中国南方稻区早籼中熟品种产量要素分析

Analysis on the Agronomical Traits of New Early Indica Varieties With Middle Maturity and High Yield Potential in China

本文选用１９８５～１９９６年间南方稻区区试早籼中熟组南昌点（北纬２８°４１’，东经１１５°５８’）资料，以泸红早为对照，比较分析了历年产量居第一位的新品种（下称优秀品种）的主要农艺性状特征，结果为：ａ．１２年中，优秀品种平均比对照增产６．５％，如除去两个减产年份，平均增产比例达８．５％；ｂ．优秀品种全生育期平均比对照延长１．２ｄ，生育期延长主要是灌浆期延长所致；ｃ．优秀品种的株高平均增加２．３ｃｍ，分蘖率增加１４．５％，而有效穗和成穗率分别下降２．１％、４．６％；ｄ．穗部性状中，以单穗总粒数、实粒数、单穗重增长率较大，而结实率为负增长；ｅ．各性状与产量间的正相关系数大小顺序为：结实率＞单穗重＞株高＞单穗实粒数＞成穗率＞穗长＞齐穗至成熟天数＞千粒重＞单穗总粒数＞有效穗数，其中结实率达极显著相关，而分蘖率、播种至齐穗日数为弱的负相关。本文指出，结实率低和成熟率低是新育成的优秀品种进一步高产的限制因素，今后南方稻区早籼中熟种育种策略应是：适当增加株高；确保较高的、年份间较稳定的结实率；提高成穗率；在不增加全生育期的情况下，适当延长灌浆期；通过增加单穗总颖花数以达到增加穗重，最终实现高产的目标。

The main agronomic characters and yields were statistically compared among the indica varieties with middle maturity attending China's National Regional Adaptability Trial from 1985 to 1996. The results were as follows: 1. The elite varieties (EVs) as a whole were 6.5% higher in yield than the control variety. Except two of the EVs that gave lower yields than CV, the yield of the EVs averaged 8.5% higher than that of CV. 2. The whole growth duration of the EVs was 1.2 days longer than that of CV mainly due to elongation of their grain-filling period. 3. Compared with CV, EVs were 2.3cm higher in plant height and 14.5% more in tillering rate, but their productive panicles in terms of unit area and percentage decreased by 2.1% and 4.6%, respectively. 4. The mean increment of panicle characters for EVs was in the order of spikelets per panicle > grain weight per panicle > fertile spikelets per panicle > 1000-grain weight > panicle length while there existed negative increase in setting rate. 5. Statistical analysis revealed that the correlation of setting rate with yield was very significant in the EVs, and significant in CV. The magnitude of the correlation coefficients (CC) with yield was in the order of setting rate > grain weight per panicle > plant height > fertile spikelets per panicle > percentage of productive panicles > panicle length > days from 80% heading to ripening > 1000-grain weight > spikelets per panicle > productive panicles per unit area. However, the correlation of tillering rate with the days from seed sowing to 80% heading was slightly negative. It could be concluded that setting rate and productive panicle rate were the main factors restricting further increase in yield potential of the EVs. The breeding strategy of early indica rice varieties with middle maturity in the southern parts of China should be focused on the following guidelines: properly increasing plant height; maintaining higher and relatively stable setting rate; enhancing productive panicle rate; appropriately elongating grain-filling period while staying the whole growth duration, and increasing grain weight per panicle by increasing spikelets per panicle.