Environmental effects of ozone depletion, UV radiation and interactions with climate change : UNEP Environmental Effects Assessment Panel, update 2017

Peer reviewe

Bruk av tilleggslys for bedre kontroll av meldugg ved produksjon av roser i veksthus

Powdery mildew caused by the Podosphaera pannosa is one of the most widespread and destructive diseases in roses and has been an increasing problem in Norwegian rose production due to lack of disease resistant cultivars. In practice, roses are frequently treated with fungicides to control powdery mildew, and the most common treatment today is with evaporated sulphur. Some fungicides used against powdery mildew, including sulphur may be toxic to biological control agents. Supplementary lighting in Norwegian rose production has been practised since the late1980s. Previous experiments clearly indicated that continuous lighting strongly reduced powdery mildew in roses, but keeping quality was significantly reduced. The main goal of this study was to investigate the effect of different components of light on rose powdery mildew, and use this knowledge to manipulate lighting regimes for improved management of the disease. This thesis consists of three papers. Experiments with day length, light quality and light intensity were conducted with pot roses (Rosa interspecific hybrid ‘Mistral’) in growth chambers with constant temperature and air humidity. Humidity boxes with two rooms were developed and used to test for germination and formation of conidia. Inoculated leaflets were placed on water agar in the upper room of the boxes. The lower room contained saturated salt solution (KCl), which maintained constant high air humidity (96 ±2% RH) in both rooms. For testing of conidia formation and release from whole plants, wind tunnels were developed. Microscope films attached to clock cylinders collected the conidia released from the diseased plants. The first two - investigations was on how day length, light quality and light intensity influenced germination, production of conidia and disease development. The third study was a molecular investigation to find a phytochrome like photoreceptors in P. pannosa. A significant reduction in conidia formation and release were noticed when exposed to 20 - 24 h day length compare to 18 h day length with white light. When trapping conidia from whole plants placed in wind tunnels, exposure to continuous lighting gave only 22 % of the conidia trapped at 18 h day length. There was no significant difference in number of trapped conidia between 20, 22 or 24 h lighting. Germination of conidia was slightly, but significantly reduced when exposed to continuous full spectrum white light or 18 h day length of blue light. While far-red light induced conidia formation, red light suppressed conidia formation and release. Red light supplied in the 6 h period following 18 h white light strongly suppressed formation and release of conidia relative to a diurnal cycle of 18 h white light and 6 h darkness. If plants were exposed to a day length of 18 h provided with a full spectrum of white light, a 1 h night break with red light was sufficient to strongly suppress formation and release of conidia compared to a 1 h night break with far-red light or no night break. However, red light night break followed by far-red light night break almost nullified the suppressive effect of red light. Under full spectrum white light, formation and release of conidia increased with increasing light intensity. PCR amplification with degenerate primers were attempted to find a phytochrome like gene(s) in P. pannosa. It was not successful. Further work is needed to confirm whether P. pannosa has photo sensory receptor. At the moment, designing of more specific primers that are suitable to detect the photo sensory receptors in powdery mildew fungi by PCR is difficult. However sequencing of its genome, proteomic analysis or transcriptome sequence analysis would be other alternatives.Rosemeldugg er forårsaket av soppen Podosphaera pannosa var. rosae. Dette er en av de alvorligste sykdommene på roser i Norge og er et økende problem på grunn av mangel på gode sorter som er resistente. I praktisk rosedyrking blir plantene behandlet med soppmidler, og mest vanlig er svovelfordamping. Noen av soppmidlene brukt mot rosemeldugg, inklusiv svovelfordampning, er skadelige for nyttedyr som brukes for biologisk kontroll av skadedyr. Videre har det utviklet seg resistens mot flere av de syntetiske soppmidlene. Tilleggsbelysning er brukt i norsk roseproduksjon siden slutten av 1980-årene. Tidligere forsøk har vist at kontinuerlig belysning reduserer angrep av meldugg i roser, men holdbarheten ble ofte dårlig. Hovedhensikten med dette forskningsarbeidet var å undersøke hvordan belysningstid, -styrke og lyskvalitet virket på rosemeldugg for å kunne bruke denne kunnskapen i bekjempelsen av rosemeldugg. Denne avhandlingen består av tre individuelle arbeider. Alle forsøkene med daglengde, belysningsstyrke og lyskvalitet foregikk med potterosesorten Mistral i vekstrom under konstant temperatur og luftfuktighet. Plantematerialet bestod enten av hele planter eller enkeltblad som ble holdt i live på kunstig medium. Det ble utviklet bokser med to rom som kunne brukes til å teste spiring og konidiedannelse på enkeltblad som ble lagt på vannagar i det øverste rommet. I den nederste delen var det en saltløsning som ble brukt til å holde en konstant høg luftfuktighet. Luften beveget seg fritt gjennom huller langs kanten av veggen mellom de to kamrene. For testing av konidiedannelse og spredning av konidier fra intakte planter ble det utviklet vindtunneler som samlet opp sporene som ble frigitt fra plantene på en mikroskoptape. I de to første arbeidene ble det undersøkt hvordan daglenden, lyskvaliteten og lysstyrken virker på spireevnen til soppens konidier, konidiedannelse, konidiespredning og sykdomsutvikling. Målet for det tredje arbeidet var å identifisere en eventuell fotoreseptor hos soppen ved hjelp av molekylære teknikker. Kontinuerlig belysning reduserte spireevnen og konidiedannelsen til soppen og ga kun 22 % av tallet på konidier som ble dannet ved 18 t belysning i vindtunnel. Det var ingen forskjell i mengde konidier fra planter som var plassert ved 20, 22 eller 24 t belysning. Ved å eksponere planter inokulert med meldugg for sykluser med 18 t vanlig vekstlys (50 μmol m-2 s-1) + 6 t med rødt lys (5 μmol m-2 s-1) ble mengde konidier redusert til 13 % sammenlignet med 18 t vekstlys + 6 t mørke. Mørkerødt lys gav ingen slik reduksjon, mens blått lys ga noe, men ikke signifikant reduksjon. En time rødt lys i den 6 t lange mørkefasen var nok til å redusere konidiedannelsen kraftig, mens 1 t mørkerødt lys etter 1 t rødt lys nesten fullstendig opphevet effekten av rødt lys. Det var en økning i dannelsen av konidier ved økende lysstyrker fra 5 til 150 μmol m-2 s-1. Fra de to første arbeidene i avhandlingen kan det konkluderes at ved å øke daglengden fra 18 t (tidligere mye brukt i roseproduksjonen) til 20-24 t, reduseres danning og spredning av konidier og sykdomsutvikling hos rosemeldugg. Små mengder med rødt lys gitt i daglengdeforlengelsen (utover 18 t) er tilstrekkelig for å oppnå denne effekten. PCR med generelle primere med etterfølgende sekvensering av genproduktene ble prøvd for om mulig å finne fytokromliknende gener i P. pannosa. Det lyktes ikke. For øyeblikket synes utvikling av mer spesifikke primere nødvendig for å identifisere organer i P.pannoa som er følsomme for lys. Ved sekvensering av hele genomet, proteomikk analyser og transkriptom sekvence analyser til P. pannosa er trolig mulighetene større for å lykkes.Norges forskningsrå

