Effects of Nitrogen Forms on Carbon and Nitrogen Metabolism and Quality of Flue-Cured Tobacco

Tobacco variety K326 was used as field experimental materials.By testing the variation trends of the relative enzyme activities and their metabolism products during tobacco growth various stages,from the perspective of nitrogen forms regulation that flue-cured tobacco production and carbon and nitrogen metabolism of tobacco plants were discussed,the results were as follows: The ratio of NO3-N/NH+4-N can affect quality of flue-cured tobacco significantly.As the increase of NO-3-N/NH+4-N ratio,the contents of soluble sugar and reducing sugar in cured flue-cured tobacco leaves obviously increased.While the contents of protein and nicotine decreased.But the ratio of NO-3-N/NH+4-N had no effect on total nitrogen contents.Applying NH+4-N and NO-3-N in different proportion is good at increasing yield and economical income.The suitable ratio of NO-3-N/NH+4-N can regulate the carbon and nitrogen metabolism and their products of tobacco plants.During tobacco growth early stage,the suitable ratio of NO-3-N/NH+4-N was good at nitrate reeducates and glutamate ammonia lipase activities,higher soluble protein and free amino acids contents.These made tobacco plants have high ability of metabolism.During tobacco growth early stage,the suitable ratio of NO-3-N/NH+4-N is good at amylase activity,increasing the contents of soluble sugar and starch.During the physical ripe stage the amylase activity was increased properly can enhance carbohydrate synthesis in the prophase and carbohydrates hydrolysis in the anaphase.This experimental results showed that 75%-50%NO-3-N +25%-50%NH+4-N was the best application proportion.