籼粳杂交稻枝梗和颖花形成的播期效应

Effects of Sowing Date on Formation of Branches and Spikelets in Indica-Japonica Hybrid Rice

【目的】探讨播期对不同籼粳杂交稻穗粒数形成规律的影响。【方法】以杂交稻偏粳型中熟中粳甬优8号、偏籼型迟熟中粳甬优15号、中熟晚籼钱优2号和常规品种迟熟中粳浙粳88为材料,通过分期播种研究不同类型水稻枝梗和颖花分化与退化的特性及其与籼粳性成分的关系。【结果】籼粳杂交稻甬优8号及甬优15号每穗总颖花分化数均显著高于籼稻钱优2号和粳稻浙粳88;甬优品种的一次枝梗及颖花分化数显著高于籼、粳稻,二次枝梗和颖花分化数以偏籼型品种甬优15号和钱优2号较高,而甬优8号二次颖花分化数与钱优2号的基本持平。随播期推迟,每穗总颖花分化数显著降低,尤为二次颖花分化数,而一次颖花分化数以适期播种最高。甬优8号和钱优2号总颖花分化数以早播显著高于适期播种和迟期播种,甬优15号则以适期播种最高,适期播种能显著提高籼粳杂交稻品种甬优8号和甬优15号的一次颖花现存数,主要体现在稻穗中上部与穗基部、顶部,这与其较高的一次枝梗分化能力有关。不同播期间,各类型品种稻穗不同部位一次枝梗上的二次枝梗分化数从穗基部到穗顶部总体呈下降趋势,而二次枝梗和颖花现存数、二次颖花分化数总体呈现"先升后降"的趋势。其中甬优8号不同部位一次枝梗上二次枝梗和颖花现存数的早播优势主要体现在穗中上部位,钱优2号早播的优势为稻穗中下部,甬优15号适期播种的优势主要体现在穗顶部,而浙粳88迟播的影响主要体现在稻穗基部。相关分析表明,各类型品种粳性成分与稻穗总颖花分化数及一次、二次枝梗和颖花分化数均呈极显著抛物线关系,相关系数分别为0.8172、0.9416、0.9004、0.8718和0.7988。【结论】与籼、粳稻相比,籼粳杂交稻具有较多的枝梗数和颖花数。推迟播期,降低每穗颖花分化数和二次枝梗分化数;早播有利于中熟品种颖花和二次枝梗的形成,而适期播种对迟熟品种的效应较好。不同播期下各类型品种粳性成分与稻穗枝梗和颖花呈极显著相关。

[Objective]The objective of the study is to elucidate the effects of sowing date on characteristics of spikelets formation of hybrid rice with different compositions of indica and japanica.[Method]The inbred and hybrid varieties with different compositions of indica and japanica, Yongyou8 and Yongyou15, Qianyou2 and Zhejing88 were used in this study. The characteristics of differentiation and degradation of branches and spikelets were investigated, and the relationship between the composition of indica ＆amp; japonica and the character of rice panicle was analyzed.[Result]The total number of differentiated spikelets per panicle of hybrid rice Yongyou 8 and Yongyou15 with indica-japonca blood were significantly higher than the indica ricen Qianyou2 and japonica rice Zhejing88. The numbers of differentiated primary branches and spikelets on primary branches of Yongyou 8 and Yongyou15 were also significantly higher than the indica and japonica rice. The number of secondary branches, and spikelets on secondary branches of Yongyou15 and Qianyou2 was more than two others rice varieties. The number of differentiated spikelets decreased significantly with the sowing date delaying （ie. 28, June）, especially the number of differentiated spikelets on secondary branches, but differentiated spikelets on primary branches on suitable sowing date （ie. 21, June） was more than other sowing date. More number of differentiated spikelets of Yongyou8 and Qianyou2 was found when the sowing date was ahead （ie.14, June）. Degradation spikelets on primary branches of Yongyou varieties decreased significantly at suitable sowing date, and low spikelets degradation was observed for Yongyou8 in the middle-upper part of panicle and the base part or top part for Yongyou15, respectively, and that caused by higher primary branches differentiation. In all sowing date treatments, the number of differentiated secondary branches decreased from base panicle to top panicle in all varieties, and the secondary branches, spikelets on secondary branches showed an increased and then decreased tendency. The advantage was that low degradation of secondary branches, spikelets on secondary branches in the middle-top of panicle of Yongyou8 when the sowing date was ahead, and that was the base-middle of panicle for Qianyou2. The low degradation of spikelets was found in the top of panicle of Yongyou15 at suitable sowing date, and the advantage of sowing date delaying was that low degradation of spikelets happened in the base of panicle of Zhejing88. There was a significantly parabolic correlation between the japonica consanguinity component and the number of differentiated spikelets, primary, secondary branches and its spikelets, and the correlation coefficient was 0.8172, 0.9416, 0.9004, 0.8718 and 0.7988, respectively.[Conclusion]There were more branches and spikelets of indica-japonica hybrid rice than indica and japonica rice. Differentiated spikelets and secondary branches per panicle were reduced significantly with sowing date delaying, and it promoted the formation of spikelets and secondary branches when the sowing date was ahead for medium-maturing varieties, while there was a positive effect for late-maturing varieties by selecting suitable sowing date. There was a significantly correlation between the japonica consanguinity component and the branches, spikelets of panicle in all sowing date treatments.