Abstract:South China Sea islands consist of more than 1130 islands with total area of approximately 35000 km2.The highest mountain in Hainan Island is Wuzhi Shan, the highest peak being 1867.1 m.The major vegetation types in the islands include tropical rain forests, tropical monsoon forests,tropical coniferous forests,mangroves, tropical coral reef island evergreen forests,shrub forests, shrubby grassland and beach vegetation.There are 3584 species (including infr4specific ranks) of spermatophytes belonging to 182 families (according to Engler System) and 1238 genera in these islands.The main families with more than 50 species are Gramineae,Leguminosae,Orchidaceae,Rubiaceae,Euphorbiaceae, Cyperaceae, Compositae, Lauraceae,Asclepiadaceae,Labiatae,Moraceae,Fagaceae, Verbenaceae, Acanthaceae, Urticaceae,Annonaceae,Theaceae and Myrtaceae.The main genera with more than 20 species are Ficus,Ilex,Syzygium,Fimbristylis,Hedyotis,Ardisia, Symplocos, Lithocarpus, Crotalaria,Cyperus. Diospyros and Carex,and most of them are of tropical and wide distribution.According to the geographical distribution,the spermatophyte genera of South China Sea Islands may be divided into 14 types and 14 subtypes, of which Tropical Asia and Pantropic elements are the main ones in the flora, and the temperate elements are relatively poor. At specific level,the Tropical Asia elements has a higher percentage,amounting to 47.49% of the total species.In this area there are 19 genera endemic to China, of which 9 genera are endemic only to South China Sea islands,and 1183 species are endemic to China, of which 523 species endemic to South China Sea Islands, some of them are the dominant species in their communities.Comparing the composition of the flora with those of 5 neighbouring regions, the flora of South China Sea islands is quite similar to those of Indo-China Peninsula and Guangdong mainland, the indices of genera similarity to Indo-China Peninsula and Guangdong mainland are 84.3% and 82.3% respectively.South China Sea islands is a part of Cathaysian ancient land, and its flora naturally belongs to the Cathaysia flora,but posseses its own characteristics.Some plants distributed from Australia northward through southeast Asia to South China Sea islands,but never reached the mainland of China.The substitute phenomenon and flora division have been also discussed in present paper.

Abstract:Two new species of bamboo, Dendrocalamus exilis and D.guiyangensis,are described.The flower description of Bambusa pervariabilis,B.eutuldoides,B.boniopsis,B.ventricosa and B.textilis cv.Purpurascens is given.

Abstract:Eleven species of 10 genera and 5 families are reported as new records to Hunan Province,China.Three species and two variaties of Lauraceae are revised. Litsea faberi Hemsl.and L.subverticillata Yang are reduced to L.elongata(Wall. ex Nees)Benth.et Hook.f., Machilus velutina Champ. ex Benth.var.longipedunculata C.J.Qi is reduced to M.velutina Champ.ex Benth.,Neolitsea brevipes H.W.Li is reduced to N. pulchella (Meissn.) Merr.,and N.wushanica(Chun)Merr.var.pubens Yang et P.H.Huang is reduced to N. wushanica (Chun) Merr..

Abstract:The natural forest in southwest slope of Hongtuzhang belongs to south-subtropical evergreen broad-leaf forest.It has transitional characteristics from tropical rain forest to subtropical evergreen broad-leaf forest.The floristic components are complicated,dominated by the species of Fagaceae,Lauraceae,Aquifoliaceae,Hamamelidaceae,Escalloniaceae and Pentaphylacaceae.It is a secondary forest with age of 35 years.Most of the trees grow up from sprouts.The forest is now in the middlelate stage of secondary succession.Suggestions on the rational utilization and protection of the forest are made.

Abstract:The relationship between Fe++-induced bronzing and stress ethylene production (SEP)was investigated both in detached rice (Oryza sativa L.)leaves and in whole plants.Fe++ was applied to the detached leaf through a transpiration stream and to whole plants through roots in culture solution.The SEP from detached leaves differed with leaf position,growth stage, and genotype.Correlation between SEP and bronzing was significant for the leaves of 16 tested genotypes(r=0.659**),but the iron concentration increment(ICI)of the detached leaf correlated neither to the bronzing nor to the SEP, suggesting that leaf tissue tolerance, not ICI, controls the bronzing deveiopment and the SEP.When the Whole plant was treated by increasing Fe++ concentration in culture solution,the SEP was negligibly small. By partially or entirely de-rooting the plant, however,stress ethylene was evoked bythe Fe++ treatment,indicating that roots limited the Fe++-induced SEP.

