Interaction Effects Of Planting Density And Nitrogen Application On Fresh Leaf Quality And Baking Characteristics Of Baked Tobacco G80

There is a close relationship between baking characteristics,fresh leaf quality and post-baking quality of roasted tobacco.Cultivation management measures,climatic factors,genetic factors,maturity,etc.,among which cultivation management measures are the most exogenous factors with the greatest human control effect.To investigate the relationship between cultivation factors such as nitrogen application and density and the baking characteristics of G80,this experiment used G80 as the test material and adopted a two-factor experiment with planting density as the main zone and nitrogen fertilizer application as the secondary zone,setting three planting density levels[D1(15150plants/hm~2),D2(16650 plants/hm~2),D3(18495 plants/hm~2)]and Three levels of nitrogen fertilizer application[N1(150.00 kg/hm~2),N2(172.50 kg/hm~2)and N3(195.00 kg/hm~2)]were used to obtain mature fresh tobacco leaves during the same harvesting period and then carry out baking tests to study the effects of planting density and nitrogen fertilizer application and their interactions on the quality and baking characteristics of roasted G80fresh tobacco leaves.The main results of the study are as follows.(1)Effects on the quality of fresh tobacco leaves of roasted tobacco G80.The SPAD value,chlorophyll content,total water content and polyphenol oxidase activity of the middle and upper leaves of high-density treatment D3(18495 plants/hm~2)were lower than those of medium density treatment D2(16650 plants/hm~2)and low-density treatment D1(15150plants/hm~2),while the total sugar content was relatively higher,so the quality of fresh tobacco leaves of treatment D3 was slightly better than those of treatment D1 and D2.At the same planting density level,the polyphenol oxidase activity of mature fresh tobacco leaves was significantly reduced with the increase in nitrogen application.The combination of planting density D3(18,495 plants/hm~2)and N3(195.00 kg/hm~2)was the most favorable for improving the quality of fresh tobacco leaves of roasted tobacco G80 and laying a good foundation for the formation of baking characteristics of tobacco leaves.(2)Effect on discoloration characteristics of roasted tobacco G80 under dark box conditions.The leaf base of treatment D3 started to turn yellow earlier than treatments D1and D2.The combination of planting density D3(18,495 plants/hm~2)and N3(195.00 kg/hm~2)in the middle and upper parts of the leaves showed better baking resistance and ease of baking under dark box conditions.(3)Effect on yellowing characteristics of roasted tobacco G80.The degradation rate of the middle leaves was higher than that of the upper leaves in the first 24 h of the baking process,and the degradation rate was faster,with good yellowing characteristics,but the degradation rate slowed down in the late baking period,and the pigment degradation was incomplete;during the baking process,the chlorophyll degradation rate of roasted G80tobacco under treatment D3 was faster than that of treatment D1 and treatment D2,and the high-density treatment D3 had a certain promotion effect on the yellowing of tobacco leaves in baking;treatment D3N3(The chlorophyll degradation rate of treatment D3N3(18495plants/hm~2,195.00kg/hm~2)was the fastest,and the baking characteristics were easy to bake.(4)Effect on water loss characteristics of roasted tobacco G80.In the small drainage stage-yellowing stage,the water loss rates of upper leaf treatment D3N3,treatment D1N3and middle leaf treatment D3N3,treatment D2N1 and treatment D2N3 were all greater than0.19%/h.The water loss rates were faster,which laid a good foundation for the large drainage stage.The water loss characteristics and coordination of treatment D3N3(planting density of 18495 plants/hm~2 with a nitrogen application rate of 195.00 kg/hm~2)were the best.(5)Effect on browning characteristics of roasted tobacco G80.The enzyme activity of polyphenol oxidase decreased with the increase of planting density and nitrogen application during baking,while the interaction effect of the two factors was not significant,and the enzyme activity of the combination of the best D treatment and the best N treatment,treatment D3N3(planting density 18495 plants/hm~2 and nitrogen application 195.00 kg/hm~2),remained at a low level in the early and late stages of color fixation.The enzyme activity of treatment D3N3(planting density 18,495 plants hm~2 and nitrogen application 195.00 kg hm~2)was kept at a low level in the early and late stages of color fixation,which had better baking tolerance and color fixation characteristics.(6)Effect on the post-baking chemical composition of roasted tobacco G80.The total sugar content of post-baking tobacco leaves in high-density treatment D3 was greater than that in medium-density treatment D2 and low-density treatment D1,and the content was appropriate.The total sugar and reducing sugar contents in the middle tobacco leaves of high N treatment N3 were significantly greater than those of low nitrogen treatment N1 and medium nitrogen treatment N2.The differences in nicotine contents between treatments were not significant.Treatment D3N3(planting density 18495 plants/hm~2 and nitrogen application 195.00 kg/hm~2)had suitable total sugar content,relatively low nicotine content,and a more harmonious chemical composition.A comprehensive comparison of the physiological indicators of different parts showed that the planting density D3(18495 plants/hm~2)had a better quality of fresh tobacco compared with D1(15150 plants/hm~2)and D2(16650 plants/hm~2),which laid the foundation for the formation of easy baking and baking resistance of tobacco leaves.The combination of planting density of 18495 plants/hm~2 and nitrogen fertilizer dosage of 195.00 kg/hm~2 was most favorable to improve the fresh tobacco leaf quality and baking characteristics of roasted tobacco G80 and improve the baking quality and chemical quality of tobacco leaves.