Results of the first International Spring Wheat Yield Nursery 1964-1965

Abstract

Adaptation is perhaps the most elusive concept in plant breeding. Not only is there surprisingly little information concerning the performance of varieties over a broad range of environments in even the major crop plants, hut there is considerable confusion among plant breeders as to whether broad adaptation is desirable or not. Even in wheat, the most extensively seeded crop in the world, there is remarkably little systematic data concerning the adaptation of the major varietal types in different areas of the world. Adaptation in wheat can be considered from many points of view. It may be measured by e. g. flowering date, maturity date, resistance to important diseases or pests, winter survival and yield. Grain yield is the most comprehensive gauge of adaptation, but it is cumbersome to measure and influenced by many inter-related factors. Yield, however, is the most meaningful measure of adaptation in terms of world food needs. The United States Department of Agriculture's International Spring Wheat Rust Nursery has obtained a lot of very valuable information concerning resistance to pathogens throughout the world's important wheat regions. Disease losses can lower yields markedly, and if yield is to be used as the measure of adaptation, disease resistance plays a very important role. Disease is, however, only one of the factors affecting yield. Beginning in 1960 a series of Inter-American yield trials were conducted to test the main varieties of the hemisphere throughout the principal spring wheat regions of the Americas. The results of these nurseries ( 1, 2, 3, 8) indicated that certain varieties showed very wide adaptation while others - particularly the North American ones - were very poorly adapted outside their areas of origin. A parallel series of yield nurseries were run in cooperation with the Food and Agriculture Organization throughout the Near East. The results ( 4, 5, 7) were quite similar to those from the Inter-American series, and many of the same varieties, such as Pitic 62, were high yielding in both sets. It was therefore <iecided to combine these into a single International Spring Wheat Yield Nursery in order to study adaptation wherever spring wheat is grown. This report- covers the first of these combined nurseries.