Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: April 21, 2001
Publication Date: February 8, 2002
Citation: Foley, M.E., Gu, X-Y. 2002. Genetics of seed covering-imposed dormancy in weedy rice. [Abstract]. Weed Science Society of America Meeting. 42:20.
We characterized the inheritance of seed dormancy in selected strains of weedy rice (Oryza sativa). Dormant lines, including three weedy strains LD, SS18-2 and TKN12-2, and a domesticated cultivar N22, were crossed with non-dormant cultivars to generate F1 and F2 generations. Germinability of intact seeds, caryopses, pericarp/testa-removed caryopses, and excised embryos was determined by germination at 30 C for 7 d. Dormancy was imposed mainly by the hull in SS18-2 and TKN12-2 and by both the hull and pericarp/testa in LD and N22. Dormancy with non- afterripened seeds in weedy strains is completely dominant and the mean degree of dominance decreased slowly with afterripening. The maximum genetic variance in all F2 populations occurred at about 20 d after harvest (DAH). The weedy rice-derived populations maintained a higher heritability (h2b > 80%) during afterripening. The F2 distributions for germination at different DAH suggest that dormancy with intact seeds is regulated by major genes and polygenes, and that more genes are involved in the genetic control at the earlier stages of afterripening. Pericarp/testa-imposed dormancy is partially dominant in the F1 generation and has a low heritability (h2b ~50%) in F2 populations. A 3/13 segregation ratio in the CO39/SS18-2 F2 population suggests the effect of at least two genes with larger effect on pericarp/testa- imposed dormancy. A significant correlation (r = 0.18* to 0.23**) between the caryopsis germination at 0 DAH and the seed germination at 0 to 30 or 40 DAH implies that some dormancy genes can play a role in both hull and pericarp/testa.