Abstract:In order to understand the species coexistence mechanism of Sinojackia rehderiana community in Yongxiu County of Jiangxi Province, the spatial distribution pattern and associations of 5 main species in 0.5 hm² plot of S. rehderiana community were studied. The results showed that the vertical structure of the community was evident, Cinnamomum camphora and Celtis biondii were in upper layer; Ilex wilsonii in middle layer, and the dominant species were S. rehderiana and Alangium platanifolium in lower layer. Celtis biondii was distributed randomly at all spatial scales, and other 4 species were clumped distribution at small scale, and showed an uniform distribution or random distribution with the increment of scale. Ilex wilsonii and A. platanifolium were negatively associated with S. rehderiana at small spatial scale. However, Cinnamomum camphora and C. biondii had negative association with S. rehderiana at large spatial scale. There was no obvious association among C. camphora, C. biondii, I. wilsonii and A. platanifolium. Therefore, it was deduced that density restriction and seed diffusion restriction play a role in the spatial pattern formation of Sinojackia rehderiana community, and the influence of habitat heterogeneity is not obvious, and the community has not reached a stable state.

Abstract:In order to understand the changes in litterfall and nutrient cycling of Eucalyptus urophylla×E. grandis plantations with different ages on Leizhou Peninsula, the litterfall amount and nutrient return of Eucalyptus plantations with different ages were surveyed continued for 12 months. The results showed that the annual contents of litterfall of Eucalyptus plantations were in the order of 5 a > 9 a > 7 a, the total litterfall of 5 a plantation was significantly higher than that of 7 a and 9 a plantations, but there was no significant difference between later plantations. The litterfall contents of Eucalyptus plantations with different ages showed obvious seasonal changes with bimodal pattern, and the peak values appeared in the early or late rainy season. There was no significant correlation between forest structure factors and amount of litterfall, but there was a significant positive correlation between the monthly average temperature and litterfall amount. The annual nutrient flux of different forest ages was dominated by amount of litterfall and nutrient content. The annual nutrient flux of nitrogen, phosphorus and potassium in Eucalyptus plantations was in the order of 9 a > 7 a > 5 a, and there were significant differences among them. The peak period of nutrient restitution was concentrated around the rainy season, while the amount of nutrient restitution in winter was low. Therefore, in order to increase the yield of Eucalyptus plantation and facilitate the recovery of plantation soil fertility, the planting years of Eucalyptus plantation should be increased and the cutting season should be in winter.

Abstract:In order to understand the spatial and temporal distribution patterns and germination of seed rain of Casuarina equisetifolia, the spatial-temporal distribution characteristics and germination dynamics of seed rain were studied in coastal protection forest of C. equisetifolia in Haikou, Hainan Province. The results showed that the seed rain of C. equisetifolia began in mid-July and finished in mid-April of next year, which was lasted for 9 months, with average density of seed rain for 1 764.63 grain m^-2a^-1. The peak of seed rain was in early-to mid-December, accounting for 43.38% of the total seed rain. Seed rain was aggregated distribution, and the seed rain density was positively correlated with the number of nearby cones. The germination rate of seed rain was low only with 11.31%, but the germinable seed rain density was still high with 199.58 grain m^-2a^-1, due to the high seed rain density. Therefore, the quantity and quality of C. equisetifolia seed rain were not the main factors in restricting its natural regeneration, but the aggregated distribution pattern made the diffusion ability of C. equisetifolia seeds very limited in the forest.

Abstract:In order to understand the effects of tree species composition in forest community on distribution of bryophytes, the responses of species composition and distribution of bryophytes to forest types in the subtropical forest communities of eastern Guangdong were studied by using multivariate methods. Forest stands were classified into 3 types according to tree species composition, such as Pterospermum heterophyllum, Schima superba + Castanopsis carlesii, and C. carlesii communities. The results showed that the species composition and distribution of both liverworts and mosses had significant difference among three forest stands. The difference in importance values (IV) for Chiloscyphus latifolius and Kurzia gonyotricha among the forest stands indicated the overall variations in liverwort distribution. The moss species, Pseudotaxiphyllum pohliaecarpum, dominated in all of three forest stands, and the difference in moss species composition was represented by the distribution of sub-dominant moss species among the forest stands. So, it was suggested that as the important biotic factors, the tree species composition of forest communities had significant influence on the species composition and distribution of bryophytes.

