Studies On Morphological Features And Its Regularities In Super Hybrid Rice Breeding

In order to explore the characteristics of plant type and its regularities of super hybrid rice and to give suggestions for further breeding on super high yield of rice, several items, such as photosynthetic production, stem traits, panicle character, root vigor, grain yield components at different growth stage, have been investigated in this study by using the Phase Ⅰ, Phase Ⅱ, Phase Ⅲ super hybrid rice varieties (varieties with super high yield) as materials and high yield hybrid rice variety of SY63(short for Shanyou63) as a control. The main results are as follows:1. Super hybrid rice has higher yield potential. The yield of LYPJ (short for Liangyoupeijiu), Y1(short for Y liangyou NO.1) and Y2(short for Y liangyou NO.2) increased by17.4%,19.8%and33.7%respectively, compared to the control SY63. Super hybrid rice has many outstanding properties as follows:a) Strong "source" that characterized with smaller leaf angle, smaller droopy angle and higher rolling index of uppermost3leaves, higher and decreasing more slowly of chlorophyll content of leaf, higher specific leaf weight; b) Efficient "flow" that characterized with higher exporting rate of dry matter in single stem and sheath of rice(above20%); c) Greater "sink" that characterized with more grain numbers per panicle and population spikelets.2. LYPJ had higher rolling index and more erect top-three leaves, as compared with SY63; LAI of LYPJ at heading stage increased by10.6%and8.0%compared to Y1and Y2, respectively. But activity of root of LYPJ declined fast during late growth stages, as well as grain-filling processes of superior and inferior grains were obviously asynchronous type, limited improvement of yield potential.3. Due to optimization of plant type in whole growth period, Y1had higher basal penetration light rate after booting, which could benefit the middle and lower leaves with more energy absorption. Meanwhile, Y1had strong root vigor and short time interval of maximum filling rate between superior and inferior grain which would be favorable for inferior grain filling.4. Due to the larger surface area of uppermost3leaves and a higher number of total spikelets in the population, as well as bigger grain-leaf ratio(the ratio of total spikelet number to leaf area at heading), Y2has a better relationship with source-sink. After mature, Y2had a higher canopy height (148.3cm), lower plant height (85.8cm), which was an ideal plant type. Meanwhile, the shorter and thicker basal internodes, as well as longer and thicker uppermost internodes, which were beneficial to the supply capability of source, as well as the lodging resistance.Finally, development regularities of plant type and breeding strategy for Phase IV super hybrid rice are discussed in the paper.