With each degree increase in temperature, a flower produces 10% less live pollen, as Chinese research already showed in 2004. Although relatively few pollen grains are needed to fertilize a plant, dead pollen “blocks” access organisms, so that plants eventually produce fewer fruits. This could have consequences for the global food supply.
Plants go on the defensive in the heat
Plants prepare at an early stage when the heat wave arrives, according to research from Radboud University Nijmegen. “Once plants notice the temperature is rising, they go into a kind of ‘stress mode’, where they focus less on surviving,” says molecular biologist Stuart Jansma, who will earn a Ph.D. on the subject in 2022. alive and to a lesser extent on reproduction.”
He investigated what happens when tomato plants are exposed to moderate heat (thirty to 34 degrees Celsius) for a longer period of time, a few degrees above the ideal temperature for the plant. Fewer live pollen grains develop under these conditions.
Pollen stimulation through genetic modification
“This is a very normal reaction, but somewhat exaggerated,” concludes Jansma. “Without it, the plants would also tolerate the heat.” By means of genetic modification, the gene that activates this reaction can be turned off – so that pollen production is preserved – but European legislation does not allow this yet.
The lower left image shows healthy, mature pollen grains that developed at a controlled temperature. Bottom right after heat stress: many pollen grains have withered and are no longer viable.
