Effects Of Soil And Climate And Their Interactions On Quality Of Flue-cured Tobacco In Different Ecological Subregions

In order to investigate the effects of ecological factors such as soil and climate on the growth and quality characteristics of flue-cured tobacco,a field experiment was conducted from the year of 2015 to 2016 in Tobacco Planting Areas of Nanxiong city,Guangdong Province,China.Based on the microscopic difference of soil and climate between the two towns,Maozifeng and Gushi,the flue-cured tobacco variety Yueyan 97 as material cultivated in four different treatments(T1,Replacing Maozifeng soil to Gushi;T2,Gushi local soil;T3,Replacing Gushi soil to Maozifeng;T4,Maozifeng local soil).It was studied that the effects of different soil,climate and their interactions on growth period,tobacco tissue structure,photosynthetic traits,chemical composition,and sensory quality of flue-cured tobacco.The main results were as follows:1.The problem was occurred that extending the roots spreading stage and shorting the fast growing stage in growth stage of flue-cured tobacco.The prolonged roots spreading stage,combined with low temperature and heavy rains during this stage,led to the weak photosynthetic traits.The shorter fast growing stage limited the synthesis and accumulation of organic matter in flue-cured tobacco leaves.The above two points were the reasons that lead to the weakening of style of flue-cured tobacco.Soil replacement treatment extended the fast growing stage by two to four days,which gained the time for photosynthesis,created the conditions for accumulation of organic matter,promoted the growth and quality of fluecured tobacco,and was helpful to solve the problem of weakening of style of flue-cured tobacco.2.In Gushi ecological subregion,comparing with the local tobacco,the thickness of palisade tissue of flue-cured at the treatment of soil replacement was notably improved 5.84%(the year of 2015),7.30%(the year of 2016).The thickness ratio of palisade tissue and spongy tissue was significantly increased 2.59 %(the year of 2015),5.22%(the year of 2016).The thickness ratio of palisade tissue and leaves was markedly improved 4.34%(the year of 2015),6.52%(the year of 2016).The above three points showed that the replacement of soil was able to optimize the distribution of palisade tissue of flue-cured tobacco and improve the light use efficiency.The treatment of soil replacement increased the net photosynthetic rate.In Gushi ecological subregion,under the treatment of soil replacement,the max net photosynthetic rate(50 days after transplant)of flue-cured tobacco comparing the local tobacco was improved 6.10%(the year of 2015),3.66%(the year of 2016).And in Maozifeng ecological subregion,it was improved 2.22%(the year of 2015),1.81%(the year of 2016).3.In Gushi ecological subregion,the chemical composition of flue-cured tobacco under the treatment of soil replacement was in or tending to optimum range of high quality fluecured tobacco than that of local flue-cured tobacco.The treatment of soil replacement was able to decrease the content of sugar and increase that of nicotine,which showed the features of strong-flavor type flue-cured tobacco.The total sugar significantly decreased 5.28%(the year of 2015),4.77%(the year of 2016),the nicotine significantly increased 10.43%(the year of 2015),6.49%(the year of 2016).The soil replacement was a reference for improving the chemical composition of flue-cured tobacco,and it could effectively improve the features of strong-flavor type flue-cured tobacco.In Gushi ecological subregion,the treatment of soil replacement was able to improve the sensory quality of flue-cured tobacco.The industrial availability,style characteristics,and quality characteristics were all improved,which effectively enhanced the quality and aroma to show the enriched flavour characteristics of flue-cured tobacco.While in Maozifeng ecological subregion,they were not significantly changed comparing with the local tobacco.4.The main ecological factors affecting growth and quality of strong-flavor type fluecured tobacco were firstly climate factors,followed by climate-soil interaction,and finally soil factors.The key climate factors which affecting the growth including tobacco tissue structure and photosynthetic traits of flue-cured tobacco were the sunshine duration during fast growing stage and maturity stage.The key climate factors which affecting the quality including chemical composition and sensory quality of flue-cured tobacco were the average temperature during roots spreading stage and fast growing stage,the sunshine duration during maturity stage,and the precipitation during all the stages.