双季杂交晚粳稻超高产形成特征

本研究旨在明确传统双季晚籼稻地区双季杂交晚粳稻超高产产量构成及其群体特征，阐明双季杂交晚粳稻超高产形成规律。以江西省上高县6.77 hm²连片双季杂交晚粳稻高产攻关示范方为依托，选用杂交粳稻甬优8号为材料，对中产(8.25~9.75 t hm^-2)、高产(9.75~10.50 t hm^-2)和超高产(>10.50 t hm^-2) 3个产量水平群体的产量构成及群体特征进行系统比较研究。结果表明，与中产、高产水平群体相比，超高产水平群体表现穗数足、穗型大、群体颖花量多(50 000×10⁴ hm⁻²以上)的显著特点，但结实率和千粒重略低，差异不显著；群体茎蘖动态上，群体起点较高，可及时够苗；够苗后增长平缓，高峰苗数量较少、下降平缓，成穗率高(78.0%左右)。群体叶面积指数前期增长较缓，最大值出现在孕穗期，为8.0左右，此后下降缓慢，成熟期仍保持3.5以上；群体光合势生育前期较小，中、后期较大，抽穗至成熟期光合势为300×10⁴ m² d hm⁻²以上，总光合势为560×10⁴ m² d hm⁻²以上。拔节前干物质量积累速度较慢，拔节后积累速度较快，至抽穗期群体生物量为10.5 t hm⁻²左右，抽穗后积累量亦高，成熟期干物重达19.0 t hm⁻²左右，后期茎鞘物质转运率大于14.0%。超高产群体根量多、活力较强；植株吸氮能力强、成熟期氮素累积量高，氮素利用率40%以上。根据双季杂交晚粳稻超高产形成特征，我们探讨了培育双季晚粳稻超高产群体的关键栽培技术。

Yield Components and Population Characteristics of Super-High-Yielding Late Japonica Hybrid Rice in Double-Cropping Rice Area

This study investigated the formation rule of super-high-yielding late japonica hybrid rice in the double-cropping rice area. Using Yongyou 8 as material in Shanggao of Jiangxi Province, we analyzed grain yield and its components and the population characteristics in three types of populations (medium yield: 8.25–9.75 t ha^-1, high yield: 9.75–10.50 t ha^-1; super high yield: >10.50 t ha^-1). Results showed that supper-high-yielding population had more panicle and spikelets per panicle than medium and high yielding population. There was no significant difference in filled-grain percentage and 1000-grain weight among the three populations. Supper-high-yielding population exhibited more tillers at the transplanting stage and achieved expected number of stems and tillers on time, maximum number of stems and tillers at jointing stage. Then, the number of population stems and tillers began to decrease stably, achieving an expected number again. At last, ratio of productive tillers to total tillers of supper-high-yielding population was about 78.0%, which was higher than that of medium and high yielding population. The leaf area index of supper-high-yielding population was lower than that of medium and high yielding population at the early growth stage, with the maximum leaf area index of about 8.0 at booting, and stably decreasing to above 3.5 at maturity. The photosynthetic potential of supper-high-yielding population was smaller at early stage and larger at middle and late stages, as compared with the medium and high yielding populations, which was above 300 × 10⁴ m² d ha^–1 from heading to maturity, and above 675 × 10⁴ m² d ha^–1 in total. The dry matter accumulation of super-high-yielding population was smaller before jointing, increased faster after jointing, and reached about 10.5 t ha^–1 at heading and 19.0 t ha^–1 at maturity, which was significantly higher than that of medium and high yielding populations. Its translocation ratio of output was above 14.0%. In the super-high-yielding population the weight of dry matter of root, root-shoot ratio at each growth stage, root bleedings, N content, N uptaking, and utilization were greater than those of the medium and high yielding populations. Based on the results of this study, we discussed the regulation approaches and key cultivation techniques for raising the super-high-yielding population.