Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 6, 2000
Publication Date: N/A
Technical Abstract: Good stand establishment is critical to high crop yields. In rice, uniform and rapid emergence also improves grain quality and reduces water needs. Unfortunately, semidwarf cultivars are generally less vigorous than tall ones. This association is due to undesirable linkage associated with universally used sd1 gene. This study identified QTLs associated with components of seedling vigor relevant to direct-seeded semidwarf rice produced in the semi-tropical conditions of southern USA. A population of 259 RILs derived from Lemont x Teqing (two tropical sd1 cultivars) was evaluated for seedling vigor under field and laboratory conditions. Interval analysis using 175 RFLP loci and three years of plot data revealed five QTLs for field emergence. Component trait analysis enhanced QTL mapping by locating these five plus 15 additional loci associated with rice seedling vigor. Two QTLs were associated with seed germination, four with shoot length, four with root length, three with mesocotyl length, eight with coleoptile length, and four for emergence through deep soil. Complementary gene action between one mesocotyl QTL located on chromosome 7 and another near the sd1 gene on chromosome 1 resulted in mesocotyl lengths and emergence rates up to four times greater than either parent. Selected progeny lines and the linked markers identified herein can be used by breeders to develop vigorous semidwarf cultivars.