Tillering Characteristics and Its Relationships with Yield Components of Mechanical Direct-seeding Rice in Different Densities

[Objective] The aim was to explore tillering characteristics of mechanical direct-seeding rice in different seeding densities in field production. [Method] The rice variety wasHuaidao 5,and the methods of combining investigating the typical rice field with the experiment was used to study the effects of different densities on tiller emergence,panicle characteristics and yield of mechanical direct-seeding cultivation methods. [Result]When the sowing density was from 180 × 104 plants / hm2 to 225 × 104 plants / hm2,panicle number per plant was more,and the main tillering zone was located between from leaf 2 to leaf 4 and good characters were observed for the panicles developed from these leaves; although the panicle number of leaf 1 had a big proportion in the composition of a tiller spike,panicle traits were bad and made little contributions to the yield. When the sowing density was grown to 270 × 104 plants / hm2,panicle number per plant was low,and the number of superior leaf position was less,only leaves 2 to 3 were the superior positions for tiller emerging and panicle formation,had better panicle traits and made great contributions to the yield. [Conclusion]The suitable sowing densities of mechanical direct-seeding rice were from 180 × 104 plants / hm2 to 225 × 104 plants / hm2 in Haifeng area. In these densities,it is of great significance to enhance the leaf 2 to leaf 4 tillers' emergence and flowering frequency; explore the way to increase yield potential of the superior leaf position through proper management measures is helpful to achieve the target of high yield of mechanical direct-seeding rice.