In 1984 the areas with double cropping of rice in China amounted to 10.4 million hectares accounting for 31.3% of the total rice areas. The mean yield obtained by double cropping was 9.87 t/ha or 61.1% higher than that by single cropping. The highest yield for 36.9 hectares amounting to 14.83 t/ha was recorded in Hunan province in 1984.
The techniques to achieve high yield included the selection of rice varieties suitable for double cropping with emphasis placed on hybrid rice varieties and proper combination of varieties, proper seeding date and use of plastic film to raise the seedlings to avoid low temperature injury in the seedlings of the first crop of rice, sowing before the critical seeding date to avoid low temperature inducing sterility in the second crop of rice, zero tillage after the first cropping rice for the transplanting of the second crop at an appropriate time, light seeding and dense transplanting with small hills to increase the amount of total filled grains per unit area.