As climate change brings increasingly earlier warm temperatures, the time that plants bud and bloom arrives earlier, too.
Plants have an ideal temperature for seed set—and then flower at a particular time of year to make sure they hit seed development just as the weather has warmed to a “sweet spot” temperature.
For a new study, researchers used computer models of Arabidopsis thaliana and discovered the plant’s ideal temperature is between 14–15 degrees C (58 degrees F). Seeds that develop in temperatures lower than 14 degrees C will almost always remain dormant and fail to germinate.
An ideal temperature allows the mother plant to produce seeds with different growth strategies, increasing the chances that some of her progeny will complete another generation successfully.
But as the climate changes, the sweet spot for seeds comes earlier in the year, so first flowers bloom correspondingly earlier too.
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.
“It was amazing to realize 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,” said Vicki Springthorpe, a biology doctoral student at the University of York.
“It means that they produce a mixture of seeds, and it’s a clever way of maintaining a stable population in unpredictable growth conditions.
“We found that setting seed at the correct temperature is vital to ensure normal germination,” said Steven Penfield, who supervised the study. “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 recognize this and adjust their flowering time accordingly and it feels like spring comes earlier in the year.”