Abstract:In order to understand the effect of vegetation types on soil physicochemical property in Island, the soil physicochemical property in East Island and Yongxing Island of Xisha Islands under three vegetation types were determined. The results showed that in the processes of vegetation types from herbaceous and vines, shrubs to trees community, the soil water content increased significantly from 5.9% to 14.15%, and microbial biomass carbon and nitrogen also increased from 176.2 and 41.2 mg kg^-1 to 391.5 and 98.8 mg kg^-1, respectively. Meanwhile, the soil pH decreased with changes in vegetation types. So, it was suggested that soil quality in Islands enhanced gradually with vegetation recovery, and the island ecosystem became more stable.

Abstract:In order to understand the stress resistance of Calophyllum inophyllum, the morphological and anatomical, eco-physiological characteristics, element contents in leaves and soil of C. inophyllum growing in Xisha Islands were analyzed. The results showed that C. inophyllum was heliophyte plant with thick leaf, well-developed spongy tissue and tightly arranged palisade tissue with low stomata density (24.40 mm^-2), which was beneficial to its water retention and drought resistance of leaves. The contents of chlorophyll a and chlorophyll b were low (0.87 and 0.43 mg g^-1, respectively), indicating that C. inophyllum had good adaptability to the high irradiation environment. The low level of malondialdehyde content (13.46 nmol g^-1), the high level of proline content (127.89 µg g^-1), and superoxide dismutase activity (149.42 U g^-1) in leaves indicated that it had strong antioxidant capacity (388.60 U g^-1), so as to alleviate membrane lipid peroxidation under stress conditions. Though the nutrient in natural growing soil was poor, the content of nutrient elements in leaves of C. inophyllum was high, indicated that it had high utilization and good adaptability to poor soil. Overall, C. inophyllum had good adaptability to strong radiation, drought and poor soil, and could be used as a tool species for rehabilitation of tropical coral islands.

Abstract:In order to understand the relationship between monthly growth of Pinus kesiya and meteorological factors, the annual growth dynamic of 17 families were studied in southern Yunnan. The family plantation was established in June 2013, 17 half-sib families of P. kesiya introduced from Thailand and Vietnam were selected with P. kesiya var. langbianensis from local seed orchard as control, the diameter at breast height (DBH), height and timing of shooting were observed for a whole year since July 2015. Meanwhile, the effects of meteorological factors on growth rhythm and shooting law were also analyzed. The results showed that there were significant differences in DBH, height and shooting times among 17 families (P<0.05). These families could be divided into two types, family No. 7, 25, 61, 104 and 41 were fast-growth type (I), with annual mean increment of DBH and height for 2.03 cm and 1.46 m, respectively, and the others was slow-growth type (Ⅱ). The both types of P. kesiya families showed similar growth tendency, of the DBH growth had two peaks occurred in February and August, of and the height growth had three peaks in February to March, June, and August to October, and shooting had three peaks in May (spring shoot), August to September (summer shoot) and November (fall shoot), respectively. The shooting times of P. kesiya were one to four in a whole year, of which the number of families with twice shooting was the largest, accounting for 47% of the total trees, mainly in spring (72.78%) and summer (77.33%). The growth of P. kesiya was influenced mainly by monthly average temperature, and growth stagnation was short in January. So, it was recommended that tending management of P. kesiya young plantation should be conducted before two peaks of DBH and height growth, i.e. May to June and December to January, and pruning in January.

