What priorities for improved agricultural technology?

With world population still rising, and the rate of growth of yields of cereal crops falling, there is a strong case for renewed investment in agricultural technology. But what are the priorities and issues? Further intensification using bio-technology? Or do we need technology that may be more suitable to poor people in marginal environments, that makes less demands on external inputs? In either case, how will that technology be developed: through the public sector, private companies or some third way?