Research On The Effects Of Ratio Of Nitrogen Morphology On The Tobacco-tar Content

Nitrogen is basis of carbon and nitrogen metabolism during the growth of tobacco leaf. Moreover,nitrogen is closely related to the leaf tissue structure and precursor substances，which impact tobacco tarcontent. In order to study the response of quality-filled low-tar tobacco for nitrogen, we mainly usethe different application and technology of nitrogen fertilization in2012, proportion of ammoniumnitrogen and nitrate were:P1（10:0）/P2（7:3）/P3（5:5）/P4（3:7）/P5（0:10）. Based on the tar delivery, the dataof the agronomic traits was recorded for sorting and anglicizing. Meanwhile，the organizationalstructure of the blade was observed. We determinate the mature tobacco photosynthetic indexes, thephysiological substance were tracked which is closely related to the tar content.We also pay attention tothe key enzyme of tar metabolism, research their accumulation and activity variation. We explored thecharacteristics of growth and quality of the quality-filled low-tar tobacco, which strives to define theoptimal combination of nitrogen fertilizer, guide the actual production. The main results are as follows:（1）Total particulate matter has a very significant positive correlation with tar, and tar has a negativecorrelation with the content of nicotine.The Nitrate dominant has the lowest tar delivery, because oflower levels of total particulate matter and higher levels of nicotine. Therefore, the Nitrate dominant hascertain practical significance to reduce the tobacco tar.（2）Maximum leaf length of budding stage and rosette leaves reflect the tobacco tar content to acertain extent. Tar content and number of leaves of the rosette stage has a significant positive correlation,a very significant negative correlation with maximum leaf length of the budding stage. Maximum leaflength and girth are also an important indicator of apparent evaluation in maturity Therefore, the higherproportion of nitrate nitrogen is conducive to lower tar content.（3）Tar content and intercellular CO₂concentration are significantly positively correlatedrelationship, and negatively correlated with net photosynthetic rate. With the increase in the proportionof nitrate nitrogen, intercellular CO₂concentration is reduced and the photosynthetic rate is increased.Therefore, reduction of intercellular CO₂concentration and increase in photosynthetic rate could be thephysiological mechanism to reduce tobacco tar delivery.（4）P3has the higher content of starch and lignin，with the increase in the proportion of nitratenitrogen, starch and lignin content tend to decrease, so as tar content.Starch and lignin could be usedfor the synthesis of other sugars and polyphones, improving the quality of tobacco and reducing the tarcontent. The amylase and tar content in maturity showed a significant negative correlation，this isconsistent with the tar content measurement results. Therefore, different forms of nitrogen can not onlyto affect the synthesis of tar precursors，but also to reduce the tar by the regulation of activity of keyenzymes, also to improve the quality of tobacco leaves.（5）Tar content showed a significant positive correlation relationship with leaf thickness andpalisade tissue thickness. P4has thick leaves and thickest palisade tissue in maturity, this structurepromote tobacco photosynthesis and inclusions metabolism, conducive to achieve the improvement ofquality and reduce the tar content at the same time.（6）There is a significant positive correlation between yield per unit area and tar delivery. This is consistent with the tar content measurement results. Different forms of nitrogen could affect theeconomic character of the tobacco tar delivery. Flue-cured tobacco with that nitrate nitrogen dominance,the nicotine, reducing sugar and total sugar content is low and higher potassium content, has minimumtar content.（7） According to the tar delivery of two last years, Tobacco tar content is not the lowest with theonly application of a nitrogen fertilizer; The dominant ammonium nitrogen enables tar delivery increase.More nitrates, tar delivery is lower than that of the other nitrogen fertilizer. Visiblely, rationalapplication of nitrate reducing the tar content has a certain practical significancefor reducing the tarcontent.The tobacco with ammonium nitrogen and nitrate ratio of5:5and3:7, its changes of agronomictraits, photosynthetic indexes, leaf tissue structure, economic traits and chemical composition areconducive to the reduction of the tar content. In the production, Northeast tobacco-growing areascontrol nitrogenous fertilizer applied, balance fertilizer forms，and are appropriate to increase theproportion of nitrate,which could help to reduce the tar content.