Changes of Major Chemical Components in Tobacco Leaf during the Growth of Different Genotypes

The changes of major chemical components in tobacco leaf during the growth of different genotypes were studied.The results indicated that NR activity and the contents of chlorophyll, total carbon, reduced sugars and total nitrogen were decreased, and the contents of petroleum ether extract and nicotinewere gradually increased during the growth of tobacco plant.Although the difference of carbonous compounds was not significant, the nicotine content was significantly different among the tested genotypes.