Influences Of Planting Density And Nitrogen Application Rate On The Quality Of Flue-cured Tobacco Leaves

The effects of interaction between planting density and nitrogen application rate on the quality of upper and middle leaves designed in the split-plot experiment was studied with Yunyan 87 as the sample from 2014 to 2015.The inner quality and the physiological changes laws of flue-cured tobacco in different conditions were analyzed and the results showed that:1.The routine chemical components of upper leaves was more suitable in medium density of 16 500 plants/hm~2 or low nitrogen rate of 45 kg/hm~2.The routine chemical compositions of middle leaves was more appropriate in high density of 19 500 plants/hm~2 or low nitrogen rate of 45 kg/hm~2.The routine chemical components was more suitable as the nitrogen application rate improved in different stalk positions of the flue-cured tobacco leaves.That both upper and middle leaves in flue-cured tobacco were suitable in the combination treatment of medium density and low nitrogen(16 500 plants/hm~2,45 kg/hm~2).2.The planting density,nitrogen rate had extremely significant positive correlations with upper and middle leaves,and significantly improved neutral aroma components contents.The upper leaves in combinations treatments of high planting density,high nitrogen(19 500 plants/hm~2,75 kg/hm~2)and high planting density,medium nitrogen rate(19 500 plants/hm~2,60 kg/hm~2)had higher total aroma amounts.The interactions of medium density,high nitrogen(16 500 plants/hm~2,75 kg/hm~2)and high density,high nitrogen(19 500 plants/hm~2,75 kg/hm~2)made the total aroma amounts of middle leaves higher.3.The interaction of planting density and nitrogen rate had a distinct influence on microelements contents of upper leaves,less on the effect of nitrogen rate,and least on the effect of planting density.Nitrogen rate have remarkable and biggest effect on macroelement contents of upper leaves.The interaction of planting density and nitrogen rate had the most significant influence on microelements contents of middle leaves,the effect of density was less than the interaction's,and the effect of nitrogen rate was the least.The sequence and extent of macroelements contents' effects on middle leaves were same to the sequence and extent of upper leaves' microelements contents.4.The upper leaves had the largest amount of total polyphenols contents of chlorogenic acid,scopoletin and rutin in the high density 19 500 plants/hm~2 or low nitrogen rate of 45 kg/hm~2.The total amount of the interaction with low density and low nitrogen rate was higher than the others.The largest amount of total polyphenols contents of middle leaves was in the low density of 13 500 plants/hm~2 or medium nitrogen rate of 60 kg/hm~2,and the maximum amount of polyphenols contents in the combination treatment was the interaction of high density with medium nitrogen rate(19 500 plants/hm~2,75 kg/hm~2).5.The upper leaves of flue-cured tobacco had better physical properties in high density of 19 500 plants/hm~2 or low nitrogen rate of 45 kg/hm~2.The middle leaves had better physical properties in low density of 16 500 plants/hm~2 or low nitrogen rate of 45 kg/hm~2.Planting density had a distinct influence on physical properties of tobacco,less on the effect of the interaction with density and nitrogen,and least on the effect of nitrogen.The influences of planting density,nitrogen rate and the interaction of both on upper leaves were more significant than middle leaves.6.The planting density was the main factor in the sensory evaluation of flue-cured tobacco,and the increase of density could control the improvement of sensory quality of upper and central leaves.The gain of nitrogen rate,in a certain degree,could improve smoking quality.The better smoking quality of upper and middle leaves were concentrated in the low planting density of 16 500 plants/hm~2.7.The flue-cured tobacco chlorophyll degradation time was early in low density and low nitrogen rate than the others and the chlorophyll contents showed a trend of decline from forty days after transplanting.Falling rate of chlorophyll were positively related to nitrogen rate,and had a negative correlation with density.The chlorophyll contents was abundant in high density of 19 500 plants/hm~2 or medium nitrogen rate of 60 kg/hm~2 in mature period.The chlorophyll had maximum contents in the interactions treatment of the low density and medium nitrogen rate(13 500 plants/hm~2,60 kg/hm~2).The carotenoid contents was abundant in high density of 19 500 plants/hm~2 or low nitrogen rate of 45 kg/hm~2.The carotenoid had maximum contents in the interactions treatment of the high density and low nitrogen rate(19 500 plants/hm~2,60 kg/hm~2).8.The quality of flue-cured tobacco showed best on planting density of 13 500 plants/hm~2 cooperated with nitrogen rate of 60 kg/hm~2 according to the influences of the interaction of different planting density and nitrogen rate on chemical quality,physical properties and sensory evaluation,etc.