Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2008
Publication Date: 11/1/2008
Citation: Tabien, R.E., Samonte, O.B., McClung, A.M. 2008. Forty eight years of rice improvement in Texas since the release of cultivar Bluebonnet in 1944. Crop Science. 48:2097-2106.
Interpretive Summary: A study was conducted to assess what changes have been made in rice cultivars developed in the public rice breeding program conducted at Beaumont, Texas over the last 50 years. Twenty-three cultivars were evaluated in three environments and two N levels. Days to heading, plant height, whole and total milled rice percentages, and grain yield were measured. A two-week decrease in days to heading and a decrease in plant height that averaged over 1 cm per year was obtained as a result of breeding efforts. These dramatic changes in the maturity and height of cultivars has reduced risk of yield losses due to lodging and late season weather related losses. Improvements in whole and total milled rice percentages were less dramatic during this time frame because these traits are very susceptible to environmental fluctuations which limit breeding advances. Grain yield increased at 42 kg ha-1 yr-1 when the crop was grown under current day fertility levels. These results demonstrate the remarkable progress that has been achieved in the Texas rice breeding program from 1942 to 1992.
Technical Abstract: The objective of this study was to determine the contribution of Texas rice breeding to changes in cultivars released during the 50 years since its first cultivar release in 1942. Twenty-three cultivars were evaluated in three environments and two N levels. Days to heading, plant height, whole and total milled rice percentages, and grain yield were measured. Significant variation among cultivars was found for all traits evaluated, while N affected all traits except milled rice. There was a two-week quadratic decrease in days to heading in cultivars released from 1942 to 1992. Plant height decreased at 1.26 and 1.09 cm yr-1 for the 190 and 95 kg ha-1 N levels, respectively, mainly due to the incorporation of the semi-dwarf gene in many cultivars starting in 1981. Plant heights of recently released cultivars were more stable across N levels and less susceptible to lodging. Although whole and total milled rice percentages increased at 0.20 and 0.03% yr-1, respectively, environmental factors limited their advances. Grain yield increased at 42 and 27 kg ha-1 yr-1 under the 190 and 90 kg ha-1 N levels, respectively, demonstrating that newer releases responded well to higher N. These show the remarkable progress in the Texas rice breeding program from 1942 to 1992.