| Machine transplanting for rice is widely accepted in Jiangsu Province at the beginning of this century.Recent changes in the machine-transplanting rice production include increment in planting density,simplification of seedling preparation and application of chemical control for seedling.Additionally,excessive application of nitrogen fertilizer is a persistent issue lasted for several decades in Jiangsu Province.Average nitrogen application rate in Jiangsu Province is 330kg per hectare,which exceeds the upper range of recommended nitrogen application at 20%and even reaches 40%to 50%in a few regions.The nitrogen utilization efficiency is generally low,resulting in waste of resources as well as environmental issues.Therefore,reducing nitrogen application rate and increasing nitrogen fertilizer utilization efficiency through cultivation management become a imperative task.In this report,machine transplanting suitable rice variety Huaidao No.5 was used as a test material for the most suitable seedling preparation scheme and field nitrogen fertilizer operation.The research results are as follows:1.Test of seeding rate:1)Yield and components:As seeding rate increases,the yield showed a significant reduction trend.The highest yield was achieved in 75g per plate treatment,being 15.37%higher than other treatments.However,the yield differences from 100g and 125g treatment was not significant.Considering all the factors,the recommendation seeding rate is 110g per plate under the plastic tray nursery method.Further analysis showed that the number of panicles per mu and the number of grains per panicles showed a reduction trend with the increase of seeding rate.They all reached the highest at 75g per plate,which was 2.41%-10.95%and 6.15%-31.73%higher than other treatments,respectively.2)The relationship of source and sink:As seeding rate increases,the high-efficiency leaf area index at heading stage,total leaf area index at heading stage,and total leaf area index at maturity showed a decreasing trend.The LAI was the highest at 75g per plate,which was 10.45%-33.42%,9.48%-33.42%,and 1.89%-22.73%higher than other treatments,respectively.With the increase of seeding rate,the sink capacity showed a significant decrease,with the highest sink size achieved in 75g per plate treatment,which was 5.24%-34.71%higher than other treatments.3)Material production and distribution:As seeding rate increases,the dry matter production before heading,maturity and after heading showed a significant decrease trend,which was the highest in 75g per plate,and increased by 0.64%-41.66%,6.23%-39.97%and 15.84%-37.52%respectively.As seeding rate increases,the economic coefficient showed a downward trend.The highest value was achieved in 75g per plate treatment,which was 0.72-4.33%higher than other treatments4)Nitrogen absorption and utilization:As seeding rate increases,nitrogen uptake showed a significant reduction trend before heading,after heading and at maturity stage,which was the highest in 75g per plate,and increased by 0.37%-70.16%,2.68%-73.53%,and 14.48%-90.45%,respectively,compared with other treatments.Nitrogen grain production efficiency and nitrogen fertilizer utilization rate decreased significantly with the increase of seeding rate.The treatments were highest at 75g per plate,and increased by 3.37%-23.68%and 0.91%-14.72%,respectively,compared with other treatments.2.Test of the number of seedlings per hole:1)Yield and componentsWith the increase in the number of seedlings per hole,the yield showed a significant increment first and then decreased.The yield was the highest at 5 seedlings per holr,which was 2.75%-17.18%higher than other treatments.Further analysis showed the number of panicles per mu increased significantly,and the number of grains per panicle,seed setting rate and 1000-grain weight showed a downward trend with the increase of the number of seedlings per hole.2)The relationship of source and sink:With the increase of the number of seedlings per hole,the high-efficiency leaf area index at heading stage,total leaf area index at heading stage,and total leaf area index at maturity showed a significant increase.All were treated with M7,which increased by 9.77%-67.95%,27.04%-89.68%,and 1.05%-77.78%,respectively.With the increase in the number of seedlings per hole,the sink capacity increased significantly.M7 treatment was the highest,increasing 19.43%-29.2%over other treatments3)Material production and distributionWith the increase of the number of seedlings per hole,the dry matter production before and during the heading period increased,which was the highest in 7 seedlings per hole,and was 24.84%-50.87%and 3.71%-24.83%higher than other treatments.The dry matter production after heading increased first and then decreased with the increase of the number of seedlings per hole.The highest treatment with 5 seedlings per hole was 12.34%-25.9%higher than other treatments,indicating that the dry matter production decreased after heading.With the increase of the number of seedlings per hole,the economic coefficient increased first and then decreased,and the treatment with 3 seedlings per hole was the highest,which increased by 4.69%-6.08%compared with other treatments.4)Nitrogen absorption and utilization:With the increase of the number of seedlings per hole,the nitrogen