The successful cultivation of hybrid rice has greatly improved the grain yield of China, but there are some breakthrough problems in hybrid rice planting. For example, the breeding cycle of hybrid rice breeding process is long. The reason is mainly because the homozygous stability of breeding materials needs to pass through continuous Multi-generation, so Xiaobian next through the dwarf treatment, short-day induction and other measures, to talk about rice breeding materials for four generations of rapid replacement breeding technology.
1 test material
The rice regenerative selection group PCT14 based on recessive nuclear sterility introduced from the International Center for Tropical Agricultural Research (CIAT) of Colombia, selected 200 excellent individual plants from the population as experimental materials, provided by the Food Crop Research Institute of Hainan Academy of Agricultural Sciences.
2 technical measures
2.1 Dry live broadcast and dense planting
Place the seedling tray (length, width, height 54cm × 38cm × 4cm) on the greenhouse seedbed, without potting 10kg of sieved paddy soil. Seeds were seeded on the seedling tray, each material was sown at 300 points, and 2 seeds were sown at each hole. The seeding density was 2cm×3cm or 3cm×4cm. After sowing, water was immersed, and the herbicide was sprayed according to the amount of field. After 15 days of sowing, one strong seedling was left in each hole.
2.2 Water control, fertilizer control
Sprinkler irrigation is used throughout the growing period to keep the soil moist and not water. For the weak growth, a small amount of urea, phosphate and potassium fertilizer should be applied according to the specific growth. Control water and fertilizer, limit nutrition, and accelerate the entry into reproductive growth.
2.3 Control
When the rice seedlings begin to divide, the tillers are pruned every 5 days, and generally only the main stem is kept to prevent excessive growth.
2.4 Temperature control
The greenhouse fans and vents are used to control the temperature during each growth period. The temperature at the rice heading stage is 30 degrees, and in other periods it is 28-35 degrees.
2.5 dwarf treatment
Spray 30~30mg/L chlormequat 30 days after sowing to make rice plants dwarf and limit vegetative growth.
2.6 Short daylight induction
35 days after sowing, the shading treatment should be carried out with a full shading cloth every day. The shading time is 14-16 hours, and the shading is continued for 15-20 days to promote early differentiation of young ears.
2.7 harvest
Seeds were harvested 20-25 days after heading, and the seeds of each material were mixed.
2.8 Breaking seed dormancy
The seeds were dried immediately after harvesting, and then treated with 0.5% H2O2 for 20 days. Immediately after the dormancy, the next season of sowing was carried out, and the cultivation and management methods of each season were the same as above.
3 Research results
By counting the above cultivation techniques, the rice breeding material plants are only 30~50cm high, and the seed amount per plant varies from ten to thirty, and the seed setting rate is 60%~80%, which can meet the breeding requirements and achieve harvest within 100d. . The growth period of field planting is 105~130d, and the growth period of each material is very inconsistent, with a difference of nearly 20~30d. This technology can be harvested 15~35d in advance, which greatly accelerates the breeding process. According to the above measures, from the end of September 2014 to the beginning of October 2015, four sowing and harvesting of rice breeding materials (as shown in Figure 1) were achieved, that is, the generation of 1a4 generation was achieved.
Figure 1 Example of rice 1a4 generation and generation technology
4 Summary and discussion
Rice has two stages of vegetative growth and reproductive growth in its growth and development. Because rice is a short-day warm-warming crop, its growth period changes with the ecological environment and cultivation conditions. Under the conditions of sufficient sunshine in Hainan, the experiment began to control the cultivation of drought, direct seeding, dense planting, water control, fertilizer control, control and temperature control in the greenhouse, and began to shading 35 days after sowing. The shading time was 14~16h per day, continuous shading. 15~20d, and spraying 20~30mg/L chlormequat for 30d, can limit the vegetative growth of rice, advance rice panicle differentiation, and achieve 1a4 generation and generation.
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