Photosynthetic and agronomic traits of an elite hybrid rice Y-Liang-You 900 with a record-high yield

Hybrid rice breeding is a major strategy used in China to gain steady increase in rice productivity. Y-Liang-You 900 (YLY900) is a recently released elite hybrid rice cultivar, which reached a record yield of 15 tons/hectare. In this report, we aims to characterize the physiological and agronomic properties of this elite cultivar by comparing it to Shan-You63 (SY63), which is a rice cultivar with large growing acreage in China. Results show that YLY900 has higher leaf chlorophyll concentration, greater leaf thickness, greater leaf area, and higher photosynthetic rate compared to SY63. YLY900 also has higher dry matter of organs and higher biomass accumulation especially in the grain filling stage. YLY900 also has a more sturdier stem, shorter internode length at the lower part of the stem, and higher sheath mass, all contributing to higher lodging-resistance. We discuss how these features together lead to the record-high yield potential of YLY900. These identified features can be used as targets for elite rice breeding.