Studies on growth and flowering characteristics of polyploid hybrid rice parents with strong heterosis

Chinese. 【目的】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,在解决了多倍体水稻育种结实率低的瓶颈问题和选育出一批多倍体籼粳亚种杂交品系的基础上,重点研究多倍体水稻不育系和恢复系的生长特性和开花匀性,为实现多倍体杂交稻生产打下良好基础。【方法】从分期播种以及倍性水平上对强优势多倍体水稻亲本恢复系Sg99012、HN2026,不育系PA64S以及对照品种9311、HD9802S的叶龄、分蘖等生长特性进行比较研究。【结果】分期播种对品系的总叶龄数有一定的影响,但对出叶动态变化趋势的影响不大。四倍体的主茎叶龄总数与其对应二倍体相比有减少的趋势,出叶速率受环境因子的影响比倍性影响更大。对总分蘖数也有一定的影响,四倍体的分蘖数比其对应二倍体少。加倍品系较其二倍体的单个颖花开放持续时间明显延长;恢复系9311、HN2026的颖花日开放时间更趋集中,但单穗开花历期及其高峰期不一致;特别是具有多倍体减数分裂稳定性和高结实特性的PMeS品系HN2026-4X,具有开花期和花时都相对集中,且不易受播期和气温影响的特点,可作为优良多倍体恢复系加以利用。【结论】染色体加倍对试验品系的各种性状存在一定的影响,但不影响杂交水稻选育中所利用的不育系和恢复系的主要特点。多倍体不育系的不育稳定性和多倍体恢复系的花期花时相对集中等特性更有利于杂交选育。

English. [Objective] Using double predominance of distant crossing and polyploidization to select super rice is a new strategy of rice breeding. Based on a series of polyploid indica-japonica hybrid plant lines obtained after solving the problem of low seed setting rate ofpolyploid rice by breeding Polyploid Meiosis Stability （PMeS） lines, it is the most urgent affair in polyploid rice breeding that to study the characteristics of polyploid rice sterile lines and restoring lines to realize the application of hetesosis of polyploid rice hybrids in production. [Method] Leafage and tillering of restoring lines Sg99012, HN2026 and sterile line PA64S of polyploid hybrids parents with strong heterosis were comparatively studied by stages and at different ploidity levels. Control materials 9311, HD9802S were studied at the same time. [ Result ] Results showed that seeding by stages had certain effects on leaf number, but had few effect on change trend of leaf growth. Main stem leaf number tended to reduce from diploid to tetraploid. Environmental factors had more influence on leaf growth speed than that at ploidity level. Furthermore, seeding by stages had influence on total tiller numbers in some degree. Tiller numbers of tetraploid was less than that of its corresponding diploids. Results of flower characteristics showed that chromosome doubling obviously prolonged the duration of spikelets opening. For restoring line 9311 and HN2026 with doubled chromosome, the flowering time of spikelets in a day became more concentrated. But the flowering duration and flowering peak of a panicle differed in each variety. The flowering stage and flowering time of PMeS line of HN2026-4X with polyploid meiosis stability and high seed setting rate, were more concentrated. The seeding date and temperature had few effect on the flowering characteristics of it. So it can be utilized as a fine polyploid restoring line. [ Conclusion ] Chromosome doubling has influence on many characteristics of experiment materials, but has no effect on characteristics of sterile lines and restoring lines used in hybrid rice breeding. On the contrary, characteristics of more stable sterility of polyploid sterile lines, more concentrated flowering stage and flowering time of polyploid restoring lines are more beneficial to hybrids breeding. This has provided a practical evidence for utilization of strong heterosis ofpolyploid hybrid rice.