Prime Minister Manmohan Singh on Thursday said transformation of the agricultural sector should be the top priority of the country's public policies including those on science and technology.

He also said that complex issues related to genetically modified food, nuclear energy or the exploration of outer space cannot be settled by faith, emotion and fear, but by a structured debate.

"Nearly 65 per cent of our people live in rural areas. The 12th Five Year Plan assumes that a sustained growth in agriculture at the rate of four per cent per annum is essential to achieve food security," Singh told the centenary session of Indian Science Congress here.

"This transformation of the agriculture sector must be the top priority concern of our public policies, including science and technology policies," Singh said.

Noting growth was constrained by shortage of water and land, he said, "We need new breakthroughs in water-saving technologies in cultivation, enhancement of land productivity and development of climate-resilient varieties".

Releasing the country's Science, Technology and Innovation Policy 2013, the Prime Minister said, "India aspires to be among the top five global scientific powers by 2020".

He said development in science and technology had been central to the phenomenal material advancement and efficiency in the use of resources.

"As India seeks a sustained growth in national income, we must endeavour to harness the tools of science and technology to cater to the needs of the underprivileged and to bridge the gap between have and have-nots," Singh said.

The Prime Minister also called upon the younger generation to adopt science-based value system in order to benefit from what the discipline could offer.