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.
2022
Abstract
No abstract has been registered
Abstract
Strawberry powdery mildew, caused by Podosphaera aphanis, can be particularly destructive in glasshouse and plastic tunnel production systems, which generally are constructed of materials that block ultraviolet (UV) solar radiation (about 280 to 400 nm). We compared epidemic progress in replicated plots in open fields and under tunnels constructed of polyethylene, which blocks nearly all solar UV-B, and two formulations of ethylene tetrafluoroethylene (ETFE), one of which contained a UV blocker and another that transmitted nearly 90% of solar UV-B. Disease severity under all plastics was higher than in open-field plots, indicating a generally more favorable environment in containment structures. However, the foliar severity of powdery mildew within the tunnels was inversely related to their UV transmissibility. Among the tunnels tested, incidence of fruit infection was highest under polyethylene and lowest under UV-transmitting ETFE. These effects probably transcend crop, and the blocking of solar UV transmission by glass and certain plastics probably contributes to the widely observed favorability of greenhouse and high-tunnel growing systems for powdery mildew.
Authors
Andreas Hagenbo Josu G. Alday Juan Martínez de Aragón Carles Castaño Sergio de-Miguel José Antonio BonetAbstract
Soil fungi are vital for regulating ecosystem carbon balance and productivity, by driving processes related to soil carbon and nutrient cycling. The rate and capacity of fungi-mediated processes are linked to fungal biomass dynamics and identifying the drivers of fungal biomass is important for predicting ecosystem responses to environmental changes. Here, ergosterol-based fungal biomass estimates and ITS2-based fungal community composition profiles were used to assess biomass of fungal guilds. Effects of forest management (thinning), environmental factors (soil chemical properties, microclimate, weather and forest stand composition) and season were related to the fungal biomass dynamics to identify the guild-specific drivers of biomass. Biomass of most fungal guilds increased with nutrient availability (nitrogen and potassium in particular) and decreased with forest thinning, and variation in total biomass was mainly driven by variation in mycorrhizal biomass. Most fungal guilds reached a minimum in biomass during summer except for mycorrhizal and root-associated ascomycetes, which instead reached a minimum during winter. Mycorrhizal fungi and root-associated ascomycetes displayed similar spatiotemporal variability in biomass. Yeasts and moulds were the only fungi displaying strong linkages with microclimate, whereas pathogenic and moss-associated fungi largely diverged in their responses to the environmental factors. The results of our study highlight that environmental factors related to the availability of soil nutrients may have an overall stronger effect on variation in biomass of fungal guilds in Mediterranean Pinus pinaster forests than direct influences of microclimate, weather and forest management.
Authors
Jutta KapferAbstract
No abstract has been registered
Authors
Michel VerheulAbstract
No abstract has been registered
Authors
Michel VerheulAbstract
No abstract has been registered
Authors
Marleen Pallandt Bernhard Ahrens Sujan Koirala Holger Lange Markus Reichstein Marion Schrumpf Sönke ZaehleAbstract
The role of soil moisture for organic matter decomposition rates remains poorly understood and underrepresented in Earth System Models (ESMs). We apply the Dual Arrhenius Michaelis-Menten (DAMM) model to a selection of ESM soil temperature and moisture outputs to investigate their effects on decomposition rates, at different soil depths, for a historical period and a future climate period. Our key finding is that the inclusion of soil moisture controls has diverging effects on both the speed and direction of projected decomposition rates (up to ± 20%), compared to a temperature-only approach. In the top soil, the majority of these changes is driven by substrate availability. In deeper soil layers, oxygen availability plays a relatively stronger role. Owing to these different moisture controls along the soil depth, our study highlights the need for depth-resolved inclusion of soil moisture effects on decomposition rates within ESMs. This is particularly important for C-rich soils in regions which may be subject to strong future warming and vertically opposing moisture changes, such as the peat soils at northern high latitudes.
