| In this experiment, we used the four-year-old Ginkgo biloba L. sapling asresearch material to study the photosynthetic characteristics under the differentseasons, the different branches type, the different leaf locations and the different timein one day. Besides, we also measured the canopy structural parameters of Ginkgobiloba L. sapling(including the angle, azimuth, insertion position, length, basaldiameter of branch)and study its regularities of distribution. Then using thephotosynthetic rates and the growth to calculate the accumulation of photosyntheticproducts. Experimental results were as follows:In sunny day, the photosynthetic rate curve of the sun leaves of Ginkgo biloba L.changes as “bimodal shape”, the photosynthetic rate curve of the shadow leaves ofGinkgo biloba L. changes as “unimodal shape”. The Photosynthetic rate in sunnyday>the photosynthetic rate in cloudy day>the photosynthetic rate in overcast. Thephotosynthetic rate of Ginkgo biloba L.in10:00changes as “unimodal shape” fromjuly to October,and it reached the peak at the beginning of August.The result by using modified rectangular hyperbolic model to fit the lightresponse curve of Ginkgo biloba L. was better than others. The light saturation pointof Ginkgo biloba L. was1078.980μmolCO2·m-2·s-1,the light compensation point ofGinkgo biloba L. was11.250μmolCO2·m-2·s-1by fitting. The photosynthetic rate ofGinkgo biloba L. was significantly positively correlated with leaf transpiration rateand stomatal conductance. The Photosynthetic rate of Ginkgo biloba L.andphotosynthetic active radiation showed a significant positive correlation. Differencesin photosynthetic rate of the leaves which were on the same level long branches butlocated in different positions were not significant. Differences in photosynthetic rateof the leaves which are on the same level but in different types of branches weresignificantly.There are significant differences of photosynthetic rate between thedifferent levels.There was a significant positive correlation between the branch angle and thebranch position of Ginkgo biloba L.. There was a significant positive correlation between the basal diameter and the branch length of Ginkgo biloba L.. The average ofthe primary branches angle of Ginkgo biloba L. was55°. The average of the primarybranches angle of Ginkgo biloba L. was decreasing as the number of layers increasing.The azimuth of the primary branches of Ginkgo biloba L. obeyed uniform distribution.The probability of bud in each direction on the trunk of Ginkgo biloba L. was close to1:1:1:1. The probability of buds distributing on east and west direction> north andsouth direction, and the basic probability of buds in east and west direction was1:1.The branches length of Ginkgo biloba L.saplings grow only once a year, its bestgrowth season was from mid-May to mid-June. The growth curve of basal diametershows a single "S". between the end of May and the end of August,the basal diameterincreases fast. The growing season of basal diameter started later than the brancheslength’s. There were two rapid growth stages of the branch density of Ginkgo bilobaL., from early May to early June and early September to early October. The density ofnew shoots consistently lower than a year old branches.The specific leaf area ofGinkgo biloba L. kept on a declining curve and it changed smoothly after July.We could establish the regression equation about the leaf length, leaf width andleaf area in different time periods by using a large sample of Ginkgo biloba L.data. Itsrelevance was significant. So we can use leaf length and leaf width data to estimateleaf area. The regression equation by using branches of length and basal diameter,which significantly correlated,could be used to estimate the volume of Ginkgo bilobaL.Using photosynthetic rate and growth to estimate the biomass of Ginkgo bilobaL., both values were close. We initially considered the above methods could be usedto estimate the biomass of Ginkgo biloba L. |
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