Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)


Plant Science


Five diverse spring and five diverse winter wheat cultivars were crossed in all possible spring by winter combinations including their reciprocals to determine whether agronomic differences in reciprocal spring by winter crosses occur, and to determine the relative contribution of spring and winter parents to general and specific combining ability. Traits examined in the F1 generation in this greenhouse study included: 1) grain yield (g/plant) 2) number of spikelets per spike 3) total kernel weight (g) per spike 4) number of kernels per spike 5) number of tillers per plant 6) weight (g) of 100 kernels 7) length (mm) of flag leaf 8) width (mm) of flag iv leaf 9) peduncle length (cm) 11) number of days to heading, and 12) number of days to anthesis. Analysis of variance, Waller-Duncan t tests, and LSMEANS were used to analyze this data. Differences in reciprocals were found to occur for yield with significantly more yield occurring when the spring cultivar was used as the female. Cross specific reciprocal differences were found to occur in all traits. The extent to which the parents differed in particular traits was not related to the number of reciprocal differences observed. Some of these differences were environmentally sensitive. The winter parents were associated with the largest range in general combining ability for the majority of the traits in 1983 and 1985 and appeared to have a more profound effect on character performance than the spring parents. Greater diversity among the winter parents may have been the cause of this phenomena. Additive genetic variance, as measured by the ratio of pooled spring and winter means to spring by winter mean square interactions, was the major source of genetic variability in character performance. Specific combining ability, although significant for some traits, was not stable from year to year, indicating environmental sensitivity. There was no association between specific V vi combining ability and heterobeltiosis. Heritability estimates were generally high. Yield component traits, with the exception of number of spikelets per spike, were lower in heritability than other traits. Winter wheat parents introduced into a spring wheat breeding program offer the potential for increasing genetic diversity as well as having an important role in cross performance.

Library of Congress Subject Headings

Wheat -- Breeding
Wheat -- Genetics




South Dakota State University