A Study of Survival in a Mixture of Fourteen Varieties of Wheat

Intergenotypic competition over six years among fourteen varieties of wheat, belonging to eleven species, as measured by percentage of survival in successive generations of mixed growing, has been studied. No consistent association existed between survival ability and a number of morphological and agronomic characters. The main factor which determined the degree of survival of any variety appeared to be its reproductive ability, i.e., its relative productivity and the capacity of the seeds so produced to reach the reproductive stage in the succeeding generation. No marked varietal differences were, however, noted with regard to mortality in the pre-reproductive stage. Rust epidemics occurred during two of the experimental years and could have been partly responsible for the sharp fall in the frequency, or complete elimination, of susceptible varieties within one or two generations. It has been suggested that less competitive varieties may suffer a decrease with regard to some of the components of productivity when grown in a mixture with more competitive varieties and, therefore, have less survival value in such mixtures. The possible agronomic importance of greater competitive ability has been pointed out.