Effects Of Nitrogen Rates On Nitrogen Metabolism And Quality Formation Of Flue-cured Tobacco

Pot-cultivation experiment was conducted for two years(2005 and 2006)to study the effects of nitrogen rates on nitrogen metabolism and quality formation of flue-cured tobacco with K326 on Fluvo-aquic soil in the science garden of He Nan Agricultural University(mao zhuang).The treatments respectively were:NO(CK): nitrogen was not applied;N1:3g N·pot^-1;N2:6g N·pot^-1.The results indicated that:1 Effects of nitrogen rates on the dry weights accumulation of different parts of flue-cured tobacco during the period of growthNitrogen stress(NO treatment)or over-applied nitrogen(N2 treatment)reduced the dry weights accumulation of total plant of flue-cured tobacco at early stage and that of stalk and roots at early and middle stages.Nitrogen stress(NO treatment)had less effect on the dry weights accumulation of leaves while over-applied nitrogen(N2 treatment)reduced that at early stage.2 Effects of nitrogen rates on enzymes actiivties in nitrogen metabolism of flue-cured tobacco during the period of growthNR and GS activities of flue-cured tobacco leaves increased with the nitrogen-applied amount increasing at different stages of the growth.Nitrogen stress (NO treatment)advanced carbon metabolism phrase while over-applied nitrogen(N2 treatment)kept enzymes activities at higher level and delayed the nitrogen metabolism phrase. Nitrogen stress(NO treatment)or over-applied nitrogen(N2 treatment)reduced GS activities at early stage and NR activities of roots by different degrees.3 Effects of nitrogen rates on the contents of pigments of flue-cured tobacco during the period of growthThe content of each pigment of the three treatments increased with the nitrogen-applied amount increasing,and the content of all pigments including chlorophyll a,chlorophyll b,lutein,neoxanthin,violaxanthin andβ-carotene of the three treatments took on decreasing tendency with the plants growing during 45～85d after transplanting.The contents ofβ-carotene,lutein and neoxanthin slightly increased and the increased extent became bigger with the nitrogen-applied amount increasing.4 Effects of nitrogen rates on the content and accumulation intensity of main N-containing compounds of flue-cured tobacco during the period of growthThe content of total-N,protein-N and free amino acids-N of flue-cured tobacco leaves decreased with the plants growing,and that of flue-cured tobacco leaves of the three treatments increased with the nitrogen-applied amount increasing at different stages of the growth.Nitrogen stress(NO treatment)or over-applied nitrogen(N2 treatment)decreased by different degrees the accumulation intensity of total-N, protein-N and free amino acids-N of flue-cured tobacco leaves before 35d after transplanting,while the accumulation intensity of that of the three treatments rapidly increased during 35～45d after transplanting.The contents of nicotine of NO treatment were very little,and theirs change extent was also small.The contents of nicotine of cutters and upper leaves of N1 treatment and N2 treatment increased with the plants growing,and that rapidly increased after 65d after transplanting.The accumulation intensity of nicotine of NO treatment were very little,and that of N1 treatment and N2 treatment were small at early and middle growth stages while that were big at later growth stage.The difference of the accumulation intensity of nicotine between the three treatments wasn't obvious during 0～35d after transplanting,and the accumulation intensity of N2 treatment was 1.2 times of that of N1 treatment during 65～75d after transplanting.The content of NO₃^--N of flue-cured tobacco leaves of the three treatments increased with the nitrogen-applied amount increasing.The content of NO₃^--N of lower leaves was high at early stage and low at later stage,and its change extent was big.The contents of NO₃^--N of cutters and upper leaves were low at every growth stage,and theirs change extents were little.The accumulation intensity of NO₃^--N was continuously small,and that increased with the nitrogen-applied amount increasing during 0～35d and 65～75d after transplanting.5 The relationship of enzymes actiivties in nitrogen metabolism,the contents of pigments and the contents of N-containing compoundsCorrelations analysis of enzymes actiivties in nitrogen assimilation and pigments indicated that the correlations of NR ativities of roots and the contents of carotenioids reached significant level,and that of other indexes reached most significant level. Grey relationship analysis on enzymes actiivties in nitrogen metabolism and the contents of N-containing compounds during the period of flue-cured tobacco growth showed that the Grey relationship coefficient between NR ativities of roots and the contents of protein-N＞that of between NR ativities of roots and the contents of total-N＞that of between NR ativities of roots and the contents of free amino acids-N. 6 Effects of nitrogen rates on the quality of flue-cured tobaccoThe midrib ratio,weight per leaf and weight per area of flue-cured tobacco leaves all increased with the nitrogen-applied amount increasing.The balance water ratio and the tensile of the three treatments took on the tendency of "N1＞N2＞NO".The contents of protein,nicotine,NO₃^--N and NO₂^--N all increased with the nitrogen-applied amount increasing,and the content of chlorine of N1 treatment was the smallest among the three treatments.The ratio of K/C1 of the three treatments was in the order of "N1＞N2＞NO".The contents of nitrogen,phosphorus and sulfur significantly increased with the nitrogen-applied amount increasing,while that of potassium,boron and manganese increased and that of magnesium,iron,copper and zinc decreased.N1 treatment increased the contents of neophytadiene,furfural,furfurol,solanone, megastignone-2,megasfignone-4,and famesyl acetone,while N2 treatment obviously decreased the contents of neophytadiene and furfurol and decreased the contents of furfural,solanone,megastignone-2,megastignone-4 and farnesyl acetone.N1 treatment obviously increased the contents of aroma constituents of cembranenoids and increased that of phenylalanines and browing reaction products,but over-applied nitrogen(N2 treatment)decreased the contents of the three kinds of aroma constituents by different degrees.The contents of malic acid,oxalic acid and malonic acid increased with the nitrogen-applied amount increasing,while that of citric acid took on the tendency of "N1＞N2＞NO".