The Application of Physiological and Molecular Understanding of the Effects of the Environment on Photosynthesis in the Selection of Novel “Fuel” Crops; With Particular Reference to C4 Perennials

Fuel crops offer a solution to two major problems confronting W. Europe on the threshold of a new century: gainful use of excess agricultural land and a decreased dependence on fossil fuels. Success with both problems will depend on the choice, selection and improvement of potential fuel crops. This will require a major change in approaches to crop improvement. Key goals will be maximizing efficiency of energy conversion but decreasing inputs of nitrogen and pesticides. Because most of the plant represents economic yield, in a fuel as opposed to a food crop, the benefits of increasing photosynthetic productivity in these crops are direct and represent the major challenge in application of physiology to improvement. A specification for an “ideal” fuel crop for W. Europe is developed and shown to correspond most closely to the characteristics of C4 herbaceous perennial plants. Despite the high potential photosynthetic capacity attributed to C4 species, yields are limited both by slow canopy development and low temperature impairment of the photosynthetic apparatus. A mechanistic model is used to assess the quantitative significance of these two limitations, both are shown to account for very significant losses in potential yield and suggest the areas in which improvement could provide the greatest returns.