Fields of genetically modified crops will see rapid expansion in Brazil now that the Biosecurity Law, approved by Congress on Mar. 2, legalizes channels for pursuing this form of biotechnology. This is evident in the heightened competition between companies that develop seed varieties — especially soybeans. The government farm research agency EMBRAPA exhibited eight types of transgenic soy last week at a fair in the southern city of Nao-Me-Toque.

''They are especially for planting in southern Brazil'' and are very high-yield and resistent to pests, Paul Bertagnolli, an EMBRAPA soy improvement expert, told Tierramérica. Other genetically modified soy varieties have already been developed for other climates and ecosystems.

Farmers have shown ''enormous interest'', but it will be years before the authorized seeds conquer the market. Unfortunately, soybean growers ''have grown accustomed'' to the illegal transgenic seeds, smuggled in from Argentina and less productive and which brought in pests.