|Abstract or Summary
- Concerns about the possible reciprocal differences resulting from
systematic crossings of winter and spring wheat gene pools prompted
this investigation. If traits can be improved by simply reversing the
direction of a cross, then identification of the best female parent in
a cross would be helpful for breeding programs.
Two reciprocal winter by spring wheat crosses and one reciprocal
winter by winter wheat cross were studied under greenhouse conditions.
These three populations, coupled with two additional winter x spring
crosses were also evaluated in the field. Data were collected on an
individual plant basis for heading and physiological maturity date,
plant height, tiller number, kernels per spike, 100 kernel weight and
grain yield in the greenhouse. Information on anthesis date was also
obtained for the material grown in the field.
Overall responses for the traits measured from winter by spring
crosses gave little evidence to suggest the widespread occurrence of
reciprocal F₁ differences; however, Yamhill/Anza and Yamhill/Siete
Cerros produced a relatively high number of reciprocal differences for
several traits compared to the other crosses.
Direction of the reciprocal cross was important in obtaining
maximum F₁ expression for specific traits. In the Yamhill x Anza F₁, maximum expression of tiller number and grain yield per plant was
obtained while in the Siete Cerros x Yamhill F₁ later heading and
anthesis dates and greater 100 kernel weight were observed. No
relationship was found in the studies relating the magnitude of
parental difference to the occurrence of reciprocal F₁ differences.
Response among the F₁ population for unidirectional
heterobeltiosis was insufficient to identify a pattern of occurrence.
Heterobeltiosis did occur for only one of the reciprocal F₁s for
anthesis date, tiller number, kernels per spike, 100 kernel weight,
and yield in five out of the six crosses grown in the field.
Although there were no consistant patterns for reciprocal F₁
differences for the populations evaluated, observations made suggest
there are some relationships between the occurrence of reciprocal F₁
differences and the use of specific cultivars in a cross.