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Title: REGISTRATION OF FC724 MONOGERM, O-TYPE, SUGARBEET GERMPLASM.

Author
item Panella, Leonard
item Hanson, Linda

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2003
Publication Date: 2/15/2004
Citation: Panella, L.W., Hanson, L.E. 2004. Registration of FC724 Monogerm, O-Type, Sugarbeet Germplasm. Crop Science 44(1):361-362. 2004.

Interpretive Summary: FC724 has high resistance to root-rotting strains (AG-2-2) of Rhizoctonia solani Kühn and good to moderate resistance to cercospora leaf spot caused by Cercospora beticola Sacc., but is curly top susceptible. FC724 is an attempt to develop a population from which to select Rhizoctonia resistant monogerm O-type parents to infuse some rhizoctonia resistance on the female side of hybrids. There is no CMS equivalent. FC724 is released from seed production 961014. The average sucrose concentration and sugar loss to molasses of three commercial varieties - Beta 6045, HM1955, Monohikari - was used as a standard for comparison. Sucrose concentration of FC724 was 96.3% of the standard, and in sugar loss to molasses, FC724 was 97.9% of the standard.

Technical Abstract: Technical Abstract FC724 is an O-type germplasm with 12% green hypocotyls (116 plants counted) and is segregating for monogerm (mm). It is a product of 9 generations of cyclic mass selection for resistance to rhizoctonia root rot and 2 cycles of recurrent selection for high general combining ability. It originated from a cross of FC702 by selfed progeny lines from FC601/2 and selfed progeny lines from several leaf spot and the beet curly top virus (BCTV) resistant lines combined in 611100-0 (SLC122-0, US22/3,US201, US22/4 [SL92], SL202 [F2 of US35/2 x US22/4]). FC601/2 consists of selected progeny lines from SL202 x SLC122-0. The original cross was approximately 20% 611100-0, 17% FC 601/2 and 63% FC702. Because the original crosses were made to male sterile plants (genetic male sterility - aa), it is possible that FC724 is segregating for genetic male sterility, but no male sterile plants were observed in the last seed production (961014). Hybrid tester lines were produced with Fort Collins breeding lines to test for general combining ability in 1974 and 1977. Remnant, selfed seed from superior lines was recombined after each cycle of testing. The population has gone through nine cycles of selection in the USDA-ARS rhizoctonia nursery in Fort Collins, has been O-type indexed to remove restorer genes, and has been selected for monogerm seed throughout the development process. The smallest population size was 19 plants. FC724 exhibited excellent resistance to rhizoctonia root rot, and its performance was not significantly different from the highly resistant check in disease index ratings from 1998 through 2001. FC724 performed significantly better than the susceptible check. In 2 years of testing for cercospora leaf spot resistance, FC724 was significantly better than the susceptible check and not significantly different from the resistant check in 1 year but had significantly less resistance than the resistant check in the other. When the average sucrose concentration and sugar loss to molasses of three commercial varieties - Beta 6045, HM1955, Monohikari - was used as a standard for comparison, sucrose concentration of FC724 was 96.3% of the standard, and in sugar loss to molasses, it was 97.9% of the standard.