Evaluation of a Rice Plant Type Designed for High Grain Yield.

Simulation and field studies have suggested that rice main crop grain yield in Texas could be improved by selecting for a plant type that has a high main culm panicle node number, fast maximum node production rate, large leaf area, and large sink size. The objectives of this study were to compare the agronomic performance of a group of lines with the targeted traits against a group of lines without the targeted traits, and determine the magnitude of the direct effect of each targeted trait on grain yield and yield components. Advance inbred lines that possessed the suggested high yielding plant type were selected at the Texas A&M AgriLife Research and Extension Center at Beaumont, Texas. Thirty-eight lines were evaluated in yield trials at Beaumont in 2008 and 2009. In addition to the four targeted traits, grain yield, plant height, maturity, tiller density, biomass of plant parts (stems, leaves, and panicles), and numbers of spikelets and filled grain per panicle were estimated. Grain yield of the advance lines ranged from 7,506 to 12,406 kg ha^-1, with a mean of 10,281 kg ha^-1 in 2008, and ranged from 7,834 to 11,366 kg ha^-1, with a mean of 9,410 kg ha^-1 in 2009. The check cultivar Cocodrie yielded 9,637 and 8,796 kg ha^-1 in 2008 and 2009, respectively. Linear contrasts will be used to determine the significance in the differences between the plant type groups for the estimated traits, while path analyses will be used to determine the direct effect (path coefficient) of suggested plant traits on grain yield and yield components. This study is useful in evaluating and planning breeding efforts for improved rice grain yield.