Morphological Changes Associated with Three Cycles of Recurrent Selection for Grain Yield Improvement in Oat1

Abstract

To assess the potential for improving grain yield via indirect morphological trait selection, the original and third cycle parents from a recurrent selection program for grain yield in oat (Avena sativa L.) were compared. Evaluation was based on hill plots grown in three field environments. This selection increased grain yield 13.5% and total dry matter 15.9%; thus, there was no increase in harvest index. All morphological structures measured increased in size. Grain yield was not closely or consistently related to any individual morphological trait, nor to the photosynthetic area of the flag leaf and panicle. Analysis of allometric relationships (the size of one plant structure relative to another) indicated that the size of morphological structures within a genotype tended to be proportional, but variability in allometric relationships was present. Therefore, selection for altered allometric relationships may be successful, but construction of an ideotype based on certain levels of expression of individual morphological traits, or photosynthetic areas, is not likely to be effective in increasing grain yield.