| The urban landscapes in the northen areas was single and boring for lack of evergreen and colorful tree species. photinia×fraseri was introduced to the the Changjiang valley in China from its native habitat and then was applyed in urban plant landscape construction in large scale.In order to get a general picture of the adaptive capacity of Photinia fraseri to environment and provide the theory and the practice basis of its large-scale commercial planting, a subject based on comprehensive observation and investigation about the climate, moisture, soil and many other habitat conditions was made in Shankou test site of Taishan Forestry Academe to assess the introduction and cultivation of Photinia fraser in Taian during June, 2006 to December, 2007. Though analyzing the difference between its native habitat and cultivating areas, a general picture of the phenological characteristics and leaf color changing law was obtained, what's more, the drought resistance, cold resistance, proper reproduction methods from cuttings, overwintering appearance and protective measures for overwintering of that tree species were also studied. The result showed that:1. Phenological observation: In the annual period, there appeared 4 growing peaks, and the buds of Photinia fraser awakened on secend, March while budbreaking happened on 10th, March and leaf-unfolding happened on 12th, March. The fast-growing period of Photinia fraseri was about between July and August, and the blooming phase is between 1st, May and 17th, May while the height increment ended in late October. The red-leaf period advanced by 3 days and lasted 10 more days compared to that in the native habitat, but only under full exposure to sunshine can the most perfect leaf-color appear, While there existed no significant impact of humidity and rainfall on its growth, the temperature has appeared to be closely related to its growth with certain rule.2. Field overwintering observation: Though continuous field observation in the cultivating area for 3 years, the freezing injury can be summarized as follows: (1) The freezing injury was relatively serious under the extremely low temperature -14.2℃in 2004, and the injury belonged to the 4th class did not significantly affect the budbreaking in the next year. (2) The freezing injury belonged to the 3rd class under the extremely low temperature -13.7℃in 2005. (3) The freezing injury belonged to the 2nd class under the extremely low temperature -10.2℃in 2006, the result of that the temperature of winter in taian can satisfy this tree's normal growth. The heat resistance of Photinia fraseri make it possible for its success of getting through the summer in Taian. This tree species was very easy to suffer from the powdery mildew and bagworm moths in summer but that did not affect its growth and ornamental characteristics.3. Drought resistance: The change of daily soil water potential and leaf water potential was a'V'shape with daily fluctuation range increasing as drought stress rose during the testing period, and the value reached the minimum of the day between 10:00 and 14:00. The daily fluctuation range of transpiration rate and net photosynthesis decreased while the peak value of transpiration rate appeared much earlier, from 10:00 at the beginning to 8:00 at the end. The correlation between transpiration rate and net photosynthesis, soil water potential, leaf water potential were significant. When the continuous natural drought lasted to the 10th day, the top shoots began to wilt. With the drought degree enhanced gradually, the total chlorophyll content and relative water content declined while the content of anthocyanin, malonadehyde and proline increased as well as the cytolemma permeability, and the activity of SOD and POD first increased then decreased. The negative correlation between chlorophyll content and anthocyanin content was significant at the 0.01 level as well as that beween the relative water content of leaf and proline content. The positive correlation between the malonaldehyde content and cytolemma permeability was significant at the 0.01 level. The negative correlation between chlorophyll content and cytolemma permeability as while as malonaldehyde content was significant at the 0.05 level.4. Cold resistance: (1) During the overwintering period the chlorophyll content of Photinia fraseri leaves first decreased and then increased while the relative electrical conductivity gradually decreased. The activity of SOD and POD of the Photinia fraser in greenhouse first increased and then decreased, and that under all the other cultivation measures first increased and then decreased but in the end icreased again. The proline content of Photinia fraseri in greenhouse had the tendency to increase as well as that under the influence of transpiration restraining agent, and that under all other cultivation measures first increased and then decreased. During the whole overwintering period, the content of soluble protein had the tendency to first increase and then decrease. The comprehensive impacts of low temperature and its lasting time on the content of chlorophyll, proline, soluble saccharide and unsaturated fatty acid as well as the relative cytolemma permeability, the activity of SOD and POD were significant. Though the method of membership function, the physiological adaptation of Photinia fraseri under different overwintering cultivation measures was assessed and the result showed that the protective effects ranged from the high to the low was: greenhouse, shading shed, ground cover, spraying antifreezing agent, spraying transpiration restraining agent, open fields. (2) With the droping of stress temperature and the lasting of stress time, only the tendency of SOD and POD's activity before upgrade then degression and then upgrade, the rest of index accompanying the degression of temperature continue degrade, this result illustrates that in the initial low temperature stage Photinia fraseri have some defensive reaction, by the defensive reaction to decrease the speed and degree of detriment. T-10 is low temperature coercion critical point of Photinia fraseri, the critical low temperature coercion duration is 24~48 hr. The negative correlation between the content of chlorophyll and that of praline, malonaldehyde and soluble saccharide as well as the relative cytolemma permeability was significant at the 0.01 level. The positive correlation between the content of chlorophyll and the activity of SOD as well as the content of unsaturated fatty acid was significant at the 0.05 level.So Photinia fraseri has a good adaptability in taian according to its growth rhythm and ornamental characteristic.Treating the indexes implying the ability and potential to overwinter successfully as the first level and that assessing the desired characteristic as the second level and involved other factors such as drought resistance, reproduction and so on, Photinia fraseri belonged to the rank of excellence and made it one of the best tree species which were proper to be use in verdurization in similar northern areas as Taian.
|
PDF Full Text Request