Wednesday, November 7, 2007
259-2

Heading Date and Flowering Duration as Potential Indirect Selection Criteria for Milling Traits in Rice.

Rodante Tabien, AgriLife Research and Extension Center at Beaumont, 1509 Aggie Drive, Beaumont, TX 77713, Stanley Omar PB. Samonte, Texas A&M University System, Texas AgriLife Research and Extension Center, 1509 Aggie Drive, Beaumont, TX 77713, and Emmanuel R. Tiongco, Philippine Rice Research Institute, Maligaya, Science City of Munoz, Nueva Ecija, Philippines.

Percent whole and total grain in rice are the two milling traits that are considered determinants of the economic value of field harvest as these traits directly affect gross income of the producers. These traits are important breeding objectives, but the genotypes with these traits are selected only after estimating milling data during the advanced generations. Indirect selection for superior milling traits is not practiced, but this can be an ideal approach in the selection of genotypes that have high whole and total milled rice percentages during the earlier generations. More than 100 long grain rice genotypes that were included in the Uniform Regional Rice Nursery at Beaumont, Texas, in 2005 and 2006 were evaluated to determine the effects of days to heading and flowering duration on whole and total milled rice percentages. Correlation analyses between days to heading and flowering duration and between flowering duration and the percentages of whole and total milled rice were conducted. The number of days from emergence to heading had a significant linear relationship with flowering duration (r = 0.54). Flowering duration was significantly and negatively related to whole (r = -0.46) and total (r = -0.42) milled rice percentage. Rice genotypes with early heading tended to have shorter flowering duration and these early genotypes generally produced higher whole and total milled rice percentages. These results indicated the potential of using the duration from start of flowering to heading (50% flowering) as an indirect selection criterion in breeding rice for high whole and total milled percentages.