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

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ABSTRACT
Doubled haploid line (DH) development is a breeding tool that has been show
to speed up the progress of plant breeding by producing homozygous individuals in a
single generation. In the sporophytically self-incompatible Brasska rapa, the
production of DH plants results in the expression of inbreeding depression and
therefore diminishes their benefit.
This study investigated the improvements in the effkiency of OH applied to
population improvement in B. rapa. Methods were investigated to overcome selfincompatibility
in B. rapa, to improve agronomic peHonnance of OH Iines through the
production of composite populations and to identify genetic variation between DH lines.
Field studies on B. rapa cv. Reward determinad that 3 and 5 % NaCl solutions
as well as bud pollination were effective at overcoming self-incompatibility. The NaCl
solutions were found to be more efficient than bud pollination in overcoming selfincompatibility.
Composite populations were produced by random interpollination of 4, 8, 12 and
22 DH lines, developed from the B. rapa cv. Reward and the B. rapa breeding line
DSC-3, for two generations. Several agronomic parameters were measured at one
and two field locations for the DH lines and the composite populations, respectively.
lntercrossing as few as 4 DH lines from the breeding line DSC-3 and 8 DH lines from
the cv Reward improved population performance over that of the wntributing OH Iines.
The development of composite populations showed that DH lines have potential for