1. The correlation of ratooning rate to the yield relating characters of main crop and ratoon crop in rice was studied with 30 different types of rice varieties and hybrids.

2. Furthermore, sugarcane ratoon stunning disease pathogen can be rapidly detected by means of television phase contrast microscope and PCR.

3. The correlative coefficient of the yield of the ratooning rice to the ratoon rate is the most.

4. The economic characters of the ratoon plants origined from the second node of the mother stem were less affected by the heading date than those origined from the fourth and third node.

5. The aim of this work was to investigate the application of PCR detection in ratoon stunting disease (RSD)of sugarcane.

6. Phloughing resulted in decrease in soil organic matter content in coming year, while successive ratoon cultivation could increase or maintain soil organic matter content.

7. The results showed that the ethephon treatment at young stage promoted the ratoon cane growth, improved the economic characters including cane yield.