The Effects Of Different Potassium Application Rate,Topping Time And Harvesting Time On The Yield And Quality Of Sun-cured Tobacco

In order to coordinate the nutrition balance of tobacco plants and optimize the cultivation techniques of sun-cured tobacco in Yanbian,the different potassium application rates were studied by using the No.6 of Yanbian sun-cured tobacco as the tested variety and the orthogonal design of L9(33)in the field.The effect of topping period and harvesting period on the yield and quality of sun-cured tobacco.The main findings are as follows:(1)The effects of different potassium application amount and topping stage on agronomic characters,leaf tissue structure and photosynthetic characteristics during the growth process of No.6 of Yanbian sun-cured tobacco:In the early growth period,potassium content has little effect on the botany traits of tobacco plants,and at a later stage,With the increase of potassium fertilizer content,the botanical characters of the tobacco plant increased significantly.And under the same potassium fertilizer level,topping could promote the growth and development of tobacco plants in different degrees;With the increase of leaf age,the maturity of tobacco leaves increased,and the appearance quality of fresh leaves was constantly improved,However,the changes of different parts are basically the same;During the whole growth of the tobacco plant,the net photosynthetic rate,stomatal conductance and transpiration rate showed a decreasing trend,however,intercellular CO2 showed a trend of decreasing first and then rising.After entering the mature period,the net photosynthetic rate and transpiration rate at the later stage were lower than that of the first smoked plant,and the intercellular CO2 and the stomatal conductance were the opposite;Under the same topping condition,blade thickness,thickness of cavernous tissue and the Ratio of leaf thickness/palisade tissue were negatively correlated with potassium application,the thickness of the palisade tissue,the tissue ratio(the thickness of the palisade tissue/the thickness of the sponge tissue)increased with the increase of potassium application.At the same potassium level,the thickness of the leaf blade,the thickness of the palisade tissue,the thickness of the spongy tissue and the tissue ratio on squaring topping were significantly higher than that of the flowering topping and full flowering topping.(2)The effects of potassium application amount,topping time and harvest time on the quality of tobacco leaves after No.6 of Yanbian sun-cured tobacco:The results of orthogonal analysis show that the content of potash is the leading factor of each indicator of economic traits,that is,with the increase of fertilizing quantity,the yield and output value both show an upward trend.However,when the potassium application reaches a certain level,the yield of tobacco leaves will no longer increase,that is,the amount of fertilization is 150kg/hm2.Compared with the 120kg/hm2 fertilizer and 180kg/hm2 the yield increased by 35.97%and 8.9%respectively.The collection of 47d or 54d after flowering topping can improve the index of economic traits;Effect of chemical composition,considering nitrogen index,the optimal combination of the Yanbian area is 150kg/hm2 of pure potassium,squaring topping,harvest on 54days after flowering topping(A2B,C3);Considering the optimal combination of carbohydrate index,cultivation of Yanbian is pure potassium 150kg/hm2,full flowering topping,harvest on 54 days after flowering topping(A2B3C3).Considering various factors,the best combination of cultivation measures forYanbian region is pure potassium 150kg/hm2,flowering topping,harvest on 54days after flowering topping(A2B2C3).The combination of the cultivation measures should be verified by extensive field experiments.