Abstract:Reproductive phenology is a key indicator of plant individual reproduction and population succession. to reveal the influence of climate factors on the flowering and fruity period of C₃ and C₄ plants of Poaceae in different regions, Guangdong Province and Inner Mongolia Autonomous Region represent the south subtropical and north temperate climatic zones of China, and three reproductive phenological traits of 395 and 265 herbaceous species of Poaceae were obtained based on floras, respectively. The differences in initial flowering time, final flowering time and flowering duration between the two regions were compared, and the correlations between phenological traits and climatic variables (mean annual temperature and mean annual precipitation) were studied. The results showed that the start flowering stage of C₃ grasses in two regions was earlier than that of C₄ grasses. The C₄ common species of two zones had earlier initial flowering time, later final flowering time and longer reproductive period in south subtropical zone, while there was no significant difference in final flowering of C₃ common species, but the initial flowering stage was earlier and the reproductive period was longer in the south subtropical region. With the increase of annual temperature, the initial flowering time in north temperate region was advanced, but it was delayed in south subtropical region. With the increase of annual precipitation, the initial flowering time and final flowering time were delayed, and the reproductive period had no relation with neither mean annual temperature nor mean annual precipitation. The cross-regional analysis showed that the final flowering time and reproductive period were positively correlated with the mean annual temperature and annual precipitation, but did not the initial flower time. The significant difference in initial flowering time of common species was caused by higher sensitivity of C₃ grasses to climatic difference between two zones than C₄ grasses. The significant difference in reproductive period of common species was driven by the late end of final flowering time of C₄ grasses, which was more sensitive to regional climate differences. Therefore, it was clarified patterns and reasons of different reproductive phenology of Poaceae herbaceous species, and their adaptation strategies to temperature and precipitation across climatic zones.

Abstract:A large canopy simulation and nitrogen deposition field control experimental platform was established on southern slope of Tiger Mountain in Shimentai National Nature Reserve, Guangdong Province, China. To further understand the characteristics of vegetation composition at the platform, 18 plots covering a total area of 0.72 hm² were set up. The results showed that there were 127 vascular species, belonging to 86 genera and 53 families. Furthermore, there were 2 465 individuals with diameter at breast height (DBH) ≥ 1.0 cm. The tree density was 0.34 ind./m², and the tallest up to 25 m. The dominant species in the community was Castanopsis chinensis, Ardisia quinquegon, and Schima superba, which was a secondary evergreen broad-leaved forest consisting of phanerophytes, medium-and small-leaf, leathery, and unentire leaf as main species. The tropical-subtropical floristic elements were dominant in the community, with the characteristics of transition from the tropical to subtropical. Among 18 plots at tree layer, the Simpson index (0.851-0.936) and Shannon-Wiener index (3.504-4.494) were similar; the Pielou's evenness index was high (0.780-1.000); and the Gleason and Margalef richness indexes were rather variable (3.209-7.738 and 16.760-40.806, respectively). The plots shared 10-26 species with Sorensen similarity coefficient of 0.377-0.722. On the contrary, in shrub layers, the above indexes all varied greatly, and only 0-10 common species among plots with Sorensen similarity coefficient of 0-0.714. Therefore, the effect of shrub layer density and species difference on community structure should be considered.

