Abstract:Seedling growth of 42 woody species of subtropical forests in Guangdong Province was studied in relation to their ecological characteristics， growt h forms and seed weight． Seedlings of tree species had significantly higher stem and greater stem biomass than those of shrub species under high light(H，66．8 μmol m_-2s_-1)，but not low light intensity(L，33．7 μmol m_-2s_-1)．There was no significant diference among heliophilic species,shade-tolerant species and intermediate light-demanding species in stem height and stem biomass．Tree seedlings had more leaf area and leaf biomass per plant than shrub seedlings，but the latter had more leaves．Diference in leaf number and leaf area was generally not obvious between large-seeded and small-seeded species，and betw een diferent types of species based on light demand．Seedlings of heliophilic species had more lateral roots than those of shade-tolerant species．Seedlings of tree species had significantly greater root biomass and higher root／shoot ratio of biomass than those of shrub species．Seedlings of heliophilic species had also higher root／shoot ratio than those of shade-tolerant species under H as compared with L condition．Root biomass was sign ificantly positively correlated with seed weight for 45 d seedlings in both H and L light,but not for 90 d seedlings．Very significant linear correlation between seedling biomass and seed weight was found for 45 d seedlings under both H and L lightconditions，but not significant for 90 d seedlings under H light condition．Tree seedlings had significantly greater biomass per plant than shrub seedlings．Relative growt h rate and leaf area ratio of seedlings were foun d to be in order of heliophillc species>intermediate light-demanding species>shade-tolerant species，and there were significant difference between heliophilic species and shade-tolerant species．Difference in unit leaf rate was not significant among species ofvarious light-demanding types．

Abstract:Abstract：Root competition experiment in three woody species was carried out in six plots，each of them was 12.4 m × 10 m on Nan-ao Island situated on the east of Guangdong Province near Shantou city． The experiment site was in the community dominated by Eucalyptus robusta．The seedlings of Eucalyptus urophylla，A cacia auriculaeformis and Schima superba were respectively planted in 3 plots and another 3 with trenches around the plots so as to prevent roots from other plants． The growth rate， biomass and root competition intensity for the seedlings of 3 species were measured after the seedlings had grown for 165 days to 640 days．Th e results indicated that the biomass increment and growt h rate of all the seedlings un der root competition were lower than those of seedlings grown in plots with trenches．The influence of un derground root competition on the seedling growth was gradually decreased with the growt h of seedling age， and was then stable when reached to a certain stage． Root competition intensity ofthe seedlings ofS．superba，E.urophylla and A.auriculaeformis were 0.22，0.19 and 0.13 respectively．It was shown that seedling growth of exotic trees E.urophylla and A．auriculaeformis had more adaptation to root competition than that of native tree species S.superb

Abstract:Anatomical features and stomatal gas exchange of the leaves of Melastoma candidum grown in hilly and swampy habitats were compared． The cells of upper epidermis was thicker with smaller cells which were closely arranged， and the stomatal density being higher in hilly melastoma compared to those in swampy one． Thicker sponge tissues，larger maximum vessel diameter，and higher ratio of palisade cell height to cell width were observed in swampy melastoma．However，the ratio of palisade thickness to sponge thickn ess was lower in swampy melastoma than that in hilly one． There were little diferences in the contents of chlorophyll a and chlorophyll b， carotenoid and chlorophyll a／b between hilly and swampy melastoma．The hilly melastoma had lower net photosynthesis rate，transpiration rate and stomatal conductan ce than those of swampy melastoma．The diurnal courses of average water use eficiency(net photosynthetic rate／transpiration rate，WUE)were similar between plants grown in two habitats．Intrinsic water use eficiency(net photosynthetic rate／stomatal conductance，Intrinsic WUE)was lightly higher in swampy melastoma than that in hilly one，but no significant diference was found． It is proposed that these diferences between two populations of melastoma might be mainly due to the diferent soil conditions． However， the above results could not confirm that the hilly an d swampy melastoma are diferent ecotypes.

Abstract:Seedlings ofnine tree species grown in pots were exposed to contamination enviroriment of sulphur and fluoride at Nanzhuang town,a ceramic industry area in Fushan city,Guangdong,and another part ofthe same plan ts were pored at South China Botanical Garden as contro1．The dry matter of seedling leaves was used to measure the gross caloric value by oxygen-bomb calorimeter．The ash content，ash-flee caloric value and the ratio of N and C were also determined．The results showed that the caloric values in Ilex rotunda,Machilus chinensis and Lysidice rhodostegia were relativelyhigh (above 19.O0 kJ g^-1 )，and the values in Koelreuteria bipinnata, Ficus annulata, Michelia chapensis，Ficus microcarpa and Camellia semiserrata were lower(between 1 8.00-1 9.00 kJ g^-1 )than the above three species，but higher than the value of athodea campanulata，which is lower than 1 8．00 kJ g^-1．The air pollution stress caused the increase of gross caloric values in Koelreuteria bipinnata,Machilus chinensis and Ilex rotunda,but decrease ofthose in Lysidice rhodostegia, Michelia chinensis，Ficus microcarpa, athodea campanulat and Camellia semiserrata． However， the caloric values ofFicus annulata had only litle change between polluted and 1ess polluted environments． The analysis of Pearson correlation coefi cients showed that the ash-flee caloric value in leaves of the seedlings of 9 species did not significantly corelate with the C／N ratio and the ash content for coresponding species．However，the fluctuations of leaf caloric values in the same species under diferent environments were related to the pollution tolerance of the species，suggesting that the caloric value in leaves can be considered as an index of species sensitivity to air pollution．

