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Scientists discover why flowers bloom earlier in a warming climate

Posted on 31 March 2015

Scientists at the University of York have discovered why the first buds of spring come increasingly earlier as the climate changes.

Arabidopsis flower

Dr Vicki Springthorpe carried out the research as part of her PhD in the Department of Biology at York. She found that plants have an ideal temperature for seed set and flower at a particular time of year to make sure they hit seed development just as the weather has warmed to this ‘sweet spot’ temperature.

Supervised by Dr Steven Penfield, now at the John Innes Centre in Norwich, she discovered the sweet spot for the model plant Arabidopsis thaliana is between 14-15˚C. Seeds that develop in temperatures lower than 14˚C will almost always remain dormant and fail to germinate. This allows the mother plant to produce seeds with different growth strategies, increasing the chances that some of her progeny will complete another generation successfully.  

As the climate changes the sweet spot for seeds comes earlier in the year, so first flowers bloom correspondingly earlier too.

The research funded by the Biotechnology and Biological Research Council (BBSRC) and  published in ELife today, used computer models for seed development of Arabidopsis thaliana. The underlying principle of a very sensitive temperature sweet spot is likely to apply to many flowering plants. This would mean that certain plants have different flowering times due to different but equally narrow temperature sensitivity windows.

Dr Springthorpe said: “It was amazing to realise that such a small change in temperature can make a big difference to the germination, and even more so that plants were timing their seed set to coincide with it even when the climate was altered. It means that they produce a mixture of seeds, and its a clever way of maintaining a stable population in unpredictable growth conditions.

Dr Penfield added: “We found that setting seed at the correct temperature is vital to ensure normal germination. It seems that plants aim to flower not at a particular time of year, but when the optimal temperature for seed set is approaching. If the climate warms plants are clever enough to recognise this and adjust their flowering time accordingly and it feels like spring comes earlier in the year.”

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