The Coupling Effect Of Water And Nitrogen On The Growth And Development Of Flue-cured Tobacco And Soil Nutrients

In order to improve the quality of tobacco,increase the production efficiency of tobacco,save the production cost of tobacco,the present research studies the leaf area index,photosynthesis,cell sap concentration,absorption efficiency to different nutrient element,soil nitrogen content,dro?ght tolerance,the economic characters and quality,chemical components,the appearance and sensory quality of the middle and upper leaves in the growth and development of flue-cured tobacco in different coupling effect of water and nitrogen.The main results are summarized below.1.The coupling effect of water and nitrogen on the leaf area index at different growing stages of flue-cured tobaccoThe coupling effect of water and nitrogen on the leaf area index at different growing stages of flue-cured tobacco is remarkable,especially notable between root elongation and vigorous growth stages.The leaf area index rises gradually with nitrogen application being increased,and increased indistinctively when the dosages of nitrogen reaches 60 kg/hm~2.The optimum N application is also different,with root,stem and leaf increasing in different degrees during different growth stages.And the leaf area index is best when the dosages of nitrogen reaches 60 kg/hm~2.However,the increase of leaf area index is smaller with the increase of soil moisture content.The dry matter accumulation is increased with the increase of soil water content and nitrogen application,but the root-shoot ratio changes small.2.The coupling effect of water and nitrogen on photosynthesis at different growing stages of flue-cured tobaccoWith the level of nitrogen increasing,the stomatal conductance firstly decreased and then increased in the root-extended period of flue-cured tobacco,and it showed the reverse change trend in the long-term period and the reduced tendency in the mature period.The stomatal conductance decreased between root elongation and vigorous growth stages with the decrease of soil moisture content,and reduced in the mature period.Meanwhile with the level of nitrogen increasing,the photosynthetic rate firstly decreased and then increased in the root-extended period of flue-cured tobacco,and it showed the reverse change trend in the long-term and the mature period.The photosynthetic rate decreased between root elongation and vigorous growth stages with the decrease of soil moisture content,and reduced in the mature period.However,the photosynthetic rate decreased between root elongation and vigorous growth stages with the decrease of soil moisture content,and reduced in the mature period.3.The coupling effect of water and nitrogen on cell sap concentration at different growing stages of flue-cured tobaccoThe cell sap concentration increases with the increase of N application under the same soil moisture content,it suddenly reduced when the N application is more than 65 kg/hm~2.And the cell sap concentration rises distinctively with soil moisture content being increased under the same nitrogen application.However,it is different at different growing stages to reach the maximum for the cell sap concentration,but between 10:00 a.m.and 14:00 p.m.Increasing N fertilizer application could delay the stage that the maximum value appeared under the same soil moisture content,and it rises gradually with soil moisture content being increased under the same nitrogen application.The stomatal conductance,and transpiration rate and photosynthetic rate have different levels of negative impact on cell sap concentration in different growing periods.It is the photosynthetic rate that is great influence on the cell sap concentration and the direct path coefficient(DPC)was-0.944 in the root-extended period,and it is the transpiration rate,the DPC-0.872 in the long-term period.While the three indicators has great effect on it in the mature period,and the DPC is-0.674,-0.669 and-0.669 respectively.4.The coupling effect of water and nitrogen on the absorption efficiency to different nutrient element of flue-cured tobaccoThe influence of N application in the soil on the accumulation of N,P,K is higher than that of soil moisture content,and T3 treatment performs better.The absorption activity of root to P and K in the soil increases gradually with N application enhanced,peaked at T3 and then fell slightly,but little change to that of N.The absorption of the three kinds of minerals firstly increases and then decreases,especially it has the biggest reduction between the N application of 65 kg/hm~2(T3)and 70 kg/hm~2(T4).But the difference in the absorption activity of stem to the three kinds of minerals is not significant with the N application of 60 kg/hm~2(T2)and 65 kg/hm~2(T3).The absorption maximum value appeared in T3(65 kg/hm~2)treatment,and it is not significant in T3 and T4 and much higher than T1 and T2.The absorption of P is positively associated with the N application in T1,T2,T3 and T4.And the absorption maximum value of K appeared in T3(65 kg/hm~2)treatment,and it is not significant in T1,T2 and T3.The absorption activity of N,P,K in tissues of flue-cured tobacco is not obvious with the increase of the soil moisture content.5.The effects on soil available nitrogen and nitrate content by nitrogen fertilizer application in different growth periodIn the growth period of Flue-cured tobacco,available nitrogen are mainly distributed in 0cm~ 20 cm,with the increase of soil depth,available nitrogen content decreased.nitrogen fertilization application has an obvious effect on soil available nitrogen absorption.Compared with the extended root period,There is a bigger change in available nitrogen content of 0 cm~ 20 cm soil,and in the 20cm-40 cm soil available nitrogen content decreased slowly.But available nitrogen in 0 