Rice is the world's largest staple crop, providing food for half of the planet's population. In the coming decades, as the number of people increases even more, rice will play an even more critical role in feeding billions.
However, there are problems on the horizon for growing rice, warn researchers at Stanford University. One of the main causes of concern is climate change that could wreak havoc on the climate in the main rice producing regions, devastating productions.
The researchers' study, published in the journal Nature Communications, shows that by the end of the century rice yields could fall by as much as 39%. That, they say, "would have devastating consequences in parts of the world that depend on crops as a basic source of food."
Worse still: warming temperatures could trigger changes in the rice field soil, leading to an increase in arsenic in rice. In fact, they argue that in the future rice could contain twice as much toxic arsenic as it does today.
"Our findings indicate that climate-induced changes in soil arsenic behavior and plant response will lead to currently unforeseen losses in rice grain productivity and quality," the scientists write.
That's bad news because by the year 2100 there could be as many as 10 billion people on the planet, and half of them depend on rice as the main staple of their diet.
"It is very likely a problem where most of the rice is consumed, so we think of South and East Asia," observes Tianmei Wang, a doctoral candidate in Earth system sciences who co-authored the study. “Especially for people like my dad. He eats rice three times a day and he just can't live without it. "
Rice is grown in flooded paddy fields, which helps to release arsenic from the soil. Today's rice contains relatively small amounts of arsenic, but in some regions that content is higher and could soon rise.
Scientists discovered this by growing rice plants in greenhouses where they controlled the temperature. They found that marked increases in temperatures caused microorganisms in the soil to leach more arsenic that was already in the soil into the water from the growing rice fields.
This caused the plants to absorb more arsenic. When that happened, the arsenic prevented the rice plants from absorbing nutrients effectively, delaying their growth. In some scenarios, returns decreased by as much as 40%.
"Future changes in the soil due to higher temperatures combined with flood conditions cause rice plants to absorb arsenic at higher levels, and the use of irrigation water with naturally high arsenic compounds the problem," explains the University of Stanford in an article on the findings. "While these factors will not affect all global commodities in the same way, they extend to other flood crops, such as taro and lotus."
Arsenic is a semi-metallic chemical that occurs naturally in soils and sediments. In smaller amounts, its harmless but prolonged exposure can lead to a variety of adverse health conditions, including cancer. Babies and children are especially at risk.
"I think this problem is also crucial for people who have young children in our society," says E. Marie Muehe, a former postdoctoral fellow at Stanford University who was the lead author of the study. "Because babies are so much smaller than us, if they eat rice, that means they absorb more arsenic in relation to their body weight."
To avoid a dramatic drop in rice yields in the coming decades, we will need to keep global temperature increases in check by reducing our emissions. We can also embrace a changing climate by growing hardier varieties of rice, experts say.
Source: https://www.sustainability-times.com/ (article in English)