Abstract:Trophic groups of soil nematodes were investigated in the rhizosphere and non-rhizosphere of Vetiveria spp. and Pennisetum spp. in South China Botanical Garden. Soil nematodes were aggregated mainly in the soil layer of 0-15 cm regardless of the biomass and the length of roots of Vetiveria and Pennisetum，and the densities of bacterivores and phytophages were significantly higher than those of the other three trophic groups, fungivores, omnivores and predators in all habitats. The proportions of bacterivores and phytophages were in the range of 87.7-97.6% and 88.5%-94.0% and those of the other three trophic groups were 2.4%-12.3% and 6.0%-11.5% under grasses of Vetiveria spp. and Pennisetum spp., respectively. The total number of nematodes was much higher in the rhizosphere than in the non-rhizosphere of grasses of Vetiveria, but this was not so obvious under grasses of Pennisetum. The proportions of phytophages under Vetiveria and under hybrid Pennisetum (P. americanum × P. purpureum) were much higher in the non-rhizosphere than in the rhizosphere, while the proportions of bacterivores were much higher in the rhizosphere than in the non-rhizosphere. Nevertheless, the proportions of phytophages and bacterivores under king grass (P. purpureum × P. thyphoides) and elephant grass (P. purpureum) habitats were opposite to that under Vetiveria. The proportions of fungivores were higher in the non-rhizosphere than in the rhizosphere under both genera of Vetiveria and Pennisetum with the exception of king grass. Higher nematode densities were found under V. zizanoides var. Karnataka and hybrid Pennisetum, indicating that the two species have good potential for the improvement of soil fertility.

Abstract:The formation and germination of cysts of the bloom causative dinoflagellate Scrippsiella trochoidea were studied from January 2001 to January 2002 in Daya Bay, South China Sea, as well as the dynamic of S. trochoidea vegetative population. Cysts were monthly collected by sediment traps and TFO gravity corer. S. trochoidea vegetative cells, water temperature, salinity, dissolved oxygen were measured throughout the annual cycle. In situ formation and germination of the cysts were assessed by cyst flux settled in sediment traps and the fraction of empty cysts in surface sediments, respectively. The annual average fluxes of calcified cyst and non-calcified cyst were 1.11×104 cysts m^-2d^-1 and 2.13×105 cysts m^-2d^-1, respectively. Calcified cysts largely formed in winter, while non-calcified cysts did in summer. Excystment occurred often in spring and autumn, less in summer, and seldom in winter. The highest proportions of empty cysts in May and October were followed by the peak abundance of vegetative cells, after which cyst concentrations in surface sediments and cyst fluxes increased rapidly. It is suggested that cyst germination inoculates sufficient vegetative cells into the water column and high cell densities contribute to the formation of cyst, which led to the next onset of algal bloom.

Abstract:Microsatellites were used to investigate the genetic diversity and relationships among 14 Chinese main banana cultivars (Musa spp.) and 33 introduced accessions from International Network for the Improvement of Banana and Plantain (INIBAP). Ten out of 47 microsatellite primer pairs amplified reproducible and discrete DNA bands, revealing a total of 92 alleles. The average number of alleles amplified by per primer was 9.2, ranging from 5 to 15. The sizes of PCR products were between 75bp and 310bp. The genetic similarity among the cultivars was estimated by the Jaccard coefficient，and the similarity value was between 0.1 and 1. Relationships among the cultivars were evaluated using the unweighted pair-grouping with arithmetic average (UPGMA) clustering. The dendrogram showed that the introduced accessions presented higher levels of genetic diversity than the main cultivars. All the cultivars tested could not be discriminated by the 10 primers.

Abstract:The transverse section of the pedicel of Hedychium coronarium Koen. is oval, including epidermis, the ground tissue and vascular bundles. The periphery vascular bundles surround the inner vascular bundles at the central zone of the pedicel. The inner vascular bundles give rise to 3 carpellary dorsal bundles (CDs) and 3 parietal bundles (PBs) below the locular region. The three CDs are radialized, alternating with the three PBs. In the locular region, the major branches of the three CDs supply 3 sepal midribs, and the small branches extend into the median region of labellum and 2 subulate appendages, accompanied by the portion of the inner bundles. Two abaxial diaphragms form 2 epigynous glands, respectively. The three PBs give rise to 3 strands, respectively. In the abaxial PBs, the outer strands supply abaxial petal midribs and the remaining strands enter into the laterals of labellum. In the baxial PB, the outer strand supplies an abaxial petal midrib, and the lateral strands move into functional stamens. The origins of the subulate appendages and the labellum are discussed. The hypothesis that two epigynous glands are special vascularized upward growths from the intramarginal portions of carpels is supported.

