| New rice yield record was continued to be made under the idea of morphological improvement and heterosis utilization in recent years. The latest breakthrough of yield ceiling has been made last year and the new world record is 15.4 t/hm~2 in Xupu county, Hunan province, China. In order to reveal the essence of high yield achieved in super hybrid rice, the phase Ⅳ pioneering combination YLY900 and the control varieties including the phase Ⅲ typical combination YLY2 and the classical three-line combination Shanyou63 were used as the experimental materials, we investigated and compared the plant morphology, leaf area index, photosynthetic capacities, panicle traits, root vigor and yield components among three rice combination in the main growth period of rice to determine the morphological characteristics, physiological characteristics, population index of YLY900 with high yield potential. On the other hand, we also investigated the tillering dynamics, regulation of water and fertilizer management practices and the yield structure of YLY900 grown in Yangguao Town, Longhui County, Hunan Province to explored the super high-yielding cultivation techniques that leading to rice yield of more than 15 t/hm~2. These findings will provide theoretical basis and technical reference for super hybrid rice breeding and super high-yielding cultivation techniques. The main results were summarized as follows:1. Compared with two control varieties, YLY900 had higher yield potential of 11.8 t/hm~2 in normal ecological conditions, and the yield of YLY900 is 6.3% and 37.2% higher than that of YLY2 and SY63, respectively.2. Compared with two control varieties, YLY900 had better plant and leaf morphology. The advantages of YLY900 were as follows: ①The leaf angle of the upper most 4 leaves were smaller; ②The light transmission rate at basal parts of rice population were higher than that of control varieties, which laying the morphological foundation of the large panicles and high seed setting rate, good posture of the basal leaves and high photosynthetic efficiency. ③YLY900 had reasonable tillering dynamics and high percentage of earbearing tiller. Its earbearing tiller Percentage was 60.1%, which was increased by 15.2% and 4.0% compared to SY63 and YLY2, respectively.4. Compared with two control varieties, YLY900 had strong root vigor and high chlorophyll content during the whole growth period, and the chlorophyll content dropped slowly after heading stage, which was beneficial to accumulate more photosynthetic product and guaranteed the source strength for super-high yield.5. The leaf area index (LAI) of YLY900 was less than SY63 before critical stage of effective tiller emergence. However, the LAI of YLY900 increased rapidly from the critical stage of effective tiller emergence to booting stage, and the increase was 80.4% that was 28.4% higher than SY63. After the booting stage, the LAI of YLY900 drop slowly compared with two control varieties. Thus, YLY900 performed a dynamic ideal plant type.6. YLY900 had high net photosynthetic rate, and the net photosynthetic rate is 22.7μmol·m-2·s-1 at heading stage, which was increased by 16.4% and 5.1% compared to SY63 and YLY2, respectively.7. YLY900 had large panicle with high seed setting rate. The number of spikelets per panicle of YLY900 is 288.7 and the seed setting rate is more than 88% under the normal conditions, which ensure the abundant "sink" and "flow" of super high-yielding.8. The total number of spikelets was up to about 4.8 X 107 per 667 m~2, which guaranteed the grain yield of YLY900 is more thanl5t/ha. The effective panicles and spikelets per panicle are two keys to achieve high yield. The yield structure were as follows: ①the Number of panicles were 2.4 × 106～2.55 × 106 per hectare; ② The spikelets per panicle were 280-300; ③The seed setting rate was over 90%; ④ The 1000-grain weight was 27.5 g.9. The correlation analysis showed that the effective panicle was obviously and positively correlated with the yield (r=0.578*); the filled grain number per panicle was positively correlated with the yield (r=0.413);the effective panicles were significantly and negatively correlated with the filled grain number per panicle (r=-0.518*). 10. Postponing nitrogen application and panicle fertilizer application timing were crucial to super high-yielding. The ratio of basic and tillering fertilizer to panicle fertilizer is around 5.5 to 4.5, ensuring big panicles and high seed setting rate. Choosing a correct stage of using panicle fertilizer is also important to realize super high-yielding. The effective application timing of panicle fertilizer was the phase II and phase IV of panicle differentiation, which can keep the balance among bigger panicles, lodging-resistance and high seed setting rate.11.11. We forecasted the yield which are 16.5t/hm~2 。 that based on the trend of yield structure of the classical three-line combination Shanyou63, the phase I to IV combination LYPP9,YLY1,YLY2,YLY900 in normal ecological conditions. When the yield is 16.5 t/hm~2, the effective panicle number is about 12.5×10/667m, the spikelets per panicle is about 470 and the total spikelets number are about 5800×104/667m~2. |
PDF Full Text Request