Abstract:In order to characterize the variance in sap flow within and between trees, and to quantify the water use of whole tree and of forest stand, Granier＇s thermal dissipation probes were applied to measure sap flux density （J_s） in 14 sample trees in an Acacia mangium forest in Heshan Station, Guangdong. It showed that the differences of sap flux density recorded on a sunny day in July of 2004 were significant within tree （of different azimuthal sides） with coefficient of variability ranging from 15.51% to 37.26%, and among trees ranging from 37.46% to 50.73%. These variations were mainly attributed to the texture of sapwood and microclimate surrounding the point on trunk where the measurements were conducted. However, the sap flux density on different azimuthal sides showed significant linear correlation （p〈0.0001）, which provided a feature value for scaling up whole-tree transpiration from sap flux density measured on only one azimuthal side. The responses of tree sap flow to environmental factors were different and depended on the time scales. The daily sap flow was mainly controlled by climatic factors such as radiation and vapor pressure deficit, whereas the soil moisture had more influence of seasonal change on the sap flow. The morphological features of tree significantiy affected sap flow. Taller trees with larger sapwood area and canopy size that were load with more radiation demonsrated higher whole-tree transpiration. A proper integration of both azimuthal and radial variations in sap flux density within a tree can be scaled for whole-tree transpiration, which can relatively accurately estimate stand transpiration. The estimation of A. magium forest transpiration from sap flow showed obvious temporal and spatial differentiations of water use within the community.

Abstract:The methods ofdrought coefficient, cluster analysis and subordinate function were used in comprehensive evaluation for drought resistance adaptability in sweet potato cultivars. The tested components included morphological characters, plant growth, economic traits, physiological and biochemical values in the cultivars grown under water stress. On the basis of correlation analysis between the drought resistance indices obtained from the above-mentioned components and the drought resistance in cultivars, it was shown that 15 tested cultivars could be divided into four classes of tolerance . Most tolerant cultivars were Y3 and Chaoshu 1, followed by 92-111-107, Yushu 34, Nanshu 88 and 92-103-30. Less tolerant were Suyu 1, 9318-58, Yusu 303, 89-1, 95-411-153 and Ximeng. The rest 3 cultivars were not tolerate at all. Above several comprehensive evaluation methods for drought resistance adaptability in sweet potato cultivars are well coincident.

Abstract:Monoembryony was observed in polyembryonic mango cultivars Tu-mang, Carabao and Aroemanis, the frequencies of monoemhryony being 1.04%, 3.85% and 5.44%, respectively. Two- to 6-embryonic cultivars appeared in Tu-mang, and 2- to 8-embryonic cultivars in Aroemanis. The morphology of cotyledons and the location of radicles in polyembryonic seeds varied with the cultivars. Germination rate and seedling survival rate of polyembryonic cultivars were negatively related with the increase of the number of embryos. Somatic chromosome number ofpolyembryonic seedlings was 2n=40, and no change in chromosome number was observed. Peroxidase analysis showed that variation existed among polyembryonic seedlings from the same seed.

Abstract:The cell skeleton of laticiferous cell might play a very important role in latex production and latex flow, and in wound healing and laticifer blocking of tapped Hevea brasiliensis. In order to understand the relationship between cell skeleton of laticiferous cells and latex exploitation and laticifer blocking, a clone R329 was isolated from the subtracted cDNA library of Hevea brasiliensis, which showed high homology with microtubuleassociated proteins. The complete cDNA ofR329 was obtained by using 3＇-and 5＇-RACE strategies. It was 788 bp long containing an 435 bp OR_F, flanked by a 173 bp 5 ＇-UTR and a 179 bp 5 ＇-UTR including a poly（A） tail of 28 bp. The DNA sequence of R329 is available from the GenBank databases under the accession number AY461412. The transcripts of R329 were observed by RT-PCR, no signal was detected in leaves of Hevea brasiliensis, whereas significant signals of transcripts were clearly shown in latex isolated from virgin rubber trees, regularly tapped trees and ethylene-treated rubber trees. These results indicate that the expression of the gene is strongly induced by stress （wound and ethylene ） treatments.

