A near-isogenic rice line carrying a QTL for larger leaf inclination angle yields heavier biomass and grain

Manipulating plant architecture is a promising strategy for further improving rice production. The canopy extinction coefficient (k), the most important parameter of canopy architecture, represents the characteristics of light penetration into the canopy, and is determined mainly by the leaf inclination angle. With its erect leaves, the high-yielding indica cultivar ‘Takanari’ has a smaller k during ripening than the elite japonica cultivar ‘Koshihikari’. Using chromosome segment substitution lines derived from a cross between ‘Takanari’ and ‘Koshihikari’ we previously detected a quantitative trait locus (QTL) for leaf inclination angle on a chromosome 3. Here, we tested a near-isogenic line (NIL-3) carrying the ‘Takanari’ allele of a QTL for larger leaf inclination angle on chromosome 3, qLIA3, in the ‘Koshihikari’ genetic background for the effects of qLIA3 on k, dry matter production, and grain yield. NIL-3 had leaves with a larger inclination angle from the full heading through ripening stages and a smaller k at the ripening stage than ‘Koshihikari’. There were no differences in plant height, panicle size, heading date, leaf area index, or individual leaf photosynthesis between NIL-3 and ‘Koshihikari’. Biomass at harvest was significantly greater in NIL-3 than in ‘Koshihikari’ owing to a higher net assimilation rate during ripening, resulting in a higher grain yield. qLIA3 might incorporate a promising gene for improving rice production.