Measures of Light in Studies on Light-Driven Plant Plasticity in Artificial Environments

Within-canopy variation in light results in profound canopy profiles in foliage structural, chemical, and physiological traits. Studies on within-canopy variations in key foliage traits are often conducted in artificial environments, including growth chambers with only artificial light, and greenhouses with and without supplemental light. Canopy patterns in these systems are considered to be representative to outdoor conditions, but in experiments with artificial and supplemental lighting, the intensity of artificial light strongly deceases with the distance from the light source, and natural light intensity in greenhouses is less than outdoors due to limited transmittance of enclosure walls. The implications of such changes in radiation conditions on canopy patterns of foliage traits have not yet been analyzed. We developed model-based methods for retrospective estimation of distance vs. light intensity relationships, for separation of the share of artificial and natural light in experiments with combined light and for estimation of average enclosure transmittance, and estimated daily integrated light at the time of sampling (Qint,C), at foliage formation (Qint,G), and during foliage lifetime (Qint,av). The implications of artificial light environments were analyzed for altogether 25 studies providing information on within-canopy gradients of key foliage traits for 70 species × treatment combinations. Across the studies with artificial light, Qint,G for leaves formed at different heights in the canopy varied from 1.8- to 6.4-fold due to changing the distance between light source and growing plants. In experiments with combined lighting, the share of natural light at the top of the plants varied threefold, and the share of natural light strongly increased with increasing depth in the canopy. Foliage nitrogen content was most strongly associated with Qint,G, but photosynthetic capacity with Qint,C, emphasizing the importance of explicit description of light environment during foliage lifetime. The reported and estimated transmittances of enclosures varied between 0.27 and 0.85, and lack of consideration of the reduction of light compared with outdoor conditions resulted in major underestimation of foliage plasticity to light. The study emphasizes that plant trait vs. light relationships in artificial systems are not directly comparable to natural environments unless modifications in lighting conditions in artificial environments are taken into account.Organismic and Evolutionary Biolog

Quantitative patterns between plant volatile emissions induced by biotic stresses and the degree of damage

Plants have to cope with a plethora of biotic stresses such as herbivory and pathogen attacks throughout their life cycle. The biotic stresses typically trigger rapid emissions of volatile products of lipoxygenase (LOX) pathway (LOX products: various C(6) aldehydes, alcohols, and derivatives, also called green leaf volatiles) associated with oxidative burst. Further a variety of defense pathways is activated, leading to induction of synthesis and emission of a complex blend of volatiles, often including methyl salicylate, indole, mono-, homo-, and sesquiterpenes. The airborne volatiles are involved in systemic responses leading to elicitation of emissions from non-damaged plant parts. For several abiotic stresses, it has been demonstrated that volatile emissions are quantitatively related to the stress dose. The biotic impacts under natural conditions vary in severity from mild to severe, but it is unclear whether volatile emissions also scale with the severity of biotic stresses in a dose-dependent manner. Furthermore, biotic impacts are typically recurrent, but it is poorly understood how direct stress-triggered and systemic emission responses are silenced during periods intervening sequential stress events. Here we review the information on induced emissions elicited in response to biotic attacks, and argue that biotic stress severity vs. emission rate relationships should follow principally the same dose–response relationships as previously demonstrated for different abiotic stresses. Analysis of several case studies investigating the elicitation of emissions in response to chewing herbivores, aphids, rust fungi, powdery mildew, and Botrytis, suggests that induced emissions do respond to stress severity in dose-dependent manner. Bi-phasic emission kinetics of several induced volatiles have been demonstrated in these experiments, suggesting that next to immediate stress-triggered emissions, biotic stress elicited emissions typically have a secondary induction response, possibly reflecting a systemic response. The dose–response relationships can also vary in dependence on plant genotype, herbivore feeding behavior, and plant pre-stress physiological status. Overall, the evidence suggests that there are quantitative relationships between the biotic stress severity and induced volatile emissions. These relationships constitute an encouraging platform to develop quantitative plant stress response models

Greenhouse gas balance of open peatlands is globally governed by soil water content and archaeal abundance : EGU21-8969

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Plant-plant interactions and N fertilization shape soil bacterial and fungal communities