Abstract:The correlations of dominant tree species of Keteleeria fortunei var. cyclolepis community in Junzifeng Nature Reserve, Fujian Province were analyzed by using 2×2 contingency table, variance ratio (R_v), x²-test, Pearson correlation coefficient test and Spearman rank correlation coefficient test, and the ecological species groups were divided based on principal component analysis (PCA). The results showed that there was not significant negative correlations existed among the 21 dominant tree species, and Keteleeria fortunei var. cyclolepis had not significant association with other species. Among 210 species pairs, 110 species pairs were positively correlated, 81 species pairs were negatively correlated, and 19 species pairs were unrelated, with a positive-negative ratio of 1.36. Most species pairs were not significantly correlated each other, and the significantly correlated rate was only 0.48%. The results of Pearson and Spearman rank correlation coefficient test were similar. The number of negative correlation species pairs was greater than that of positive correlation species pairs, and most species pairs were not significantly, and the significantly rates were 6.19% and 7.14%, respectively. Compared with x²-test, the other two test were more sensitive. The dominant tree species could be divided into four ecological species groups by PCA two-dimensional sequence. The ecological habits and resource requirements of species in the same group were similar, most of them were positively correlated, and interde-pendence coexisted. There was a negative correlation among species in different ecological species groups, and species pairs competed with each other. The interspecific association of dominant tree species of Keteleeria fortunei var. cyclolepis community was relatively non-significant, and most species were independently distributed. The seedlings were difficult to renew, saplings face greater competitive pressure, and population size is gradually shrinking trend. In order to promote the normal growth and regeneration of Keteleeria fortunei var. cyclolepis population, the seedlings should be protected.

Abstract:Epiphyte is a special phytogroup in tropical rainforest, which live in stones or stems of other plants, and can not directly absorb water from the soil. In order to know whether cuticular transpiration of the epiphytes is lower or more fog (dew) can enter their leaves through cuticles compared to non-epiphytes. Four epiphytes and four non-epiphytes were selected to determine cuticular permeability of transpiration (P_T), cuticular permeability of water absorption (P_A) and the ratio of P_A/P_T (R) in Xishuangbanna Tropical Botanical Garden of Chinese Academy of Science. The results showed that R was higher for epiphytic leaves (R>1) than non-epiphytic leaves, indicating that epiphytes absorb more water than water loss through leaf cuticle, and fog had a more important ecological significance for epiphytes than non-epiphytes. P_T and P_A were different among plants, and might relate with the chemical composition and physical structure. Except for Coelogyne occultata, Staurochilus dawsonianus and Garcinia xanthochymus, P_T and P_A under 30℃ were higher than those undern 20℃, which indicated that temperature could play a crucial role in cuticular permeability. Therefore, it was indicated that fog might be an important water resources for epiphytes in Xishuangbanna, and play more important role in adaptation to dry season for epiphytes than for non-epiphytes.

Abstract:In order to understand the effects of human disturbance on forest nutrient utilization and biogeo-chemical cycling, the stoichiometric characteristics of fine roots in Castanopsis carlesii secondary forest and natural forest and their variation trend with soil depth (0-80 cm) were studied. The results showed that the main effect of stand and soil depth on fine root stoichiometry was significant by mixed linear model, but the interaction effect was not significant. The contents of N and P in fine roots of secondary forest were significantly lower than those in natural forest, while the C content, C:N and C:P in fine roots were significantly higher than those in natural forest. The C content of fine root at 1-2 mm diameter in secondary forest was significantly higher than that of natural forest. Fine root The N and P contents of fine root in natural and secondary forest decreased significantly with the increase of soil depth, while C:N, C:P, N:P increased with the increase of soil depth, and the change trend of root stoichiometric characteristics with soil layer were similar between secondary forest and natural forest. The contents of N, P and N:P in fine roots of natural and secondary forests were linear with the contents of total N, total P and N:P in soil, respectively. The contents of N, P and N:P in fine roots were significantly correlated with the soil depth, but not with the specific root length (SRL). Therefore, the stoichio-metric characteristics of fine roots did not change with soil depth in the natural forest after human disturbance, but the concentrations of N and P in fine roots decreased significantly.

