Study On The Optimized Cultivation Techniques Of Mechanical Transplanting Fertilizer Density For Rice Seeding

The experiment was conducted at Kalima Rice Experimental Station,Shenyang Agricultural University,Liaozhong District,Shenyang from 2020 to 2021.The tested rice varieties are Beijing 1702 and Shennong 9816,both of which are mid-late maturing varieties.Fertilizer treatment was carried out in three stages:base fertilizer,tiller fertilizer and ear fertilizer.Urea was applied in base fertilizer before rake,ammonium sulfate was applied in tiller fertilizer at 60%leaf age,and ammonium sulfate was applied in ear fertilizer at 80%leaf age.Each hm² contained N:195kg,and the nitrogen content ratio of basal fertilizer and tillering fertilizer was 6:4.On this basis,the ratio of basal tillering fertilizer and ear fertilizer was 6:4,7:3 and 8:2,and the control（CK）without nitrogen fertilizer was set.All phosphate fertilizer is applied before harrowing;potassium fertilizer was applied according to 50%of base fertilizer and 50%of panicle fertilizer,and the period was the same as nitrogen fertilizer.The total amount of phosphorus and potassium was used according to N:P₂O₅:K₂O=2:1:1.Two mechanical transplanting methods were set,namely pot seedling mechanical transplanting（b）and carpet seedling mechanical transplanting（t）,and two density levels,namely row spacing of 30 cm×14 cm and 30 cm×20 cm,respectively.The yield formation and nitrogen absorption and utilization characteristics of pot-seedling mechanical transplanting and carpet-seedling mechanical transplanting under different nitrogen application modes and densities were studied in order to explore the suitable nitrogen application mode and row hole configuration of rice pot-seedling mechanical transplanting,so as to provide theoretical support for the construction of high yield and high efficiency technology of rice pot-seedling mechanical transplanting.The main results are as follows:1.The plant height,leaf age,stem base width,aboveground fresh weight,aboveground dry matter,underground dry matter and seedling index of bowl tray seedling at 53 days after sowing were significantly higher than those of blanket tray seedling,which increased by 11.88%,14.64%,73.75%,31.46%,23.75%,70.83%and 95.00%,respectively.The tolerance time of bowl tray seedling was longer than that of blanket seedling.2.The yields of the b14（pot seedling transplanting spacing 14 cm）model and b20（pot seedling transplanting spacing 20 cm）model with the ratio of basal tiller to panicle fertilization of 6:4 were higher than those of other models.Compared with the b20 model,the yields of Beijing 1702 and Shennong 9816 increased by 2.36%and 13.06%,respectively.Fertilization ratio of 6:4 b14 mode spike grain number increased significantly,b20mode effective spike number and spike grain number increased significantly,and the two models spike rate is higher,the impact on1000-grain weight is not obvious.3.The leaf area index of b14 model with fertilization ratio of 6:4 was larger at filling stage,and the photosynthetic potential increased from heading stage to filling stage.The net photosynthetic rate of b14 and b20 models with fertilization ratio of 6:4 was significantly higher than that of other models at heading and filling stages.The b14 model with the fertilization ratio of 6:4 was helpful for the dry matter accumulation of panicles at maturity stage.The dry matter accumulation of Beijing 1702 was about 17534.92 kg/hm^-2,and that of Shennong 9816 was about 12620.63 kg/hm^-2.The dry matter accumulation at grain filling stage and maturity stage was significantly higher than that of other models.4.The b14 model with fertilization ratio of 6:4 had obvious effects on nitrogen accumulation at heading stage and maturity stage,which was more beneficial to the stage absorption of tillering stage–heading stage and heading stage–maturity stage,and accelerated the nitrogen stage absorption rate.Conducive to leaf,stem sheath output,strengthen the transport capacity of leaves;Nitrogen dry matter production efficiency and Nitrogen grain production efficiency showed a downward trend compared with CK;more stable to improve nitrogen uptake efficiency,nitrogen agronomic efficiency,nitrogen partial productivity.Under the b14 mode of basal tillering:panicle fertilization ratio of 6:4（pot seedling machine spacing of 14 cm）,the mechanized production of rice achieved stable and high yield effect,and obtained efficient fertilization technology.