Expression of dormancy in a spring wheat cross grown in field and controlled environment conditions

Pre-harvest sprouting resistance in white-seeded wheat, Triticum aestivum L. is a genetically complex trait that varies with environmental conditions. Such variation causes difficulty in phenotypic characterization of populations to study inheritance or develop suitable DNA markers. To minimize random environmental effects, we evaluated controlled environments to measure dormancy. A population of 380 doubled haploid lines, AC Karma/SC8021V2, was evaluated in the glasshouse where the developing grains would not be exposed to moisture and greater consistency in temperature could be achieved. AC Karma is sprouting susceptible and SC8021-V2 is sprouting resistant. The population plus eight checks were seeded in early spring so the plants would reach physiological maturity under long days, requiring less supplemental light, and when the external temperature would be low enough that it would not cause difficulty in cooling the glasshouse. An alpha-lattice in a randomized complete block design with three replications was used. The blocks were arranged to minimize the environmental sources of variability in the glasshouse within each block. A sub-set of this population was tested in six field environments. Dormancy was characterized by germination of seed harvested near physiological maturity, from which a germination resistance index was calculated. The dormancy expressed in the glasshouse was significantly correlated with five of six field environments and highly significant in two of these. There was significant bidirectional transgressive segregation in both field and glasshouse environments. We are currently repeating this glasshouse experiment to confirm the results.