ABSTRACT
Seed germination tests on 374 wheat varieties from various regions of China indicated that dormancy characteristics among varieties differed markedly, varying from non-dormancy to a dormancy period of 7 or more weeks. Seed dormancy was generally associated with red seed coat. However, a few stable dormant types with white seed coats were found. Dormancy and red seed coat were ecological characters of those indigenous varieties which were adapted to the southern winter wheat regions and north-eastern spring wheat region with heavy precipitation during ripening stage.
Reciprocal differences in four sets of crosses between two dormant parents and two non-dormant parents showed the presence of maternal effect. The observed F2 segregation data from these crosses showed that dormancy was not simply inherited. The paucity of dormant types with white seed coat confirmed the conclusion that there were several other genes for dormancy not associated with red seed coat. Among various mechanical treatments applied to the dormant seeds, tearing off the seed coat over the embryo was the most effective in breaking dormancy. This implied that the seed coat is a source of germination inhibitor(s) and/or a barrier to the leaching of inhibitor(s).
Investigations on germinability during grain development in 31 cultivars and lines indicated that germination in the spike was significantly correlated with isolated grain at each stage. There were significant varietal differences in germinability at various grain development stages, but the heritabilities were relatively low.
A preliminary study involving 15 cultivars indicated that varietal differences in endogenous ABA level and 409falling number were significant, yet their correlations with germinability were insignificant.
