Rice farmers in Japan will have to avoid planting in the soil contaminated by nuclear radiation, the government announced.

That is a particularly heavy blow to the battered Fukushima and Miyagi regions, both economically and culturally. Fukushima, where the troubled Dai-ichi plant is located, is a major producer of rice, totaling 450,000 tons of rice in 2010, making it the country's fourth-largest producing prefecture.

More symbolically, rice is the key ingredient in sake, the wildly popular tea for which the country is famous. The tradition of eating rice is so ingrained in Japanese culture that the word for cooked rice also means meal.

At the Fukushima Dai-ichi Nuclear Power Plant, workers reported success at plugging a leak that had resulted in contamination in soil and water. They also continued to pump nitrogen into the troubled Number 1 reactor, in an effort to prevent a hydrogen explosion similar to the one that wiped out the walls surrounding the reactor.

Power plant officials also announced that they would continue to pump mildly radioactive water into the Pacific Ocean, in an attempt to make room in the plant's storage tanks for even more radioactive water.

In response to the 7.1 aftershock, many stores returned to rationing of basic items, in the wake of another round of panic buying after the latest reminder of the March 11 9.0-magnitude earthquake and tsunami.

The death toll has passed 12,000, and another 16,000 people are still listed as missing. More than 150,000 people, their homes wiped out by the tsunami or off-limits because of the nuclear leakage, are still living in temporary shelters such as school gymnasiums.