Abstract:The floral organogenesis of Tsoongiodendron odorum Chun was observed under scanning electron microscope (SEM). The floral primordium is initially circular, along with the edge of which slight concaves occur. The outmost whorl of tepal primordia arises as a result of apical meristem division and the floral primordium then is in the shape of triangle. Two further whorls of tepal primordia arise in spiral acropetal sequence and are alternately arranged. When the innermost whorl of tepal primordia is at the late developmental stage, the foremost stamen primordia arise almost simultaneously in spiral acropetal succession and all of the stamen primordia are ultimately arranged in a triangle-cone form. Late in stamen primordium development, carpel primordia arise as same as the young stamen primordia and grow laterally. Grooves are present on the adaxial side of each carpel and develop into ventral sutures gradually closing up. Concrescence of ventral sutures indicates that T. odorum with advanced characteristics is close to Michelia L..

Abstract:Ten chemical constituents were isolated from the barks of Endospermum chinensis Benth. On the basis of spectral data, they were identified as 3-oxo-12-oleanen-28-oic acid (1), oleanolic acid (2), 7-oxo-β-sitosterol (3), β-sitosterol (4), β-daucosterol (5), 7-ketone-β-daucosterol (6), 4-hydroxy-3-methoxybenzaldehyde (7), scopoletin (8), 2-hydroxy-4-methoxybenzoic acid (9) and nonanedioic acid (10). All these compounds were obtained from the species for the first time.

Abstract:Five endophytic diazotroph strains, including POJy11, POG12, POGy22, POGy612 and POG4 from rhizosphere and stalks of Paspalum orbiculare, were studied in acetylene reduction activity (ARA). ARA was maximal at pH 6.0-10.0 in POGy612 and POG4 strains and did at pH 6.0-8.0 in POJy11, POG12 and POGy22 strains. The maximum activity occurred at 35℃ in POGy22 strain and did at 30℃ in the other strains. The activity in those strains remarkably declined as NH4+ or NaCl concentration increased. ARA was mostly inhibited by NH4+ in POGy22 strain, and lost activity over 1.0 m mol /L NH4+. ARA showed a peak of activity at 2.5 mmol/L NH4+ in POGy612 strain and did at 0.5％NaCl in POJy11 and POGy22 strains.

Abstract:The responses of net photosynthetic rate (Pn) to light intensity and the CO2 concentration in leaves of homologous wild and cultivar Artemisia annua were studied. The maximum net photosynthetic rate (Pmax) was 18.78 μmol m^-2s^-1 for the wild-type and 22.38 μmol m-2s-1 for the cultivar. The light saturation point (LSP) was 1 183 μmol m^-2s^-1for the wild-type and 1 564 μmol m^-2s^-1 for the cultivar. The light compensation point (LCP) was 17 μmol m-^-2s^-1for the wild-type and 18 μmol m^-2s^-1 for the cultivar. The apparent quantum yield (AQY) was 0.08μmol m^-2s^-1 for the wild-type and 0.075 μmol m^-2s^-1 for the cultivar. Those data indicated that A. annua could utilize high light irradiance and perfectly acclimate to low light condition. Pmax, LSP and maximum carboxylation rate of Rubisco (Vcmax) were significantly higher in cultivar A. annua than in the wild-type. LCP, AQY, maximum rate of electron transport (Jmax), rate of non-photorespiratory CO2 evolution in the light (Rd) and CO2 compensation point in absence of respiration in the light (Г*) were not significant difference between the wild-type and cultivar. High light irradiance enhanced A annua in photosynthetic capacity by increasing Vcmax and Jmax and therefore A annua should be cultivated in an open and sun-filled habitat.

Abstract:Semi-quantitative RT-PCR was performed to detect the expression pattern of phenylalanine ammonia-lyase (PAL) gene during Phalaenopsis sp. leaf explant browning. Transcript RNA of PAL was rapidly increased at day 3 after in vitro culture, maintained at a high level until day 8 after culture and then declined. PAL mRNA was present one day earlier than the control after cultured on MS containing 55.6mg/L FeSO4, and PAL activity was higher than the control. The total phenol content in leaf explants on both media increased with browning. It is suggested that PAL gene expression is associated with Phalaenopsis sp. leaf explant browning.

