Studies on Yield and Characteristics of Plant Population Quality of Direct-seeded Rice Cultivars of Different Panicle Types

10 typical mid-maturity mid-season Japonica rice cultivars newly bred in Jiangsu Province in recent years were used as materials,and were classified by the panicle weight into three types of big panicle type cultivars,middle panicle type cultivars and small panicle type cultivars.All the cultivars for test were field grown under the direct seeding conditions.The characteristics of grain yield and its components and characteristics of plant population quality were investigated.The results showed that the middle panicle type cultivars had higher grain yield than other panicle type cultivars.High grain yield of middle panicle type cultivars was mainly due to the increase in total number of spikelets,and increase in spikelets resulted mainly from large panicles based on a suitable number of panicles,and also the high grain yield of middle panicle type was due to the higher leaf area index and biomass accumulation and higher output and higher appearing transformation and appearing convertion of dry matter of the stem and sheath as well as the higher rate of effect ears.Approaches to choosing suitable direct seeding cultivars and getting high yield are discussed based on the characteristics of grain yield and its components and characteristics of the plant population quality.