Effects Of Sowing Date And Seedling Age On Yield Formation Of Triple-cropping Mechanized Transplanting Seedling Under The Single Seed Sowing & Close Planting Technology

For explore suitable sowing date and seedling age of triple-cropping mechanized transplanting seedling under the single seed sowing&close planting technology,from Mar.to Oct.2016in the Yongan town,Liuyang City,Hunan province,the traditional sowing technology as the control,the paper was carried out the effects of different sowing date and seedling age under the single seed sowing technology on seedling quality,growth characteristics and yield formation under the condition of the mechanized transplanting in the double-season rice.There was 4 sowing date and 4 seedling age in the early rice,and 5sowing date and 5 seedling age in the late rice.The main results were shown as follows:?1?No significant difference of yield among different sowing date was observed in the early rice season.However,there was significant difference of yield among different sowing date in the late rice season.Compared with control,yield of the sowing date of 25^th Mar.,30^th Mar.,and 1^st Apr.increased averagely by 7.4%,3.4%and 0.6%,respectively.Compared with control,yield of the seedling age of 1^st Jul.,6^th Jul.increased averagely by 4.2%and8.8%,respectively.Compared with the traditional sowing technology,single seed sowing&close planting technique could appropriately postpone sowing period,which could improve effective daily accumulated temperature,shorten the field growth time,coordinate the seasonal contradiction;meanwhile,increase leaf area index,increase the tillering rate and tillering potential,reduce the redundancy growth,improve material conversion efficiency and resource utilization.?2?There was significant difference of yield among different seedling age in the early-and late-rice season under single dense planting cultivation.The average yield in the 25,30and 35days of seedling age was 25%,17%and 5%,respectively,in the early rice season compared to the control?20 days of seedling age?.Compared with the control?15 days seedling age?,yield in the 20,25 and 30days of seedling age increased by 16%,4%and 12%,respectively,in the of late rice season.Compared with the traditional sowing technology,single seed sowing technique could effectively reduce 70%seeding quantity,and extend the seedling age under the condition of mechanized without affecting the quality of transplanting seedlings,improve dry matter accumulation and harvest index,and acquire stable and high yield.Therefore,under single dense planting technology,ensuring high&stable yield in the double cropping rice the suitable sowing date in the double-season rice under the mechanized rice-rice-oilseed rape triple-cropping system could be postponed until 4^th Apr.in the early season and 6^th Jul..Meanwhile,machine-transplanting seedling age could be extended about 5days and 10days.