在盆栽条件下以粳稻品种武育粳3号和86优8号为材，穗肥施氮量设高、中、低三个水平，研究水稻植株穗分化过程中幼穗与茎的生长动态与每穗颖花数的关系。结果表明，穗分化前期幼穗生长较慢，对营养物质的竞争能力小于茎秆，86优8号（大穗型品种）穗分化前期经历的时间比武育粳3号（小穗型品种）长4 d。从抽穗前16 d开始，幼穗进入旺盛生长阶段，并与由上而下的第3节间伸长期相同，对营养物质的竞争能力超过茎秆。大穗型品种的穗茎比大于小穗型品种。抽穗期穗重、茎重与每穗颖花数呈正相关。抽穗前4~16 d穗重增长率与茎重增长率之比与颖花数也关系密切，该时期氮肥充足，穗重增加快，对促进颖花分化有利。
Because the process of panicle differentiation determined spikelets per panicle, it is necessary to investigate their relationship. In this research, we employed two japonica rice cultivars (Wuyujing 3 and 86 you 8) to explore the relationships between both panicle and stem growth and spikelets number per panicle during rice panicle differentiation period by performing three panicle fertilizer treatments (NH, NM, and NL) in pot experiment. Samplings were made one time every 4 days. The results were as follows: The younger panicle grew slowly at the early stage of panicle differentiation (i.e. bud and branch differentiation stage) as compare with the base internodes of stem, which syncing with young panicle in growth. The competitive ability of younger panicle for assimilation was weaker than that of stem at the early stage. The growth rate of younger panicle of 86 you 8 (with more spikelets per panicle, MP) at the early stage was lower than that of Wuyujing 3 (with few spikelets number per panicle, FP). From the meiosis phase on, panicle grew rapidly, and the third internode from top elongated at the same time, the weight ratio of spike/stem increased gradually, panicle got more nutrient than internodes, and compared with the FP cultivar, the MP cultivar had lager weight ratio of panicle to internodes. The time of younger panicle differentiation in 86 you 8 at early stage was 4 days lengthen than that in Wuyujing 3. Younger panicle grew rapidly from 16 days before heading. The weight ratio of panicle/stem for 86 you 8 was larger than that of Wuyujing 3. The fresh weight of panicle and stem at the heading stage was correlated positively to spikelet number per panicle; and the weight ratio of diurnal increases of panicle/stem from 4 to 16 days before heading was correlated to the spikelet number per panicle significantly. The more rapidly the panicle weight increased under enough N, the more spikelet number increased at this stage.
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