Variation in UV-mediated damage recovery among Pseudoidium neolycopersici isolates: possible mechanisms.

publishedVersio

Use of supplemental lighting towards efficient management of powdery mildew in greenhouse roses

Powdery mildew caused by the Podosphaera pannosa is one of the most widespread and destructive diseases in roses and has been an increasing problem in Norwegian rose production due to lack of disease resistant cultivars. In practice, roses are frequently treated with fungicides to control powdery mildew, and the most common treatment today is with evaporated sulphur. Some fungicides used against powdery mildew, including sulphur may be toxic to biological control agents. Supplementary lighting in Norwegian rose production has been practised since the late1980s. Previous experiments clearly indicated that continuous lighting strongly reduced powdery mildew in roses, but keeping quality was significantly reduced. The main goal of this study was to investigate the effect of different components of light on rose powdery mildew, and use this knowledge to manipulate lighting regimes for improved management of the disease. This thesis consists of three papers. Experiments with day length, light quality and light intensity were conducted with pot roses (Rosa interspecific hybrid ‘Mistral’) in growth chambers with constant temperature and air humidity. Humidity boxes with two rooms were developed and used to test for germination and formation of conidia. Inoculated leaflets were placed on water agar in the upper room of the boxes. The lower room contained saturated salt solution (KCl), which maintained constant high air humidity (96 ±2% RH) in both rooms. For testing of conidia formation and release from whole plants, wind tunnels were developed. Microscope films attached to clock cylinders collected the conidia released from the diseased plants. The first two - investigations was on how day length, light quality and light intensity influenced germination, production of conidia and disease development. The third study was a molecular investigation to find a phytochrome like photoreceptors in P. pannosa. A significant reduction in conidia formation and release were noticed when exposed to 20 - 24 h day length compare to 18 h day length with white light. When trapping conidia from whole plants placed in wind tunnels, exposure to continuous lighting gave only 22 % of the conidia trapped at 18 h day length. There was no significant difference in number of trapped conidia between 20, 22 or 24 h lighting. Germination of conidia was slightly, but significantly reduced when exposed to continuous full spectrum white light or 18 h day length of blue light. While far-red light induced conidia formation, red light suppressed conidia formation and release. Red light supplied in the 6 h period following 18 h white light strongly suppressed formation and release of conidia relative to a diurnal cycle of 18 h white light and 6 h darkness. If plants were exposed to a day length of 18 h provided with a full spectrum of white light, a 1 h night break with red light was sufficient to strongly suppress formation and release of conidia compared to a 1 h night break with far-red light or no night break. However, red light night break followed by far-red light night break almost nullified the suppressive effect of red light. Under full spectrum white light, formation and release of conidia increased with increasing light intensity. PCR amplification with degenerate primers were attempted to find a phytochrome like gene(s) in P. pannosa. It was not successful. Further work is needed to confirm whether P. pannosa has photo sensory receptor. At the moment, designing of more specific primers that are suitable to detect the photo sensory receptors in powdery mildew fungi by PCR is difficult. However sequencing of its genome, proteomic analysis or transcriptome sequence analysis would be other alternatives

Variation in UV-mediated damage recovery among Pseudoidium neolycopersici isolates: possible mechanisms.

publishedVersio

Licht als gewasbeschermingsmiddel kan, maar fine-tuning is nog nodig : Combinatie van UV en rood licht sleutel tot succes

Langzamerhand groeien de mogelijkheden van licht als gewasbeschermingsmiddel. Schimmels zijn vatbaar voor UV-straling en rood licht, en de combinatie werkt nog beter. Er valt echter nog veel te verbeteren. Het ziektewerende effect is alleen te zien waar het licht direct op valt. Bovendien kan de plant bij hoge doses ook lijden onder de behandeling