Effects Of Nitrogen Nutrition On Nitrogen Metabolism And Quality Of Different Flue-cured Tobacco Varieties

In Henan tobacco planting areas,due to the unstable existing nitrogen application amount,flue-cured tobacco leaves is not mature enough,organic matter transformation is not sufficient,so that it affect the flue-cured tobacco yield&quality.Based on the different flue-cured tobacco varieties in different nitrogen treatments,it studies the effects of nitrogen on leaves growth and senescence systematically,the nitrogen metabolism in the flue-cured tobacco leaves,yield&quality,and explores the causes of the differences between varieties to provide theoretical basis and technical guidance for the production of nitrogen application in Henan flue-cured tobacco cultivated area.The results show as follows:1.Effects of nitrogen applied rate on the flue-cured tobacco growth&development,yield&out-put valueIncreasing nitrogen fertilizer applied rate could effectively promote the growth and development of the flue-cured tobacco plant,but there are slight differences between varieties.Yunyan 87 normally grew with high N applied rate,but the growth of NC89 was blocked and its leaves growth was prolonged 11 days;plant types of NC89 changed in high nitrogen conditions,and its growth was not consistent,the leaves were dark green,the angle between stems and leaves was large.NC89 is the highest with stem diameter,intermode length,number of leaves,leaf length and width among the varieties,but Yun Yan 87 is the lowest.The growth period of Yunyan87 is short from 103 to 109 days,and its plant type is stable.Response of the yield and ratio of the first-class tobacco leaves of different varieties to nitrogen were different,and the yield increased significantly from 55.07kg/hm2 to 163.39kg/hm2 with N applied rate increased,but NC89's output value did not rise significantly and ratio of the first-class tobacco leaves decreased from 0.07%to 2.33%.Therefore,the appropriate N applied rate could promote the flue-cured tobacco growth and increased its yield,so not enough N applied rate could slow down the flue-cured tobacco growth and development,and reduced its output value.A suitable N applied rate could provided nitrogen demand of the flue-cured tobacco and improve its yield and quality.2.Effects of N applied rate on the flue-cured tobacco nitrogenous metabolismSoluble protein and total nitrogen content of flue-cured tobacco leaves are increased with N applied rate increased,so did the nitrogen metabolism intensity;Especially with the high N applied rate,NC89 is not tolerant to nitrogen fertilizer and has high nitrogen nutrition with 2.51%-2.79%at the late stage of maturity as before which is not benefit to the improving the quality and tobacco leaves maturity.The peak concentration of NH4+ in leaves increases with N applied rate increased,the peak value of NC89 began to decrease after 50D planted with high nitrogen conditions,but the varieties among all varieties were not consistent.About the activity of GS and NR,GDH is high,NC89 is low,especially the activity of GS of GDH in leaves whose leaf age is 40d dropped significantly,and is significantly lower than NC89 and the nitrogen assimilation ability is weak.At the same time,the concentration of ammonia and ammonia compensation point was higher,and the amount of ammonia volatilization was high;when the nitrogen application rate increased,The concentration of ammonium and ammonia compensation point of leaves are increased in different degree,Yunyan 87 was significantly higher than that of NC89,especially the ammonium concentration and ammonia compensation point in the leaves of tobacco leaves were all kept at a higher concentration or value in the late stage of tobacco leaf senescence.That ammonia volatilization potential of Yunyan 87 was significantly higher than that of NC89,and then transfer ability of nitrogen is high.3.Effects of nitrogen applied rate on tobacco leaves agingThe changes of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)were basically the same,with the increase of nitrogen application rate,the activity of enzyme was enhanced,the enzyme activity increased significantly when the leaf age is 30-40 days,which showed that the ability of scavenging active oxygen in tobacco leaves was enhanced.At the same time,with the increase of the amount of nitrogen fertilizer,the activity of lipoprotein(LOX)decreased.This indicates that the oxidation of tobacco leaves decreases,the aging delays,the activity of the LOX is different.Malondialdehyde(MDA)content showed a gradual accumulation of the trend,under different nitrogen treatments,the content in the low nitrogen treatment is highest,the early accumulation is slow,the late is fast.It showed that the growth period of tobacco leaves increased with the increase of nitrogen application rate,the antioxidant capacity of tobacco leaves increased,the aging rate slowed down,and the maturity of leaf was decreased.4.Effects of nitrogen applied rate on flue-cured tobacco qualityThe chlorophyll content of leaves was highest under the treatment of high nitrogen,Yunyan 87 carotenoid was highest in high nitrogen treatment,NC89 was highest under the treatment of medium nitrogen.The interaction effect of variety and nitrogen application amount was existed in the presence of carotenoid accumulation.The degradation amount of chromoplast pigment showed that because the accumulation of chlorophyll of NC89 is large,the degradation amount of chromoplast pigment carotenoid is largest.The degradation amount of carotenoid in Yunyan87 was significantly higher than that neutral aroma components of NC.89,the browning reaction products,phenylalanine degradation products,solanone,neophytadiene and the total amount of degradation of carotenoid were the highest,and there were differences among varieties.The total score of Yunyan 87 appearance quality was higher than NC89,the main performance in the leaf structure,identity,leaf tissue and flexibility have a large difference.With the increase of the amount of nitrogen fertilizer,the score of the leaf structure and oil content decreased,the degree of maturity decreased and the degree of leaf tissue increased.The chemical quality of tobacco leaves also existed the differences between varieties and treatments.Therefore,with the increase of nitrogen application rate,reducing sugar and total sugar content increased,the contents of total nitrogen,nicotine and potassium decreased,tobacco sweet aroma weakened,irritation and strength increased,too much nitrogen amount had adverse effect for the formation of tobacco quality.