Studies On Germplasm Characteristics And Variation Of Camellia Semiserrata Chi.

Oil-tea camellia belonging to the family Theaceae and the genus Camellia, which is the most important eatable woody oil tree in south of China. Camellia semiserrata Chi. is an important cultivated oil-tea camellia species, which have high content and fine quality of the seed oil. It not only is excellent woody oil tree, but also is highly valued ornamental tree species. However, there is little knowledge about the genetic variation, biological characteristics, selecting of fine germplasm, breeding and other aspects of the research of C. semiserrata Chi.. In this study, population morphology, reproductive physiology, grease characteristics of C. semiserrata Chi. were conducted at the core distribution area, this study provides a theoretical basis and technical support for the breeding and screening of C. semiserrata Chi..The results are as follows:(1) This study indicated that the phenotypic variation was abundant. There was a large selection potential in C. semiserrata Chi. species. The largest coefficient of variation of tree body properties was brunch number (CV56.67%). The minimum coefficient of variation was tree height (CV19.53%). The maximum and minimum coefficient in leaf traits were the proportion of leaf serrated margins (CV27.3%) and leaf blade length/leaf blade width (CV15.03%). The largest and smallest coefficients of variation about shoot characters were the number of newly shoots (CV57.44%) and the number of leaves (CV25.10%) respectively. About the floral organ traits, the largest coefficients of variation was corolla crown (CV43.6%), the smallest was the number of internal stamen (CV11.45%), which indicate that is relatively stable. The maximum and minimum coefficients were the seed weight of individual fruit (CV39.98%) and the fruit width (CV11.58%) in fruit features. The largest and smallest value of coefficient of variation of economic traits were the fruit yield of individual tree (CV85.86%) and oil-bearing in seed kernel (CV4.62%) respectively. The oil-bearing in seed kernel trait was relatively stable economic trait.(2) The curve of diurnal variation of photosynthetic rate of C. semiserrata Chi. demonstrated double apexes, the maximum and minimum values of net photosynthetic rate of C. semiserrata appeared in October and December, the values were7.278μmol·m-2·s-1and5.473μmol·m-2·s-1respectively. The diurnal changes of leaf transpiration rate showed a single peak curve, and the water using efficiency curve demonstrated double apexes. The light saturation point (LSP) of the mature trees of C. semiserrata is1274.6μmol·m·2·s-1, and the light compensation point (LCP) is21.59μmol·m·-2·s-1, the result indicated that the mature trees of C. semiserrata is sun plant, which have a higher photosynthesis rate under strong lights. The stomata conductance, intercellular CO2concentration, and air temperature could effect on net photosynthetic rate of C. semiserrata significantly.(3) The vegetative organ and floral organ formation characteristics were demonstrated. By the anatomy approach, the result indicated that the leaf of C. semiserrata belongs to bifacial leaf, and the stomata only scattering over the lower epidemis of the leaf, stomatal density (SD)138/mm2The leaf could divide into three parts, the epidermis, mesophyll and vein, the primary vein with a U-type vein vascular. The caulicle was mainly composed of epidermis, cortex and vascular cylinder. The overgrown stem contained two parts, which were periderm and partial vascular tissue.The primary structure of root was composed of epidermis, cortex and vascular cylinder, the secondary structure of root divided into periderm and secondary vascular tissue. The floral development of C. semiserrata Chi. was observed under scanning electron microscope (SEM) for the first time up to date. Both perianth were initiated spirally and centripetally, in the species four to five carpel primordial originated from a ring meristem, in the flowering developmental process, the carpels in C. semiserrata Chi. developed nearly into syncarpous gynoecium, and the carpels developed into connate stylus, the surface of stigma had a lot of papilla cells, and divided into3-5cleft. The stamen divided into two wheels, the internal stamen primordia all arise on a ring meristem,15～21stamen primordia in the inner whorl first arise simultaneously, the outer whorl of stamen primordia divided into3-5layers, the same layer arise simultaneously on a ring meristem, different layers irregularly initiate, in the flowering development process the outer stamen primordia developed nearly into1/3～1/2of based connate stamens.(4) The fruit size increased sharply from the beginning of July to the end of August, the fruit weight and the weight of50fresh seeds increased with the fruit growth, the fat acid accumulate stably from July to September. Near infrared reflectance spectroscopy of132seed was used for its oil content detection, compared with the oil content of132samples of C. semiserrata Chi. seeds obtained by conventional Soxhlet extraction method. The spectral pre-treatment method and regression analysis method were screened, the combination of Stand Normal Variable (SNV)+1st derivative was suitable for spectral pre-treatment, and the optimal regression method is Partial Least Squares (PLS). An accurate model was well established with seed kernels after grinding, the correlation of calibration (RC) and root mean square errors of calibration (RMSEC) were0.9560,0.5960respectively, the correlation of cross-validation (RCV) and the root mean square errors of cross-validation (RMESCV) were0.9521,0.6712respectively. Ten samples were used to test the model, the correlation coefficient between predict values and chemical values was0.98, with the standard error0.33, all parameters indicated that the near infrared reflectance spectra of C. semiserrata Chi. seeds could be used to predict the oil content quickly and exactly.(5)13excellent plasms were selected from138samples. Comprehensive evaluation of13excellent germplasms was carried out by grey relational degree analysis, and the relationship between comprehensive performance and each character was overall analyzed. The result indicated that the weighted relational degrees of13excellent trees in order of HY6, H6, HY5, HY4, Y23, Y9, Y28, HY11, HY1, HY8, B42, B55, HY3. The affinity degree on oil output per hm2was oil-bearing in seed kernel, oil concentration of fresh fruit, kernel rate of fresh fruit, crown area, fruit yield of individual tree, oil yield of individual tree, in fact attention should be given to these traits in further screening process of excellent plasm of Camellia semiserrata Chi..