Photosynthetic Physiology Basis for Efficient Expression of Yield-enhancing QTL from Oryza rufipogon Griff.

Some photosynthetic characteristics of the hybrids derived from Yuanhui 611,a new late-season indica hybrid rice restorer line which contains two yield-enhancing quantitative trait loci (QTL) alleles yld1.1 and yld2.1 from Oryza rufipogon Griff.,were surveyed with Weiyou 64,an elite hybrid rice combination derived from Ce 64-7,the acceptor of yield-enhancing QTL and the original parent of Yuanhui 611,as check. The hybrids of Yuanhui 611 showed strong heterosis,such as big panicle with many spikelets,large sink size and super high-yielding potential,and their grain yields were significantly higher than that of the check. They had better functional leaves at late growth stage with leaf areas larger,leaf angles smaller,leaf thicknesses bigger and net photosynthetic rates of flag leaves higher than those of the check. Very large sink size and strong source were both the main physiological reasons for high grain yields of the hybrids of Yuanhui 611 and may be the major physiological basis for efficient expression of yield-enhancing QTL from O. rufipogon Griff.