Researchers at the National Agriculture and Food Research Organization (NARO) in Japan may have found a solution for rice farmers facing the recurring problem of “chalky grains” thanks to nitrogen fertilizers.
Hiroshi Nakano, researcher at Kyushu Okinawa Agricultural Research Center, NARO and his partners share their research in a study recently published in the Agronomy Journal.
Chalky grains are the result of exposing rice plants to high temperatures. Once exposed, these beans are easily crushed throughout the milling process, resulting in lost profits from the damaged beans.
The right amount of nitrogen fertilizer is essential, according to Japanese researchers. Too much nitrogen, and rice protein levels will increase. The quality of the rice is then at stake because the grain thins out during cooking. Too little nitrogen, and the grain of rice goes back to square one: a chalky grain.
Tools useful to farmers to predict the percentage of chalky kernels were one of the research focuses.
“Our goal is to facilitate stable rice production in a changing climate,” Nakano said.
“It is important to establish an ideal nitrogen supply rate using a growth diagnostic. In this study, we identified factors useful in regulating white-backed kernels (a type of chalky kernel) and protein content.
Different growing seasons and weather conditions bring variables. Therefore, nitrogen application should be modified according to growing conditions.
“Our mission is to develop ways to protect rice from global climate change,” adds Nakano. “In Japan, rice-growing areas account for about 36% of all agricultural land. In recent years, rice plants have been exposed to higher air temperatures during the ripening phase. This can result in white-backed grains.
Two devices were used to test two types of measurements in the study. A device measured the concentration of nitrogen in the leaves of rice plants. The second looked at the nitrogen absorption capacities in plants. Soil and Plant Analyzer Development (SPAD) readings were also used.
What does this mean for rice farmers?
The researchers believe the readings will allow farmers to adjust nitrogen application in real time during rice production. Finding the right timing during a plant’s development helped regulate the protein content of grains, according to the study.
“We recommend that farmers perform growth diagnosis using portable meters,” Nakano said. “These counters are not expensive and obtaining this information will allow them to harvest high quality rice grains.”
“Our correlation coefficient and modeling analyzes showed that SPAD readings at 4-2 weeks before heading and SPAD and NDVI readings at 1 week before heading could be useful indicators for determining application rate. of appropriate N during the reproduction phase in order to reduce the occurrence of powdery mildew in cereals and to regulate the protein content of cereals,” continued Nakano.
Increasing yields for profit is just one of the goals of the study. These improved yields also present a potential solution for food security.
“This research is broadly significant because the global average temperature is expected to increase due to global warming,” Nakano said. “The occurrence of white-backed kernels increases when rice plants mature under high air temperatures. Rice is the staple food for about 50% of the world’s population. Therefore, this issue is important for farmers but also for consumers.
Farmers with many rice paddies may still find it difficult to collect enough data despite various tools. Researchers are working to solve this problem by developing a system to take measurements using unmanned aerial vehicles.
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