Analysis Of Heredity And Variance Of Petrolum Ether Extract Content And Correlativity Of Other Main Characters In Flue-Cured Tobacco Leaf

Studies were done on the content of petrolum ether extract(PEE) in flue-cured tobacco leaves from different ecological regions, different flue-cured tobacco genotypes, different stalk positions and the changes of carbon and nitrogen compounds in different growing stages. The results shown: I. There were significant or extremely significant differences in the content of PEE in tobacco leaves of different ecological regions, flue-cured tobacco genotypes, stalk positions and different growing stages. The analysis of PEE content in different stalk position indicated: top>middle>bottom. And the content of PEE was increased with the growing of tobacco leaves. 2. During the whole growth of tobacco leaves, the change of total carbon content was small. The content of reduced sugar, total nitrogen and chlorophyll and the activity of Nitrate Reductase (NR) were reduced sharply in the first 40 days after the formation of tobacco leaves, then decreased gradually. But the content of nicotine was increased. All flue-cured tobacco genotypes were similar. 3. The ratio of carbon to nitrogen was increased with the growing of tobacco leaves. The change of ratio value was caused by the decreasing of nitrogen content. Moreover, there was double curve correlation between the content of PEE and the ratio of carbon to nitrogen, the activity of NR andchlorophyll content in different growing stages. Therefore, the content of PEE was affected by the harmony degree of metabolism of carbon and nitrogen. 4. The analysis of hereditary correlation indicated that the additive and dominant covariance between the content of PEE and length of tobacco leaf and the ratio of length and width of tobacco leaf were significant. 5. There were different degree heterosis in the content of PEE and other correlated characters. There was definite difference in the general combining ability and special combining ability variance of every experimental genotypes. The heterosis could be used to develop the content of PEE by cross-breeding. When the plant with high content of PEE was chosen, it should be done by choosing plant with broad leaves. All the results above can provide the theoretical bases for tobacco breeding.