Studies On Genetic Diversity,Seed Germination And Photosynthetic Characteristics Of Keteleeria Calcarea

Keteleeria calcarea Cheng et L. K, an endemic and endangered species unique to China, which mainly occurs in limestone area of Guizhou, Hunan and Guangxi. It has high ornamental, ecological, economic and scientific value. Since the 1970s, the natural populations of Keteleeria calcarea were severely destroyed. There is a sharp drop in the natural populations, and their distribution area is very narrow. In addition, its blossom is less, seed is dysplastic, and natural regeneration ability is weak. It is an endangered species. The study focused on genetic diversity, seed germination and photosynthetic characteristics of Keteleeria calcarea. The endangered mechanism of Keteleeria calcarea was studied, and the protection strategy was proposed. The main results were as follows.(1) ISSR markers were used to investigate the genetic diversity of 7 natural populations of Keteleeria calcarea. Twelve ISSR primers produced 125 loci. At the species level, the percentage of polymorphic loci(PPL) was 100.00%, Shannon's Information index (?) was 0.4177 and Nei's gene diversity index (H) was 0.2666. At the population level, the percentage of polymorphic loci was 71.20%?92.00% and the average value was 80.69%, Shannon's Information index (?) was 0.3273?0.3886 with the average value 0.3548 and Nei's gene diversity index (H) was 0.2139-0.2478 with the average value 0.2291. Keteleeria calcarea in both species and population levels showed higher genetic diversity. Nei's genetic diversity analysis (Gst=0.1433) and AMOVA analysis (?st=17.91%) showed that the genetic variation of Keteleeria calcarea mainly occurred within populations, and the genetic differentiation among populations was low. The gene flow (Nm) between populations was high (2.9890). Mantel test analysis showed that the genetic distance of Keteleeria calcarea natural populations was no significant correlation with their geographic distance (r=0.4567, P=0.0610>0.05).(2) The cone of Keteleeria calcarea was cylindrical, which average length was 14.50cm, the average diameter of 3.71cm, the average weight of 82.45g, and its average plump seed ratio was 14.9%. The seed of Keteleeria calcarea was sandy beige, with smooth surface and a larger seed wing. And its average length was 1.54cm, the mean breadth of 0.61cm, the average thickness of 0.47cm, the average weight of 0.21 g, the 1000-seed weight of 214.81 g. The seed weight of Keteleeria calcarea was bigger, and its plump seed ratio was low, this was a reproductive strategy, which produced a small amount of big weight seed.Light, temperature, substrate, storage temperatures and storage time had significant effect on seed germination of Keteleeria calcarea, and soil moistures had no significant effect on seed germination. On 25?, periodic illumination (3000 lx,12 h/d) training conditions, seed germination rate of perlite or peat soil was 75.00%,72.00% respectively. The seed of Keteleeria calcarea should be stored at low temperature, and should not be stored for a long time, should be sown in time.(3) The light saturation point (Isat) of Keteleeria calcarea was 850.45?mol·m-2·s-1, the light compensation point (Ic) of 7.86?.mol·m-2·s-1, the maximum net photosynthetic rate (Pnmax) of 5.06?mol·m-2·s-1; and its CO2 saturation point was greater than 1200?mol·mol-1, the CO2 compensation point (CCP) of 97.29?mol·mol-1 the Carboxylation efficiency (CE) of 0.0267?mol·mol-1, the maximum carboxylation rate (Vcmax) of 26.24?mol·m-2·s-1, the maximum electron transfer rate(Jmax) of 81.58?mol·m-2·s-1. Results showed that the photosynthetic ability of Keteleeria calcarea was weak, it's not consistent with its upper dominant species in community, specific reason remains to be further research.