Pre-harvest sprouting, dormancy and germination inhibitors in bracts of 50 diverse wheat genotypes

Fifty wheat genotypes have been sown in northwestern Croatia, in 1994/95 and 1995/96 in order to determine variation for pre-harvest sprouting susceptibility, dormancy and the presence of germination inhibitors in the bracts. 24 genotypes in 1995 and 20 genotypes in 1996 had the same level of sprouting resistance at physiological maturity as the sprouting resistant standard RL.4137. By comparison, a smaller number of genotypes were ranked equal to RL.4137 on the basis of the level of dormancy measured at 4 intervals after harvest. More genotypes appeared similar to RL.4137 on the third than after the seventh day of germination. Compared with RL.4137 large numbers of genotypes showed strong germination inhibition in the presence of bract extracts, especially in 1995. Differences in the sensitivity of seeds of different wheat genotypes to germination inhibitors from common sources of bract extracts were also observed.