Abstract:Tropical coral islands have adverse natural conditions, and a very fragile vegetation ecosystem. In order to investigate the suitability of Thuarea involuta in arid environment of tropical coral islands, the physiological indexes of stress resistance of leaves were studied. The results showed that there was no significant difference in malondialdehyde (MDA) content of leaves among drought degrees at early stress stage. The MDA content rapidly increased at first and then decreased quickly under severe drought stress, which had little change under other drought treatments. The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) increased with the increment of drought degree. Along the treatment time, SOD activity increased, POD activity was basically stable, and CAT activity decreased first and then increased. The soluble protein (SP) content under light drought stress was lower than that under control, which increased with increment of drought stress. The change in proline (Pro) content increased first and then decreased with the treatment time, but there was no significant difference among stress treatments at 18th day. Therefore, Thuare involuta had strong drought resistance ability and could be used for artificial plant community construction, vegetation restoration and improving environmental conditions of Nansha Islands.

Abstract:In order to explore the effects of citrus essential oil (0.25%,0.75%,1.5%) and chitosan (0.25%,0.75%,1.5%) on postharvest physiology and storability of Chinese olive (Canarium album) fruits, the fruit decay rate, browning index, relative conductivity, respiratory intensity, malondialdehyde content, endogenous antioxidant substance glutathione content, activities of peroxidase (POD) and ascorbate peroxidase (APX) of cv. ‘Tanxiang’ and ‘Meipu 2’ fresh fruits during postharvest storage were determined to screen the best concentration combination of compound preservatives. The results showed that the combinations of citrus essential oil and chitosan could effectively reduce decay rate, browning index and malondialdehyde content in fruits during storage, inhibit respiration, maintain a high content of endogenous antioxidant glutathione, as well as activities of POD and APX. Therefore, the combination of citrus essential oil and chitosan could effectively prolong the fresh-keeping period of Chinese olive fruits and improve the storability, the mixed 1.5% citrus essential oil and 1.5% chitosan had the best fresh-keeping effect.

Abstract:In order to understand the genetic diversity and correlation of leaf traits and fruit weight in loquat (Eriobotrya japonica), the correlation between 7 leaf traits and fruit weight in F₁ population (123 individuals) of ‘Ninghaibai’ and ‘Dafang’ hybrid were analyzed. The results showed that the five traits, including length, width and thickness of leaf, petiole length, and fruit weight, inhibited normal distribution with good continuity in offspring. The genetic trend of fruit weight, leaf length, width and thickness was smaller, while petiole length tended to moderate variation. For the F₁ hybrid population, the leaf surface morphology was mainly "rugulose", the leaf shape was mainly "elliptic", and the leaf base shape was mainly "cuneate". The fruit weight had significant positive correlation with petiole length and length, width and thickness of leaf. Therefore, petiole length could be considered as one of the indicators for early screening of excellent plants with large fruits.

Abstract:In order to analyze the genetic identification of the natural hybrid progenies of tea, EST-SSR capillary electrophoresis fluorescence maker technique was used to analyze 65 the natural hybrid progenies of ‘Jinmudan’ tea. The results showed that a total of 192 polymorphic alleles were detected by 28 SSR markers, the average number of alleles (Na), observed heterozygosity (Ho) and polymorphism information content (PIC) was 0.58, 0.58 and 0.98, respectively. When the parental genotype was known, the combined exclusion probability was all reached 0.999, indicating that the 28 selected SSR marker sites had high polymorphism and high probability of exclusion, which were suitable for genetic analysis and paternity identification of individuals. The results of genetic identification showed that the 15 natural hybrid progenies of ‘Jinmudan’ tea could be divided into 4 types, JMD44, JMD45, JMD47 and JMD32 were early green tea, JMD51 and JMD53 were ‘Rougui’ oolong tea in northern Fujian, MD2 and JMD56 were ‘Tieguanyin’ oolong tea in southern Fujian, JMD24, JMD26, JMD29, JMD55, JMD59 and JMD27 were ‘Huangdan’ oolong tea.

