Modified rice may help combat China’s smog problem, scientists claim

Mainland scientists claim to have found a way to change the genetic make-up of a popular type of rice, which could require less fertiliser and thus help the environment.

Chinese rice, especially the japonica subspecies  grown in northern provinces like Heilongjiang  province, requires the heavy use of fertilisers because of the poor rate at which it absorbs nitride from soil and water. Plants need nitride to grow healthily.

But the fertiliser harms the soil, water and air – several studies have tied the nation’s smog levels to nitrogen fertilisers.

When nitric oxides are released into the atmosphere, they undergo a series of photochemical reactions that transform them into harmful fine particulates, which in turn become smog.

Although it has just 7 per cent of the world’s farmland, the mainland consumes 35 per cent of its nitrogen fertilisers. But it has been difficult to persuade farmers to scale back their use.

Scientists claim to have made headway against the problem.

A team led by Professor Chu Chengcai  at the Chinese Academy of Sciences’ Institute of Genetics and Developmental Biology  in Beijing, claims to have boosted the rate at which the japonica variety can absorb nitride by more than a third. The higher absorption was made possible by cloning a gene called NRT1 from Indica rice.

Their research was published in the latest issue of the journal Nature Genetics.

The transplantation of the nitric booster gene “had significantly improved grain yield and nitrogen use efficiency”, the team said, adding the discovery would have “enormous application value” in the fight against nitrogen pollution.

The breakthrough was hailed as “a great discovery” by an anonymous peer reviewer.

During a series of field experiments in Beijing, Shanghai and Changsha  in Hunan  province, the team found that the modified rice species needed only half as much fertiliser to achieve similarly high grain yields as regular japonica.

Indica belongs to the same family as japonica but is grown mostly in southern China as well as in tropical regions like Thailand and the Philippines, and in India.

Indica absorbs nitrogen more easily than its northern cousin. Yet its area of cultivation is limited because it cannot survive in northern China’s cold climate, despite this region serving as the country’s largest rice production centre. Moreover, Chinese consumers prefer the rich and sticky taste of japonica.

In their paper, the scientists said the discovery also represented an important milestone for the “green super rice project”, an international effort to develop new species of rice to meet the growing global demand for food resources.