Study On Population Ecology Of Zoysia Japonica

This is the first time to study the biology and population of Zoysia japon.ica in China, and get some results as follows. 1. The morphological and anatomic characteristics of Zoysia japonica are studied in detail. The anatomic basis of drought and tramp resistance and good elasticity of Zoysia japoiica is discovered 2. The leaf梞odular population of Zoysia japonica is studied. Both the biological zero temperature for growth and sensitive temperature for color change of leaf are 10C. The relationship between leaf number and effective accumulative temperatures is power function. The general trend of birth and death of leaf is found. 3. The age structure of natural clonal population of Zoysia japonlca is studied by generational and morphological methods. The results show that if the relationship between age and tiller?s morphology has been found, the morphological method is better because it can show the seasonal change of age structure. 4.The seasonal expanding trends of rhizome in artificial populations of Zoysia j~iponica is that the expanding speed increases with time in the growing season and gets a maximum by the end of July and the beginning of August, thueuu the speed decreased. If there is no disturbance from other plant, which means the ecological space is large enough, the relationship between area梕xpanding of individual clouia] population and time is power function. The increment of area has a I inearitv relationship with basic area of the clone. 5.The influence of densities on individual elonal populations is studied. The fractal dimension value increases with the decreasing of density. The result shows the ability of clone to use and hold resources improves whueti density (Iecreases and cloinal population of Zoysia japonica could adjust growth pattern according t.o the environment. This is a kind of adaptable ecological policy. There are other phenomena to show the policy. When densit.y decreases, the internode of rhizomes becomes longer, node number increases, rhizome elongates quickly and ramification intensifies. So the clone could possess more space and resource. Clonal population of Zaysia japonica allocates more resource to rhizomes whetu density decreases so as to possess plane space but allocates more resource to tillers when density increases so as to possess more upright space. 6. An important influence of food chain for the spreading of Zoysia japonica population is found during the study of sexual reproduction. Seeds of Zoysiu japonica can reserve high germination rate within 2 years under normal condition. II 4? Then the rate decreases with time. 7. The variation within Zoysia japonica genus is studied. Some regular variations are found. The length of spike, spikelets number per spike and weight per 1000 seeds vary with latitude and the distance to sea. Leaf color in autumn changes with latitude too. Morphology and esterase isozyme researches show that there are many variations among populations of Zoysia japonica Some valuable ecotypes have been chosen. 8. A new theor germplasin resources protection by industrial production is put forward on the basis of grazing and enclosing experiments.