A double blow is coming for the opponents of genetically modified (GM) foods, from two of the world's big farming nations. China, where many farmers already grow GM cotton, is likely soon to authorise commercial growing of GM rice. And Brazil is close to setting up a mechanism that could legalise all GM crops.

Brazil's farmers already plant lots of GM soya, especially in the far south where seed is easily smuggled in from Argentina. In theory this is illegal. But last month, well after planting had begun, it was authorised by presidential decree, as happened last year. The government knows it cannot enforce current law, and would face trouble if it tried. Instead, a bill to regulate GM crops has already passed the Senate and is now back with the Chamber of Deputies. These latter are not hurrying, since the bill also covers human stem-cell research, a far more contentious issue. But few doubt it will be passed. And because the GM regulators will be named by the ministry of science, their hand will probably be light.

The effects could be significant. Brazil is the world's second-largest grower of soya after the United States (where nearly all soya is GM). Brazil expects a huge soya crop, maybe 60m tonnes, in the new season, and up to a third could be GM. With long-term legality assured, that proportion might rise fast-and future harvests with it: the GM seed, derived from Monsanto's herbicide-resistant variety, does not in itself raise yields, but it does cut costs, making soya more attractive to plant.

Soya traders in Brazil face an opportunity and a problem. They will probably have more to export, and it will be welcomed by some markets. But new European Union rules require GM and non-GM crops, even if destined only for cattle-feed, to be kept strictly apart. The big traders, multinationals such as Bunge and Cargill, say this can be done, at a price. But many others have doubts, given Brazil's huge number of growers and the long supply chain. At best, it will be costly.

Such an obstacle to trade has given GM's foes one big victory this year: Monsanto stopped trying to sell a GM wheat, because North American farmers feared a loss of exports, both to Europe and Japan. But Chinese backers of an approval for GM rice turn that argument on its head.

Global trade in rice is small: only about 25m of the 400m-odd tonnes (in milled-rice terms) that the world produces. And China's share is tiny: it grows nearly 30% of the world crop, but trades only 1m tonnes or so each way. So why worry, ask its GM scientists? China stopped growing GM tobacco a few years ago, for trade reasons. But if Japan and South Korea, its main rice-export markets, object to GM, so be it, say GM's backers: nearly all of China's growers and all its consumers will benefit.

China's rice bowl

Technically, China is well prepared. Its scientists have been developing GM rice varieties-mainly pest-resistant, but also herbicide- or disease-resistant-for years. And for three years now they have conducted "pre-production" trials, giving the new seeds to many farmers in diverse areas and leaving them to get on with it. So far, says Jikun Huang, director of the Centre for Chinese Agricultural Policy, the trials show pesticide use down by 80% and yields 4-8% up. The scientists are also conducting their own regional trials in Hubei and Fujian provinces, partly as a check on the farmers' results. The new harvest is just in, and if all has gone well, the scientists argue, why wait for still more trials?

A go-ahead is not certain. China's environmental-protection agency shares the standard doubts about GM; and in today's China, even unofficial environmental campaigners are not negligible. Greenpeace has been campaigning among farmers in Yunnan province against the new rice. And some agriculture-ministry officials see the present ban on it as a useful protectionist tool. Yet China's biosafety committee, due to meet soon, looks likely to say yes. One reason is the health of farmers themselves: in China, crop-spraying is not as safe as in richer countries. And consumers know and fear the risk from pesticide residues. Overall, Mr Huang says, a consumer survey done for his centre found 80% ready, at equal prices, to buy GM rice. Greenpeace offers a less creditable reason: some scientists on the committee, it says, have interests in firms set up by their institutes to develop GM varieties.

If the committee says yes, the final government decision would probably be the same. At which point, enter Monsanto? It would have the incentive. The new GM rice is all hybrid, so seeds can not be saved from one harvest to sow for the next (unlike GM cotton, whose Monsanto variety is widespread in China, but brings Monsanto few follow-on sales there). And all China's maize is hybrid, and much of its non-GM rice; so farmers are accustomed to buying fresh seed. Yet, in rice, China's scientists are ahead of Monsanto's.

The big effects could come in another way, argues Scott Rozelle, an economist at the University of California who has worked closely with Mr Huang. India's farmers, once they were allowed to do so, rushed to sow GM cotton. And India's scientists have plenty of biotech-rice skills. If its government, fearful of lagging behind China again, were to set both boffins and farmers free, India also might rush into GM rice. Brazil too, maybe: its new law will not apply only to soya. So quite soon big new rice supplies might be available for export-and the genie of GM food truly out of the bottle.