The impact of conspecific and heterospecific neighboring plants on soil bacterial and fungal communities has never been explored in a forest ecosystem. In the present study, we first investigated soil microbial communities in three plantations: Larix kaempferi monoculture, L. olgensis monoculture and their mixture. Then, a two-year growth experiment was conducted to investigate the effects of intra- and inter-specific interactions of L. kaempferi and L. olgensis on rhizosphere microbial communities at two different nitrogen levels. The results demonstrated clear differences in the beta-diversity and composition of bacteria and fungi among the three plantations, which implied the presence of different effects of plant-plant interactions on soil microbial communities. The results of the pot experiment showed that L. kaempferi suffered from greater neighbor effects from its conspecific neighbor regardless of N fertilization, although the effect declined when L. kaempferi was grown with L. olgensis under N fertilization. Changes in intra- and inter-specific plant interactions significantly impacted the chemical and biological properties of soil under N fertilization, with lower concentrations of NH4+, and lower soil microbial biomass (C-Mic) and soil carbon nitrogen biomass (N-Mic) under intra-specific plant interactions of L. kaempferi (KK) compared to inter-specific interactions of L. kaempferi and L. olgensis (KO). N fertilization increased bacterial and fungal alpha diversities in the rhizosphere soil of KO. For the beta diversity, the PERMANOVA results demonstrated that there was a significant impact of intra- and inter-specific plant interactions on soil microbial communities, with KK significantly differing from intra-specific plant interactions of L. olgensis (OO) and KO. The two plant species and N fertilization showed specific effects on the soil microbial composition, particularly on the fungal community. Both L. olgensis and N fertilization increased the abundance of Ascomycota but reduced that of Basidiomycota, and even shifted the dominance from Basidiomycota to Ascomycota under KO combined with N fertilization.Peer reviewe

EVALUATION OF DOWNY MILDEW (HYALOPERONOSPORA BRASSICAE) INFECTION SEVERITY ON DIFFERENT CRUCIFEROUS OILSEED CROPS

Diseases constitute an important economic problem in oilseed rape (Brassica napus) cultivation. Although downy mildew has been counted so far as a minor disease, under intensive cultivation system and short rotation interval, the impact of diseases could increase in the future, especially under predicted more humid northern climatic conditions. This research study is the first report about the severity of downy mildew infection on cruciferous crops in Estonia. During two years (2010 − 2011), downy mildew infection severity was assessed in six different cruciferous crops (B. napus, B. juncea, B. nigra, Sinapis alba, Raphanus sativus, Eruca sativa) in field trials located in Eerika, Tartu County, Estonia. On both study years, four disease assessments were done. Downy mildew infection started a week earlier in 2010, but the overall disease pressure was lower compared to 2011. Based on our field trial results, S. alba, E. sativa and R. sativus plants were significantly more resistant to downy mildew compared to other tested crops. Furthermore, in 2010 downy mildew symptoms were not recorded on two cruciferous species E. sativa and R. sativus. Brassica nigra and B. napus plants were the most susceptible to downy mildew, with especially severe infection in 2011. Based on our two years data, downy mildew can damage foliage on spring oilseed rape (B. napus) and black mustard (B. nigra) in a notable extent. We conclude that downy mildew is an important pathogen, which should be monitored on different oilseed cruciferous crops in Estonia

El rol dels terpens en la competència entre plantes invasores i natives a Hawaii

Els terpens, hidrocarburs derivats de l'isoprè, són emesos i emmagatzemats per moltes plantes. La seva funció biològica i ecològica és estudiada des de fa uns anys, havent estat proposades diverses possibles funcions, com per exemple la protecció davant dels herbívors o com a mecanisme antiestrès metabòlic. Investigacions realitzades per científics del CREAF a les illes Hawaii han permès detectar diferències en l'acumulació foliar de terpens entre les espècies nadiues i invasives a través de l'screening efectuat en una àmplia mostra de les principals espècies forestals natives i invasives a l'illa d'Oahu. Aquests resultats aporten noves pistes per conèixer els mecanismes que expliquen l'èxit competitiu que permet que moltes espècies introduïdes en un nou hàbitat esdevinguin un problema ecològic per la seva expansió i exclusió competitiva d'espècies nadiues.Los terpenos, hidrocarburos derivados del isopreno, son emitidos y almacenados por muchas plantas. Su función biológica y ecológica está siendo estudiada desde hace unos años, habiendo sido propuestas varias posibles funciones, como por ejemplo la protección frente a los herbívoros o como mecanismo antiestrés metabólico. Investigaciones realizadas por científicos del CREAF en las islas Hawai han permitido detectar diferencias en la acumulación foliar de terpenos entre las especies nativas e invasivas a través del screening efectuado en una amplia muestra de las principales especies forestales nativas y invasivas en la Isla de Oahu. Estos resultados aportan nuevas pistas para conocer los mecanismos que explican el éxito competitivo que permite que muchas especies introducidas en un nuevo hábitat se conviertan en un problema ecológico por su expansión y exclusión competitiva de especies nativas

