USE OF DIVERSE GERMPLASM FOR GENETIC IMPROVEMENT OF RICE
Location: Dale Bumpers National Rice Research Center
Title: The indica revolution. II. Improving Chinese germplasm for the U.S.
Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 1, 2006
Publication Date: February 15, 2006
Citation: Yan, W., Bryant, R.J., Gibbons, J.W., Lee, F.N., Bernhardt, L., Rutger, J.N. 2006. The indica revolution. II. Improving Chinese germplasm for the U.S. Rice Technical Working Group Meeting Proceedings, February 29-March 1, 2006, Houston, Texas. 2006 CDROM.
In the USDA rice collection, 85% of the Chinese accessions were introduced before 1977 when yield in China was 3.64 t ha-1 . Rice yield in China is almost double nowadays (6.27 t ha-1 in 2002). Hence, it is desirable to update Chinese germplasm in our collection and introduce advanced rice cultivars from China. Over 200 Chinese lines, mostly indicas, were introduced in 1996 in exchange for 50 U.S. cultivars. Indica lines GP-2, 4594, R 312, 4597, 4612, Taizhongxian 255, 4641 and Shufeng 121, were observed to have yield advantages from 20 to 40% over U.S. cultivars in 2000. However, they were either too high or too low in amylose content for the grain types, and most of them were tall and lodging susceptible. Line 4484 yielded the same as Francis in both 2002 and 2003, and 16% more than Francis in the 2004 URN. For example, it had a total grain yield (main + ratoon) of 12,500 kg ha-1 and ranked second after hybrid XL 8 in the 2004 Louisiana URN. In 2004 entry 4484-1693, selected from the M4 generation of 4484 seed irradiated at 300 Gy, was 10 cm shorter in height and 4% higher in amylose than the parent 4484. This change decreased lodging risk and made it a typical long grain in cooking quality while its yield potential was maintained. Molecular marker analysis revealed heterozygous alleles associated with amylose content in parent line 4484. Besides, 4484-1693 had broad spectrum blast resistance, 0 rate for all blast races including IB-33, IE-1K and BC3-1, the new races to which most cultivars having the Pi-ta resistance gene are susceptible.