Changes Of Physiology And Biochemistry During Leafcolor Transformation In The Three Kinds Taxodiaceae In Autumn

In order to investigate the relationship of color of leaves with physiological and biochemicalindexes of the three kinds of Taxodiaceae, Taxodium distichum(Linn.)Rich., Taxodium ascendensBrongn., Metasequoia glyptostrobodies Hu et Cheng, during leaf coloration process in autumn whenleaves senesce. we use grown tree of the three kinds of Taxodiaceae growen in the natural environmentas materials, studied the change of the color of leaves and the pigment content, soluble sugar content,pH value, PAL activity, antioxidant enzymes (SOD, POD, CAT) activity, the main conclusions are asfollows:(1) The started time and duration of the three kinds of Taxodiaceae in autumn and winter are notidentical,which leaves start changing in chronological order as follows: Taxodium distichum(Linn.)Rich.,Taxodium ascendens Brongn., Metasequoia glyptostrobodies Hu et Cheng, the length of viewing period:Taxodium distichum(Linn.)Rich., Taxodium ascendens Brongn., Metasequoia glyptostrobodies Hu etCheng. The process of autumn color leaf formation and changes three kinds of Taxodiaceae are alsodifferences, the process of Taxodium distichum(Linn.)Rich leaf color change during viewing periodare: yellow-green, orange-red, dark red; the process of Taxodium ascendens Brongn. leaf color changeduring viewing period are: light orange-red, orange-red, crimson; the process of Taxodiumdistichum(Linn.)Rich leaf color change during viewing period are: yellow-green, red-brown, tan.(2) During the leaf coloration process in the three kinds of Taxodiaceae, brightness L value and hueb value have little change before and after leaf color changed, the trends of hue a value are basically thesame, are gradually increasing,and have big variations.This indicating that we can use hue a value as atypical parameter to describe that the phenomenon of green faded and red apeard during the leafcoloration process in the three kinds of Taxodiaceae.(3) During the leaf coloration process in the three kinds of Taxodiaceae, chlorophyll a, chlorophyllb, total chlorophyll concentrations are decreased, carotenoid content did not change significantly,anthocyanin content increased. The changes of percentage of pigment are as follows,the proportion ofchlorophyll is gradually decreased, the proportion of carotenoids is decreased, the proportion ofanthocyanin is gradually increased, the ratio of anthocyanin content and chlorophyll content is alsoincreased. Correlation analysis showed that, hue a value of the three kinds of Taxodiaceae branch has anegative correlation with total chlorophyll content，and has a positive correlation wiht the ratio ofanthocyanin content and chlorophyll content. The results of this study showed that, the decreasing ofchlorophyll content, and the accumulating of anthocyanin content, making the leaves anthocyaninproportion is much higher than the proportion of chlorophyll, making the color of leaves in three kindsof Taxodiaceae changes from green to orange-red or dark red.(4) During the leaf coloration process in the three kinds of Taxodiaceae, pH values changed in theacidic range, and is gradually increasing, and the results of the study showed that, pH value in the acidicrange increased to some extent in favor of the three kinds Taxodiaceae autumn leaves formation. During the leaf coloration process in the three kinds of Taxodiaceae, the soluble sugar content were firstincreased and then decreased,. This can promote anthocyanin synthesis, thereby affecting the leaves turnred.(5) During the leaf coloration process in the three kinds of Taxodiaceae, PAL activity showed agrowing trend, and the correlation analysis also showed that PAL activity and hue a value has a positivecorrelation. The results showed that, During the leaf coloration process in the three kinds ofTaxodiaceae, phenylalanine ammonia lyase (PAL) activity increased gradually contribute to theformation of autumn leaves.(6) The change of antioxidant enzyme protection system during the leaf coloration process in thethree kinds of Taxodiaceae have little different. superoxide dismutase (SOD) activity increasedsignificantly after the first slight decline, showing its positive response to low temperature and leafsenescence. Peroxidase (POD), catalase (CAT) activity have shown a downward trend, indicating thatthey and superoxide dismutase (SOD) have a synergistic effect in the anti-aging and other aspects.