Sunrise over rice terraces in Bali, Indonesia
Aliaksandr Mazurkevich / Alamy
A common sunscreen ingredient, zinc nanoparticles, can help protect rice from heat stress, an increasingly common problem amid climate change.
Zinc is known to play an important role in plant metabolism. A salt form of the mineral is often added to the soil or sprayed on the leaves as fertilizer, but this is not very effective. Another approach is to deliver zinc in the form of particles smaller than 100 nanometers, which can pass through microscopic pores in leaves and accumulate in a plant.
Researchers have explored these nanoparticle carriers as a way to deliver more nutrients to plants, helping to maintain crop yields while reducing environmental impact. damage from excessive fertilizer use. NOW Hu Xiangang at Nankai University in China and colleagues tested how these zinc oxide nanoparticles affect crop performance under heatwave conditions.
They grew flowering rice plants in a greenhouse under normal conditions and under a simulated heat wave where temperatures exceeded 37°C for six consecutive days. Some plants were sprayed with nanoparticles and others were not treated at all.
At harvest, the average grain yield of plants treated with zinc nanoparticles was 22.1% higher than plants that had not been sprayed, and this rice also had higher nutrient levels. Zinc was also found to be beneficial even outside of heatwave conditions: in these cases, the difference in yield between treated and untreated plants was even greater.
Based on detailed measurements of nutrients in the leaves, the researchers concluded that zinc increased yields by improving enzymes involved in photosynthesis and antioxidants that protect plants against harmful molecules known as reactive species. oxygen.
“Nanoscale micronutrients have enormous potential to increase climate resilience of crops through a number of unique mechanisms linked to reactive oxygen species,” says Jason White at the Connecticut Agricultural Experiment Station.
The researchers also found that rice treated with zinc nanoparticles maintained greater diversity among microbes living on the leaves – called the phyllosphere – which may have contributed to better growth.
Tests of zinc oxide nanoparticles on other crops like pumpkin and alfalfa have also shown yield increases. But Hu says more research is needed to verify whether it could benefit other crops.
