Meanwhile, the bill's supporters — mainly associations of large-scale farmers — are lobbying senators to back it.
At issue is the legal implementation in Chile of the latest version of the International Convention for the Protection of New Varieties of Plants (UPOV 91).
As a signatory to the 1978 version, Chile already protects plant breeders' rights, but campaigners claim that the new version of the convention suits commercial rather than conventional breeders.
"UPOV 91 extends the intellectual property rights of companies that produce seeds, thus increasing their monopoly over seed production and exchange," Iván Santandreu, co-founder of the NGO Chile without GMOs (genetically modified organisms), tells SciDev.Net.
"If UPOV 91 becomes law, it will become illegal for farmers to save and exchange seeds," he adds.
But Miguel Sánchez, executive director of ChileBIO, an association that represents agricultural biotechnology companies, says: "UPOV 91 allows a seed developer to charge a farmer for using any intellectually protected seed, even retroactively.
"But nobody forces this farmer to buy and use intellectually protected plant varieties. If he does, it is because he believes the protected seed will increase his yields."
Sánchez adds that campaigners' fears that UPOV 91 will not stop large firms from appropriating native vegetable species and varieties or their agricultural or medicinal uses are misplaced.
"A seed developer cannot claim intellectual property rights for a vegetable species such as maize. He can only do so if he has bred a maize variety that is new and distinct," Sánchez tells SciDev.Net.
“If UPOV 91 becomes law, it will become illegal for farmers to save and exchange seeds.”
Chile without GMOs
Another of the campaigners' concerns is that the proposed law would introduce GMOs into the country through the backdoor by allowing companies to register GM seeds (GMOs are banned in Chile).
"This allegation is wrong: UPOV 91 does not mention GMOs," Patricio Parodi, scientific advisor to the Ministry of Agriculture of Chile, tells SciDev.Net.
"Campaigners are conflating it with the bill on genetically modified plants, which has been stagnating in the National Congress since 2006. Only this law would make way for the general use of GMOs in Chile," he adds.
Santandreu replies that, while UPOV 91 may not mention GMOs by name, it refers to genetic improvement and defines this process as ranging from hybridisation to genetic engineering.
But the politicians, large farm owners and agricultural companies backing the bill argue that an agricultural exporter such as Chile needs solid intellectual property rights.
"We cannot be seen as a country that practises intellectual property piracy. Chile has signed many free trade agreements, including with the US and Japan, on the basis of reciprocal intellectual property rights," says Parodi.
José Antonio Poblete, commercial manager of the Fruit Nurseries Association of Chile, told the Constitutional Court last year: "If Chile does not adhere to UPOV 91, there will be no reward for all the efforts made by 12 new, state-backed genetic programmes that are developing new fruit varieties".
But anti-GMO campaigners remain unconvinced.
"We are waiting for the next significant development in Congress before we march again," Santandreu says.
Link to International Convention for the Protection of New Varieties of Plants