Abstract:The effects of simulated N deposition on acidity and inorganic N concentrations in soil solution collected at 20 cm soil depth under pine forest， needle broadleaved mixed forest， and mature monsoon evergreen broadleaved forest in subtropical China were studied．Additional N(NH₄NO₃ solution)treatments were established for mature forest：Low N(50 kg N hm_-2 a_-1)，Medium N(100 kg N hm_-2 a_-1 )and High N(150 kg N hm_-2 a_-1), and Low N and M edium N treatm ents were established for mixed an d pine forests．PH values in soil solution in the control plots ofthe 3 forests ranged from 3.82 to 4.24，but pH values decreased bV 0.08—0.1 8 in plots treated by spraying additional nitrogen under the forests for 5 months． NH⁴₊-N concentrations in soil solution increased averagely by 74.0％ ，355.6％ and 57.9％ in low N treatm ent and by 68.4％ ，93.2％ ，and l88.8％ in medium N treatment for pine forest，mixed forest，and mature forest，respectively．As in high N treatm ent it increased by 1254．7％ for mature forest．The increases of N0³_--N concentrations were by 56.4％-88.5％ in low N treatment by 65.6％-l32.2％ in medium N treatment，and by 85.5％ in high N treatment．The results showed that additional N deposition increased the potential of inorgan ic N leaching losses and enhanced soil acidity.

Abstract:The floristic composition, ecological characteristics and ethnoecology of plants of Harboi rangeland (Kalat,Pakistan) were done during 1997 to 1999. There were 202 species that belonged to 45 plant families Asteraceae, Papilionaceae, Poaceae, Brassicaceae and Lamiaceae were the leading families. Juniperus macropoda was the only tree species while A rtemesia maritima, Sophora griffithii, Hertia intermedia, Nepetajuncea, Perovskia abrotanoides, Convolvulus leiocalycinus and A stragalus spp. were the most common shrubs. The dominant life forms were therophyte and hemicryptophyte while nanophylls, microphylls and leptophylls were dominant leaf sizes. The growing season lasts from March to November with two flowering periods. Most, i.e. 83.6% plants flowered during April to June while 63.3% plants bloomed during July to September. Some 145 species had various local uses. They included 129 fodder species, 50 medicinal species, 12 vegetable/fruits species, 7 fuel wood species, 3 species each were used for roof thatching and making herbal tea. Deforestation, over grazing and over collection 0f medicinal and fuel wood species have led to the degradation of this rangeland. There is need to conserve these resources with the participation of local communities.

Abstract:Vertical distribution of Viola species in Nanling Nature Reserve，Guangdong Province，was investigated at eight diferent altitudinal gradients from 500 m to 1 902 m in an area of 100 km² in the centre ofthe Reserve． It was revealed that the number of Viola species was in the order of 5，8，9，1 0，9，7，3 and 1 from low altitude to high with approximately 200 meters for each gradient． More species abundance appeared at elevation of 1 000—1 200 m. Among the altitudinal gradients，the nearer the height，the greater the similarity coeficient was．The vertical distribution pattem of Viola species in the Reserve is in accordance with that of common woody plants． which might be related with moisture and heat conditions

Abstract:A mentotaxus yunnanensis Li(Taxaceae)is a rare and relict species with limited distribution．RAPD markers were used to determine the genetic variation within and among 4 populations of A.yunnanensis and one population of A. formosana. Although high level ofgenetic diversity was found in A. yunnanensis at the species level(Percentage of polymorphic loci：79.0％，Nei’S genetic diversity：0.2718)，there existed much lower genetic variation within populations(Percentage of polymorphic loci：18.0％ and 6.9％：Nei’s genetic diversity：0.0688 and 0.0198，for A. yunnanensis and A. formosana. respectively)．A high degree of diferentiation among populations was detected in A．yunnanensis(0.76ll，0.7503 and 0.7526 for AMOVA，Nei’S coefficient of diferentiation(G_ST) and Shannon inform ation index，respectively)．It is suggested that the historical factors，including severe bottleneck and subsequent genetic drift during Quatemary glaciations and fragmentation in postglaciation，small population sizeandlow seedling establishment would have contributed to such a population genetic structure in A．yunrumensis．Based on these results，strategies are proposed for the genetic conservation and management of A．yunnanensis

