| Taining County in Sanming City is a key district planted flue-cured tobacco in Fujian province,in which CB-1 is the main cultivar and has a typical Fen-flavor style.In production,the leaves of CB-1 have an irreplaceable role in cigarette blending,and well received by industrial enterprise.However,aromas with Fen-flavor style were weakened and the corresponding qualities have an obvious declining trend in recent years.Further investigation indicated that improper fertilization and excessive growth made CB-1 into an oversized plant type,the oversized plant type might be the main reasons for causing the deterioration of its quality.The moderate plant types were considered as ideal plant types in production.However,as different cultivars and ecological conditions in the main production areas of tobacco the represented index and threshold value used to judge morphological and physiological indexes,technical parameters of management have thus the significant difference.Particularly,there was no specific technical index for the threshold of plant type parameters since different ecological types and different varieties.At present,the description for the plant type characteristics of the tobacco CB-1 in Taining area were summary with experience,and there were no clear reference threshold range and management paradigm.It has a guiding significance to shaping the characteristic of CB-1 plant type to construct a specific criteria and parameters that was suitable for the moderate plant type of tobacco CB-1 in Taining.Herein,according to the critical measures that control the plant type of flue-cured tobacco,the effects of different nitrogen application strategies on soil fertility,physiological and ecological indexes,economic trait,quality and yield of flue-cured tobacco CB-1 were in detail studied.And then,we studied At same time,on basis of 17 indexes including the individual morphology and the population structure of the moderate flue-cured tobacco CB-1,six representative indexes were screened as threshold range for determining high quality tobacco CB-1 in Taining while under nitrogen regulation by factor analysis methods.Based on above studies,the nitrogen fertilizer strategy suitable for the construction of the high quality flue-cured tobacco in Taining tobacco planting area were put forward.Furthermore,this indexes and strategy provide the necessary reference for guaranteeing the Fen-flavor style and improving the quality of tobacco CB-1 in Taining tobacco area.The main result showed as follows:1.Effects of different inorganic nitrogen levels on the yield and quality of CB-1.The effects of the inorganic nitrogen fertilizer with three different gradients on the yield and quality of CB-1 were studied.As a result,the yield of CB-1 was decreased while reducing nitrogenous fertilizer based on recommendatory nitrogenous fertilizer(nitrogen application 7.0 kg/667sq.m).but it had got higher average price and better commercial grade,and resulting the final output value have no significant difference with that of nitrogen application with 7.0 kg/667sq.m.Especially when the inorganic nitrogen with 6.0 kg/667sq.m were applied,CB-1 have a better appearance quality,and chemical composition with an overall coordination including gain higher total sugar,reducing sugar,the content of nicotine moderate total nitrogen.2.The effects of different nitrogen application on soil fertility.On the basis of the results that the effect of nitrogen application rate on yield and quality of tobacco leaves in previous year.In present years,the nitrogen application with amount 6.0 kg/667sq.m were set as reference,the nine different nitrogen application strategies were proposed from three aspects including,and effects of these strategies on soil nutrient index and soil enzyme activities fertilizer and different nitrogen forms were further studied.The results showed that potential ability of soils planted tobacco that supplied nitrogen will accordingly change while different nitrogen strategies were applicated and simultaneously the supply of phosphorus and potassium in tobacco planting soil have similarly changed.Moreover,some soil enzymes including soil urease,cellulase and sucrase were more sensitive to the content of nitrogen ion in the soil,and their activity could be significantly enhanced when high nitrogen ion nutrition was maintained in the soil.In addition,reducing of total nitrogen application and increasing of rates of organic nitrogen was beneficial to improve soil fertility.Overall,the soil properties that were applied by T5,T7 and T8 better could meet the nutritional needs of tobacco plants among 9 nitrogen regulation.3.The effects of different nitrogen application strategies on the growth and development of flue-cured tobacco CB-1.Different nutrient have certain influences on the absorption characteristics,photosynthetic characteristics,key enzyme activities of carbon and nitrogen metabolism and accumulation of dry matter of tobacco CB-1.On the whole,the growth and development of tobacco plant had more advantages in T5,T7 and T8 treatment compared to others.For details,the tobacco plant will have an moderate levels of nitrogen,phosphorus,potassium and SPAD during growing period while reducing nitrogen(total nitrogen control in 6.0 kg/667sq.m),adding some soya bean cake(20 kg/667sq.m)or applying the mixture of different proportions of organic and inorganic nitrogen(organic nitrogen ratio control in 40%-60%).At same time,under above three strategies tobacco leaves showed strong activities of transferring from nitrogen metabolism to active carbon metabolism in later growing stages,and have better the accumulation of the dry matter in compared to other nitrogen applications.4.The effects of different nitrogen application on the quality and economic benefit of the flue-cured tobacco leaves.The results showed that when some strategies including reducing the amount of nitrogen(total nitrogen control in 6.0 kg/667sq.m),adding some soya-bean cake(20kg/667sq.m)or mixed different proportions of organic and inorganic nitrogen(organic nitrogen ratio control in 40%-60%)were applied,some key indexes for tobacco leaves,such as the content of reducing sugar and total sugar,reduce the total nitrogen and total alkali content in the upper leaves,the ratio of sugar to nicotine,ratio of potassium to chlorine became more coordination,the content of protein and nicotine,were significantly improved to more fit the standard of high quality tobacco.At the same time,the quality of aroma and aroma quantity of tobacco CB-1,and the taste characteristics such as sweet taste and aftertaste are also obviously enhanced.Under this nitrogen application strategy,the tobacco CB-1 obtained a higher average price,proportion of superior tobacco,proportion of middle grade or classy tobacco,class index and yield index.5.Screening of indexes for the individuals and population structure represented the traits of moderate plant type flue-cured tobacco CB-1,and determining of the threshold of indexes for high quality CB-1'5 plant type under nitrogen application strategies.The main factor analyses were conducted for 17 individual morphological and population structure index using factor analysis method.Resulting six indexes including maximum leaf length,leaf width,waist girth,pitch and the population structure index maximum leaf area coefficient,total leaf area coefficient field coefficient were considered as core index.Additionally,through comprehendsively analyzing effects of different nitrogen application strategies on yield,quality and plant type characteristics of tobacco leaves,the threshold value of the plant type characteristics with the high quality tobacco in Taining county were determined,which consists of the maxi-mum leaf length of 71.49-74.13 centimeter,the width of lumbar leaf of 27.55-29.45 centimeter,Stem girth of 9.94-11.2 centimeter,Pitch of 4.69-5.18 centimeter,the maximum leaf area index of tobacco plant was 2.33 to 2.46,and the total leaf area coefficient was from 3.03 to 3.2.In summary,this study indicated that nitrogen application strategies could significantly improve the tobacco yield and quality.Especially,by reducing the nitrogen application(total nitrogen control in 6.0 kg/667 sq.m),adding some soya bean cake(20 kg/667sq.m)or using the mixture of different proportions of organic and inorganic nitrogen(organic nitrogen ratio control in 40%-60%)on regular nitrogen application level,Flue-cured tobacco CB-1 could obtain a better production and quality and economic benefits.Furthermore,these nitrogen application strategies could shaped a suitable plant type,provided an important theoretical basis for further building evaluation system of tobacco plant type in Taining production. |
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