| To evaluate the effects on the growth of4-leaf umbrellas young rubber tree of the different leaf number and different parts of the leaf-umbrellas, then provide a theoretical basis for control the number of the rubber tree canopy leaves. In this experiment, the research object is the4leaf-umbrellas CATAS7-33-97rubber budding saplings, remove part of the leaf-umbrellas then observing the growth of the rubber trees and the photosynthetic characteristics of the retention leaf-umbrellas. To study the mechanism of the impact on the growth of rubber tree by the different leaf number and different parts of the leaf-umbrellas on the photosynthetic characteristics. The results as follows:1.The impact on the growth of rubber tree by the different leaf number and different parts of the leaf-umbrellas was decided by the number of leaves and the part of the leaf-umbrella.In the8months of the experiment, the average trunk diamete of the4leaf-umbrellas rubber trees incremented10.3mm, and the plant height increased25.0cm. Removed the1leaf-umbrellas, the average trunk diamete of the rubber trees incremented8.7mm, and the plant height increased20.9cm, respectively was84.22%and83.40%of the control groups and the extreme significant difference.But the different parts of the leaf-umbrellas affect the different increased of the trunk diamete and the height of rubber trees, such as the average trunk diamete of rubber trees which remove the4th leaf-umbrella(The lowest leaf-umbrella) increased10.3mm, was99.61%of the control groups,, no significant difference. Removed2leaf-umbrellas, the average trunk diamete of the rubber trees increment5.3mm, and the plant height increased16.5cm, respectively was50.92%and66.08%of the control groups and the extreme significant difference, in this treatment b12and b13growed best, which trunk diamete of the rubber trees increased7.4mm、7.4mm and trunk height increased17.9cm、18.5cm, respectively was71.83%、71.53%、71.72%、74.12%of the control groups and the extreme significant difference. Removed3leaf-umbrellas, the average trunk diamete of the rubber trees increased1.76mm, and the plant height increased5.8cm, respectively was16.99%and23.13%of the control groups and the extreme significant difference, the descending order of the trunk diameter incrementd:al、a2、a3、a4and the difference of them is extreme significant, the trunk diamete of the rubber trees increase2.3mm、1.8mm、1.6mm、1.3mm, respectively was22.36%、17.13%、15.88%、12.32%of the control groups and the extreme significant difference.2. The impact of photosynthes on the removed leaf-umbrellas rubber tree decided by the different time, different leaf number and different parts of the leaf-umbrellas.2.1Removed the leaf-umbrellas for30days, the photosynthesis of the young rubber trees which removed leaf-umbrellas had significantly improved, but removed the leaf-umbrellas for60days, the photosynthesis of young rubber trees which removed leaf-umbrellas had significantly reduced. Removed the leaf-umbrellas for30days, the Pn, the energy which absorbed by the antenna pigments of the chloroplasts was used transfer photochemistry, the effective of Ps Ⅱ photochemistry quantum yield and the electron transport rate of the Ps Ⅰ and PsⅡ were all extremely significantly improved compared with the control group. But has removed the leaf-umbrellas for60days, the Pn,the value of the SPAD, the energy which absorbed by the antenna pigments of the chloroplasts was used transfer photochemistry, the effective of Ps Ⅱ photochemistry quantum yield and the electron transport rate of the Ps Ⅰ and Ps Ⅱ were all extremely significantly reduced compared with the control group.2.2The impact of photosynthesis on the has removed leaf-umbrellas young rubber trees decided by the different number of the leaf-umbrellas. Removed the leaf-umbrellas for30days, the photosynthesis of the young rubber trees which has removed1or2leaf-umbrellas were extremely significantly improved compared with the young rubber trees which has removed3leaf-umbrellas and the control group. There was no significantly different with young rubber trees which has removed3leaf-umbrellas and the control group. Removed the leaf-umbrellas for60days, the photosynthesis of the young rubber trees which has removed1leaf-umbrellas, removed2leaf-umbrellas or removed3leaf-umbrellas were successively reduced compared with the control group, and the difference was extremely significant. Removed the leaf-umbrellas for30days, the Pn of the the young rubber trees which has removed1leaf-umbrellas was extremely