Abstract:In order to understand the role of UBE1 gene in self-incompatibility (SI) response of Citrus reticulata ‘Wuzishatangju’, a WUBE1 gene from the self-incompatible cultivar 'Wuzishatangju' was transferred into tobacco (Nicotiana tabacum) mediated by Agrobacterium tumefaciens. The results showed that the WUBE1 gene was integrated into genome and expressed in transgenic tobacco. Some pollen tubes of self-pollinated transgenic tobacco with WUBE1 became twisted and could not enter the embryo sac. The number of pollen tube entering into ovules in self-pollinated WUBE1 tobacco was fewer than that in wild type (WT) and cross-pollination (transgenic tobacco×WT). However, there was no significant difference in pollen viability, germination rate and seed number per pod between transgenic tobacco and WT. Therefore, it was suggested that only the WUBE1 could not regulate SI response of ‘Wuzishatangju’, and it was possible to form a complex in Ub/26S pathway involved in the SI reaction.

Abstract:Based on the previous research about Ipomoea pes-caprae cDNA library screening, a full length cDNA encoding dehydrin was characterized and named as IpDHN (GenBank accession:No. KX426069). In order to explore the transcriptional activity of the IpDHN promoter and the characteristics of this promoter region responding to abiotic stresses and ABA, the 5' upstream sequence of IpDHN (974 bp), named as IpDHN-Pro was cloned by genomic walking method, and then was subcloned into plant expression vector, in which GUS is under control of IpDHN-Pro. The transgenic Arabidopsis plants harboring IpDHN-Pro::GUS were checked by GUS staining assay, then the expression of GUS was further detected by qRT-PCR after the transgenic plants were challenged by NaCl, mannitol and ABA. The results showed that the IpDHN-Pro contained several cis-acting elements, including an ABRE, three Myb transcription factor binding sites, a TC-rich repeat, and a Skn-1 motif. The GUS staining and qRT-PCR showed that IpDHN-Pro could drive the stable expression of GUS gene in transgenic Arabidopsis, and this promoter was up-regulated by high salinity, osmotic stress and ABA treatment. Therefore, it was indicated that IpDHN-Pro was a salt/dehydration and ABA induced promoter sequence, and can be applied in plant genetic engineering research aiming at abiotic stress tolerance.

Abstract:MADS-box family proteins are important transcription factors associated with the regulation of growth and development, especially in floral development of higher plants. HAM23-like, a new member of the MADS-box genes, was cloned from Helianthus annuus. The bioinformatic results revealed that HAM23-like gene had an open reading frame of 831 bp, encoding a protein with 276 amino acid; the protein possessed a relative molecular weight of 30.52 kD and a theoretical isoelectric point of 9.42. The analysis of phylogenetic tree showed that HAM23-like was closely homologous to the AGL18 gene of Arabidopsis thaliana. Moreover, the qRT-PCR results indicated that the HAM 23-like gene were highly expressed in flower and mature fruit in tissue expression pattern, and in different floral organ of flowering day, the expression of HAM23-like reached the highest level in stamen. In addition, the expression of the HAM23-like gene was gradually raised during the floral development, and reached the highest expression on 5 days after flower blooming. These results implied that HAM23-like gene would be involved in the later stage of floral organs development and the earlier stage of achene development in H. annuus. The results of this study could provide some preliminary data and theoretical basis for further study, especially, it will help to explore the regulatory role of HAM23-like in floral development and achene formation in H. annuus.

Abstract:In order to screen excellent germplasm of Hylocereus undatus, the fruit genetic diversity analysis in phenotypic traits, agronomic traits and quality traits of 22 germplasms were studied. The results showed that the phenotypic, agronomic and quality traits of H. undatus fruit had abundant genetic diversity and high variability. The diversity indexes (H') of fruit phenotypic and quality traits were 0-1.04 and 0.40-2.01, respectively. The coefficient of variation (CV) of agronomic traits and quality traits were 0.01-0.62 and 0.06-0.38, respectively. Cluster analysis showed that 22 germplasms of H. undatus could be devided into 5 groups at genetic distance of 15, indicating that different germplasms were far related. These would lay a foundation for exploring the breeding potential of H. undatus, screening excellent genetic resources and improving germplasm.

