| In order to improve the yield and quality of flue-cured tobacco in Chenzhou,the field experiments were carried out in 2015-2016 to study the effects of planting density,nitrogen fertilizer,plant configuration and the interaction between plant density and nitrogen on flue-cured tobacco Yunyan 99.The suitable tobacco planting density,nitrogen fertilizer and plant configuration in Chenzhou was further clarified.The main results are as follows:1.With the increment of nitrogen fertilizer rate,the plant height,stem diameter and leaf area increased and the economic characteristics of flue-cured tobacco were significantly improved.The proportion of high-grade and middle-grade leaves,yield,average price and output of N3(N 172.5kg/hm~2)were significantly higher than that of N1(N 127.5kg/hm~2)and N2(N 150.0kg/hm~2).Whereas in consideration of the chemical components of the flue-cured tobacco,N2 treatment had better quality of flue-cured tobacco.2.The planting density had significant effects on plant height,while no obvious effect on other agronomic characteristics.The economic characteristics of D1(16500 plant/hm~2)was slightly better than that of D2.There were some differences in the content of chemical components of tobacco leaves between D1 and D2(18000 plant/hm~2)and mainly embodied in the middle and lower part of tobacco leaves.In comprehensive consideration of the chemical components index,D1 treatment on tobacco quality better.3.The effects of plant configuration on agronomic characteristics during the maturity period was relatively large.In general,the economic characteristics of T1(1.2m×0.5m)was better than that of T2(1.0m×0.6m).There was no significant effect of plant configuration on chemical components of flue-cured tobacco leaves.The potassium content in tobacco leaves increased with 1.2m×0.5m plant configuration mode.4.In the double factor experiment,the key factors affecting agronomic characteristics in rosette stage and maturity stage were the amount of nitrogen fertilizer and planting density respectively.The key factors affecting the economic characteristics of tobacco was the planting density,nitrogen rate and the interaction could also affect.With the increase of planting density and nitrogen rate,the tobacco yield gradually increased,while the other economic characteristics were first increased and then decreased.The best economic characteristics was gained in treatment of planting density of 16500 plants/hm~2 and nitrogen rate of 157.5kg/hm~2.There was significant effects of planting density and the amount of nitrogen fertilizer on photosynthesis of tobacco.The interaction had significant effect on Pn and Tr of the flue-cured tobacco.Overall,the planting density played a major role in Pn and Gs,the amount of nitrogen fertilizer played a major role in Tr,and the interaction effect was relatively small.Pn,Gs and Tr was highest,Ci was relatively low,and the of photosynthetic capacity flue-cured tobacco was the strongest with the planting density of 16500 plants/hm~2and the amount of nitrogen fertilizer of 157.5kg/hm~2.5.In the double factor experiment,the key factor affecting the physical indexes of flue-cured tobacco was the interaction of planting density and nitrogen rate.The physical indexes of flue-cured leaves was best with the planting density of 16500 tobacco plants/hm~2and nitrogen rate of 135-157.5kg/hm~2.The key factors affecting the chemical components of tobacco leaves was nitrogen rate,and the secondary factor was planting density.Through the adjustment of the combination of planting density and nitrogen rate,chemical components of tobacco leaves could be coordinated.The chemical components of Yunyan 99 was relative coordinated and the nicotine content was relative low with the planting density of16500-18000 tobacco plants/hm~2 and nitrogen rate of 135-157.5 kg/hm~2.In the respect the contents of neutral aroma substances of middle leaves,the accumulation of neutral aroma substances in tobacco leaves was larger with the planting density between 16500-18000tobacco plants/hm~2 and nitrogen rate of 157.5kg/hm~2.Treatment of planting density of 16500plants/hm~2 and nitrogen rate of 157.5kg/hm~2,which was most recommended combination,had more neutral aroma content.The smoking quality of middle leaves in treatment of planting density of 16500 plants/hm~2 and nitrogen rate of 180 kg/hm~2 scored the highest overall.In general,smoking quality of flue-cured tobacco leaves was better under planting density of 16500 plants/hm~2.So the suitable nitrogen rate,density and plant configuration of Yunyan 99 planted in Jiahe,Chenzhou was 135~157.5kg/hm~2,16500/hm~2 and 1.2m×0.5m,respectively. |
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