| Wulong County in Chongqing City that located in junction between Wuling and Dalou Mountain in the upper reaches of the Yangtze River belonged to the subtropical humid monsoon climate with warm and humid climate and distinct four seasons.It is one of the important places produced high quality middle flavor flue-cured tobacco in China.The flue-cured tobacco from the planting base in the Wulong County of Jiangsu Tobacco Industry Co.,Ltd,was found to have low potassium contents and high nicotine contents.To solve the above questions,this study started with improving of fertilization method and investigated the effects of cultivated measures on potassium and nicotine contents in Yunyan 97 by spraying different types of foliar fertilizers and sectional application of potassium fertilizer.Based on above works,the roles of the fertilization measures in potassium-increasing and nicotine-reducing were in detail described in this study.These measures will finally provides important technical support for the standard cultivation of flue-cured tobacco in Wulong tobacco base of Jiangsu Province.The main results are as follows:1.The effects of sectional application of potassium fertilizer on the soil physical and chemical properties were studied.The results showed that in the case where the same kind of fertilizer were applied,the disposable increasing of potassium fertilizer(treatment A1,applying potassium fertilizer for 120 kg/hm2 at 40 d after transplanting)could reduce the losses of available potassium in the soils in a short time,and at same time leaded to more loss of potassium content with of flue-cured tobacco growth.Three treatments for sectional application of potassium fertilizer could provide better soil potassium for the later growth of flue-cured tobacco.The available potassium contents in soil under different treatment at 75 days after transplanting was in order A3(applying potassium 60 kg/hm2 40 d,60 d after transplanting)>A2(applying 60 kg/hm2potassium 40 d,50 d after transplanting)>A1.At same time,the effect of sectional application of potassium fertilizer have significant effects on the contents of available nitrogen,available phosphorus and organic matter in soil.2.The effects of sectional application of potassium fertilizer on the changes of potassium and nicotine in flue-cured tobacco were studied.The results showed that sectional application of potassium fertilizer could significantly increased potassium accumulation in the flue-cured tobacco leaves in comparison to the control group.At the same time,the rapid increasing for nicotine accumulation in topping period of the flue-cured tobacco were inhibited by sectional application of potassium fertilizer.3.The effect of two experiments on the chemical composition of flue-cured tobacco leaves was studied.The results showed that the contents of potassium in flue-cured tobacco were increased and the nicotine contents were reduced.the chemical composition of flue cured tobacco was simultaneously more coordinated in different treatments compared to the control.Of which,F1(spraying foliar fertilizer 675 g/hm2)and F2(spraying foliar fertilizer 1350 g/hm2),increased the contents of potassium in upper tobacco leaves above for 2%,and reduced the nicotine contents in upper tobacco leaves for 3.5%.In the sectional application of potassium fertilizer,A3 treatment raised the potassium contents for more than 2%in the middle tobacco leaves.4.The effect of two experiments on neutral aroma substances in tobacco leaves.The results showed that the different treatments increased the total amount of aroma substances in the middle tobacco leaves compared with the control.Total amount of aroma substances in treatment T2(spraying concentration of potassium dihydrogen phosphate solution 0.1%),T3(spraying concentration of potassium dihydrogen phosphate solution 0.2%),T4(spraying concentration of potassium dihydrogen phosphate solution 0.3%),F1 and F2 was in order more than 1.71%,2.71%,2.93%,5.4%and 7.83%in comparison to controls T1.For the sectional application of potassium fertilizer,total amount of aroma substances in treatment A2,A3 was more than 5.43%,6.68%in comparison to control A1.5.The effect of two experiments on sensory quality of flue-cured tobacco leaves.The results showed that the different treatments could improve the sensory quality of flue-cured tobacco and enhanced the aroma of flue-cured tobacco,leading to moderate flue-cured tobacco and good aftertaste.Treatment F1 was the best among different types of foliar fertilizers,and treatment A3 was best among sectional application of potassium fertilizer.6.The effect of two experiments on economic traits of flue-cured tobacco.Compared with the control group,the different treatments increased the yield and output value of flue-cured tobacco in varying degrees.For treatments for different kinds of foliar fertilizer,the treatment F2 have highest yield that reached to 1754.6 kg/hm2,and treatment F1 have highest output value that approached to 45451.4 yuan/hm2,which respectively increased by 10.1%in T1,7.8%in T2,2.9%in T3,4.8%in T4,2.3%in T6.For sectional application of potassium fertilizer,treatment A2 have higher yield that reached to 1771.4 kg/hm2,and A3 treatment was the best for the output value that reached to 46547.2 yuan/hm2,which respectively increased by 12%in Al,5.4%in A2.Above all,in a certain amount of potassium,the sectional application of potassium fertilizer can effectively improve the potassium level in the later stage of the tobacco-growing soil,which could promoted the accumulation of potassium and reducing of nicotine in the field growth period of the flue-cured tobacco.The two groups of experiments including increasing potassium fertilizer at sectional application and applying foliar fertilizer after topping,can effectively improve the yield and quality of baked tobacco.F1(Spraying foliar fertilizer 675 g/hm2)and A3 treatments(potassium 60 kg/hm2 40 d,60 d after transplanting),have obvious effect for increasing potassium content and decreasing nicotine content,which were suitable for the promotion and application in local flue-cured tobacco production. |
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