The biggest environmental summit for a decade must make meaningful progress on global food security and sustainable agriculture, say researchers.
CGIAR, the world's largest publicly funded research body, has published a seven-point "call to action" plan.
Ahead of the Rio gathering, scientists are calling for an improved commitment to deliver nutrition security and lessen the need to aid.
Agriculture is estimated to provide jobs for 40% of the world's population.
In its statement, CGIAR said: "Faced with environmental degradation, climate change... and a world population that is continuing to climb, it is critical for farm and natural resources management and policies to play a more central role in shaping the broader development and environmental agendas."
The organisations listed a seven-point "call to action" list , which they will present at the gathering in the Brazilian city, including:
- Improved partnerships to maximise the management of agriculture, aquaculture, forest and water resources;
- need to address unequal sharing of natural resources via better governance and dissemination of technology;
- support for a knowledge sharing system to improve production and minimise adverse impacts;
- adopting measures to restore degraded environments and ecosystems.
"One reason why it is necessary to push attention on to agriculture in Rio is because negotiations are going really slowly," explained CGIAR spokesman Bruce Campbell.
"We thought it was really important to put the focus on agriculture in Rio, and the 15 research organisations have come together in order to form a consortium and speak with one voice for the first time."
Dr Campbell added that the agencies were calling on the negotiators to reaffirm the role of science and technology.
"We are also looking for an improvement between the links between policy and science so then scientists are so much more linked into the processes that matter," he said.
The Rio+20 Conference , formally known as the UN Conference on Sustainable Development (UNCSD), will take place in Brazil on 20-22 June 2012.
The summit marks the 20th anniversary of the 1992 United Nations Conference on Environment and Development (UNCED), which was also held in Rio de Janeiro, and the 10th anniversary of the 2002 World Summit on Sustainable Development (WSSD) in Johannesburg, South Africa.
Organisers say that the conference will focus on two themes: a green economy in the context of sustainable development poverty eradication; and the institutional framework for sustainable development.
Seven priority areas have also been identified, including: decent jobs, energy, sustainable cities, food security and sustainable agriculture, water, oceans and disaster readiness.
Heads of states from more than 100 nations are expected to attend the summit.