Jätkusuutlikud teadlaskarjääri kontseptsioonid ja mudelid Eesti kontekstis : lõpparuanne

Uuringu tellis SA Eesti Teadusagentuur. Uuringu tegi Eesti Teaduste Akadeemia koostöös Tallinna Ülikooli ja Tallinna Tehnikaülikooliga.Esitatakse ülevaade kaasaegsete teadlaskarjääri mudelite põhimõtetest, peamistest elemen-tidest, nende teisenemisest viimastel aastakümnetel ning erinevate mudelite rakendamisel ilmnenud kitsaskohtadest teaduskirjanduses 2011–2017 ilmunud artiklite, üksikutes riikides rakendatud mudelite võrdlevate ülevaadete ja neis esitatud materjalide ekspertarutelude alusel. Sama andmestiku alusel analüüsitakse teadlaskarjääride kujunemise dünaamikat ja teadlaskarjääri iseärasuste seoseid teadlaste mõjukuse ja teadussüsteemi toimimisega. Tõdetakse, et optimaalne teadlaskarjääri mudel on üks teadmispõhise ühiskonna tugedest ning ideaalis mehhanism, mis realiseerib parimal moel teadlaste potentsiaali ühiskonna vaja-dusteks. Identifitseeritakse Eesti jaoks sobivate mudelite kontseptuaalsed alused, soovitus-likud ülesehituse printsiibid ja võimalikud proportsioonid ning ajaline dünaamika. Leitakse, et Eestis tuleks käivitada selge ja läbipaistev ning samas piisavalt paindlik ja erisusi aktsepteeriv karjäärimudel, mis annaks julgustava signaali võimekatele noorteadlastele, võimaldaks selekteerida välja säravad teadlased juba suhteliselt varases staadiumis ning aitaks kaasa võrdsete võimaluste tagamisele. Mudeli eesmärk on väga häid tippe Eesti akadeemilisele maastikule juurde saada ja neid siin hoida. Sellise mudeli selgroona soovitatakse luua tenuurisüsteem (tähtajalised ametikohad tenuu-rirajal, millele järgnevad tähtajatud tenuuri ametikohad) olemasoleva süsteemi täiendusena. Süsteem peaks haarama väikese hulga tippteadlasi (ligikaudu 1/5 teadlastest ja õppejõudu-dest) ning toimima lävendipõhiselt õigustatud ootuse printsiibi alusel. Tenuurisüsteem eel-dab stabiilset rahastust, mis peab olema garanteeritud asutuste, mitte teadlaste endi ega nende allüksuste poolt. Tenuurisüsteemi põhimõtted tuleks sätestada seaduse tasemel, jättes ülikoolidele ulatusliku otsustusõiguse detailide kujundamisel. Jõutakse järeldusele, et taoline süsteem teeb teadlaskarjääri atraktiivseks, pakkudes tenuuri jõudnutele töökohakindlust ja rahvusvaheliselt konkurentsivõimelisi töötingimusi. Paralleel-selt tenuurisüsteemiga tuleb käigus hoida laiapõhjaline akadeemiline kogukond, mille ole-masolu tagab teadusmaastiku paindlikkuse. Analüüsitakse tenuuri tüüpi mudelite spetsiifikat teadlaste mobiilsuse, tippteaduse toeta-mise, teaduskoostöö kujunemise ja pärssivate tegurite seisukohalt. Antakse ülevaade soolise ebavõrdsuse problemaatikast karjäärimudeli kontekstis. Peetakse vajalikuks lähtuda teadlas-te soorituse hindamisel nende saavutustest selle aja vältel, mil nad on olnud aktiivselt tege-vad teadusmaastikul. Formuleeritakse soovitused karjääri üksikute elementide rakendamiseks Eesti tingimustes. Skitseeritakse tenuurisüsteemi rahastamise võimalused. Leitakse, et süsteemi tõrgeteta funktsioneerimiseks on vaja tagada õigeaegne väärikas väljumine nii, et pensionile jäämisega ei kaasne olulist elukvaliteedi langust. Kirjeldatakse võimalusi kujundada Eestis laiendatud akadeemiline tööturg. Soovitatakse jätkata tööstusdoktorantuuri institutsionaliseerimist ning käivitada teemapõhise uurija-professori institutsioon.The principles of contemporary research career models are outlined together with descriptions of their chief elements, modifications in the recent past, and known bottlenecks. The study is based on research papers published in scholarly journals in 2011–2017, comparative surveys of various models, and expert discussions over materials from these sources. The same dataset serves as the basis for analysing the dynamics of research career formation and links of research career peculiarities with researchers’ scientific prestige and functionality of the R&D system. An optimal research career model is found to be among the cornerstones of a knowledge-based society. Ideally, it is also a transfer mechanism of scientists’ capacity into practices meeting societal needs in the best possible way. The conceptual framework, recommended basic principles, as well as possible proportions of models suitable for Estonia are identified. The best suited career model to be implemented in Estonia has to be clear and transparent and, at the same time, sufficiently flexible and exception-tolerant. It is expected to communicate a motivating message to talented young scientists, enable creaming off excellent researchers in a relatively early stage of their careers, and contribute to promoting equal opportunities. The chief aim of the model is to attract the very best (top) scientists into the Estonian academic landscape and to keep them here. It is recommended that the core of such a model is formed by a tenure system (temporary positions on the tenure track followed by permanent tenure positions), launched as an extension to the currently existing R&D system. Desirably, the tenure system should encompass a relatively small cohort of top scientists (about 1/5 of research scientists and university teachers). Career paths in the tenure system should be threshold-based and follow the principle of legitimate expectation. Stable funding is an undisputed prerequisite for the tenure system and must be the responsibility of the entire institution. While the principles of the tenure system should be established by law, it makes good sense to give universities a wide span of control for determining the details. In all probability this kind of a system will make research careers attractive, offering enhanced job security and internationally competitive working conditions to the successful candidates. A broad-based academic community has to be upheld in parallel with the tenure system to ensure the flexibility of the research landscape. The specific features of tenure-type models are analysed with respect to research mobility, fostering of cutting edge science, evolution of research collaboration, and hindering factors. Also, the issues of gender inequality in context of career models are described. For evaluation of researchers’ performance it would be fair to take into account their achievements during the period of time when they were actively involved in the research. Recommendations for implementing single elements of such a system in Estonia are formulated and possible sources for its funding are indicated. Smooth functioning of the system is guaranteed only if the researchers’ exit occurs in a timely and dignified manner. The possible solutions for shaping an extended academic labour market in Estonia are described. Continuing the institutionalisation of the so-called industrial PhD education and launching topical Academy Research Professors’ institution are recommended.Tööd rahastatakse „Valdkondliku teadus- ja arendustegevuse tugevdamise (RITA)“ tegevuse 4 raames Euroopa Regionaalarengu Fondist

