Soybeans produce a quarter more beans if the sun protection regimen is genetically altered. This is evident from field experiments conducted by American researchers. Their results are this Thursday in Sciences Posted. They expect their invention to eventually increase crop yields, especially in sub-Saharan Africa and southern Asia, where production is too low to feed their rapidly growing populations.
Plants need sunlight, in combination with carbon monoxide2 and water to make sugars and to store energy. But when there’s a lot of sunlight, the extra energy is used to convert oxygen into oxygen radicals, which damage photosynthesis, among other things.
“With a lot of sunlight, all kinds of things can go wrong in a plant,” says Herbert van Amirongen, professor of biophysics at Wageningen University and Research, who was not involved in the now-published research. Plants protect themselves from too much sunlight by operating a system that “doesn’t convert excess incoming energy into electrons, but dissipates it in the form of heat,” says van Amerongen, who researches this system.
The drawback of this protection system is that although it turns on within seconds to minutes if there is a lot of sunlight, it turns off much slower when this abundance passes. While the system is still active, photosynthesis does not operate at maximum amplitude.
“Our idea was that a plant could grow faster if the protective system was turned off faster,” explains Stephen Long. The study was coordinated by a professor of crop sciences at the University of Illinois. The principle has long been proven earlier with genetically modified tobacco plants in which the three-part protective system (two enzymes and one part of the photosynthetic apparatus) were altered. As a result, the weight of the above-ground part of tobacco plants increased by 14 to 21 percent. The Results in 2016 in Sciences Posted.
But subsequent experiments with the genetically modified cress did not show an increase in weight. The researchers then tested whether they could improve the yield of an important agricultural crop using the same procedure. They chose soybeans.
Their tests showed that in 2020, the soybean yield, measured by weight, increased on average by 24.5 percent. They tested five different soybean cultivars, one of which gave a 33 percent higher yield.
But in 2021, the yield was lower, matching that of non-engineered soybean varieties. Although the researchers counted an average of 13 percent of the pods on the manipulated soy plants, the weight of the beans was no higher. They explain that because of a violent storm just as the soybean plants began producing beans (the pods had already been planted by then). As a result, the lower leaves were more covered by the upper leaves, and they were in a semi-permanent shade. So they did not benefit from genetic engineering. In addition, according to the researchers, cloud cover in 2021 was less diverse than in 2020, and with it changes between sun and shade.
Van Amerongen finds a yield increase of nearly a quarter “too much”. He says he was surprised. Also because trials with tobacco and cress showed different results. “Tobacco is an easy plant. Not many people thought it would work in soybeans.” According to Van Amerongen, it is remarkable that the researchers have now shown that the intervention also works in an important agricultural crop. “But we still don’t know how it works.”
Long’s research received funding from the Bill and Melinda Gates Foundation, among others. Long: “The condition is that any technology we develop, including this technology, must be available to farmers in poor countries duty-free.”
A version of this article also appeared in the August 19, 2022 newspaper
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