The analysis of relationships between the contents of nitrate and nitrite in flue-cured tobacco leaves and the soil nutrient conditions
烤烟硝酸盐含量与土壤养分的关系

Nitrate and nitrite in tobacco leaves are the precursors of tobacco-specific nitrosamines(TSNA).All the factors influencing contents of the above two precursors would affect the formation and accumulation of TSNA.In order to produce high quality and less harmful raw tobacco leaves,it is of great significance to reduce the TSNA content by controlling soil nutrient-supplying conditions to moderate the accumulation of nitrates and nitrites in tobacco leaves.The multivariate analysis was done on the relationships between the contents of nitrate and nitrite in flue-cured tobacco leaves and soil nutrient contents in Hunan tobacco-growing areas.(1) The correlation analysis showed that the contents of nitrate and nitrite in flue-cured tobacco leaves were highly positively correlated with the amounts of main nitrogen-containing nutrients(including total N,alkali-hydrolysable N and ammonium N) and soil organic matter,with a higher coefficient for nitrate.(2) The cluster analysis showed that the higher the amount of soil organic matter,the higher the contents of soil N-containing nutrients(total N,alkali-hydrolysable N and ammonium N) and the leaf nitrate and nitrite,indicating a direct influence of high soil organic matter contents on the soil N supply,and consequently the accumulation of nitrate N in tobacco leaves.(3) Discriminant functions,built by the cluster analysis based on the contents of nitrate and nitrite in tobacco leaves of different class levels,could be used as a reference to judge the nitrate N content in tobacco leaves under different soil fertilities.