The Chinese government unveiled new regulations yesterday for genetically engineered foods that they hope will make the use of the technology more widespread. Genetically engineered cotton, soybeans, rice, potatoes, and other crops are already commonly planted in the country. Among other things, the rules require that genetically engineered foods be clearly labeled on packages. Chinese leaders are faced with the problem of feeding 1.3 billion people even as arable land in the country is shrinking due to desertification and many farmers are giving up the agricultural life and moving to the city.