significant improved compared with the control group and others control; the Pn of the the young rubber trees which has removed21eaf-umbrellas was extremely significant improved compared with the young rubber trees which has removed3leaf-umbrellas; The Pn were on significantly different between the young rubber trees which has removed3leaf-umbrellas and the control group. The energy which absorbed by the antenna pigments of the chloroplasts was used transfer photochemistry, the effective of Ps II photochemistry quantum yield and the electron transport rate of the PS I and PS II of the which has removed1or2leaf-umbrellas were extremely significant than the young rubber trees which has removed31eaf-umbrellas and the control group. Removed the leaf-umbrellas for60days, the Pn, the Value of the SPAD, the energy which absorbed by the antenna pigments of the chloroplasts was used transfer photochemistry, the effective of PS II photochemistry quantum yield and the electron transport rate of the PS I and PS IIof the young rubber trees which has removed1,2or3leaf-umbrellas were all extremely significantly reduced compared with the control group.2.3Removed the leaf-umbrellas for30days, the photosynthesis of the3rd leaf-umbrella has increased, followed by the2nd and the1st leaf-umbrella Removed the leaf-umbrellas for60days,all of the leaf-umbrellas has reduced. Removed the leaf-umbrellas for30days, the average of the Pn to the1st leaf-umbrellas improved9.38%than the control group, the1st leaf-umbrella of the experimental group which has removed3rd、4th leaf-umbrellas, removed2nd、3rd、4th leaf-umbrellas and removed4th leaf-umbrellas, had the extremely significant improved of the energy which absorbed by the antenna pigments of the chloroplasts was used transfer photochemistry, the effective of PSⅡ photochemistry quantum yield and the electron transport rate than the control group; The average of the Pn to the2nd leaf-umbrellas improved9.64%than the control group, the2nd leaf-umbrella of the experimental group which has removed3rd,4th leaf-umbrellas, removed1st.3rd leaf-umbrellas and removed4th leaf-umbrellas, had the extremely significant improved of the energy which absorbed by the antenna pigments of the chloroplasts was used transfer photochemistry, the effective of PSII photochemistry quantum yield and the electron transport rate than the control group; The average of the Pn to the3rd leaf-umbrellas improved13.67%than the control group, the3rd leaf-umbrella of the experimental group which has removed2nd leaf-umbrellas, removed1st、4th leaf-umbrellas, removed1st、2nd leaf-umbrellas and removed4th leaf-umbrellas, had the extremely significant improved of the energy which absorbed by the antenna pigments of the chloroplasts was used transfer photochemistry, the effective of PS Ⅱ photochemistry quantum yield and the electron transport rate than the control group;The average of the Pn to the4th leaf-umbrellas improved5.17%than the control group, all the4th leaf-umbrella of the experimental group had the extremely significant reduced of the energy which absorbed by the antenna pigments of the chloroplasts was used transfer photochemistry, the effective of PSII photochemistry quantum yield and the electron transport rate than the control group, the photosynthetic systemof the4th leaf-umbrellas has been damaged. Removed the leaf-umbrellas for60days, the average of the Pn to the1st leaf-umbrellas reduced15.56%than the control group; the average of the Pn to the2nd leaf-umbrellas reduced23.50%than the control group; the average of the Pn to the3rd leaf-umbrellas reduced22.46%than the control group; the average of the Pn to the4th leaf-umbrellas reduced15.09%than the control group; Removed the leaf-umbrellas for60days, most of the different leaf-umbrellas of experimental group the Pn, the energy which absorbed by the antenna pigments of the chloroplasts was used transfer photochemistry, the effective of Ps II photochemistry quantum yield and the electron transport rate were reduced compared with the control groupIn summary, the number leaf-umbrella of the young rubber trees is4could be more appropriate for the trees growing, at least the1st,2nd and3rd leaf-umbrellas was essential, because these3leaf-umbrellas had significant effects on stem diameter growing, and4th leaf-umbrella only have a significant effect on high growth. So, the young rubber trees should not be trimmed, at least should not be trimmed the leaf-umbrellas of young rubber trees. |
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