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.
2018
Sammendrag
The effect of controlled nutrient feeding during the period of short day (SD) induction of flowering has been studied in three SD berry crops. An experimental system with standardized plant material grown with trickle fertigation in controlled environments was used. In strawberry, flowering was advanced and increased when an additional N pulse was given 1-2 weeks after commencement of a 4-week SD induction period, while the opposite resulted when the treatment was applied 2 weeks before start of SD. In blackcurrant, the highest flowering and yield were obtained when fertilization was applied shortly after the natural photoperiod had declined to the inductive length in September. While generous nutrient supply during spring and summer reduced berry soluble solids in blackcurrant, this was not observed with autumn fertilization. Autumn fertilization did not adversely affect plant winter survival or growth vigour in spring. Withdrawal of fertilization prior to, or at various stages during floral induction, did not significantly affect flowering and yield in raspberry, but marginally advanced flowering and fruit ripening.
Forfattere
Daniel R. Hirmas Daniel Gimenez Attila Nemes Ruth Kerry Nathaniel A. Brunsell Cassandra J. WilsonSammendrag
Soil macroporosity affects field-scale water-cycle processes, such as infiltration, nutrient transport and runoff1,2, that are important for the development of successful global strategies that address challenges of food security, water scarcity, human health and loss of biodiversity3. Macropores—large pores that freely drain water under the influence of gravity—often represent less than 1 per cent of the soil volume, but can contribute more than 70 per cent of the total soil water infiltration4, which greatly magnifies their influence on the regional and global water cycle. Although climate influences the development of macropores through soil-forming processes, the extent and rate of such development and its effect on the water cycle are currently unknown. Here we show that drier climates induce the formation of greater soil macroporosity than do more humid ones, and that such climate-induced changes occur over shorter timescales than have previously been considered—probably years to decades. Furthermore, we find that changes in the effective porosity, a proxy for macroporosity, predicted from mean annual precipitation at the end of the century would result in changes in saturated soil hydraulic conductivity ranging from −55 to 34 per cent for five physiographic regions in the USA. Our results indicate that soil macroporosity may be altered rapidly in response to climate change and that associated continental-scale changes in soil hydraulic properties may set up unexplored feedbacks between climate and the land surface and thus intensify the water cycle.
Forfattere
Katharina Strobl Claudia Schmidt Johannes KollmannSammendrag
Phytometers are indicator transplants that provide information on site conditions based on plant survival,growth and reproduction. Since this is a relatively new approach, standards for its implementation remain to bedefined, for example, during peatland restoration. Peatland restoration frequently aims at recovering char-acteristic communities, and a key attribute of successfully restored ecosystems is their capacity to sustain viablepopulations of target species. When not actively introduced, these species are expected to establish on their ownafter improving site conditions, for example by rewetting. Assessments to determine whether this goal is metrequire the long-term monitoring of species’ presence, whereas the underlying causes of these observations, i.e.site or dispersal limitation, often remain unknown. Using phytometers within ecological restoration helps ad-dressing this question. The goal of this study is to compare the responses of several species and traits to en-vironmental conditions in restored peatlands. Three target species (Drosera rotundifolia, Eriophorum vaginatum,Vaccinium oxycoccos) were planted in restored montane peatlands in central Germany, while in a greenhouseexperiment, the same species were grown on peat from the field sites and exposed to two water levels. Severalplant traits were measured and compared with variation in light, water and soil conditions. The response tohabitat conditions was species-specific, indicating that the use of different phytometers increases the reliabilityof monitoring. Survival and growth traits were suitable to assess a wide range of abiotic conditions, whiledifferences in reproductive output were more time-consuming to measure. Survival provided the most conclusiveresults for species sensitive to stressful habitat conditions. Biomass and other size metrics of the phytometers, aswell as growth and reproductive traits were partly redundant. Thus, we suggest recording survival and biomassand use non-destructive growth measurements for repeated assessments, while the choice of the most suitablesize trait should depend on the growth form. Our study stresses the potential of phytometers for monitoring therestoration outcome, while highlighting the importance of species and trait selection.
