Biologic Diversity And Physiologic Characteristics In Castanea Mollissima Bl.

Biologic diversity is the synthetic characteristics of genetic and ecologic diversity. In Castanea mollissima Bl., the biologic and physiologic characteristics are the important component parts of biologic diversity. By studying the biologic and physiologic properties and corrlation of properties to yield, biologic diversity and the high-yield mechanism will be better understood. Meanwhile the study will offer a scientific basis for conserving and applying the variety resource and identifying the genetic relationship between different characteristics.Based on the data collected from field tests and lab experiments, including morphological marking, this dissertation presents a comprehensive research report on the genetic diversity of the economic characters and biologic characteristics in Castanea mollissima. The correlation of yield to the main biologic characteristics such as the tree structure, and the phonological and flowering phases are also statistically analysed. The results are shown as follows. (1) The 28 varieties studied differ genetically remarkably in such biologic charcteristics as the yield, precocity, prolificacy, tree shape, and pollen morphology. (2) Analysis of the yield measured in the test plots indicates a great difference with the geographic location and variety planted, where the fruiting branch, tree shape and crown canopy are the main factors which affect the yield, and the yield is most obviously correlated to the number of fruiting branches. (3) The number of female flowers and dichogamy have a marked effect on yield. (4) The phenological phase and flowering all are very closely related with the yield. (5) The number of female flowers and fruiting branches, and dichogamy prove to be the most important biologic factors affecting the yield.Physiologic characteristics in the form of living patterns and mechanism are the responses of living things to a variety of environmental conditions. In this dissertation the mechanism of high yield is explored, and the findings are as follows. (1) The main physiologic factors that affect the yield include the photosynthetic characteristics, content of chlorophyll, mineral elements, plant hormones, water metabolism, fluorescence dynamics, nitrate reduction enzyme, and tolerance to unfavorable conditions. (2) With different chestnut varieties, the photosynthetic characteristics varied considerably. The diurnal variation of the photosynthetic rate is great and it is closely related with the light intensity, stomatal aperture, water metabolism, and concentration of CO₂. The nut yield is closely correlated with such photosynthetic factors as the photosynthetic rate, content of chlorophyll, and photochemical efficiency, and these factors also interact with one another among themselves. (3) The characteristic fluorescent parameters vary greatly with the varieties, and among them the photochemical efficiency (Fv/Fm) and the photosynthetic elctron transfer rate (ETR) are the main factors in photo-system that obviously affect the yield. (4) Under stress, the change of Fv/Fm reflects the capability of tolerance in different varieties, and tolerance is positively correlated to the photosynthetic rate and the activity of the nitrate reduction enzyme. (5) No regular pattern is found of the content of major nutritional elements and trace elements among the varieties, but when taking the N, P and K as a whole and compound element, it shows certain regularities and is closely correlated with yield and number of female flowers. (6) The C-N ratio, which is regulated by the photosynthetic rate and content of chlorophyll, varies with the variety and significantly affects...