Crop evolution, adaptation, and yield

The efforts of countless agriculturalists over the past ten thousand years have led to the improvement of a wide range of agricultural crops. In this major new work, Lloyd Evans provides an integrated view of their domestication, adaptation and improvement, bringing together genetic diversity, plant breeding, physiology and aspects of agronomy. Considerations of yield and maximum yield provide continuity throughout the book. Food, feed, libre, fuel and pharmaceutical crops are all discussed. Cereals, grain legumes and root crops, both temperate and tropical, provide many of the examples, but pasture plants, oilseeds, leafy crops, fruit trees and others are also considered. The introductory chapter traverses the overall argument linking those that follow. The increasing significance of crop yields to the world's food supply is then highlighted. The next three chapters consider changes to crop plants over the past ten thousand years. First there are those conferring adaptedness to cultivation, through the process of domestication. Then there are those required for adaptation to different environments as the domesticated crops spread around the world. Finally there are those changes involved in the improvement of yield potential. These are treated at length because their nature is often misunderstood, yet has important implications for the relation between plant breeding and agronomy, for development policy and for environmental management. Trends in yield from early times to the present day are then considered, along with the scope for, and constraints on, further increases. The crucial roles of input innovation and synergism are illustrated, along with examples of how diminishing returns to input energy have been avoided. The final chapter on the future of yield hazards some guesses about the way in which agriculture may be transformed over the next fifty years. Although aimed at research workers and advanced students in crop physiology and ecology, agronomy and plant breeding, this book reaches conclusions of relevance to those concerned with developmental policy, agricultural research and management, environmental quality, resource depletion and human history.