[Problems and outlook for plant production]

Environmental damages due to very intensive cropping systems do exist. A lot of people think it is necessary to prohibit the use of chemical fertilizers and pesticides, as well as in developed and developing countries. If so, global production would dramatically decrease while human population is increasing. The objective of feeding population of the world could not be met, particularly in Africa. On the other hand, crop modelling shows that theoretical potential plant production in the world is sufficient, if environmental damages are avoided. Future challenge is double: increasing food production and protecting the environment. Different ways to achieve this goal are analyzed. Increasing food production only in developed countries is environmentally and economically not practicable because of high cost and social damages in developing countries. Each country has to increase its own production, particularly in the South. But adopting the very intensive cropping systems existing in the North is not possible. The challenge is to be able to increase crop production in each place, taking into account biophysical, sociological, economical and political peculiarities. In some places, existing extensive cropping systems cause damages to the environment, because population pressure lead to increase cultivated areas, consequently reducing follow and pasture of forest areas: these systems are not sustainable if not intensified. In other places, even in the South, water pollution results from excessive use of fertilizers and pesticides. A new paradigm is proposed to take into account this great diversity of situations: the "Doubly Green Revolution" will allow to define adapted and sustainable cropping systems. Scientific results obtained along last century and including recent results in biotechnology, will be at the basis of these new systems.