| For the stability of quality and output of new flue-cured tobacco variety Yunyan99 in Lijiang tobacco,improving tobacco quality and industrial availability,the orthogonal test method was carried out in Yongsheng County of Lijiang Cityin2016.The effect of different planting density,nitrogen rate and leaf number index on agronomictraits,root activity,photosynthetic parameters,neutral aroma substanc and economic traits ofYunyan 99 was systematically studied.The suitable planting density,nitrogen application amount and leaf numberof Yunyan 99 was explored out to expand efforts to promote and improve the quality of tobacco production,and to provide technical guidancefor Yunyan 99 in Lijiang tobacco area.The main results are as follows:1 Nitrogen fertilizer had influences on Agronomic Traits of Yunyan 99 at early stage,and planting densitywas significantly correlated to agronomic traits at the late stage of growth;The plant height increase significantly with theincrease ofthe amount of nitrogen and number of leaves.The maximum leaf length and leaf area were positively correlated with nitrogen rate and planting density was negatively.With the increase of the number of leaves,the maximum leaf width had a decreasing trend.Generally speaking,when the planting density of Yunyan 99 was 16500/hm2,the amount of nitrogen was between 157.5kg/hm2-180kg/hm~2 and the number of remained leaves was 17,the agronomic characters of the field were better.2 The root activity of Yunyan 99 was firstly increased and then decreased with the growth of plant.There was a significant correlation between the amount of nitrogen application and planting density and rosette stage root activity.The plant density,nitrogen application amount and leaf number had significantcorrelation with root activity at fast-growing stage.The planting density and leaf number had significantcorrelationon root activity at the mature stage;With the increase of planting density,the root activity of tobacco plantfirst increased and then decreased;Increasing the amount of nitrogen fertilizer could increase the root activity in a certain range,but the amount of nitrogen was higher,the root activity value was not obviously increased;When the number of leaves was higher,the root activity of Yunyan 99 was higher.In general,the root activity of the combination of N3(180kg/hm~2),M2(16500 plants/hm~2)and L3(19 leaves)was better.3 Effects of planting density and the number of leaves on photosynthetic characteristics of Yunyan 99 were larger.With the increase of planting density,the net photosynthetic rate increased first and then decreased.Increasing number of leaves could improve the photosynthetic characteristics of Yunyan 99.In general,the photosynthetic characteristics of N2(157.5kg/hm~2),M2(16500 plants/hm~2)and L3(19 leaves)were better than those of the other treatments.4 Nitrogen had positive correlation with chlorophyll and carotenoid content of Yunyan 99.The chlorophyll content first increased and then decreased with the increase of planting density,the increase in a certain range of the number of leaves would increase the content of carotenoids.Generally speaking,when the nitrogen application rate of Yunyan 99 was 157.5kg/hm~2,the planting density was between16500-18000 plants/hm~2,and thenumber of remained leaves was 17,the content of chlorophyll and carotenoid in Yunyan 99 were more coordinated.5 The planting density,nitrogen amount and leaf number all had correlations with neutral aroma substances.The number of leaves had greater effect on the neutral aroma substances;The total aroma content increasewith the increase of number of leaves remained.It showed a trend of first increasing and then decreasingwith the increase of nitrogen.The increase of planting density at a certain range was conducive to the accumulation of neutral aroma substances.In general,when the planting density was between 16500-18000 plants/hm~2,the nitrogen amount was 157.5kg/hm~2 and the leaves remained 19 times,the content of neutral aroma substances in Yunyan 99 was abundant.6There was a significant correlation between planting density and economic traits of Yunyan 99.The amount of nitrogen had a significant correlation with the yield and output value,and leaves numberhad a significant effect on the proportion of high-grade tobacco;When the planting density and nitrogen application amount were too large or too small,it was not conducive to the qualityformation of Yunyan 99,and theeconomic benefitsreduced.Increase the number of leaves would enhance the effect on economic characters of Yunyan 99.When the planting density was 16500plants/hm~2,the amount of nitrogen was 157.5kg/hm~2,and the number of remained leaves was 15-17,Yunyan 99 could get better economic benefits in the local.7 The amount of nitrogen had great effect onchemical components of tobacco leaves of different parts of Yunyan 99.Increasing nitrogen fertilizer could increase the content of total sugar,reducing sugar and total nitrogen of upper leaves.The total sugar and reducing sugarin middle leaves was lower with higher nitrogen content.The reducing sugar,total nitrogen and nicotine content showed a trend of first increasing and then decreasing in lower leaves;Thetotal sugar and reducing sugar of upper and middle leaveswere positively correlated with planting density,and the content of starch reduced with the increase of planting density.The smaller or larger planting density would result in the increasechemical composition of of lower leaf;The increase number of leaves would obviouslyreduce the nicotine content of upperand lower leaves.Generally speaking,when the nitrogen application rate was157.5kg/hm~2,the planting density was 16500 plants/hm~2 and the leaves number was19,the chemical composition of Yunyan 99 was relatively coordinated.In conclusion,when the planting density of Yunyan 99 in Yongsheng tobacco growing area of Lijiang was 16500 plants/hm~2,the nitrogen application rate was157.5kg/hm~2,and the number of leaves remained was 17-19,the comprehensive performance was better. |
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