Abstract:To explore the common response mode and disease resistance mechanism of tea plants (Camellia sinensis) to pathogenic stress, bioinformatics methods were used to extract, integrate and function enrich of multiple sets of RNA-seq data, and the main regulatory molecules and protein interaction modules were analyzed by combining various tools and database resources. This results showed that the expression of cytochrome P450 family members in tea plant was significantly up-regulated under the fungal pathogen stress. The metabolic processes of steroid and hormone, and phenylpropanoid synthesis pathway were activated, and the biological processes, such as mitotic cell cycle regulation, DNA methylation and photosynthesis pathway were inhibited. The major regulatory molecules, such as WRKY and NAC transcription factors, the RLK-Pelle and CAMK family of kinases were mainly up-regulated. The differentially expressed protein interaction modules showed that the modules involved in mitotic cycle regulation, microtubule motion-based, starch and sucrose metabolism, cell wall polysaccharide synthesis, photosynthesis, flavonoid metabolism were down-regulated, while lignin synthesis and terpenoid biosynthesis were up-regulated. There may be interactions between modules. The key genes in lignin and terpenoid synthesis pathways activated by pathogen stress included ferulic acid-5-hydroxylase gene (F5H), peroxidase gene (POD) and terpenoid synthase gene HMGR. Cytochrome P450 gene might play a key role in fungus stress of tea plants. Enhancing the synthesis of lignin and terpenoids, and weakening photosynthesis might be the core modes of tea plants responding to fungus stress.

Abstract:In order to species identify of Hedychium flavum complex, the morphological characteristics of specimen collected from Guizhou, Chongqing, Sichuan, Yunnan, Guangxi, and transplanted plants were observated. The results showed that the characteristics of floret aroma, ligule, bracts, labellum, lateral vestigial stamens and fruits were important indexes for species identification of H. flavum complexes. Then H. panzhuum Z. Y. Zhu was classified into H. flavum Roxb., and H. emeiense Z. Y. Zhu into H. chrysoleucum Hook. rather than H. flavescens. It was suggested that there were 4 species in H. flavum complex, including H. flavum Roxb., H. bipartitum G. Z. Li, H. chrysoleucum Hook. and undescribed species Hedychium sp.

Abstract:Glochidion nubigenum Hook. f. was described as a newly recorded species to China in 1988, however the voucher specimen (B.S. Li & S.Z. Chen 4533; collected in Motuo County, China) cited then was misidentified and it actually belongs to G. mishmiense Hook. f. In addition, the morphological description of G. nubigenum provided in both Flora Republica Popularis Sinicae and Flora of China also conflicted with the morphology of the voucher specimen mentioned above and also the actual G. nubigenum, thus it is evident that the distribution of G. nubigenum in China as recorded previously seems to be questionable. Recently, during a field investigation conducted in Yadong County, Tibet, China, a wild population of the actual G. nubigenum was discovered. Thus the information about the distribution of G. nubigenum in China is revised and detailed morphological description as well as the field images of the species are provided here.

Abstract:A new species of Lirianthe (Magnoliaceae) from Guangxi, China, L. jingxiensis Y. H. Tong & N. H. Xia, is described and illustrated here. This species is morphologically most similar to L. albosericea (Chun & C. H. Tsoong) N. H. Xia & C. Y. Wu, but differs in having a much shorter height, young branches, petioles and leaf blades with yellowish-brown sericeous trichomes, wider petiole, wider leaf blades with an obovate or obovate-elliptic shape and an obtuse or shortly acuminate apex, larger tepals and more carpels covered with yellowish-brown sericeous trichomes.

Abstract:Impatiens glandulifera Royle, an annual species native to India and West Himalayas, has invaded rapidly in many regions of Europe and North America. It was found to be naturalized newly in Mohe City, Heilongjiang Province, China. This species might have been introduced as an ornamental at least two years ago, and would produce large numbers of offspring by seed after one year of planting. The morphological characters, geographical distribution, biological habit, invasive hazards, and control methods were presented for species identification and control.

