Effect of Ratio Source to Sink on Percentage of Head Milled Rice and Chalky Rice of Combinations of Mid-season Hybrid Rice in the South-East Districts of Sichuan Province under High Temperature and Summer Drought Cultivation Strategy of Hybrid Mid-Season Rice for Further High Yield in Winter Water-Logged Field in the Southeast of Sichuan Province Evaluation Method of Ratooning Ability of Mid-season Hybrid Rice EFFECT OF SUPER SPARSE CULTIVATION ON HEAD MILLED RICE PERCENTAGE AND CHALKINESS IN HYBRID RICE VARIETIES IN THE EASTERN AND SOUTHERN DISTRICTS OF SICHUAN PROVINCE