Abstract:An efficient and rapid micropropagation system by using auxiliary buds as explants has been established for Musella lasiocarpa. Murashige and Skoog (MS) medium supplemented with 4.0 mg L^-1 6-benzylaminopurine, 0.2 mg L^-1 1-naphthaleneacetic acid, 150 mg L^-1 vitamin C, 10% coconut milk and 3% sucrose was suitable for shoot induction and proliferation from divided buds. Each explant produced an average of 4.10 shoots after 60-day culture. After the sixth subculture, the shoot proliferation rate of plantlets was 4.23-fold. The half-strength MS medium supplemented with 1.0 mg L^-1 indole-3-butyric acid and 150 mg L^-1 activated charcoal was suitable for rooting. When micropropagated plantlets with well-developed root systems were transferred to planting bed containing a mixture of sand, sieved peat and perlite (1:1:1; v/v) in a greenhouse, 93.5% of the plantlets survived. About 10 000 plantlets were produced successfully for field transfer after 12 months of culture initiation. This production system is useful for ex situ conservation and large-scale multiplication of M. lasiocarpa.

Abstract:In Wolong Nature Reserve, there are 1 648 species and 81 varieties of seed plants belonging to 658 genera and 144 families. Thirty-three species represent 17 genera and 8 families of gymnosperms. The flora of Wolong is old and rich in oligotypic families and genera (58.97%). The flora is composed mainly of the families (> 20 species) and the genera (>10 species) which amount to 14.58% of the total families and 4.25% of the total genera, respectively. It is characterized by tropical origin and temperate.

Abstract:There are 1 267 species of seed plants belonging to 528 genera and 121 families, including gymnosperms (9 species, 6 genera and 4 families) and angiosperms (117 families, 522 genera and 1,258 species) in Laojun Mountain Natural Reserve in Pingshan County, Sichuan Province. Thirty-nine pantropic families account for 44.83% of the total families, while 114 north temperate genera amount to 23.55% of the total genera. The flora of Laojun Mountain Natural Reserve is close to the semitropical type which is spread in Hengduan mountains, Middle China and East China, though it is in the cross area of Yunnan, Guizhou and Guangxi characterized with the transition from tropical to semitropical zones.

Abstract:The flora of Qian Mountain in Liaodong peninsula was compared the adjacent mountains including Changbai Mountain, Wutai Mountain, Xiaowutai Mountain, Tai Mountain, Culai Mountain, Kuyu Mountain and Lu Mountain using similarity coefficients at genus and species levels and clustering analysis. Qian Mountain flora is much closer to Xiaowutai Mountain and Wutai Mountain than.Kunyu Mountain, Tai Mountain and Culai Mountain, whereas it is distant with Lu Mountain. The present data indicate that Qian Mountain should belong to the North China flora. The classification of Liaodong peninsula flora is discussed.

Abstract:Bryophyte species were investigated in Tangdan Copper Mine site in Dongchuan district of Kunming City, Yunnan Province. Twenty–two species belonging to 16 genera (Barbula, Gymnostomum, Didymodon, etc.) of 6 families (Pottiaceae, Bryaceae, Brachytheciaceae, Thuidiaceae, Ditrichaceae and Entodontaceae) were found, 59% of which was Pottiaceae as a dominant family. Sixty-eight percent of the species lived on cupreous rocks covered with patina, while 32% grew on cupreous soil. The species were divided into 3 life forms: short turfs (68%), high turfs (14%) and wefts (18%). There were 7 areal types (Eastern Asia and North America, Endemic to China, Tropical Asia and Tropical Africa, Eastern Asia, Cosmopolitan, Tropical Asia, North Temperate), among which Eastern Asia was dominant. The classical “Copper Mosses” were absent.

Abstract:Progress in the study of the influences of light, water, herbivory and fungal symbiont on the growth and survival of Dipterocarpaceae seedlings is briefly summarized, and the prospects in the future are also discussed. Light is the most important resource condition influencing the growth and survival of Dipterocarpaceae seedlings and the higher irradiance in canopy gaps is benefitial to seedling growth and survival. The death of Dipterocarpaceae seedlings is closely linked to the drought and greatly increased by the vertebrate herbivory, but only a high proportion of foliar herbivory caused by insect could result in the death of seedlings, especially small individuals. Dipterocarpaceae seedlings have the ability to establish the fungal symbiont, which helps them to absorb nutrients and water from mature plants and benefits to their growth, especially in the extreme deficiency of resources.