Study On Genetic Variation And Regulation Of Agronomic Measures For Starch Content In Flue-Cured Tobacco Leaves

The high starch content is not favorable to quality of flue-cured tobacco leaves. Too high starch content could make leaves' burning not enough, and produce scorching odor, and decrease smoke quality and safety. It has been a limiting factor to improve tobacco leaf quality because of high starch content. Dialle mating of 6 parents with different genetic basis was conducted to study genetic variation of starch content of flue-cured tobacco leaves; different genotypes of flue-cured tobacco were used to compare the difference of starch content and some enzyme activity; effects of agronomic measures of picking up film, soil dressing during the blooming period, mulching and topping on starch content were analyzed. The results were as follows1. Genotypes and environments are very important to starch content of flue-cured tobacco leaves. The variation of starch content was highly significant at 0.01 level among different genotypes and locations. As far as different leaf positions were concerned, the mean starch content showed the trend of upper leaves >cutters >lower leaves, and the coefficients of variation of starch content showed the trend of cutters > upper leaves > lower leaves. As far as different locations were concerned, the trend of range, standard deviation and means of starch content was Xinyang > Shangqiu > Zhengzhou, and the trend of CV was Shangqiu > Xinyang > Zhengzhou. The variance of non-additive gene effects of starch content among different leaf positions was bigger than that of additive effects, which indicted that starch content was mainly controlled by gene non-additive effects. The hB2 % of starch content was larger than hN2 %. The value of hN2% among different leaf positions was similar, and showed the trend of cutters > lower leaves > upper leaves.2. F-test results showed that difference of amylase activity was significant at 0.05 level for cutters and 0.01 level for upper leaves among different genotypes. Difference of INV activity of cutters and upper leaves were also significant at 0.01 level among different genotypes. Amylase and INV had close relationship to carbon metabolism, and their change of activity during field growth period was important to use and transition of photosynthesis products. Amylase and INV activity (except INV of upper leaves) of NC89 leaves were highest among materials studied, and its carbon metabolism is more strong. The accumulation of starch content has no significant correlation with amylase and INV activity, and the accumulation of soluble sugar content showed...