Canopy airspace of riparian forest mitigates soil N2O emission during hot moments

This study was supported by the Ministry of Education and Science of Estonia (SF0180127s08 grant), the Estonian Research Council (IUT2-16, PRG-352, and MOBERC20), the Czech Science Foundation (17-18112Y) and project SustES - Adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.02.1.01/0.0/0.0/16_019/0000797), the EU through the European Regional Development Fund (Centres of Excellence ENVIRON, grant number TK-107, EcolChange, grant number TK-131, and the MOBTP101 returning researcher grant by the Mobilitas Pluss programme) and the European Social Fund (Doctoral School of Earth Sciences and Ecology). This work was also supported by Academy of Finland (294088, 288494), and from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme under grant agreement No [757695]. We would like to thank Marek Jakubík for his technical supportPreprin

Forest canopy mitigates soil N2O emission during hot moments

Funding Information: This study was supported by the Ministry of Education and Science of Estonia (SF0180127s08 grant), the Estonian Research Council (IUT2-16, PRG-352, and MOBERC20), the Czech Science Foundation (17-18112Y) and project SustES— Adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.02.1.01/0.0/0.0/16_019/0000797), the EU through the European Regional Development Fund (Centres of Excellence ENVIRON, grant number TK-107, EcolChange, grant number TK-131, and the MOBTP101 returning researcher grant by the Mobilitas Pluss program) and the European Social Fund (Doctoral School of Earth Sciences and Ecology). This work was also supported by the Academy of Finland (294088, 288494), and from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program under grant agreement No [757695]. We would like to thank Marek Jakubík for his technical support. Publisher Copyright: © 2021, The Author(s).Peer reviewedPublisher PD