Abstract:In order to understand the leaf epidermal morphology of Diospyros (Ebenaceae), the leaf epidermal characters of 46 species and 2 varieties were observed under light microscopes, and then the major characters were analyzed by principal component analysis. The results showed that the micro-morphology of the leaf in Diospyros could be divided into two groups, Group A and Gruop B. The epidermal cells were irregular with repand or sinuous anticlinal walls in Group A, and which were polygonal with straight or arched anticlinal walls in Group B. The leaves of the genus were hypostomatic. The stomata were mainly anomocytic and sometimes actinocytic, cyclocytic or staurocytic. The trichomes were found in most species, which were either simple non-glandular or capitate glandular. Therefore, the epidermal characters would provide valuable morphological evidences for classification in some taxa of the genus.

Abstract:In order to investigate the volatile constituents from fresh flowers of Psidium guajava, the volatile components of ten guava varieties, including ‘Cuiyu’, ‘Diwang’, ‘Bentu’, ‘Hongye’, ‘Fenhongmi’, ‘Zhenzhu’, ‘Xigua’, ‘Shuimi’, ‘Mugua’ and ‘Hongbaoshi’, were determined by headspace-GC-MS method. The results showed that a total of 43 volatile components with relative content of more than 0.1% were detected, contained 10 common components, mainly consisted of terpenes with the content of 89.77%-97.40%. β-Ocimene, d-limonene, eucalyptol and β-caryophyllene were the main volatile components in the ten varieties. Seven volatile compounds, including α-pinene, β-ocimene, d-limonene, 3-carene, alloaromadendrene, β-longipinene and 1-isopropyl-4,7-dimethyl-1,2,3,5,6,8a-hexahydronaphthalene, mainly caused the volatile components differences in different varieties. Ten guava varieties could be divided into 4 groups according to aroma similarity. ‘Cuiyu’ and ‘Diwang’ falled into a group, while ‘Shuimi’ and ‘Bentu’ belonged to one group, ‘Fenhongmi’, ‘Xigua’, ‘Hongye’, ‘Mugua’ and ‘Hongbaoshi’ were clustered one group, and the fourth group had only ‘Zhenzhu’. There were similarities and differences in the volatile components of different varieties of guava flowers, which provide a theoretical basis for the mixed picking and personalized development and utilization of guava flowers.

Abstract:To understand the chemical constituents of Swietenia macrophylla barks, nine compounds were isolated and purified from bark extracts by using silica gel, gel and MPLC. Based on the physicochemical properties and spectral data, their structures were identified as vanillic acid (1), scopoletin (2), physcion (3), 3,4,5-trimeth-oxyphenyl-β-d-glucopyranoside (4), (+)-catechin (5), (+)-5'-methoxy-isolariciresinol-9'-O-β-dxylopyranoside (6), lyoniresinol-9'-O-β-d-xylopyranoside (7), stigmasterol (8), stigmasterol-3-O-β-d-glucopyranoside (9). Except for compound 5, the remaining compounds were isolated from this plant for the first time. The cytotoxicity assay showed that none of the compounds had significant cytotoxic activities.

Abstract:To understand the chemical composition of Hedyotis diffusa, nine compounds were isolated from the 70% ethanol extract by column chromatography on silica gel and preparative high-performance liquid chromatography. Based on physicochemical properties and spectral data, their structures were identified as stigmasterol (1), β-sitosterol (2), rubiadin (3), 2,6-dihydroxy-1-methoxyanthraquinone (4), β-sitosterol-3-O-β-d-glucoside (5), p-coumaric acid (6), kaempferol (7), quercetin (8) and 2-hydroxy-3-methoxy-7-methylanthraquinone (9). Compound 4 was a new compound. The Fr.4, Fr.4-2 and Fr.4-4 fractions in chloroform extract had strong activity against human endometrial carcinoma Ishikawa cells in vitro, with IC₅₀ of 52.8, 78.1 and 27.5 μg/mL, respectively.