| In this paper, resistance physiology characteristics of the different provenances on Dichondra repens were studied by way of measureing some physiology indexes from its leaf under stress. The micromorphological features of leaf epidermis and vegetative organ were investigated by means of light microsocope(LM). Reproduction characteristics of Dichondra repens were studied through experiment and observation. This study is helpful to breading, spreading wildlife resources utilization and turfgrass genetic engineering of Dichondra repens. The results were as follows: (1) Comparative studies on the cold resistance of the wild Dichondra repens and the cultivated Dichondra repens when temperature fell were made. Results showed that the content of free proline decreased first and increased later; content of soluble sugar increased first and decreased afterwards. Relative electric conductivity gradually increased. The content of free proline of leaves from the wild species was higher than that of the cultivated species during four phases. The content of soluble sugar of leaves from the wild species increased more quickly than that from the cultivated species. Relative electric conductivity of the cultivated species increased more quickly than that of the cultivated species. The result shows that the wild species is more cold-resistant than the cultivated species. (2) Under water stress, the contents of free proline, soluble sugar, nitrate and nitrite; the activities of peroxidase (POD), superoxide dismutas (SOD) and nitrate reductase changed significantly. With the water stress, some leaf physiological indexes of wild Dichondra repens increased more quickly than that of the cultivated species. DNA damage degree of the cultivated species was more serious than that of the wild species, and the water content of leaf from the wild species was more than that of the cultivated species. The results indicated that the wild species was more drought-resistant than the cultivated species. (3) The contents of two heavy metal elements (Cu, Pb) in Dichondra repens growing in Cu, Pb contaminated soil were analysed in order to seek for some hyperaccumulators of these two elements. The results indicated that the total content of Cu in the plants was higher than that of Pb, moreover, the contents of these two elements in roots and stems were higher than those of leaves. The total contents of them in the plants were increasing with the their contamination in soil. The accumulation coefficient of Cu was higher than that of Pb. The analysis of physiological indexes in plants growing in Cu, Pb contaminated soil was carried out to evaluate the effects of contaminations. The results were shown as follows: Both the contents of chlorophyll a and chlorophyll a/b ratio in leaves decreased with the increase of the concentration of two heavy metals. The activity of SOD increased at the peak (106.494U.g-1FW ) and decreased subsequently, however, the activity of POD was always keeping the increasing trend. The membrane permeability of cell was not significantly different from each other. (4) Observations of reproductive characteristics on Dichondra repens were made. The results showed Dichondra repens possesses asexual reproduction and sexual reproduction. Sexual reproduction was by way of self-pollinated and fruit-set ratios was low, being only 2.04%. The effects of alternating temperature at 20℃/25℃,25℃/35℃, room temperature (under 20℃)on seed germination of Dichondra repens were studied. The results showed the germination rate under 20℃was the lowest, that under 20℃/25℃was the highest. The germination rate of the seeds of Dichondra repens after treated by different 6-BA concentration was raised, treatment of 10-3mg /L contentration6-BA can improved markedly The germination rate of the seeds of Dichondra repens, and the growth of root and bud were accelerated. The populations of this species were mainly produced by creeping stem. The fastest growth period of creeping stem was from June to July. (5) Anatomical observations on the root, stem... |
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