Population Characteristics for Super-high Yielding Hybrid Rice Yongyou 12(>13.5 t ha~(–1))

Using indica-japonica super rice Yongyou 12, by transplanting seedlings with tillers at the age of four leaves with one leaf bud and applying super sparse cultivation technology, we compared and studied grain yield and its components, tiller dynamic, leaf area dynamic and accumulation dynamic of dry matter in three types of populations(high yield: 10.5–12.0 t ha–1; higher yield: 12.0–13.5 t ha–1; super-high yield: 13.5 t ha–1). The results showed that super-high yielding rice had more population spikelets, and slightly lower seed-setting rate and 1000-grain weight than high yielding and higher yielding rice. Compared with high yielding and higher yielding rice, super-high yielding rice showed more number of stems and tillers at transplanting stage and achieved the expected number of stems and tillers at the critical leaf-age for productive tillers. During jointing stage the number of stems and tillers increased steadily and up to the maximum with a panicle rate of nearly 60%. The leaf area index of super-high yielding rice was relatively smaller at the early stage and the maximum of 9.17 at booting stage, and then slowly declined to more than 4.0 at maturity; the dry matter weight was relatively smaller at jointing stage and then the highest at each phase of the super-high yielding rice, which was 14.38 t ha–1 at heading stage, 9.73 t ha–1 from heading to maturity stage, and 24.11 t ha–1 at maturity stage. The root dry weight, ratio of root to shoot and root bleeding intensity per stem of the super-high yielding rice population were all the highest from heading to maturity stages.