Studies on the Growth Habits and Characteristics of Two Polyploid Indica-japonica Hybrids with Powerful Heterosis

Chinese. 利用远缘杂交和多倍体双重优势选育超级稻是水稻育种的新战略。在获得一批多倍体籼粳亚种杂交稻株系的基础上，为了更大规模地展示这种杂种优势和更全面地研究多倍体籼粳亚种杂交稻的特点。以PSR073和PSR120为材料，对其叶龄、分蘖、开花习性及外部形态等进行观察统计，研究其生长习性。PSR073、PSR120在株高、穗长、粒长、粒宽、千粒重等农艺性状上均表现出明显的多倍体优势，并且具有高达83%以上的结实率；叶龄、分蘖及开花习性等方面表现出与二倍体水稻相似的特点。这两个多倍体水稻杂种的特点与以前报道的多倍体水稻的情况明显不同，远缘杂交和多倍体化并没有对其生长习性产生不利影响，相反具有强大的杂种优势，这为其应用于生产提供了理论和实践依据。

Chinese. Based on a series of polyploid indica-japonica hybrid plant lines obtained from a new breeding strategy of using double heterosis of wide cross and polyploidization to select super rice, two polyploid indica-japonica hybrids, PSR073 and PSR120 were studied in their growth period to show the powerful heterosis in a larger scale and study the characters of polyploid indica-japonica hybrids more completely. The leaf age, tiller growth, flowering habit and morphology characteristics of them were observed to analyze their growth habits and characteristics. The results showed that the agronomic traits of PSR073 and PSR120, such as plant height, length of panicles, grain length, grain width and 1000-grain weight, all took on obvious predominance of polyploid. And the seed-setting percentage was more than 83%. No difference was observed between the two tetraploids and common diploids in leaf age, tiller growth and flowering habit. It is concluded that the characteristics of the two powerful heterosis polyploid hybrids are different from those of the polyploid rice reported before. Wide cross and polyploidization have no negative effects on the growth habits and characteristics of them, on the contrary they have powerful heterosis. This has provided theoretic and practical evidences for their application to agricultural production.