Effects Of Three Cultivation Techniques On Harvest Maturity,Yield And Quality Of Flue-cured Tobacco In Mountainous Area Of Chongqing

The low temperature conditions during later growth stage of tobacco in mountainous area of Chongqing is very unfavorable factor for normal maturity of tobacco leaves.Therefore,how to raise maturity level of tobacco leaf have become key technologies for improving the quality of flue-cured tobacco in mountainous area of Chongqing-In this study,tobacco cultivar Yunyan 97 was used as experimental material.the spectral reflectance of fresh tobacco leaves with different maturity were measured and the criteria of quantitative maturity of fresh tobacco leaf was established by using USB4000 spectrometer.This study investigated in detail the effects of critical regulated technologies including transplanting periods and topping periods and foliar fertilizer on maturity and yield and quality of Flue-cured tobacco in mountain of Chongqing.Based on above,the optimal control scheme for harvesting tobacco leafwere described.These results lays the theoretical foundation and technical support for improving the quality of flue-cured tobacco in mountainous area of Chongqing.The main researches are as follows:(1)This experiments investigated the relationship among the spectral reflectance,the maturity of fresh tobacco leaves and the quality of flue cured tobacco leaves.The results showed that there was a significant positive correlation between the spectral reflectance and the maturity offresh tobacco leaves.At the same time,fresh tobacco leaves with different maturity level had significant effects on the economic characters,chemical compositions and sensory evaluations of flue-cured tobacco leaves.In addition,with the increasing of harvest maturity of tobacco leaf,some key economical indexes including the yield,average price and the proportion of middle and superior tobacco leaves were increased,and simultaneously more harmonious chemical components were obtained and the sensory evaluation was obviously improved.The results indicated that the spectral reflectance could be used as the index to represent the harvest maturity of tobacco leaf.(2)This experiments studied on the effects of transplanting periods on harvest maturity and yield and quality of tobacco leaf.The results showed that the transplanting time had a significant effect on the maturity level of tobacco leaves,and the fresh tobacco leaf with highest maturity was achieved on May 15th.At the same time,some indexes,such as the economic characters,chemical components and sensory evaluation of flue-cured tobacco were significantly affected by transplanting time.Of which,the economic characters including the yield,average price,output value and proportion of superior tobacco reached highest level when transplanted on May 15th.With the delay of transplanting time,the chemical composition including nicotine content,total nitrogen and chlorine in flue-cured tobacco leaves at different positions have a decreasing trend,and total sugar,reducing sugar have a increasing trend,but potassium was not obvious.On the whole,the chemical composition of tobacco leaves were more harmonious when transplanted on May 15th.For sensory quality,the total score was the highest when transplanted on May 15th.(3)This experiments explored on the effects of topping periods on harvest maturity and yield and quality of tobacco leaf.The results showed that the topping time had a significant effect on the maturity level of tobacco leaves,and for the special ecological conditions in mountain areas of Chongqing the topping delay significantly improved the maturity of tobacco leaf.At the same time,topping time had significant effects on the economic characters,chemical components and sensory evaluation of flue-cured tobacco.Of which,the highest yield level for middle and upper leaves of flue-cured tobacco was on topping around budding period,followed by around first flower period,and finally around the full flower period.Some indexes including output value,average price,the proportion of superior tobacco has reached highest on topping around the first flower period.The chemical composition including nicotine content,total nitrogen,total sugar and reducing sugar in flue-cured tobacco leaves at different positions have a decreasing trend with the delay of topping stage,but the total nitrogen content in lower leaves,the reducing sugar content in middle leaves was not obvious.The potassium content in the upper tobacco leaves showed a clear upward trend,while the changes in the lower and middle leaves was not obvious.The chlorine content in lower leaves and upper leaves were significantly decreased,and this changes in middle leaves was not obvious.On the whole,topping around first flower period could improve the ratio of sugar and nicotine,the ratio of potassium to chlorine in middle leaves,the ratio of sugar to nicotine in upper leaves,and made more harmonious for the chemical composition of tobacco leaves.For sensory quality results,the total score for sensory evaluation was the highest in middle and upper leaves on topping around the first flower period,followed by topping around budding period.(4)This experiments studied on the effects of different foliar fertilizer on harvest maturity of tobacco leaf and yield and quality.The results indicated that the foliar fertilizer had a significant effect on the maturity of tobacco leaves.The application of foliar fertilizer "Yanboshi" and"Saikun" could delay the maturity for middle and lower leaves,and increased the maturity for upper tobacco leaves.At the same time,foliar fertilizer have significant influenced on the economic characters,chemical components and sensory evaluation of flue-cured tobacco.Of which,the application of foliar fertilizer could increase the economic characters,such as,the yield,and average price,output value.At same time application of foliar fertilizer improved the proportion of middle and superior tobacco in middle and upper leaves.In addition,the application of foliar fertilizer decreased the nicotine and total nitrogen content,especially for upper leaves,and was conducive to the accumulation of total sugar and reducing sugar and potassium content,but the effect on the chlorine content is not obvious.On the whole,the application of foliar fertilizer promoted the coordination of the ratio of sugar and nicotine,the ratio of nitrogen to nicotine,the ratio of potassium to chloride and Shmuck value.Furthermore,the application of foliar fertilizer could significantly improve the sensory evaluation of flue-cured tobacco leaves,in which "Yanboshi" foliar fertilizer was better effects than "Saikun".