Abstract:ACC （1-aminocyclopropane-l-carboxylic acid） synthase （ACS）is one of the key rate-limiting enzymes for ethylene biosynthesis in higher plants. In this paper, two degenerate oligonucleotide primers were designed, coding for conservative amino acid regions in ACC synthase protein family. PCR amplification was performed on sugarcane DNA template, and produced three fragments, 1 041 bp （Sc-ACS1）, 1 345 bp （Sc-A CS2） and 1 707 bp （Sc-A CS3）. By using the program of BLAST on NCBI GenBank database, three sequences were all ACC synthase genes, coded 326, 242 and 310 amino acids, respectively. The identity of Sc-A CS1 and Sc-A CS3 was 98% in DNA sequence and 96% at amino acid level, and that ofA CS genes from other grass plant species Zea mays （Zm A CS6）, Oryza stativa （OS-A CS2） and Phyllostaehys edulis （BA-A CS） reached to 88%-98% in DNA sequence and 73%-81% in amino acid sequence. The identity of Sc-A CS2, compared to OS-A CS5 from Oryza stativa, was 91% in DNA sequence and 79% at amino acid level, which was higher than that for Sc-A CS1 （45%） and Sc-A CS3 （49%） from sugarcane. Phylogenetic analysis showed that the genes of Sc-ACS1 and Sc-ACS3 in sugarcane were closely related to Zm A CS6 in maize, while Sc-A CS2 was closely related to OS-A CS5 in rice. Southern blotting analysis showed that these genes were presented in the genomic DNA with multiple copies. The three sequences have been registered in GenBank with the accession numbers AY620985, AY620986 and AY788919.

Abstract:The stability of red pigment in fruits of Viburnum luzonicum Rolfe and factors of influencing the colour stability were studied in vitro. The results showed that the red pigment was stable below 6022 and at pH〈4, but sensitive to high temperature, strong light and oxidation-reduction media. Fe³⁺, Cu²⁺ could alter the colour of red pigment solution, caused precipitation, and decreased its stability, but Mn²⁺, Zn²⁺, Al³⁺, Mg²⁺, gluscose and sodium benzoate had no effect on the stability, and showed a certain colour maintenance, especially Al³⁺, which could obviously increase the stability of red pigment. Vitamin C enhanced the degradation and decoloration of red pigment, which showed a significantly negative relationship between colouration and Vitamin C concentration.

Abstract:Callus was induced from the young leaves of Pseudostellaria heterophyll （Miq.） Pax and saponin was obtained by way of cell suspension culture. Plenty of incompact and rapid growing suspension cells were obtained from cultures grown in liquid medium of MS supplemented with 0.2 mg L^-1 BA, 1.0 mg L^-1 2,4-D and 1.0 mg L^-1 KT. The HPLC chromatograms of saponin from suspension cell culture to that from conventionally field-grown or tissue culture seedlings. After about 30 days＇cell suspension culture, the total content of saponin in cultural fluid reached 2.13-2.92 mg g^-1 DW cells, which was slightly lower than that from the roots of conventionally field-grown seedlings, and was close to that from the roots of tissue culture plantlets.

Abstract:Fatty acids in the seed oil of Calophyllum polyanthum growing in Xishuangbanna, Yunnan Province were analyzed by means of GC-MS. Twelve fatty acids amounting to 99.39% of the total contents detected were identified. The main components were linoleic acid （38.75%）, palmitic acid （22.42%）, oleic acid （22.11%） and stearic acid （9.81%）.

Abstract:The anatomy of the roots, stems and leaves of Bowenia spectabilis Hook. ex Hook. f were studied. The primary structure of roots consists of epidermis, cortex and stele. Primary xylem is diarch. There are a large number of parenchyma cells with abundant starch grains in stems. The vascular bundles are collateral bundle. There are 5-8 vascular bundles in petioles and arranged in the shape of arch. Cuticle of the upper epidermis is thicker than that of the lower one, and stomata are restricted to the lower epidermis. There are small veins in mesophyll of pinnae. The xylem in roots, stems and leaves mainly consists of spiral and reticulated or pitted tracheids, and small amount of fibers. The tracheid wall in stems appears convexo-concave, and some tracheids are forked or branched.

Abstract:Chromosome numbers and of the two Cyccls species from China are all 2n=2x=22, and the karyotypes are classified to be 3B according to stebbin＇s category. The karyotype formulas are 2n=2x=22=4m＋2sm＋4st＋12T for C. hainanensis, and 2n=2x=22=2m＋4sm＋4st＋12T for C. szechuanensis subsp.fairylakea. The two karyotypes are reported for the first time. The results support that Cycas can be divided into two groups based on the chromosome data.

