Effects on Source-sink of Ratoon Rice Under Simplified Cultivation of Different Seeding Stages

The high-yield ratoon rice system under simplified cultivation(direct-seeding and seedling-throwing) was studied by the experiment of different planting patterns and seeding stage in 2009 and 2010 at Yujiang country,Jiangxi Province,and the source-sink characteristics,biomass,nitrogen accumulation and yield of ratoon rice were also analyzed.The results showed that leaf area index of direct-seeding and seedling-throwing in main ratoon rice were lower than transporting by 5.1%-57.8%.In main rice,grain numbers were decreased than transplanting by 25.3%-41.2% in direct-seeding and seedling-throwing,and reduced by 9.9%-46.5% in ratoon rice.Biomass of direct-seeding and seedling-throwing were decreased by 23.7%-53.2% in ratoon rice,and nitrogen accumulation were reduced by 20.0%-54.4%.This indicted that grain yield of direct-seeding and seedling-throwing were lower than transporting by 30.1%-35.1%.However,temperature and solar of different seeding stages were different in main and ratoon rice,and seeding earlier could attain more temperature and solar in ratoon rice.Source-sink relations,biomass and nitrogen accumulation and yield were significantly higher than others when main rice was seeded in late March and early April.So,source-sink relations of direct-seeding and seedling-throwing could be improved and ratoon rice yield could be increased through adjusting seeding stage.