Forfattere
Zelalem Bekeko Chemeda Fininsa Shimelis Hussien Temam Hussien Dagne Wegari Belachew Asalf TadesseSammendrag
Fourteen advanced maize inbred lines and locally adapted hybrid maize (BH-540) as a check were used to investigate their reaction to GLS disease. Field experiments were conducted at Bako National Maize Research Centre in 2015 and 2016 main plan ng seasons arranged in a randomized complete block design (RCBD) with three replications. Artificial inoculation with Cercospora zeae-maydis was conducted by applying dry, ground, infected maize leaves into the whorls of younger maize plants. Data on agronomic and disease parameters (latent period, disease severity, disease incidence and lesion type) were recorded from the middle two rows. From the combined analysis of variance, maize genotypes showed significant differences with reaction to GLS indicating the existence of genetic variability among the selected genotypes. Highly significant differences were also observed among entries for all agronomic parameters in both seasons. Gray leaf spot incidence and severity varied among genotypes and between years. The mean GLS incidence and severity were higher in 2016 than 2015. GLS disease incidence in two years ranged from 35% on Sc22 to 95% on CML-387 and severity ranged from 15% on A-7016 to 75% on CKL05003. Significant differences in epidemic variability were also observed among genotypes and seasons. From the analysis of disease progress curves Logistic model (R2=94.55) better described the disease progress curves than the Gompertz model (R2=91.50). Parents; P6 and P8 had the most desirable quality for the most of agronomic traits whereas P2, P7 and P9 were the best parents for grain yield. Among all inbred lines, P6, P7 and P14 were iden fied as the most desirable sources of genes for GLS disease resistance. But P6, P7, P8 and P14 were iden fied as the best genotypes in yield, yield related traits and GLS disease parameters. Thus, these parents were recommended to be used in breeding programs with a purpose of developing high yielder and GLS disease resistant open pollinated varieties. In conclusion this study identified potential and promising high yielding and GLS resistant open pollinated genotypes (CKL05017-B-B, CML-395, CML-387, A-7016, Gu o and Sc22). Therefore, it is recommended that these OPVs can be used by resource poor farmers for direct production where this disease is the most prevalent and/or for further breeding programs in generating novel hybrids for future use.
Forfattere
Monika Suškevičs Sebastian Eiter Stanislav Martinat Dina Stober Elis Vollmer Cheryl L. de Boer Matthias BucheckerSammendrag
Det er ikke registrert sammendrag
Sammendrag
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Sammendrag
The present work focuses on an assessment of the applicability of groundwater table (GWT) measures in the modelling of soil water retention characteristics (SWRC) using artificial neural network (ANN) methods. Model development, testing, validation and verification were performed using data collected across two decades from soil profiles at full-scale research objects located in Southwest Poland. A positive effect was observed between the initial GWT position data and the accuracy of soil water reserve estimation. On the other hand, no significant effects were observed following the implementation of GWT fluctuation data over the entire growing season. The ANN tests that used data of either soil water content or GWT position gave analogous results. This revealed that the easily obtained data (temperature, precipitation and GWT position) are the most accurate modelling parameters. These outcomes can be used to simplify modelling input data/parameters/variables in the practical implementation of the proposed SWRC modelling variants.
