Abstract:Calycanthaceae is a small family with 4 genera and 10 species. In the present paper, a cladistic analysis is made using the methods of Maximal Same Steps, Minimal Parallel Evolution and Synthetic Maximal Diversity Method developed by Xu. According to the cladistic analysis, it is suggested that Chimonanthus may be an earliest branch from pre-Calycanthaceae, which almost retains all primitive characters of the ancestor, while Sinocalycanthus is closely related to Calycanthus. Both Sinocalycanthus and Calycanthus are of transit genera from primitive to advanced taxa in the Calycanthaceae， and Idiospermum is the most advanced in the family．

Abstract:Zingiberaceous plants including 135 species, 3 varieties and 3 forms in 23 genera have been introduced from home and abroad to the South China Botanical Garden at Guangzhou for more than two decades. Of all the plants introduced, 103 species with 2 varieties and 2 forms in 18 genera can grow well. Siliquamomum tonkinense Baill. and Etlingera yunnanensis (T. L. Wu et Senjen) R. M. Smith, which are of rare and endangered species, are in ex situ conservation in the Garden. Of all the introduced species, the survival rate is 74.5％，and the percentages of spedes which can flower and fruit are 56.3％ and 33．8％，respectively. From the 8 important genera，the survival rate is 100％ in species of Costus and Curcuma, but species of Cautleya and Roscoea fail to survive．The survival rate in both Alpinia and Kaemferia species is 83.3％, and survival rates in species of Hedychium and Zingiber are 57.1％ and 85.7％, respectively．The factors， such as climatic，soil， geographical and biological factors, which affect the introduced plants are elucidated.

Abstract:The seedling survival and growth of 21 native tree species were studied by transplanting into two natural forest sites and an open site for approximately 22 months during June-August ]989 and April-October 1991. The results showed that the seedlings of most species had some tolerance to shading and could survive in forests. Only a few species showed extreme tolerance or intolerance to shade. The seedlings of most pioneer species died directly from shading or insect damage and pathogens in forests. The extremely shadeintolerant species in the study were Pinus massoniana, Sapium discolor, and Trema tomentosa.These species with a typical syndrome of pioneer characters do not play an important role in secondary succession in Hong Kong. The major components in current secondary forest,such as Machilus chekiangensis and Gordonia axillaris, have mixed and intermediate characters,which may be an adaptation to the soil degradation caused by centuries of fire and erosion.Bird-dispersed species play an important role in secondary forest of Hong Kong. Research and application of the bird-dispersed woody flora must be enhanced. Some hypotheses on the current floristic succession are briefly discussed.

Abstract:The kernel density estimation method of species abundance distribution was used to simulate the species abundance distribution of two communities which were dominated respectively by rare species Tsoongiodendron odorum Chun and by vulnerable species Tsuga longibracteata Cheng. The results show that the species abundance distribution in tree and shrub layers and all woody plants of the two forests all can well be described by using nonparametric kernel method based on the sample data without assuming the species abundance distribution．The nonparamefic kernel density estimation is suggested to be a useful method for species abundance distribution simulation．

Abstract:Anther culture of a dual-purpose genic male sterile rice (DGMSR) Peiai 64S resulted in 1969 regenerated plants from 26 callus lines. According to the ploidy and fertility in the first generation of anther plants (H1 ), they were divided into three types: a) Haploid, all of the 41 plants in 1 callus line were haploid, b) Uniform type, including 19 callus lines, all of which were sterile during the sterility period, and no remarkable differences in other characters were observed, c) Segregation type, including the remaining 6 callus lines which exhibited segregation．In this type，3 lines with 2 to 7 individuals each were haploid．Some plants in this type had higher pollen staining rate and seed setting percentage. In the control line (Peiai 64S)，there were 1.5％ of individuals being fertile in sterility period，indicating that Peiai 64S was not a pure line. After selection for two generations，their fertility has been stable in H₃. The experiments of sowing at intervals in spring with seven lines in the H₄ generation showed，the later the sowing date，the earlier the initia1 heading date．It was shown that these 1ines were susceptible to tem perature．It was also observed that the duration of stable sterility period in the selected plant lines was longer by 3 days or so than that in the control，and in fertility transformation period，the seed set percentages from self-pollination in these lines were over 5 8％ higher compared to the contro1．The characters of F₁ hybrids from 108 test cross combinations showed potential high-yield trait. It is suggested that anther culture is an effective way for purifying and improving DGMSR.

Abstract:The explants from seed and leaf segments of Delphinium grandiflorum were used to establish culture in vitro and regeneration system. The experiments showed that most explants induced calli, few of them could form plantlets directly from seed or leaf segments. Under suitable culture condition, high regeneration rates could be obtained from explants of seed and leaf segments, each explant regenerating 10-20 plantlets. Optimum medium for seed segments of Delphinium grandiflorum was the modified MS medium (half of macronutrients and sucrose，10 times the amount of Vit B₁) supplemented with 3 mg L^-1 ZT and 0.3 mg L^-1 NAA，and for leaf segments，the medium of MS with 3 mg L^-1 6-BA and O.3 mg L^-1 NAA．

Abstract:Young leaf segments from micropropagated plants were used to study the optimum medium and growth regulators for callus induction of Ilex kudingcha. The highest multiplication rate for callus induction and subculture of calluses was obtained using MS medium supplemented with 2.0 mg L^-1 BA and 4.0 mg L^-1 NAA. 0.1% phytic acid could markedly promote the growth of calluses and inhibit callus browning. Multiplication rate of calluses was highest in calluses cultured for 40 - 50 days, and decreased after 27th generation in subculture.

