A Study On Shading-tolerance And Freezing-resistance Of Ligustrum Japonicum 'Howardii' And Cyclcobalanopsis Glauca

In this paper the rule of different temperature on three years old Ligustrum japonicum'Howardii'and Cyclcobalanopsis glauca were discussed, compared with Ligustrum japonicum Thunb. Change of the relative conductivity, SOD, POD, soluble protein, soluble sugar, proline, malondialdehyde were analyzed. Change of growth and developmemt, leafanatom, photosynthetic characters, chloroplast pigment content, chlorophyⅡfluorescence paramenters and enzyme activity wear searched with differrent shading treatments.The main findings were summarized as follows:1) Applications for the regression equation of Logistic half lethal temperature, half lethal temperature of Ligustrum japonicum'Howardii'was -17.48℃, compared with Ligustrum japonicum Thunb of -19.21℃and Cyclcobalanopsis glauca was 18.54℃. As the temperature decreaced, SOD, POD protective enzyme curve increased at first and then decreased ; soluble protein rose at first, then decreased, soluble sugar raising - decreases– rising, proline rose at first and then fell sharply, malondialdehyde changing regularity was poorer.2) From the result of correlation analysis, no significant correlation among those indexes in the process of cryogenic stress existed. Those indexes can be divided into three groups from the clustering analysis results, although some index close to others, but their cold-tolerance aspect role were different. Therefore, more comparative indicators of freezing-resistance was needed.3) In the 40% shading treatment, Ligustrum japonicum'Howardii'performed better. Cyclcobalanopsis glauca growed better in full light and 20% shading treatment compared with 40% and 60% shading treatment. Photosynthetic daily variation patterns was changed under shading treatment: undersecretary change law:"double-peak"mode in full light and 20% shading treatment while"single-peak''mode in 40% - 60% shading treatment. In every processing conditions, Ligustrum japonicum'Howardii'has the largest net photosynthetic rate in full light, but the biggest grain fluorescence parameter was in 40% shading treatment. The Chlorophyll fluorescence parameter showed that the daily change range of Fv/Fm was relatively small under shading treatment ,and the more the shading treatment was , the lower the amplitude of variation was. The daily Change range was the smallest when it ws under the 60% shading treatment. and the daily change trend decreased first and rose later .whatever the Fv/Fm recovered much faster under weak illumination conditions,and the level of morning and at nightfall was basic agreement ,and it showed that the photosynthetic institutions would has reversible inactivation, but did not have the photodamage.Above all , freezing-resistance of Ligustrum japonicum'Howardii'was somewhat weak, so protected cultivation was necessary when it was introduced. Ligustrum japonicum'Howardii'would be planted in someplace with good illumination conditions ,such as road, square, or bad illumination conditions ,such as the northside of buildings , the middle and under layer of the plant landscape community. shading tolerance of Cyclcobalanopsis glauca is somewhat weak, so places such as the south side of buildings or the top and middle layer of the plant landscape community is more suitable to it.