Abstract:Chromosome numbers of five species and one hybrid （Michelia sirindhorniae （Noot. ＆ P. Chalermglin） N. H. Xia et X. H. Zhang, comb. nov., Michelia sphaerantha C. Y. Wu ex Law et Y. F. Wu, Michelia doltsopa Buch. -Ham ex DC., Michelia coriacea Chang et B.L. Chen, Manglietia garrettii Craib, Michelia maudiae Dunn x Michelia macclurei var. sublanea Dandy） of Magnoliaceae were observed. The results indicated that they have the same basic number of chromosome （x=19）, and that they are diploids （2n=38）. Chromosome numbers of all taxa except Michelia doltsopa are reported for the first time.

Abstract:Based on the list of wild plant species of national importance issued in 1999 （first part） and the recorded data, there are 9 taxa of national protection grade I distributed in Guangdong Province, viz. Cacys taiwaniana, Cycas fairylakea, Ginkgo biloba, Glyptostrobus pensilis, Mussaenda anomala, Primulina tabacum, Sinia rhodoleuca Taxus wallichiana var. mairei and Bretschneidera sinensis. A survey of the 9 taxa was made during 1998 to 2001, with complementary investigation afterwards. According to IUCN red list 2001 categories and criteria, Cacys taiwaniana, Glyptostrobus pensilis and Mussaenda anomala are extinct in the wild （EW）. Ginkgo biloba is critically endangered （CR）. Bretschneidera sinensis, Sinia rhodoleuca, Primulina tabacum and Cycas fairylakea are endangered （EN）. Taxus wallichiana vat. mairei is nearly threatened （NT）. Conservation strategies of the 9 taxa are suggested.

Abstract:Chloroplast DNA trnL-F region was sequenced to investigate intraspecific phylogeography in Primula obconica Hance in China. Twenty haplotypes were recognized in total, and most of the haplotypes were geographically structured. There are three major clades in the most parsimonious trees obtained from those haplotypes. Eastern clade was widely distributed from Nanping, Fujian （eastern China） to Weixi, Yunnan （western China）. Sichuan clade was confined in western Sichuan, and Yunnan clade existed in north-western Yunnan. It was shown that the topology within Eastern clade was hierarchical slightly, and most of the haplotypes in Eastern clade mainly confined in Wuling Mountains and Nanling Mountains. The haplotypes in eastern clade might be correlated with the climate oscillation in the glacial period, which might migrate from western China to eastern China. In contrast, the haplotypes from Sichuan clade and Yunnan clade might survive in glacial period, suggesting there were several glacial refuges in western China. Taxonomical relationships among subspecies ofP. obconica were also discussed.

Abstract:In the course of preparing the manuscript of Acanthaceae for Flora of Guangdong, broad concept of Justicia is accepted. Two new names （J. demissa and J. neolinerifolia） and two new combinations （J. hainanensis and J. neolinerifolia subsp. liangkwangensis） are proposed.

Abstract:The newly described species Leptostachya rependa Q. H. Chen is reduced to Codonacanthus pauciflorus （Nees） Nees.

Abstract:The information in the literature concerning the concept ofheteranthery, the distribution ofheteranthery in angiosperm, the function of heteranthery in pollinating processes, as well as stamen development are reviewed, and the prospects in heteranthery studies are also discussed. Heteranthery, the phenomenon of stamens in a flower differing notably in shape, size, color and with labor discrimination, was first described more than one hundred years ago. Heteranthery exists in several angiosperm families, such as Melastomataceae, Solanaceae, Lythraceae, Leguminosae and Pontederiaceae, but the aspects and extent of differentiation often vary in taxa. Although people had realized this phenomenon for a long time, the studies are much less in-depth. Studies on heteranthery could strengthen people＇ s understanding about the relationship between plants and their pollinators, and provide new purviews and inspiration for pollination biology and plant breeding system research.

Abstract:This review describes effects of high oxygen concentration on postharvest physiology and quality of fresh fruits and vegetables, including respiration, ethylene production and action, tissue browning, reactive oxygen species metabolism and antioxidative activity, and flavor. Responses of microorganisms in vivo and in vitro to elevated oxygen are also discussed.