cm~ 20 cm increased in mature stage in all the processing,the available nitrogen content in 20cm-40 cm has a big difference;The nitrate content of soil in depth of 0cm-40 cm change quite differently,and all the content of soil nitrate nitrogen reach a maximum at 60 d after transplanting,but differ from the processing at 90 d.6.The effects on dro?ght resistance,oxidation resistance of Flue-cured tobacco by Water and nitrogen couplingWater and nitrogen coupling has the certain positive effect on dro?ght resistance,oxidation resistance and the cell vitality in Flue-cured tobacco growth and development,and T3 treatment shows better.Within a certain range N application rate Flue-cured tobacco dro?ght resistance increase with the increase of N application,exceeding a certain N application the dro?ght resistance decreased;With the increase of N application rate the praline of Flue-cured tobacco content increased gradually,but the content of soluble s?gar increased at first and then decrease,and T3(65 kg/hm~2)'s reach the highest levels;The content of MDA decrease at first and then increase,and T3(65 kg/hm~2)'s at a minimum.With the reduction of soil moisture content of Flue-cured tobacco of praline,soluble s?gar and MDA content are increased significantly,but there is minimal difference between T2(60 kg/hm~2)and T5(55 kg/hm~2).7.The effects on yield and quality traits and economy of Flue-cured tobacco by water and nitrogen couplingWater and nitrogen coupling has a great influence on economic character and quality of Flue-cured tobacco.Research shows that within a certain range leaf production was positively correlated with nitrogen fertilizer's content,when the N application rate in 70 kg/hm~2 it has highest yield,but under the condition of low soil moisture,the content of Flue-cured tobacco production is relatively low.As N consumption increasing The proportion of superior tobacco shows the first increase to reduce the trend,when N fertilizer application rate in 65 kg/hm~2 the superior tobacco reach a maximum;with the loss of the moisture content the proportion of superior tobacco greatly reduced.8.The coupling effect of water and nitrogen on the content of neutral aroma components of flue-cured tobaccoThe content of neutral aroma components of upper tobacco leaves increased firstly and then decreased with the increase of nitrogen application,and the highest level was found in the treatment of 65kg/hm~2.The effect of soil moisture rate on the amount of neutral aroma components was smaller,however,a different scenario occurred with phenylalanine and neophytadiene.The content of neutral aroma components of middle tobacco leaves increased with the increase of nitrogen application,and the highest level was found in the treatment of 70kg/hm~2,which is little different from T3(65kg/hm~2).The effect of soil moisture rate on the amount of neutral aroma components was considerable,and the difference mainly came from carotenoid and neophytadiene.9.The coupling effect of water and nitrogen on the content of routine chemical composition of flue-cured tobaccoThe contents of total nitrogen,nicotine and protein of upper tobacco leaves varied in each treatment with different nitrogen application,and the highest level was found in the treatment of 70kg/hm~2,but little difference in starch,total and reducing s?gar,potassium and chlorine.The difference of starch,protein,total and reducing s?gar of middle tobacco leaves was remarkable,but little difference in nicotine and total nitrogen.Moreover,potassium content was higher than that of upper tobacco leaves,and chlorine content varied in different treatments.10.The coupling effect of water and nitrogen on the appearance quality of upper and middle tobacco leavesApplying nitrogen of 70 kg/hm~2(T4)nitrogen,resulted in the highest score in the appearance quality of upper tobacco leaves.The score showed a tendency of increase in response to increased nitrogen application,and it was obviously improved from 60 kg/hm~2 to 65 kg/hm~2.Compared with T5(55kg/hm~2),the score of T1(55kg/hm~2)was lower with the decrease of soil moisture content,and T2(60 kg/hm~2)was higher than T6(55 kg/hm~2).And at the same time,there was little difference in the leaf maturity,colour and structure of all treatments,but great difference in status,chroma and oil.Moreover,the highest score in the appearance quality of middle tobacco leaves was T3(65 kg/hm~2).The score was firstly increased and then decreased with the increase of nitrogen application,and it was obviously improved from 55 kg/hm~2 to 60 kg/hm~2.With decreasing moisture content,the score decreased slightly,and there was little difference in the leaf maturity,colour and structure of all treatments,but great difference in status,chroma and oil.11.The coupling effect of water and nitrogen on the sensory quality of upper and middle tobacco leavesThe highest score in the sensory quality of upper tobacco leaves was T3,and the score was firstly increased and then decreased with the increase of nitrogen application.With decreased moisture content,the score declined very slightly,and there was little difference in the quality and aroma of incense,smoke concentration,aftertaste,combustibility and irritation of all treatments,but great difference in offensive odor,physiological strength and color of cigarette ash.Furthermore,the highest score in the sensory quality of middle tobacco leaves was T4 compared with the lowest score of T5.With the increase of nitrogen application,the score was firstly decreased and then increased.Compared with T5,the score of T1 was higher with the decrease of soil moisture content,and T2 was lower than T6.At the same time,there was little difference in the quality and aroma of incense,smoke concentration and irritation of all treatments,with significant differences in the other indicators.