Sammendrag
In spite of its important role as predator of small game species, estimating the density of red fox Vulpes vulpes has been hampered by the species’ highly variable ranging pattern and elusive behavior. DNA analysis from scats combined with spatially explicit capture–recapture (SECR) modeling might remedy this. In a 50-km2 coniferous forest in southeast Norway, we collected scats on logging roads in late winter. DNA was extracted, amplified, and genotyped using 11 microsatellite markers. Of 184 samples collected, 126 were genotyped successfully, of which 46 (36.5%) produced individual genetic profiles. Twenty-five of these were different individuals: 13 females and 12 males. Nine of them were identified in multiple scats; mean recapture rate among all was 1.8/animal. Applying a conventional capture–recapture model (CAPWIRE) to the genotyped samples, 36 (95% CI 26–52) different individuals were estimated to have been present in the area during the sampling period. For estimating population density, we constructed three differently sized occupancy areas based on distances between recaptures, viz. ½ and 1/1 mean maximum distance moved (MMDM) and the local convex hull home range method (LoCoH). Areas varied from 60 km2 (½MMDM) to 112 km2 (MMDM), producing density estimates of 0.60 and 0.32 foxes/km2, respectively; the 95% LoCoH range method produced an estimate of 0.44 animals/km2 . Based on SECR modeling, the density was estimated at 0.38 (95% CI 0.21–0.70) animals/km2 . Smaller confidence intervals are expected with more appropriate sampling design than used in this pilot study.
Forfattere
Kalev Jogiste Lee E. Frelich Diana Laarmann Floortje Vodde Endijs Baders Janis Donis Aris Jansons Ahto Kangur Henn Korjus Kajar Köster Jürgen Kusmin Timo Kuuluvainen Vitas Marozas Marek Metslaid Sandra Metslaid Olga Polyachenko Anneli Poska Sille Rebane John A. StanturfSammendrag
Det er ikke registrert sammendrag
Forfattere
Habtamu AlemSammendrag
This doctoral thesis incorporates an integrated framework for the measurement and analysis of the performance of Norwegian farms, focusing on crop-producing and dairy farms. Farm-level datasets were used in the analysis. The thesis comprises an introductory chapter and five independent research articles. The aim of the first article is to explore the effects of model specifications and estimate short-run and long-run inefficiency. We used the transcendental logarithmic (translog) cost function and the analysis is based on unbalanced farm-level panel data for the period 1991–2013 from 455 Norwegian farms that specialise in crop production in the Eastern and Central regions of Norway. It was found that cost efficiency scores are sensitive to how the inefficiency is modelled and interpreted. Empirical analysis demonstrates that the magnitude of long-run inefficiency (5%) is lower than the level of short-run inefficiency (6%). It would be possible to reduce crop production costs by, on average, up to 5% if shortfalls in managerial capabilities were reduced. Such shortfalls in farmers’ management abilities derive from such factors as lack of farming experience and lack of farm ownership. On the other hand, it would be possible to reduce crop production costs by up to 6% if transient inefficiencies could be eliminated. On average, actual costs could be reduced by 11% without reducing output if both forms of inefficiency were eliminated from Norwegian crop production. Policy interventions to this end might include providing training in farm-management practices, and policy changes to ease rigidity in farm ownership. The objective of the second article is to measure the economic performance of two crop-producing Norwegian farms while accounting for both unobserved heterogeneity and environmental variables. The analysis employs a translog cost function and is based on unbalanced farm-level panel data comprising 3,855 observations (1,004 observations from the central region and 2,884 from the eastern region). We found that the mean minimum costs for the period 1991–2013 were approximately 93% and 92% of the actual production costs for crop farms in the central and eastern regions, respectively. The marginal effects of crop rotation, land tenure, off-farm activity, direct government support, and experience positively correlated with the economic performance of crop farms. In both regions, the marginal contribution of these variables to economic performance increased for the period 2000–2013 compared to 1991–1999. The aim of Article 3 is to measure the contribution of productivity and price change to changes in the profitability of crop-producing family farms in Norway. The results indicate that the average annual productivity growth rate for grain and forage production decreased by 0.11% per annum over the period 1991–2013. Profits decreased by 0.14% per annum primarily due to the effect of the trend of increasing input prices and a decline in total factor productivity. Interventions to improve the productivity of farms would also improve farm profitability.