Abstract:In order to understand the effects of exogenous GA₃ and Spd on florescence and flowering quality of Rhododendron simsii, the changes in photosynthetic characters and antioxidant system during the flowering period were studied. The results showed that GA₃ had a significant ahead effect on florescence, while Spd delayed. Both of GA₃ and Spd could prolong florescence, increase flower diameter and flowering formation rate. Both of GA₃ and Spd significantly promoted photosynthetic rate (Pn), stomatal conductance (Gs) and intercellular CO₂ concentration (Ci). The transpiration rate (Tr) increased by GA₃, but inhibited by Spd. Both of GA₃ and Spd had relieve effect on decline of chlorophyll content at the end of the flowering. MDA content in petals significantly decreased treated with GA₃ and Spd, and the activities of SOD, POD and CAT increased. At the same time, The decrease of SOD activity in the end flowering stage was slowed down treated with GA₃ and Spd, relieved the ageing process, and extended the flowering. In conclusion, it was better with 1 600 mg L^-1 GA₃ and 0.10 mmol L^-1 Spd, could improve effectively the quality of flowers.

Abstract:In order to construct rapid propagation system of yellow nutsedge (Cyperus esculentus), the effect of growth regulator combinations, including 6-BA, KT and NAA, was studied by using orthogonal design method with shoot tip as explants on basic medium of MS. The results showed that the effects of growth regulators on proliferation of multiole shoots was in order of 6-BA > NAA > KT. The optimal growth regulator combination was 1.0 mg L^-1 6-BA+0.2 mg L^-1 KT with proliferation coefficient of 7.58 after cultured for 4 weeks. MS medium was optimal rooting medium with rooting rate of 88.10%, and an average roots was 2.04. So, these would lay a foundation for efficient breeding of high quality seedlings and optimization of germplasm resource of yellow nutsedge.

Abstract:In order to understand the response to low temperature of loquat (Eriobotrya japonica) seedlings, the changes in cell ultrastructure of leaves and roots of ‘Jiefangzhong’ seedlings were studied under cold stress by artificial cooling, and leaf browning rate, root activity as well as plasma membrane permeabilities (PMPs) were measured. The results showed that the root activity decreased by 26.09%, and the leaf browning rate increased by 17.15% under light cold stress (0℃). The PMP of root increased and the PMP of leaf decreased. The number of mitochondria had significant increment in root and mesophyll cells under electron microscope, indicating that mesophyll cells and root cells resisted low temperature injury by enhancing respiration and energy metabolism. The intercellular freezing in roots was appeared at 0℃ for 36 h, causing vacuoles disappearance, mitochondrial enlargement, double membrane and cristae disappearance, cell wall structure damage, but in mesophyll cells, chloroplast destruction, starch grains became small, and mitochondria intact. Intracellular freezing would be caused in root cells and mesophyll cells at sever low temperature (-3℃, -5℃), and the damage degree in root cell wall under low temperature was more serious than that in mesophyll cell wall. The time of intracellular freezing in root cells was earlier than that in mesophyll cells. These were indicated that the root cell was high sensitive than mesophyll cell to low temperature. Thus, the insulation measure to underground parts of loquat before low temperature had positive roles in mitigating the injury to the aboveground parts.

Abstract:Two little known species of Pleione (Orchidaceae) from China were noted, i.e., Pleione arunachalensis Hareesh, P. Kumar & M. Sabu and P. humilis (Sm.) D. Don. Detailed morphological descriptions and photographs were provided. The voucher specimens were deposited in the herbarium of Yunnan Academy of Forestry and Grassland (YAF).

Abstract:Persicaria odorata (Lour.) Soják is a perennial odoriferous herb and native to Indo-China. The species has been widely transplanted in China by Dai and Hakka peoples of Guangdong, Guangxi, Jiangxi and Yunnan provinces, and recently found to be naturalized in some tropical regions of Yunnan. Persicaria odorata is most similar to the Chinese endemics P. wugongshanensis B. Li in having leaves and tepals minutely glandular, inflorescences spike-like and interrupted, flowers dimorphic, and pedicels longer than bracts, but clearly different from the latter by having developed rhizomes, lanceolate to narrowly lanceolate leaf blades, and shiny achenes. The present study reports the morphology, distribution and usages of P. odorata and provides its illustration.