uptake before heading,maturity and after heading increased first and then decreased,and the highest was treated with 5 seedlings per hole,which increased by 5.46%-21.36%,9.95%-20.52%and 16.4%-40.3%,respectively.With the increase of the number of seedlings per hole,nitrogen grain production efficiency was the highest in 7 seedlings per hole,which increased by 8.52%-10.83%compared with other treatments.The nitrogen fertilizer utilization rate increased first and then decreased,and the treatment with 5 seedlings per hole was the highest,which increased by 6.05%-14.95%compared with other treatments.3.Test of the interaction between nitrogen application and planting density;1)Yield and components:Under the same nitrogen treatment,the yield increased significantly with the increase of planting density,with the highest treatment at 22,000 holes per mu,which was 24.59%-35.00%higher than other treatments.Further analysis showed that with the increase of planting density,the number of panicles per mu increased significantly,and the number of grains per panicle,seed setting rate and 1000-grain weight did not change significantly.Under the same density treatment,with the increase of nitrogen application rate,the yield increased first and then decreased.The treatment with 20kg per mu was the highest,which was 1.19%-40.8%higher than other treatments.Further analysis showed that with the increase of nitrogen application rate,the number of panicles per mu and the number of grains per panicles increased first and then decreased,and the seed setting rate and 1000-grain weight decreased.2)The relationship of source and sink:Under the same nitrogen treatment,with the increase of planting density,the high-efficiency leaf area index at heading stage,total leaf area index at heading stage,and total leaf area index at maturity showed a significant increase trend,with the highest treatment at 22,000 hole per mu,which was higher than other treatments,with the increase of 17.98%-128.72%,29.36%-118.77%,13.64%-41.10%.The sink capacity showed an increasing trend,with the highest treatment at 22,000 holes per mu,which increased by 18.10%-22.55%compared with other treatments.Under the same density treatment,with the increase of nitrogen application rate,the high leaf area coefficient at heading stage and the total leaf area coefficient at heading stage showed a significant increase trend,and the treatment with N3 was the highest,which increased by 5.34%-133.89%,4.81%-109.00%,respectively,compared with other treatments.The leaf area coefficient increased first and then decreased.The treatment with N2 was the highest,which increased by 5.35%-50.99%compared with other treatments.The sink capacity increased first and then decreased,and the treatment with N2 was the highest,which increased by 22.90%-52.50%compared with other treatments.3)Material production and distribution:Under the same nitrogen treatment,the dry matter production at jointing stage,heading stage and maturity increased with the increase of planting density,and the highest treatment was carried out at 22,000 holes per mu which increased by 17.26%-40.15%,15.13%-19.63%and 22.54%-32.18%respectively compared with other treatments.The dry matter production before heading and the dry matter production after heading showed an increasing trend,with the highest treatment at 22,000 holes per mu,which increased by 11.53%-14.10%and 40.46%-66.85%,respectively.At the heading stage,the proportion of dry weight of stems decreased,and the ratio of leaf dry weight and panicle dry weight increased.Under the same density treatment,with the increase of nitrogen application rate,the dry matter production at jointing stage increased,and the treatment with N3 was the highest,which increased by 0.73%-51.65%compared with other treatments.The dry matter production at the heading stage and maturity stage increased first and then decreased,and the highest was treated by N2,which increased by 0.57%-48.93%and 0.65%-45.86%,respectively.The dry matter production before heading increased first and then decreased,and the highest treatment with N1 was 12.10%-21.32%higher than other treatments.The dry matter production after heading increased first and then decreased,and the highest was treated with N2,which was 0.81%-83.29%higher than other treatments.At the heading stage,the dry weight ratio of leaf dry matter increased,and the dry weight ratio of panicle dry matter decreased.At the maturity stage,the proportion of stem dry matter and the dry weight of leaf dry matter increased,and the ratio of dry weight to dry weight decreased.The economic coefficient is decreasing.4)Nitrogen absorption and utilization:Under the same nitrogen application level,with the increase of planting density,the nitrogen accumulation of most of the heading,after heading and maturity stages increased.At the same density level,with the increase of nitrogen application rate,the nitrogen accumulation in the heading stage increased at the heading stage.The nitrogen accumulation in the mature stage was 15,000 and the highest in N2-1.5.The density of 18,000 and 22,000 was the highest in N3.The lowest nitrogen accumulation in the population after heading was N3.Increasing the density is conducive to the utilization of nitrogen fertilizer,the agronomic utilization rate of nitrogen fertilizer,and