Abstract
Compatibility and synchrony between specialized tissues of the pistil, female gametophytes and male gametophytes, are necessary for successful pollination, fertilization, and fruit set in angiosperms. The aim of the present work was to study the development and viability of embryo sacs, as well as fertilization success, in relation to the fruit set of the cultivars ‘Mallard’, ‘Edda’, ‘Jubileum’, and ‘Reeves’, under specific Norwegian climatic conditions. Emasculated, unpollinated, and open-pollinated flowers were collected at the beginning of flowering, and on the 3rd, 6th, 9th, and 12th days after flowering, from all four plum cultivars over two years (2018/2019). Ovaries were dehydrated, embedded in paraffin wax, sectioned, stained, and observed under a light microscope. Results showed the existence of synchronization between successive phases in the development of the embryo sac and individual phases of flowering. All plum cultivars had higher percentages of viable embryo sacs, fertilized embryo sacs, and fruit set in 2018 than in 2019. These differences may be related to the very low temperatures during the post-full-flowering period in 2019, and to the low adaptation of some studied cultivars to unfavorable conditions. In our study, the cultivar ‘Jubileum’ showed the highest percentage of viable embryo sacs, fertilized embryo sacs, and fruit set compared to other cultivars, i.e., the best low-temperature adaptation.
Abstract
Plants and fungi emit volatile organic compounds (VOCs) that are either constitutively produced or are produced in response to changes in their physico-chemical status. We hypothesized that these chemical signals could be utilized as diagnostic tools for plant diseases. VOCs from several common wheat pathogens in pure culture (Fusarium graminearum, Fusarium culmorum, Fusarium avenaceum, Fusarium poae, and Parastagonospora nodorum) were collected and compared among isolates of the same fungus, between pathogens from different species, and between pathogens causing different disease groups [Fusarium head blight (FHB) and Septoria nodorum blotch (SNB)]. In addition, we inoculated two wheat varieties with either F. graminearum or P. nodorum, while one variety was also inoculated with Blumeria graminis f.sp. tritici (powdery mildew, PM). VOCs were collected 7, 14, and 21 days after inoculation. Each fungal species in pure culture emitted a different VOC blend, and each isolate could be classified into its respective disease group based on VOCs with an accuracy of 71.4 and 84.2% for FHB and SNB, respectively. When all collection times were combined, the classification of the tested diseases was correct in 84 and 86% of all cases evaluated. Germacrene D and sativene, which were associated with FHB infection, and mellein and heptadecanone, which were associated with SNB infection, were consistently emitted by both wheat varieties. Wheat plants infected with PM emitted significant amounts of 1-octen-3-ol and 3,5,5-trimethyl-2-hexene. Our study suggests that VOC blends could be used to classify wheat diseases. This is the first step toward a real-time disease detection in the field based on chemical signatures of wheat diseases.
Authors
M. Helbig T. Živković P. Alekseychik M. Aurela T. S. El-Madany E. S. Euskirchen L. B. Flanagan T. J. Griffis P. J. Hanson J. Hattakka C. Helfter T. Hirano E. R. Humphreys G. Kiely R. K. Kolka T. Laurila P. G. Leahy A. Lohila I. Mammarella M. B. Nilsson A. Panov Frans-Jan W. Parmentier M. Peichl J. Rinne D. T. Roman O. Sonnentag E.-S. Tuittila M. Ueyama T. Vesala P. Vestin Simon Weldon P. Weslien S. ZaehleAbstract
Peatlands have acted as net CO2 sinks over millennia, exerting a global climate cooling effect. Rapid warming at northern latitudes, where peatlands are abundant, can disturb their CO2 sink function. Here we show that sensitivity of peatland net CO2 exchange to warming changes in sign and magnitude across seasons, resulting in complex net CO2 sink responses. We use multiannual net CO2 exchange observations from 20 northern peatlands to show that warmer early summers are linked to increased net CO2 uptake, while warmer late summers lead to decreased net CO2 uptake. Thus, net CO2 sinks of peatlands in regions experiencing early summer warming, such as central Siberia, are more likely to persist under warmer climate conditions than are those in other regions. Our results will be useful to improve the design of future warming experiments and to better interpret large-scale trends in peatland net CO2 uptake over the coming few decades.