the proportion of stained tissue declined proportionally with the distance from the roots. The total area of stained stem xylem was larger for the two vigorous rootstocks compared to Gisela 5. Small differences were observed between cultivars and propagation methods.
Sammendrag
Trees of `Discovery" apples growing on dwarf and semi-dwarf rootstocks were assessed in field trials at two sites (western and eastern Norway) at 60° North. The rootstocks included two selections of M.9 (EMLA, RN.29), two from the Polish (P) series (P.59, P.60), three from the Geneva (G) series (G.30, G.78730-026, G.202) and M.26. Trees were planted in the spring 1997 as two years old feather trees, spaced 1.5 x 4 m, trained as slender spindles and evaluated for five subsequent years. Soil management were grass in the alleyways and herbicide strips 1-m wide along the tree rows. Tree size was significantly affected by the rootstocks after five years growth. P.59, G.78730-026 and M.9 RN.29 produced the smallest and G.30 and G.202 the largest trees as measured by trunk cross-sectional area. P.59 and G.30 had the greatest yields per tree, followed by G.202, P.60 and M.9 EMLA. Trees on P.59 were the most yield efficient followed by the two M.9 clones. The fruit density measured as number of fruits per trunk-cross-sectional area showed similar results. The different rootstocks affected little the fruit weights. Fruit quality characterized by the content of soluble solids was in general high and did not differ between trees on the various rootstocks.
Sammendrag
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Sammendrag
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Forfattere
Michel VerheulSammendrag
The Norwegian government aims that ten percent of the total agricultural area must be grown ecologically by 2010. A further goal is that ecologically grown vegetables should cover 15 % of the market. In spite of earlier efforts, the production and sale of ecological vegetables is still on a very low level. Successful production of organic greenhouse vegetables requires a good knowledge of both organic principles and effective greenhouse production. In order to increase the marketable yield, agronomical problems concerning the transition from conventional to organic greenhouse production should be solved. The main challenge in this sense is the proper use of organic growing media and fertilisers. In 2003, Planteforsk Særheim Research Centre started a trial to develop a growing concept for ecologically grown greenhouse tomatoes following the standards set up by the Norwegian Food Safety Authority and controlled by "Debio". In order to avoid problems with soil borne pests and diseases and to reduce the risk of losses of plant nutrients, plants were grown in limited beds. This system gave good results in earlier experiments in Sweden (Gäredal and Lundegårdh, 1998) and might quicken the transition from conventional to ecologic production. Growing media used in the trail were peat, a mixture of peat and bark or a mixture of soil and straw with a volume of 25 or 75 litres per m2. Some of the treatments received a basic fertiliser, consisting of composted chicken or pig manure, while other treatments received no basic fertiliser. In order to meet the nutritional requirements of the plants, organic fertiliser was given regularly during the growing season. A solution of organic nutrients using drip irrigation or the coarse fraction of cattle manure applied three times a week was used. In a control treatment, plants were grown on peat bags with a volume of 25 litres per m2 and fertilised with conventional mineral nutrition. Tomato transplants were planted in week 10 and harvested until week 44. Input and output of nutrients were recorded. Results showed great differences in marketable yield between the different treatments. Plants grown in peat with a volume of 25 litres and only given a solution of organic nutrients gave a low yield (26 kg/m2) and problems with blossom end rot (33 %). Low volume hampered a proper supply of organic fertilisers. Plants grown on 75 litres of a mixture of peat and bark or a mixture of soil and straw, including compost and fertilised with cattle manure, gave a yield of 39 and 37 kg/m2 respectively. Control plants yielded 39 kg/m2. This shows that a normal yield can be achieved using organic growing media and fertilisers. In 2004 the growing concept will be further developed. It is also planned to develop a growing system for organic cucumber and lettuce production.