Effects Of Soil Moisture Regulation On Physical And Chemical Properties Of Upper Leaves Of Flue-cured Tobacco

In view of the current poor irrigation conditions in the hilly tobacco areas in China and the low availability of the upper tobacco industry,this experiment uses the flue-cured tobacco variety NC102 as the experimental material,and adopts pot experiment under the field rain shelter to design different soil moisture content,different drought time and rehydration treatment.The basic agronomic traits,leaf area dynamics,leaf tissue structure,leaf enzyme activity,photosynthesis indicator and chemical composition of roasted tobacco leaves are determined.The effects of different soil moisture conditions on the physical and chemical indicators of flue-cured tobacco are determined.The compensation effect of the physical and chemical properties of leaves provides a theoretical basis for improving the availability and quality of upper tobacco leaves.The research results are as follows:(1)Drought stress significantly affectes the growth and development of flue-cured tobacco and the physical and chemical properties of the upper leaves.The soil relative water content is in the range of 45%-85%.With the increase of soil drought degree,the leaf area decreases significantly,the central leaf area decreases by 4.5%~68.1%;the upper leaf area decreases by 9.3%~45.3%;the leaf thickness increases significantly by 8.1%~18.2%;the ratio of fence to sponge tissue significantly increases by 25.0% to 75.0%;the tissue structure tends to be dense;free proline content(Pro)gradually increases;photosynthesis,superoxide dismutase(SOD)activity,nitrate reductase(NR)is significantly reduced;total nitrogen content increases by 13.0% to 60.9%;nicotine content increases significantly by 10.6% to 57.8%,and chemical composition is uncoordinated.(2)Moisture regulation has a significant positive compensation effect on the damage caused by the early drought stress to flue-cured tobacco and the improvement of the upper tobacco leaf availability.With the advance of rehydration time,compared with the control,the leaf area of the upper tobacco leaves increases significantly,from less than 45.3% to more than 8.1%;the leaf thickness decreases significantly,from more than 9.6% to the control level,fence and sponge The tissue ratio is significantly reduced,from more than 49.0% to less than 11.0%,the tissue structure tends to be loose;photosynthesis increases,leaf weight is compensated to less than 8.2% to the control level;total nitrogen content is significantly lower,higher than 28.6% compensation to less than 12.8%,nicotine content decreases significantly,from more than 17.0% to less than 13.9%,total sugar content increases significantly,from less than 12.4% to more than 9.1%,the content of nitrogen compounds decreases and the chemical composition tends to be coordinated.(3)The critical time point for effective regulation of rehydration of moderately dry tobacco plants with soil relative water content of 50% to 60% is 50 days after transplanting;the rehydration of severe drought tobacco plants with soil relative water content of 40% to 50% The critical point of effective regulation time is 40 days after transplanting;the earlier the rehydration time is,the more obvious the rehydration compensation effect is,and the higher the industrial availability of the upper tobacco leaves.