SURVIVAL OF COMMON SPRING WHEAT CULTIVARS GROWN IN MIXTURES IN THREE ENVIRONMENTS

Abstract

Population shifts occurred in mixtures of six cultivars of common spring wheat (Triticum aestivum L.) grown for 6 or 7 yr in three different environments, nonirrigated, irrigated, and infested with the wheat stem sawfly (Cephus cinctus Nort.). On the nonirrigated site, ranking of cultivars was the same for percent survival in the mixture as for yield in pure stand. Rankings, with one exception, for average number of kernels per spike were similar to those for average yield and survival on the nonirrigated site. On the irrigated site, rankings for percent survival in the mixture and for yield in pure stand were similar except that one cultivar was at a disadvantage due to shorter height. Rankings for average kernel weight, again with one exception, were similar to rankings for survival on the irrigated site. On the sawfly-infested site, rankings for survival in the mixture were similar to those for yield in pure stand. On all three sites, the data support the contention that natural selection will increase the frequency of high-yielding plants in mixed population of spring wheat in southern Alberta.