Y两优900是利用广适性光温敏不育系Y58S为母本，籼粳交强优恢复系R900为父本选育的第四期超级杂交稻苗头组合，2013年在湖南创造了较大面积单产14.82 t/hm2的世界纪录。该组合根系发达、耐肥抗倒，穗大粒多，结实率高，具有株叶形态理想、熟期适中、适应性广、高产稳产、优质多抗等特点。本文对Y两优900与Y两优2号的产量构成因素进行了比较，并分析了其叶龄及苗穗数动态，提出优化栽培的技术途径。

A record of average yield of 14.82 t/hm2 was created in an area of 6.75 hm2 in 2013 in Hunan for Y Liangyou 900, which is a new combination with potential  yield of phase Ⅳ super hybrid rice. Y Liangyou 900 has stong root system, high lodging resistance, large panicles with plenty of spikelets, high seed setting rate, ideal plant type, suitable growth duration, wide adaptability, good grain quality and multiple resistance to biotic and abiotic stresses. The leaf age, plants and ears dynamics and yield components of Y Liangyou 900（2013） and Y Liangyou 2（2011） are analysed, optimizing cultivation approaches of Y Liangyou 900 are discussed in the paper.