Hopp til hovedinnholdet

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.

2019

To document

Abstract

Sweet cherry production worldwide is grown in the open land. Production technique is more or less similar with scions grafted on dwarfing and semi-dwarfing rootstock and trees arranged in single rows. Sweet cherries can be grown in Norway in areas with suitable local climatic conditions up to 60°N. All orchards have high-density planting systems and are rain covered. Rain-induced fruit cracking in cherries remains a problem at an international level. The most common systems in Norway are multibay high tunnel systems and retractable rain covers. Covered orchard tunnel systems offer not only the advantage of rain exclusion but also allow additional manipulation of the environment, tree growth and fruiting. In general, sweet cherry high tunnel production gives increased yields of larger fruit than in the open land, but investment costs are higher. One more advanced way of producing sweet cherries is to grow the trees in small pots in greenhouses. A greenhouse gives opportunity to control the temperature regime and in that way program the maturity of the fruits. Research is conducted to test different cultivars, rootstocks, training methods in high-density production systems (1 tree m-2) with different fertigation levels. Preliminary results show that the yield potential is much higher than in the open land with larger fruits. Challenges are to optimize the water and nutrition supply and adjust the temperatures to obtain large yields of high quality fruits during different periods of the season.

To document

Abstract

High-throughput sequencing is increasingly favoured to assay the presence and abundance of microRNAs (miRNAs) in biological samples, even from low RNA amounts, and a number of commercial vendors now offer kits that allow miRNA sequencing from sub-nanogram (ng) inputs. Although biases introduced during library preparation have been documented, the relative performance of current reagent kits has not been investigated in detail. Here, six commercial kits capable of handling <100ng total RNA input were used for library preparation, performed by kit manufactures, on synthetic miRNAs of known quantities and human total RNA samples. We compared the performance of miRNA detection sensitivity, reliability, titration response and the ability to detect differentially expressed miRNAs. In addition, we assessed the use of unique molecular identifiers (UMI) sequence tags in one kit. We observed differences in detection sensitivity and ability to identify differentially expressed miRNAs between the kits, but none were able to detect the full repertoire of synthetic miRNAs. The reliability within the replicates of all kits was good, while larger differences were observed between the kits, although none could accurately quantify the relative levels of the majority of miRNAs. UMI tags, at least within the input ranges tested, offered little advantage to improve data utility. In conclusion, biases in miRNA abundance are heavily influenced by the kit used for library preparation, suggesting that comparisons of datasets prepared by different procedures should be made with caution. This article is intended to assist researchers select the most appropriate kit for their experimental conditions.

To document

Abstract

We grew young sweet cherry (Prunus avium L.) trees under controlled temperature and natural summer daylight conditions in order to study the control of flowering of the species. Two experiments with the cultivars ‘Lapins’ and ‘Van’, were conducted and compared with field results with the same cultivars at Ås in southeast Norway (59° 40′N, 10° 50′E, 90 m a.s.l.). Shoot growth increased with increasing temperature in the 12–21 °C range, but ceased in late summer (August) regardless of temperature conditions. A marked drop in temperature always induced an immediate cessation of growth. Under field conditions at Ås, both growth cessation and floral initiation took place by about 1 August. Low temperature (12–15 °C) significantly enhanced flowering of both cultivars compared with 21 °C, which tended to depress flower bud formation during the summer but stimulated the subsequent flower differentiation process. These results concur with earlier regression analyses, which revealed a close positive correlation between historical records of sweet cherry yields over a 40-year period in farmer’s fields in the fjord districts of western Norway and previous year August-September temperature, and a negative correlation with previous year July temperature. Practical implications of the results are discussed and it is suggested that inadequate temperature control in rain-protected cultivation in plastic tunnels might have negative consequences for next year’s flowering and yield.