The Application of Ooubled Haploid Plants to Population ... - MSpace

4.14
importance of the time between anthesis and mahirity by intmducing genes for early
flowefing into a B. napus line and a 8. rapa population. Thurling (1991) concluded that
the earlier flowefing resulted in a longer period of dry matter accumulation and greater
seed yields. The later Rowering did not adversely affêct the performance of the
composite populations in this study with the exception of the Reward Ct4 which was
later flowering in Cannan. There was a positive correlation between days to Rowering
and seed yield for the Reward C, population in Carman (Table 4.8). A negative
correlation between days to flowering and seed yield was found with the Reward and
DSC-3 DH lines and DSC-3 C, and C, populations in Cannan (Table 4.8).
CONCLUSION
The production of composite populations from DH lines has the potential of
speeding up cultivar devalopment. As a breeding tool, irnprovements can be made in
B. rapa populations by selecting OH lines with fixed traits followed by randorn
interpollination to recover pertomance. This method avoids the short comings of
traditional breeding systems such as the time required for repeated generations of
inbreeding and selection seen with mass selection, the difficulty in producing a reliable
pollination control system for hybrid production and the maintenance of original entries
for reconstitution of a population as a synthetic.
The individual DH lines do not exceed donor population performance but, when
crossed to establish a composite, population performance can be recovered. This