Abstract:

The new rice variety, Zhongke Fa No.5, was developed by the team led by Academician Li Jiayang using the concept of molecular design breeding. By combining phenotypic and molecular marker selection, it has integrated the genotype combination of multiple copies of GL7, GS3, and GW5, resulting in slender grains. It also contains high-yield QTLs such as qSB2, qSB8, qSB10, and SCM2, and carries the blast resistance alleles Pib, qBR10, Pi-ta and Ptr. Based on this, this variety demonstrates outstanding agronomic traits including high yield, multi-resistance and excellent quality. In 2014, it ranked among China’s top ten cultivated varieties and has become a signature variety in Northeast China. In the face of this situation, in the future, Northeastern japonica rice should take it as a benchmark and strive to surpass it. Taking into account the supply and demand situation of rice, the overall breeding goal should be a long-grain fragrant variety with high yield. Specifically, the yield target should be above 9 500.0 kg·hm^-2, and the trait combination to achieve this target is a plant height of 95.0-105.0 cm, a total of 3.75 million to 4.2 million effective panicle number per hectare, a grain number of 120.0 or more per spike, and a thousand-grain weight of more than 25.0 grams. The quality target is a grain length greater than 6.0 mm, a length-to-width ratio greater than 2.8, an overall polished rice rate meeting the approved standards, excellent appearance, a taste score of over 80 points. And it also has good adaptability and resistance. To achieve this goal, the first step is to enhance dialectical thinking. In practice, we must resolutely eliminate a large number of materials that fail to meet the breeding objectives. At the same time, we should strengthen the practice of combining superior traits and the dialectical thinking of their adaptability to local cultivation conditions. During the breeding process, high-yield resources and long-grain resources should be coordinated and utilized, and multiple cross should be strengthened. At the same time, the breeding process should be optimized, and modern breeding technologies such as molecular breeding should be actively adopted. The key to the breeding strategy lies in expanding the application of hybrid rice restorer lines derived from indica-japonica subtypes, especially those of high-yield indica-japonica three-line hybrids. Since the high-yield three-line hybrids themselves have a relatively high yield, and their gametes have extensive recombination, there is greater expectation for the emergence of breakthrough types. To better achieve the breeding goals of long-grain rice, it seems that using japonica rice restorer lines with wide compatibility and crossing them with long-grain indica hybrid rice is the best strategy. However, further verification is needed.

Key words: japonica rice, Zhongke Fa No.5, dialectical thinking, breeding objective, breeding strategy