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Global warming leads to increasing irregular and unexpected warm spells during autumn, and therefore natural chilling requirements to break dormancy are at risk. Controlled cold treatment can provide an answer to this problem. Nevertheless, artificial cold treatment will have consequences for carbon reserves and photosynthesis. In this paper, the effect of dark cold storage at 7 °C to break flower bud dormancy in the evergreen Rhododendron simsii was quantified. Carbohydrate and starch content inleaves and flower buds of an early (‘Nordlicht’), semi-early (‘M. Marie’) and late (‘Mw.G. Kint’) flowering cultivar showed that carbon loss due to respiration was lowest in‘M. Marie’, while ‘Mw. G. Kint’ was completely depleted of starch reserves at the endof cold treatment. Gene isolation resulted in a candidate gene for sucrose synthase(SUS) RsSus, which appears to be homologous to AtSus3 and had a clear increase inexpression in leaves during cold treatment. Photosynthesis measurements on ‘Nordlicht’and the late-flowering cultivar ‘Thesla’ showed that during cold treatment, darkrespiration decreased 58% and 63%, respectively. Immediately after cold treatment,dark respiration increased and stabilised after 3 days. The light compensation pointfollowed the same trend as dark respiration. Quantum efficiency showed no significantchanges during the first days after cold treatment, but was significantly higherthan in plants with dormant flower buds at the start of cold treatment. In conclusion,photosynthesis stabilised 3 days after cold treatment and was improved compared tothe level before cold treatment
Original languageEnglish
JournalPlant Biology
Volume17
Issue number1
Pages (from-to)97-105
ISSN1435-8603
Publication statusPublished - 2015

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