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Abstract:Some basic characteristics of tropical mountain rain forest communities with emphasis only on tree layer of primary and regenerated stands in Jianfengling, Hainan Island, were studied since 1983. The results indicated that the forest communities showed rich floristic composition, and high diversity index being up to 5.8-6.3 for 2 primary stands and 4.5-4.8 for 3 regenerated stands as calculated by the Shannon-Wiener diversity index.Over 8O% of the total genera in the conununities were of tropical components. The diameter at breast height and tree height classes showed a reasonable distribution in the primary and regenerated stands. Based on the results of frequency measurement, the frequency va1ues of most tree populations (more than 8o% of the totals) were less than O.2 in the communities,and the frequency distribution showed the special pattern that was different from the Raunkiaer's Frequency Law.

Abstract:Heat balance in lower-subtropical hillslope ecosystem in Heshan Experiment Centre, Guangdong Province, was measured. The results indicated that the total evapotranspiration heat flux and the sensible heat flux were 74.7% and 21.2% of the net radiation, respectively. There was less heat storage in the soil and vegetation. Although the amount of gross solar radiation and precipitation was suffcient, the water condition did not match with the heat condition in several months, which decreased the productivity of vegetation.

Abstract:Monthly changes in number of bacteria, filamentous fungi and actinomycetes in the layers of litter, decay and top soil (at 0 - 20 cm depth) of Hexi subtropical rain forest in Fujian Province were studied in 1989. The results showed that dricrobial number in all the three layers was great for bacteria, and less in descending order for filamentous fungi, and actinomycetes. Microbes found in litter and decay 1ayers were more than those in the top soil layer. Distinctive seasonal change in quantity of each microbial group and a similar pattern of monthly dynamics were observed. There was a peak of microbial increasing during the year, in April for bacteria, in May for fungi, and in August for actinomycetes. The number of bacteria and filamentous fungi in each layer was positively correlated with the month1y litter fall, precipitation and mean temperature (p <0.01 or 0.05), while the number of actinomycetes was correlated only with monthly mean temperature.

Abstract:Age and height structures of Cryptocarya concinna seedlings in Heishidingsubtropical forest, Guangdong Province, were analyzed. The seedlings in permanent transects were tagged, measured and censused at bimonthly intervals during one year period from April 1993. Due to the seedlings having no obvious morphological characters for age identification, a method for conjecturing seedling age by dualityy linear regression with the seedling height and basal diameter of the seedlings was suggested. This method provides a tool for studying age structure of C. concinna seedlings. Seedlings of 2 and 3 years old constituted overwhelming majorty. Seedling abundance showed annual tluctuation as the number of seedlings with 3 to 4 years old decreased markedly. If the seedlings were grouped into height class based on an interval of 10 cm, it appeared that there was a seedling pool at 10- 30 cm height, which composed of 2-4 years old seedlings.

Abstract:According to Miami model and Thornthwaite memorial model, the net primary productivity, the outputs of cereals and wood in Guangdong Province were assessed by using data of annual temperature, rainfall and evaporation. Then, plant climatic productivity maps were drawn. The results showed that the vegetation potential productivity in most areas of Guangdong was large, and decreased gradually from the coastland to the inland,and the trend of the isopleth roughly paralled with the coastline except few areas, the highest values were in Haifeng, Yangiiang, Qingyuan and Fogang counties, on the contrary,the lowest in the north and northeast of Guangdong and on Leizhou Peninsula.

Abstract:Three plots of CyclobalanoPsis glauca populations suffered to different extent from flood disturbance in valleys of Huangshan Mountain, Anhui Province, were chozen to study the seedling characteristics of the populations. The results showed that one of the plots, i.e.plot 3, which was least disturbed by the flood had more seedlings than the others, the population density of the seedlings being 0.5825 individual m-2. The density in plot 1 being heavily suffered from the flood was 0.1 150 individual m2 only, but the proportion of seedling sprouts was the highest in this plot. In all the three plots, the percentage of seedling sprouts increased with the seedling height. The distribution of seedling sprout height was nearly symmetric and platykurtic, but was positively skewed for the seedling plants. All the Gini coefficients were high (0.503l -0.5623), indicating that the size inequality was large.The seedling sprouts in all plots were in clumped distribution, while the seedling plants in plot 2 and 3 were in random distribution. However, clumped distribution was found in plot 1 for seedling plants distributed at higher edge due to the flood disturbance. It is concluded that C. glauca populations at sites disturbed by flood regenerated mainly by vegetative propagation instead of sexual propagation.

Abstract:Leaf discs of spinach were exposed to high light in the presence of active oxygen,protein modifiers and denaturants, and chlorophyll fluorescence kinetics was detected and compared with high light treatment alone.The addition of H2O2, O2-, OH and 'O2 enhanced photoinhibition, showing the decrease of Fv/Fm, qp and PSⅡ, which were accompanied by the increase of qN and 1 -qp. Treatment of four protein modifiers, NBS, DEPC, BDE and pCMB, also exhibited the similar changes of fluorescence parameters. More evident change was caused by BDE, an Arg-modifier of protein. SDS affected significantly on Fm, Fv and qp, but didn't change qN. A complete lose of qp associated with maximum qN were induced by Gu-HCl. Urea and DMSO at low concentration reduced the PSⅡ activitv and increased qN in less extent. The results suggest that any change in conformation or structure of chloroplast protein all led to the enhancement of PSll photoinactivation.

Abstract:Two hybrid rice Qingyou 159, Guangyou No.4 and their parents were used to study on the activities of Hill reaction and photophosphorylation, ATPase activity and ATP content. It was found that the activities of Hill reaction and photophosphorylation in leaves of both hybrids were much higher than those of their respective parents with marked heterobeltiosis and mid-parent heterosis, and showed significant positive correlation with photosynthetic rates. The activities of ATPase (Ca+ +-ATPase and Mg+ +-ATPase) and ATP content of leaves in both rice hybrids were much higher than those of their respective parents. Statistical analysis also showed that ATP content and activity of ATPase possessed marked heterobeltiosis and drid-parent heterosis, and were positive correlation with photosynthetic rates. These photosynthetic properties may be used as the indices of heterosis for rice hybrids of high photosynthetic rate.

Abstract:One cultivar (Teqing) and 3 hybrids (W6154s/Teqing, Weiyou 64 and Yayou Ⅱ) were used to study the changes of sucrose content in the flag leaf and grains, the seed setting percentage and grain dry weight, the grain weight in relation to the plump grain percentage, and the effect of organic nutrient on seed setting. The results indicated that seed setting percentage of hybrid rice was affected mainly by the number of imperfect grains in the middle and lower spikelet branches, especially by that in lower branches. In comparison with conventional rice, in hybrid rice, the sucrose contents in flag leaf and grains were high and the grain weight increased rapidly at early stage of grain filling, while those were lower and slowly at late stage, respectively. Hybrid rice showed much difference in seed setting percentage and grain dry weight between upper and lower branches. Low percentage of plump grains was shown in hybrid rice when the grain dry weight was the same as that in conventional rice. Plump grains of hybrid rice were more affected by the changes of organic nutrient at later stage of grain filling. The seed setting percentage and grain weight were much different in different growing season or in the case that the relationship between asource" and "sink" was changed as compared with conventional rice. The reason that the seed setting percentage of hybrid rice was lower and unstab1e was discussed.

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