| In order to relieve the harm on the growth and development of flue-cured tobacco and the economic loss caused by the drought,and provide a new technical referenc to solve the problem of drought of Huili County,we used randomized block design to set up treatments of plastic mulching(CK),straw mulching(T1),“Feng Yu” water-retaining agent and plastic mulching(T2),“Hui Zhi Yuan”water-retaining agent and plastic mulching(T3),“Feng Yu” water-retaining agent and straw mulching(T4),“Hui Zhi Yuan” water-retaining agent straw mulching(T5),K326 as material in Huili County of Sichuan Province in the year2014-2015,studied the effect of straw mulching and water-retaining agent on the soil physical and chemical properties,growth and quality of flue-cured tobacco.The main results were as follows:Straw mulching and application of water-retaining agent could affect the growth and development of tobacco plant,and in the initial transplanting effective leaf number,waist leaf length,waist width had increased.From the middle of growth the tobacco plants growrd better,and plant height,leaf number,pitch,stem circumference,waist leaf length and waist width were better than the control.With the development of the growth period,the leaf area coefficient of straw mulching and water-retaining agent treatment increased rapidly and reached the optimum state.Finally,the leaf area coefficient of T3 and T4 was the largest.The amount of dry matter accumulation in tobacco plant which used traw mulching and water-retaining agent increased sharply and was higher than the control,as the accumulative amoun of T3 and T4 was the highest.While the root-shoot ratio of T1 was big in the whole growth period,the root-shoot ratio of T3 and T4 was bigger at the earlier stage and smaller at the middle and later stage.As the chlorophyll content of T3 and T4 maintained at a higher level at earlier stage and reduced at later stage gradually,the carotenoid content was always high.Straw mulching and water-retaining agent could improve the moisture content ofsoil effectively,and the properties of retaining water of T2,T3 and T4 was better.Under the same conditions,the moisture content of T1 is lower.Application of water-retaining agent and straw mulching reduced the soil temperature,and the effect of T4 and T5 was more obvious.With the increase of soil depth,the difference between the processing temperature was gradually narrowing.The catalase activity of processing T1 in the initial transplanting was lower.The soil enzyme activity of T3 and T4 maintained at a high level during each period compared with other treatments.Straw mulching and water-retaining agent could improve the content of alkaline hydrolysis nitrogen,available phosphorus and organic matter of soil,and the effect of straw mulching was more significant than the film mulching.The content of available potassium in soil of processing T1 was lower than CK,and other treatments had different degrees of improvement.The content of available potassium of T3 and T4 was higher.The content of total sugar and reducing sugar in tobacco leaves could be improved after straw mulching and application of water retaining agent,and the contents of nicotine and chlorine were decreased.The total nitrogen content of each treatment increased slightly,the potassium content was significantly higher than that of CK,and the ratio of sugar and nicotine,nitrogen and nicotine,and potassium and chloride were increased.Chemical composition of tobacco leaves of processing T3 was more coordination,then was T4.Compared with T1,T2 and T5,content of neutral aroma compounds of upper leaves and middle leaves of T3 and T4 was higher.The content of neutral aroma compounds of upper leaves of T1 was lower than the control and that of middle leaves of T2 was lower than the control,as that of the upper leaves and middle leaves T5 were lower than the control.In addition to the content of phenylalanine degradation products of middle leaves were decreased,content of various types of neutral aroma components of T3 and T4 was higher than that in the control and other treatments.Straw mulching and application of water-retaining agent could improve the smoking quality of tobacco leaves significantly,as upper leaves and middle leaves of T3 and T4 had better performance,stimulus of processing T1 was bigger,and mixed gas of upper leaves of processing T1 was heavier.Dry feeling of upper leaves of processing T5 was bigger,and the taste properties was poor,too.As only use of straw mulch could reduce the economic indicators of tobacco leaf,economic benefit of other treatments had different degrees of improvement.As yield,output value and proportion of high quality tobacco of T3 and T4 were thehighest,fold of T3 and T5 was the highest.Proportion of high and middle quality tobacco of T2 and T3 was higher,and the comprehensive benefits of T3 and T4 was the best.Overall,when only use straw mulching the moisture content of soil was lower and ratio of potassium and chloride of flue-cured tobacco was less than 4,and contents of neutral aroma constituents of middle leaf was lower than the control while irritation was bigger and economic benefit was poor.The moisture content of soil of other treatments increased,while the soil physical and chemical properties improved and tobacco plants grew well.The ratio of potassium and chloride of lower leaves of T2 and upper leaves of T5 did not reach the standard of high quality flue-cured tobacco and contents of neutral aroma constituents of T5 was lower than that of control.The chemical composition of tobacco of T3 and T4 was more coordination and the contents of neutral aroma components was the highest,as the sensory quality and economic benefits were better than other treatments.That was “Hui Zhi Yuan”water-retaining agent and plastic mulching and “Feng Yu” water-retaining agent and straw mulching could improved the soil physical and chemical properties and tobacco quality better,and could reduce the loss caused by the drought effectively. |
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