In a blow to opponents of genetically modified crops worldwide, India approved commercial production of some GM versions of cotton yesterday. Up till now, the country, the world’s third largest producer of cotton, allowed only a few field trials of genetically engineered crops. But times are changing. In recent years, Monsanto bought several of the country’s largest seed companies and lobbied the Indian government to okay commercial use of GM crops. Proponents of GM cotton say it cuts in half the amount of insecticides needed to control pests and increases yields by up to 30 percent. Environmentalists, advocates for small farmers, and many academics, however, discouraged the country from approving the technology, arguing that not enough was known about its environmental implications. Opponents also fear that purchasing GM seeds could push family farmers even deeper into debt and eventually off the land.