Manipulating photosynthetic metabolism to improve crops: an inversion of ends and means

Abstract

Abstract The manipulation of photosynthetic carbon metabolism to bring about crop improvement or increased crop productivity is discussed against the background of population increase and an increasing tendency to favour investigations perceived to be of immediate practical advantage rather than supporting research of a more fundamental nature. The feasibility of improving productivity at a rate capable of matching the current daily increase in population of approximately 350 000 is considered and thought is given to the consequences of achieving that goal. Some environmental and intrinsic factors which are known to constrain photosynthesis are examined and it is proposed that, whereas there is no reasonable possibility of increasing quantum efficiency, there are many aspects of photosynthesis which are worthy of investigation in their own right and that these, if subjected to further investigation of a fundamental nature, could result in improvements in ‘efficiency’ in the wider sense of the word. It is concluded, nevertheless, that the greatest limitation on global agriculture is not water, temperature, pests or disease, but the cost and availability of fossil fuels, and that this fact should be kept uppermost when defining priorities in the light of future scenarios in which fossil fuel reserves are bound to dwindle more and more quickly during a period of massive population increase.