Genetic variation of seed dormancy in tetraploid wheat species
In western Canada, durum wheat cultivars (Triticum turgidum L. Var durum) have low to moderate levels of seed dormancy and are susceptible to pre-harvest sprouting .The objective of this study was to assess the level of seed dormancy and the length of after ripening in diverse tetraploid wheat species. The plants were grown under field conditions, spikes harvested at Zadok’s Growth Stage 92 (ZGS92), dried for one week and stored in a freezer at -20 “C .In 1995 and 1996, length of after ripening was assessed in 17 durum cultivars and three common hexaploid wheats over a period of seven weeks . Most durum cultivars showed little or no dormancy at ZGS92 . Kyle was the only cultivar that exhibited some seed dormancy. On average, all cultivars but the hexaploid line RL4137 lost dormancy in a markedly similar pattern. Four species , Triticum turgidurn, T. turanicum, T. carthlicum and T. polonicum obtained from the USDA wheat collection were screened for seed dormancy over a two year period. Averaged over years, accessions ranged from 2% to 100% in germination .The accessions in this experiment can be grouped into four classes: non-dormant, slightly dormant, moderately dormant and highly dormant. With the exception of turanicum, the tetraploid species contained highly dormant genotypes . The 10 most dormant wheat accessions were evaluated for length of after ripening. A number of accessions with higher levels of seed dormancy than the durum cultivar Kyle was identified.
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