Study On Adjustment To Accumulation And Distribution Of Nicotine In Flue-cured Tobacco

Tobacco leaves directly influences the prospects of tobacco industry, and hence,is relevant in many tobacco farmers' behaves. Tobacco leaves being the staple ofcigarette manufacturing, upper leaves are being more and more widely used ascigarette tar reducing activities are carried out. Nonetheless, upper leaves in ourcountry are poor in quality, mainly due to rich nicotine, leading to tremendousoverstock. This is a huge fall-behind when, in other countries upper leaves in cigaretteprescript account for 40% of the total use of all tobacco leaves. Therefore, at home,what is to be urgently addressed in production is the issue of over-abundance ofnicotine in cured upper leaves. This paper, from botanical biology-chemistry'sstandpoint, studies the effects of various pH values and temperatures upon the growthof lateral roots and adventitious roots, and upon the accumulation of nicotine;meanwhile, searches the distributive pattern of nicotine over all sections of tobaccoplants and influences of different harvesting methods upon upper leaves' growth,nicotine accumulation and chemical variation during pro-decapitation cropping. Themajor conclusions are as follows:1. Effects of different rhizosphere pH value on tobacco growth and nicotineaccumulation.When tobacco seedling rhizosphere pH value are between 6.5 and 7.5,metabolism in roots is active, which is beneficial to nutrient element absorption andtobacco dry matter accumulation so that the proportion and the accumulation rate ofnicotine are higher than that in tobacco plants by other processing.2. Effects of different rhizosphere temperatures on tobacco growth and nicotineaccumulation is seriously.When tobacco seedling day/night rhizosphere temperatures are respectively30/22℃, metabolism in roots is active, which is beneficial to nutrient elementabsorption and tobacco dry matter accumulation so that the proportion and theaccumulation rate of nicotine are higher than that in tobacco plants by other processing. However, nicotine accumulation at rhizosphere temperatures 25/17l℃islarger than that at 35/27℃. It's not propitious to the growth of tobacco althoughrhizosphere temperatures 35/27℃allay the synthesis of nicotine.3. Effects of Decapitation on tobacco growth and nicotine accumulation.Decapitation during seedling expedites enormous synthesis of nicotine. 6 daysafter topping with the greatest impact are the young leaves in the upper-middle sectionand less impact in the low section.4. Root restraining, de-rooting and girdling all tamper with nicotine accumulation.The synthesizing capacity in adventitious roots is larger than that in lateral roots.Restricting the absorption of nutrients in part of the roots, cutting off part of them orringing phloem can also decrease the synthesis and, at the same time, decelerate thegrowth. Part of the roots having been restrained or removed, the accumulation ofnicotine in the remaining roots is stimulated but the total amount is still lower than thecontrol group which is with no such procedures.5. The distribution patterns of nicotine in tobacco are studied by sampling ofequal-interval and plant-organic segregation after decapitation.The results suggest that 21 days after topping, nicotine proportion in variousorganic are generally follow these laws:upper section＞middle section＞lowersection;mesophyll＞venula＞nervure;phloem＞hadromestome＞core;adventitiousroots＞lateral roots.6. The effect of the different harvest ways on upper leaf about the nicotine content.The results showed that differents of harvest way can regulate the accumulationof nicotine in upper leaf of flue-cured tobacco, it is unfavorable to harvest the upperleaf frequently and hold down the upper leaf during the harvest time to control thenicotine content of upper leaves, but one time harvest the six of upper leaf can controlthe percentage of nicotine content effective and totally reduce the accumulation ofnicotine in upper leaf of flue-cured tobacco.