Study On Genetic Diversity And Photosynthetic Characteristics Of Dendrocalamus Brandisii In Pu’er City

Dendrocalamus brandisii is a bamboo specie with high economic value for both shoots and wood.The intraspecific genetic diversity of 5 cultivated species of Dendrocalamus brandisii was studied by using simple sequence repeats（SSR）molecular markers.According to the genetic diversity analysis of Dendrocalamus brandisii and the market prospect of‘Manxie1’,a new variety of Dendrocalamus brandisii,the net photosynthetic rate of‘Manxie 1’was determined under shading treatment to explore its photosynthetic characteristics,the chlorophyll fluorescence parameters of‘Manxie 1’was determined under apex truncation treatment to study its chlorophyll fluorescence characteristics under dwarf cultivation in greenhouse,and the photosynthetic capacity of stem of‘Manxie 1’was studied by the vary of CO₂emission.This study aims to study the intraspecific genetic diversity and establish the molecular marker identification method for genetic diversity study of Dendrocalamus brandisii,study the photosynthetic characteristics and chlorophyll fluorescence characteristics of‘Manxie 1’under different treatments to provide a theoretical basis in its introduction to northern China and cultivation in greenhouse.The main results are as follows:（1）Genetic diversity analysis and genetic relationship of Dendrocalamus brandisii based on SSR molecular markers:5 cultivated species of Dendrocalamus brandisii variation range of genetic similarity coefficient is 0.90-0.98.The two cultivated species,1 and 2,of Dendrocalamus brandisii had a close genetic relationship with each other.‘Manxie 1’and the other four cultivated species were relatively distantly related at the genetic coefficient of 0.900.（2）3 cultivated species of Dendrocalamus brandisii could be identified by 3 SSR molecular markers,4162,DLTGMS＿472 and Phye SSR6,two cultivated species,1 and 2,of Dendrocalamus brandisii could not be identified.（3）Analysis of photosynthetic characteristics of‘Manxie 1’:The net photosynthetic rate of leaves of‘Manxie 1’was measured at 100%,75%and 60%light transmittance,and its light response curve was fitted with a fitting degree between 0.982 and 0.993.Its light saturation point was 923.24μmol·m^-2·s^-1,660.40μmol·m^-2·s^-1and 423.24μmol·m^-2·s^-1under 100%,75%and 60%light transmittance,respectively.The light saturation point changed greatly under different light transmittance.In the range of 360-900μmol·m^-2·s^-1,the plant exhibited the characteristics of Yang plants.At 100%,75%and 60%transmittance,the light compensation points were 33.08μmol·m^-2·s^-1,29.13μmol·m^-2·s^-1and 27.05μmol·m^-2·s^-1,which decreased with the decrease of transmittance,and the apparent quantum efficiency gradually increased,corresponding to 0.013,0.115 and 0.021.（4）Based on the analysis of chlorophyll fluorescence characteristics of‘Manxie 1’,it was found that the maximum light quantum yield and photosynthetic performance index of stem changed slightly before and after truncation dwarfing,which were about 0.729-0.823 and 1.2,respectively.The maximum light quantum yield of leaves changed slightly,but the photosynthetic performance index of leaves increased significantly from 0.8 to 1.4 after peak truncation.The changes of OJIP curves showed that the accumulation of QA^-in the PSⅡreaction center of the leaves was significantly reduced after the truncation of‘Manxie 1’,and the fluorescence yield of the J phase was reduced,while the OIP phase had no significant changes.The OIJP phases of stem changed slightly before and after the apex.However,the J phase of leaf was always higher than that of stem.Notably,both leaves and stems had a complete OJIP curve,which proved that PSⅡof both were well developed and could carry out normal photosynthesis.（5）The amount of CO₂emission from the stem of‘Manxie 1’had no significant change within 3 minutes,and the concentration ranged from 428 to 433μL·L^-1,the amount of CO₂consumed by photosynthesis and emission by respiration of the stem was basically equal to each other.