Abstract:The changes in contents of endogenous IAA,CTK, ABA and RNA in the in vitro cultural cutting stem excised from mature and juvenile plant of tube plantlet of Paulownia fortunei(Seem.)Hemsl. were analysed during the development of adventitious root.The endogenous hormones were measured by HPLC. The results showed that the contents of endogenous IAA and CTK in the stem cutting from plantlet(juvenile state)reached their peaks on the second day of culture, whereas the peaks of endogenous IAA and CTK in stem cutting from mature plant (mature state) appeared on the fourth day. From the stem paraffin sections, it was observed that the emergence time of root primordia was the same as that of endogenous IAA and CTK peaks in two states of cultural materials. However, the variation in endogenous ABA content was different between juvenile and mature states. During the rooting period,the level of RNA in both juvenile and mature states of stem cutting slightly decreased on the second day of culture, and then increased markedly.The origin of root primordia come from some peripheral cells of vascular cylinder,and some cells between vascular bundles as well as some pith cells recovering cell division. But the emergence of root primordia in mature stem cutting was 2 days later than that in juvenile cutting of plantlets,and the number of adventitious root in the former was less than that in the latter.

Abstract:The study of the relationship between the accumulation of storage proteins and the formation of vigor of peanut seed showed that the process of formation of seed vigor was not a symmetrical process,and the germination capability was completed before 40 days after pegging (DAP)and vigor formation speeded up after 40 DAP. The synthesis and accumulation of storage proteins coincided with the formation of seed vigor. With the accumulation process of different storage proteins, arachin was degraded more rapidly than conarachin and 2S peptides.As it consists of the parts of the storage protein, it was concluded that arachin was more correlative with the formation of seed vigor.

Abstract:The leaf essential oil of Cinnamomum septentrionale collected from an artificial planting population in Chengdu city, Sichuan province were analyzed by capillary GC/MS.The results showed that their main chemical constituents were quite different among some trees, and could be divided into four chemotypes, namely 1, 8-cineole, camphor, methyl isoeugenol and 9-oxonerolidol.Except the type of methyl isoeugenol, the other three were first reported. According to the researched results of chemotypes in genus Cinnamomum, multi chemotypes within one species and general characters of chemotypes in different species are universally existed.

Abstract:The changes of lipofuscin-like pigment(LFLP)content in anthers of male-sterility rice were studied for examining the possible lipid peroxidative damage in relation to male-sterility.During the pollen development from uninucleate to trinucleate stages, LFLP contents in fertile and sterile anthers all increased gradually to different extents in the tested cytoplasmic male-sterile line rice Zhenshan 97A and its maintainer Zhenshan 97B,the photoperiod(temperature)-sensitive genie male-sterile rice W6154s and Peiai 64s.The LFLP content and accumulative rate in both types of male-sterile rice were higher than those in fertile anthers.In trinucleate stage,the sterile anthers from Zhenshan 97A and W6154s showed 24% higher LFLP content than their fertile anthers.From uninucleate to trinucleate stages of pollen, the average accumulative rates of LFLP in sterile and fertile anthers were 41% and 26% perstage, respectively.When the isolated fresh anthers at uninucleate and trinucleate stages were treated by using N2 and antioxidants glutathione(reduced)and butylated hydroxytoluene,the LFLP content was partially reduced by glutathion treatment at uninucleate stage.The results indicated that the expression of male-sterility of rice was associated with the accumulation of a fluorescent product of lipid peroxidation,lipofuscin-like pigments.

Abstract:Histological studies revealed that there were two different regeneration modes when cotyledon petioles of Brassica parachinensis as the explants were cultured in the medium with or without AgNO₃ and ABA. In mode Ⅰ,in medium with AgNO₃ and ABA,shoots regenerated directly from the cut end of cotyledon petioles and did not pass through callus stage. After 4 days of inoculation, the vascular parenchyma cells at the cut end of the explant initiated to active division and became meristem centre and then adventitious buds were regenerated. In mode Ⅱ,in medium without AgNO₃ and ABA, vascular parenchyma cells at the cut end initiated to division and gave rise to form root meristem or/and callus from which shoots and roots were subsequently regenerated. So the two modes of plant regeneration resulted in whether the medium contained AgNO₃ and ABA or not.

Abstract:马铃薯是世界上最重要的粮食作物之一，但其生产却受到病害的严重限制．本文简介了马铃薯抗病育种新途径一生物技术的应用及其研究进展，主要包括：茎尖脱毒，离体试管薯诱导，花药和花粉培养，胚挽救，抗病突变体离体筛选，原生质体融合技术和农杆菌介导的外源基因转化．这些技术与常规育种手段相结合已取得具有应用价值的结果．