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 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 Effects of potassium fertilizer and potassium use efficiency on early-, mid- and late-season rice in Hubei province, China Evaluation Method of Ratooning Ability of Mid-season Hybrid Rice Cultivation Strategy of Hybrid Mid-Season Rice for Further High Yield in Winter Water-Logged Field in the Southeast of Sichuan Province