BUENOS AIRES - Scientists from Argentina's Universidad del Litoral have isolated a gene that, once introduced into the sunflower, helps this crop tolerate extreme drought.

Researchers from the university's cellular and molecular biology laboratory made the discovery after working on the project for several years.

Raquel Chan, the program's co-director, told Tierramérica that they first isolated a gene that proved effective in unfavorable environmental conditions, particularly under ''hydric stress'', or water deficiency.

Fellow researcher Daniel González said that by introducing this resistant gene into a sunflower plant -- using biotechnology and under experimental conditions -- they created a transgenic organism that may one day be used in commercial farm production.

BOGOTA - Nine Colombian flower-growing companies received ''Florverde'' certification from SGS (Société Générale de Surveillance, an international quality and testing company), for their contributions to protecting the environment and improving the working conditions of their employees.

The companies, members of Asocolflores, the Colombian association of flower exporters, are La Valvanera, Rosas Colombianas, Industrias Agrícolas Megaflor, Flores Jaivaná, Agrícola Cunday, The Elite Flower, Flores de Bojacá, Flores Las Acacias and Mountain Roses.

Asocolflores said that in granting the certificates SGS took into account the firms' compliance with best business practices in managing personnel, health and working conditions.

The society also evaluated farming practices related to use of water and soil, the reduction of agro-chemical application and responsible management of chemical waste, among other factors.

MEXICO CITY - The environmental watchdog group Greenpeace will exhaust its legal options to force the Mexican government to release a report on contamination of traditional corn crops with pollen from genetically modified maize. The study was prepared by the North American Commission for Environmental Cooperation (CEC).

The study has been ready since June, but because it contradicts the position of the U.S. transnational corporations that promote transgenic crops it has not been released, Areli Carrión, Greenpeace-Mexico's consumers campaign coordinator, told Tierramérica.

The CEC said it did not receive the report until Sep. 13. Work on the study began in 2002, and it has 60 days to be presented to the Council, comprising the governments of Canada, Mexico and the United States, which decides if it will be made public.

Carrión said Greenpeace will use Mexico's transparency laws to obtain the study's release. If that doesn't work, the group will turn to international law.

LIMA - The contamination of the Rímac River, which supplies water to the Peruvian capital, can be reversed by running it through a tube of at least 70 km, says engineer Nicolás Morales in a proposal to the authorities.

''The water that Lima consumes starts out pure, sterilized by the high ultraviolet rays in the mountains more than 4,000 meters above sea level, but it reaches the city contaminated by run-off from towns and the liquid waste of 175 mining and industrial companies along its 110-km route,'' Morales explained to Tierramérica.

Currently, water in Lima is treated with chemicals and through sedimentation, processes that ''clarify the liquid but don't totally decontaminate it,'' said the engineer, an expert in industrial materials and toxicology.

Running the river through a duct two meters in diameter ''will have a relatively high cost, but would reduce water treatment costs and, furthermore, would help conserve water, because currently 50 percent of it is lost through filtration and evaporation along the course of the river,'' he said.

GUATEMALA CITY - The aquifers that provide water to around two million people in the Guatemalan capital are running dry, say assessors from Empagua, the municipal water agency.

''Forty years ago we found water at 600 feet underground, but now we have to dig to 1,700 feet to develop the Empagua wells,'' Carlos Quezada, the city's water advisor, told Tierramérica.

''In addition to that problem is climate variability. In recent years we have seen extended summers and winters in which it has rained a great deal but over short periods, and only in certain places, which does not recharge the aquifers,'' he said.

Julio Escoto, director of Empagua's project execution unit, said in a Tierramérica interview that ''in the valley of the capital the areas of rainwater filtration (into the aquifers) have been reduced while exploitation of water has increased.''

''In the city there is an upper and a lower aquifer. The first has already been exhausted, and we are now using the second,'' Escoto said.