Inter-genotypic plant competition in wheat under single seed descent breeding

Summary The effects of inter-genotypic competition were studied in wheat under conditions of single seed descent in the glasshouse. Four genotypes were grown mixed in diallelic combinations of two, making six mixtures and four component (pure) stands. It was found that genotypic differences in most cases over-rode initial effects of phenotypic differences in seed size, and played a dominant role in determining what plants, if any, were eliminated from the mixtures.Low genotypic competitive ability accounted for 8 to 14% losses, in a single generation, in representation in the population through failure to produce at least one fertile tiller. Howerver, under single seed descent where artificial selection assures retention if even only one seed is produced, the loss of weak competitors was slower than it might have been under natural selection in the field.