Method for breeding new variety of ratoon rice crop and cultivation method for new variety of ratoon rice crop

A method for rice ratooning, comprising selecting a photosensitive variety and cultivating under long-day conditions after harvesting a main crop of rice;

• wherein the photosensitive variety refers to a variety that long day may delay or prevent its photoperiod induction and thereby prolonging growth period;
• wherein the long day refers to an illumination time per day longer than critical day length of the photosensitive variety;
• wherein,
• a. in the equatorial region or the vicinity of the equator, the method comprises selecting a photosensitive variety with a critical day length shorter than 12 hours and 6 minutes, applying shading treatment for 8 to 30 days and giving 9-10 hours of natural illumination every day for completion of photoperiod induction, harvesting a main crop of rice, cultivating under long-day conditions, leaving low stubbles while maintaining a no-water layer or a thin-water layer with a water depth of no more than 3 cm within 7 days of the harvest of the main rice, applying fertilizer in the ratoon season to promote ratoon shoots with large number of tillers, and harvesting the ratoon rice;
• b. in the tropics, the method comprises selecting a photosensitive variety with a critical day length between 12 hours and 39 minutes and 13 hours and 10 minutes, completing photoperiod induction, harvesting a main crop of rice, cultivating under long-day conditions, leaving low stubbles while maintaining a no-water layer or a thin-water layer with a water depth of no more than 3 cm within 7 days of the harvest of the main rice, applying fertilizer in the ratoon season to promote ratoon shoots with large number of tillers, and harvesting the ratoon rice;
• and
• c. in the subtropics, the method comprises selecting a photosensitive variety with a critical day length between 12 hours and 47 minutes to 13 hours and 20 minutes, completing photoperiod induction, harvesting a main crop of rice, cultivating under long-day conditions, leaving low stubbles while maintaining a no-water layer or a thin-water layer with a water depth of no more than 3 cm within 7 days of the harvest of the main rice, applying fertilizer in the ratoon season to promote ratoon shoots with large number of tillers, and harvesting the ratoon rice.