the increase of nitrogen fertilizer partial productivity.However,the nitrogen demand of 100 kg of grain is reduced,the nitrogen fertilizer utilization rate of nitrogen fertilizer,the agronomic utilization rate of nitrogen fertilizer,and the partial productivity of nitrogen fertilizer are firstly increased and then decreased,but the nitrogen demand for 100 kg of grain showed an increasing trend.Under the same nitrogen application level,with the increase of density,the nitrogen accumulation of most individuals at heading,heading and maturity increased.At the same density level,with the increase of nitrogen application,heading Nitrogen accumulation in individuals at the maturity and maturity stages showed an increasing trend,and there was no significant change in nitrogen accumulation in individuals after heading.Increasing the density is beneficial to the nitrogen uptake intensity of the heading stage,the nitrogen uptake intensity of the population after heading,the nitrogen uptake intensity of the mature stage,the nitrogen uptake intensity of the individual at the heading stage,and the nitrogen uptake intensity of the mature stage.At the heading stage,the nitrogen uptake intensity of the individuals increased,but the nitrogen uptake intensity at the heading stage,the nitrogen uptake intensity at the maturity stage group,and the individual nitrogen uptake intensity after heading increased first and then decreased.4.Application proportion test of panicle fertilizer:1)yield and components:The yield of straw returning to the field was 2.69%higher than that of straw without returning to the field.In the straw returning treatment,the yield of S21 treatment was the highest,which was 1.09%-7.81%higher than other treatments.The yield of S11 treatment was the highest when straw was not returned to the field,which was 1.19%-12.92%higher than other treatments.Further analysis showed that under the condition of returning straw to field,the number of grains per panicle and the seed setting rate were higher under S21 treatment,and the number of spikes per seed and the seed setting rate were higher under S11 treatment.2)The relationship of source and sink:Under the condition of returning straw to field,total leaf area index at heading stage,and total leaf area index at maturity of S21 treatment were the highest,which were 6.25%-23.10%and 14.01%-45.53%higher than other treatments,total leaf area index at heading stage,and total leaf area index at maturity of S11 were the highest at the heading stage without straw returning,which was 0.91%-14.31%and 4.33%-14.48%,respectively.The S21 treatment had the highest sink capacity under straw returning conditions,which was 2.66%and 12.33%higher than other treatments.The S11 treatment had the highest sink capacity when straw was not returned to the field,which was 2.62%and 14.57%higher than other treatments.3)Material production and distribution:Under the condition of returning straw to field,S21 treatment had the highest dry matter production before heading,after heading and at maturity stage,which was 1.72%-1.84%,1.45%-4.79%and 1.12%-10.15%higher than other treatments.Under the condition of no returning to the field,the S11 treatment the dry matter production before heading,after heading and at maturity stage was the highest,which was 1.92%-14.53%,1.6%-11.35%and 0.85%-6.32%higher than other treatments.Under the condition of straw returning to field,the economic coefficient of S21 treatment was the highest,which was 1.92%and 8.16%higher than other treatments.The S11 treatment had the highest economic coefficient under the condition of no straw returning,which was 3.92%and 8.16%higher than other treatments.4)Nitrogen absorption and utilization:Under the condition of returning straw to field,the nitrogen uptake before heading,after heading and at maturity stage was the highest,which was 3.12%-7.32%,3.50%-13.89%and 5.69%-74.71%higher than other treatments;The nitrogen uptake of S11 before heading,after heading and at maturity stage was the highest,which was 5.27%-5.62%,4.65%-10.10%,1.10%-36.73%higher than other treatments.Under the condition of straw returning to field,the utilization rate of nitrogen fertilizer was the highest in S21 treatment,which was 0.41%-8.82%higher than other treatments.The production efficiency of nitrogen in S12 treatment was the highest.The utilization rate of nitrogen fertilizer was the highest in S11 treatment under straw returning,which was 2.91%-7.76%higher than other treatments.S21 nitrogen grain production efficiency was the highest.5.Console:Under the conditions of this experiment,the optimum seeding rate of the dry seeds of rice transplanted rice is between 100g and 125g.The best suitable planting transplanting density is 22,000 holes/666.7m2 during transplanting.The suitable planting seedlings number is 5 seedlings per hole.The optimum nitrogen application rate after transplanting is 20kg/666.7m2.Under the conditions of wheat and straw returning to the field,the proportion of spikelet-promoting fertilizer and protecting-flower fertilizer in the panicle fertilizer period is the best application ratio 2:1.These cultural practices are conducive to the realization of high quality,high yield and high efficiency production targets for rice. |
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