Abstract:Three aporphine alkaloids, laurolitsine, boldine and N-acetyllaurolitsine were isolated from the stems of both Litsea rotundifolia and L. rotundifolia var. oblongifolia. Their structures were identified on the basis of spectral analysis and chemical correlation. Among them, N-acetyllaurolitsine was found as a naturally occurring compound for the first time.

Abstract:The leaves of 3- to 5-year-old ginkgo (Ginkgo biloba) were collected from Pixian County in Jiangsu Province in September, and a yellow essential oil was obtained by water distillation. Forty-four compounds from the essential oil were determined by GC and GC-MS, which consisted of 31 .14% hydrocarbons, 5.61 % alcohols, 1.78% aldehydes, 46.17% ketones, 5.41 % acids and 1.1% esters. In ketones of the oil, the content of hexahydrofarnesyl acetone was found highest (11.15%), followed by nerylacetone (8.68%), β-ionone and farnesyl acetone, amounting to 5.24% and 3.73%, respectively.

Abstract:Leaf scorch in mango (Mangifera indica L.) trees was investigated in March, 1997 in 13 sites at 30-300 m from seashore of Xiamen City. Symptom of leaf scorch in shoot leaves was divided into 6 grades. Soil properties and elements in leaves were tested. The results showed that soil pH and the total N, P, K and Na contents were not related to the leaf scorch damage. The degrees of injury caused by leaf scorch were positively related to the content of Cl and K in leaves and to the Cl and salt contents in soil at 30-40 cm depth. It is concluded that the main factor resulting in leaf seerch is salt，and Cl plays an important role Mango trees grow normally in soil under 0.489‰ salinity．

Abstract:Three major components of salt-soluble proteins in peanut seeds were roughly purified on Sephadex G-100 gel filtration. Five purified polypeptides, 60.5, 41, 38.5, 18 and 17.5 kDa polypeptides, were harvested with high purity and productivity. Amino acid composition of the three major components (arachin, conarachin I and conarachin II) and the five purified polypeptides were analyzed. It was shown that 17 amino acids, including 7 essential amino acids, were detectable. The contents of asparatic acid, were detectable．The contents of asparatic acid, glutamic acid and arginine were high，whereas methionine and cysteine were extremely low．The methionine levels of three major components in methionine-rich cultivar Shanyou 523 were obviously higher than those in cultivar Haihua 1 The methionine level of conarachin II in three major components was the highest in the two cultivars．Results showed that highest methionine in 17.5 kDa polypeptide was observed in the five purified polypeptides．Western blot showed synthetic changes in 17.5 kDa polypeptide during development of peanut seeds．

Abstract:Progress in the study of electron transport pathways such as photorespiration, Mehler reaction, cyclic electron transport and reduction of nitrate against photodamage in photosynthetic apparatus is reviewed.

Abstract:Acid rain, greenhouse effect and depletion of earth's stratospheric ozone layer are most serious environmental problems in the world at present. Both plant and animal life are greatly affected by enhanced UV-B radiation due to destruction of ozone layer and by continued aggregation of SO₂ in air. A brief of the studies in the last two decades concerned with the effects of the two stress factors on plants are presented.

Abstract:Flooding induced the changes in net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of 17-month-old seedlings of Cleistocalyx operculatus. Pn, Gs and Tr began to decline progressively after 5 days of flooding. However, a few seedlings which developed adventitious roots (AR) on submerged portion of the stem starting on the 35th day of flooding showed a gradual increase in Pn, Gs and Tr, and maintained a higher level of Pn, Gs and Tr by the 80th day of flooding. The daily courses of Pn，Gs and Tr of seedlings with AR showed a pattern of two peaks，and the regression analysis indicated that Pn was positively correlated with Gs (r=0.69,p<0.05)．

Abstract:Seeds of Chinese medicinal plants Leonurus artemisia (Lour.) S. Y Hu, Platycodon grandoforus (Jacq.) A DC. and Atractylodes macrocephala Koidz. were used as materials for germination test under various storage conditions. The optimal germination temperature for L. artemisia and P grandoflorus were 25℃1℃, and that for A. macrocepha;a was 15 1℃. At optimal temperature, seed germination percentages of L. artemisia (25℃), P. grandiflorus (25℃) and A. macrocephala (15℃) were 69.8%, 39.8% and 46.8%, respectively. 15% of relative humidity (RH) was the optimal storage condition，followed by 43% RH．15℃ was the optimal temperature of seed storage for L. artemisia but 5 ℃ for P．grandiflorus．The germination percentage of P. grandiflorus seeds could be raised by PEG 6000 treatment，but contrary effect was observed in L. artemisia seeds．