Abstract:Population genetic structure ofPrimula sikkimensis distributed in Himalayan．Hengduan Mountains was studied using Inter-simple sequence repeat(ISSR)markers．Ten ISSR primers were used to amplify 254 individuals of 13 populations，which successfully detected 91 loci，all of which being polymorphic．The Shannon diversity index(H_O)ranged from O.2293 to O.4016，with an average of 0.321l at the population level(H_POP)and O.5576 at the species level(H_SP )．Moreover，the AMOVA analysis showed that 50.28％ of the total genetic diversity was among populations；the index(G_ST=0.4127) based on POPGENE indicated tIlat 41.27％of molecular variation was among populations． which was lower than that in the result of AMOVA． The variation of genetic distance ranged from 0.0780 to 0.4748，genetic identity from 0.6220 to 0.9250．In addition, the gene flow am ong population was low (Nm=0.7l14)；relatively lower gene flow might be one of important factors influencing the genetic structure of the species．The present analysis reveals that 13 populations of P sikkimensis in Himalayan-Hengduan Mountains have high genetic diversity and high genetic diferentiation.

Abstract:A 398-bp plantified encoding fragment of porcine α-lactalbumin， was cloned into plasmid under the control of the cauliflower mosaic virus 35S promoter． The expression cassette was introduced into A rabidopsis with Agrobacterium mediated transformation． Some herbicide-resistant lines of transform ed A rabidopsis were selected． The gene integration of chromosomal DNA level were confirmed in regenerated plants． All of them are positive for porcine α-lactalbumin gene via genomic DNA PCR． The expression at the protein level could be confirmed only in the transgenic A rabidopsis．The arabidopsis-expressed lactalbumin (LA) migrated in SDS- PAGE with identical mobility to human LA prepared from human milk． indicating that the LA was correctly processed to yield a mature protein in plants.

Abstract:Sixteen pollen samples from 11 species and 1 form of the genus iradiclis B1．were examined under LM， SEM and TEM ．Results revealed that pollen grains of iradiclis were single， small or medium-sized， spheroidal to prolate，radial symmetry，usually 3-colporate，sometimes 4-colporate，and with perforated tectate. The exine consisted of inconsistent perforated tectate，columellae and foot layer．Both exine and intine were obvious．Pollen dimorphism and bubble-like protrusions were foun d in Spiradiclis．Pollen characters of Spiradiclis have little value for distinguishing infra-genus taxa，but they can provide much information in the phylogenetic relationships among species，e.g.，the taxon having same pollen is more advanced than that having dimorphic pollen．

Abstract:One steroid, three triterpenes, two phenolics, and one indole alkaloid were isolated from the stems and leaves of Nauclea officinalis. On the basis of spectral data, the structures of these constituents were elucidated as stigmast-4-en-3-one (1), rotundic acid (2),hederagenin (3), 3-oxoquinovic acid (4), 2,5-dimethoxybenzoic acid (5), 3,4,5-trimethoxybenzoic acid (6), and strictosamide (7). All these compounds are isolated from this plant for the first time.

Abstract:Four glycosides, (2R)-2-O-β-D-glucopyranosyl-2H-1,4-benzoxazin-3(4H)- one (1), (2R)-2-O-β-D-glucopyranosyl-4-hydroxy-2H-1,4-benzoxazin-3(4H)-one (2), pinoresinol-4-O-β-D-apiosyl-(1→2)-β-D-glucopy-ranoside (3), and uridine, were isolated from the roots of Baphicacanthus cusia (Nees) Bremek. All these constituents are reported from this plant for the first time. The presence of benzoxazinoids (1 and 2) is in agreement with the anti-inflammatory effect of this plant.

Abstract:Nine species, Callistopteris apiifolia, Impatiens claviger, Munronia hainanensis, Ardisia filiciformis,Ardisia virens, Tetraglochidium jugorum, Peliosanthes teta, Alpinia strobiliformis var. glabra and Liparis luteola are reported as new records from Guangdong Province. In addition, the genera Callistopteris and Tetraglochidium have not been previously recorded in Guangdong.

Abstract:Genus Paspalum，a perennial or an ual grass of Gramineae， is one of the with great economic value groups．The gneus Paspalum includes many complex species and most of them are polypoloid．Due to the causes such as polyploidy and self-incompatibility，the plants ofPaspalum，with the greatest number of apomictic species，show much complex and various reproduction characteristics．In this paper，a list of apomitic species of Paspalum is given．The cytological and embryological bases，and the characters of apomixis are described．Advances in genetics and molecular biology of apomixis aye in Paspalum also reviewed．