Effects of mechanical transplanted methods on yield formation of rice following winter wheat
【摘要】：[Objective]The objective of this 2-year field experiments were to compare the grian yield under three different mechanical rice-planting methods.[Methods]Using cultivars Chunyou84(japonica hybrid rice) and Zhendao18(conventional japonica rice) in 2014,and cultivars Yongyou538(Japonica hybrid rice) and Zhendao18 in 2015 as materials,the growth characteristics,canopy architecture and their effects on grain yield formation for rice transplanted by different methods were determined.The three treatments were a blanket-type nursery tray(Flat-S treatment),a bowl-type nursery tray(Pot-S treatment),and a pot-style/blanket-type nursery tray(Pot-flat-S treatment).The sowing rate refers to field production across both years and all three cultivars.In the Pot-S treatment,each tray was sown with the 2 BD-300 seeding machine(LSP-40 AM;Yameike Inc.,China) contained about 1800 seeds(3 seeds per hole,and 448 holes).In the Flat-S and Pot-flat-S treatment,each tray was sown with the 2 BZP-800 machine(SR-K800 CN;Kubota Inc.,Japan) contained approximately 2300~2600 seeds(60 g seeds).For all treatments,the 25-day-old seedlings were machinical transplanted to field with three plants per hill in both years.And,plant spacing was 33 cm×12 cm(row lengthx row width) in the Pot-S treatment,and 30 cm×13.2 cm(row lengthx row width) in other treatments.The net photosynthetic rate,leaf area index,dry matter accumulation,and matter translocation from the sheath at flowering to the kernel were significantly higher in the Pot-S treatment than that in other two treatments(p0.05).[Results]The Pot-S treatment(9.15-11.81×10~3 kg hm~(-2)) showed the highest grain yield,followed by the Pot-flat-S treatment(8.84-10.62×10~3 kg hm~(-2)),and then the Flat-S treatment(8.3-9.78×10~3 kg hm~(-2)) across three cultivars and two years.The relative heights of the1~(st),2~(nd),and 3~(rd) leaves from the top of the plant were higher in the Pot-S treatment than that in the other two treatments,and there was more space between adjacent leaves at the top of the canopy in the Pot-S treatment than in the other two treatments.The relative height of the 1~(st) and 2~(nd) leaves,the droop angle of the 1~(st) and 2~(nd) leaves,and the height difference between the 1~(st)and 2~(nd) leaves affected the source and sink traits,and therefore,significantly affected yield.[Conclusion]Thus,the spatial distribution characteristics of the 1~(st) and 2~(nd) leaves were crucial for the high yield formation of mechanically transplanted rice.