Study On Leaf Color Changes And Physiological Characteristics Of Pyrus Calleryana

In contrast to green Pyrus calleryana, red varieties was used to study physiological indices during leaf color change period, including chlorophyll content, carotenoid content,anthocyanin content, leaf color parameter(L~*, a~*, b~*), osmotic adjusting matters(soluble sugar, soluble protein, the activity of enzyme(PAL, CHI, UFGT), the stability of anthocyanins and degradation of related enzymes(PPO, POD), in order to explore the relationship between anthocyanin content, osmotic adjusting matters, enzyme activity and leaf color. The physiological mechanisms of leaf coloration in Pyrus calleryana were discussed.The main results were submitted as follows:1. The relationship of Pyrus calleryana between the pigment content of leaf color changes and the change of leaf color.The leaves of Pyrus calleryana started to color in mid-October. Leaves changed from green to purple and to red, the change regularity of Pyrus calleryana was different from the contrast. Because of the different characteristics in Pyrus calleryana, the color performance was also slightly different. The anthocyanin relative content of Pyrus calleryana was significantly higher than the green conrtast, which kept red or orange red. Chlorophyll content in Pyrus calleryana leaves was a downward trend, but the ratio of anthocyanins and chlorophyll was small, leaves contained a large number of chlorophyll, so that the leaf color was dark in the middle. In the process of the leaf turning to red, with the difference of anthocyanin, the carotenoid content was declined. It showed that chlorophyll and anthocyanin content was the key factor to leaf color, but the carotenoid content was not the main pigment to turn red.2. The relationship of Pyrus calleryana between the parameter of leaf color and the change of leaf color.In the change process of leaf color,lightness(L~*) and hue(b~*) were due to the different varieties, while the contrast was higher,and the leaf color was brighter yellow-green. What’s more, the data of L~* and b~* had little change in Pyrus calleryana. The lightness was lower and the leaf color slants dark with dark green. The data of a~* was almost the same change trend between Pyrus calleryana and the contrast leaf, and amplitude changes was increased.The correlation of a~* and leaf color pigment was significant statistically. It showed that the pigment content was not the main influence of the data of L~* and b~*,and the data of a~* can be used as a typical parameter to describe the leaf color changes appeared in the process of green fading and red showing.3. The relationship of Pyrus calleryana between the contained material and the change of leaf color.Soluble sugar and protein was the important inclusions to plant. They played a key role in the growth of plants. There was no significant correlation between soluble sugar and the content of anthocyanin in Pyrus calleryana, but the trend of soluble sugar was slowly rising,and always maintained a higher level in the leaf color expression, so that we can know that soluble sugar can provide enough energy and precursor substances for the synthesis of anthocyanins. There was no significant correlation between soluble sugar and anthocyanins in Pyrus calleryana. Research suggested that the conditions of anthocyanin were not necessarily conducive to the formation of protein synthesis. The protein content of Pyrus calleryana changed smoothly, so it could be used as a osmotic substances to adjust the ability of plant to resist the low temperature environment in autumn and winter.4. The relationship of Pyrus calleryana between the related enzyme activity of anthocyanin synthesis and the change of leaf color.The activity of PAL was negatively related to the content of anthocyanin, and the activity of PAL in the contrast was higher than the red varieties during the leaf change period. It showed that PAL was not the key enzyme to anthocyanin. Under the condition of sufficient precursor, CHI can promote the synthesis of anthocyanins, because of its own feedback mechanism that make its activity decreased in the late of leaf color changes. It showed that CHI enzyme was one of the important enzymes to anthocyanins synthesis. UFGT was closely related to the stability of anthocyanins.The activity of UFGT was positively correlated with the anthocyanin content in the different varieties. And the activity of UFGT had remained high level in the period of anthocyanins synthesis. It showed that UFGT was one of the key enzymes to leaf color.5. The stability of anthocyanins of Pyrus calleryana.Anthocyanins had different degrees of decomposition in the different conditions, but under the condition of the dark, anthocyanin’s absorbance was the slowest fell. In the condition of 4C, anthocyanin was stable, the rate of degradation was the slowest and the half-life was the largest. p H had an important effect on the color of the anthocyanins. In the condition of acidic, the anthocyanin had the slowest decline solution and kept red. Studies showed that in the condition of dark, low temperature and low p H was helpful to extract, use and save. So that we can change the environment to prolong the color stage in the application of landscape and the cultivation management.6. The influence of enzymes related to anthocyanin degradation to leaf color in Pyrus calleryana.At the same time of anthocyanin synthesis, the degradation was also done in the body,but the quantity of anthocyanin synthesis was far greater than the degradation, so that the leaves kept red in Pyrus calleryana. From the correlation, the activity of PPO was significantly positive correlated with the content of anthocyanin, so that PPO was the main cause of anthocyanins degradation enzyme in ‘Capital’ 、‘Aristocrat’ and ‘New Bradford’.POD was the main enzyme of anthocyanins degradation in ‘New Bradford’.PPO and POD were commonly played a role in the anthocyanin degradation in ‘Red Spire’.