Abstract:In order to determine the optimal hyperspectral characteristic variables of subtropical tree species and construct the estimation model of leaf area index (LAI), the leaf reflectance and LAI of 50 tree species in the campus of South China Agricultural University (SCAU) were measured. At the same time, the relationship model of LAI with the six hyperspectral characteristic variables, including NDVI, RVI, FREP, CI_Green, CI_Red-edge and MSAVI₂, were constructed through statistical analysis, respectively. The results showed that there were significant correlations between the six hyperspectral characteristic variables and LAI of tree species. The R² of fitting equations between LAI with red edge position reflectivity (FREP) and the ratio vegetation index RVI were more than 0.8 with correlation coefficients for 0.820 and 0.811, respectively. The root mean square error (RMSE) of FREP estimation is only 0.13, so the regression model is the best model for estimating the LAI of typical subtropical tree species. Combining subtropical vegetation community structure and hyperspectral remote sensing, the regression model between red edge position reflectivity and leaf area index generally has a high fitting degree. Therefore, using hyperspectral characteristic variables inverted subtropical leaves of the leaf area index and other vegetation parameters had better application prospects.

Abstract:In order to understand the effect of climate change on geographical distribution of Actinidia deliciosa, the distribution change trend of A. deliciosa in China under current and future climate scenarios was predicted by using Maxent model. The results showed that the AUC values of distribution models established under current and future climate scenarios were all excellent. Under the present climatic conditions, the potential suitable zone for A. deliciosa were mainly distributed from north latitude 22° to 38°, and east longitude from 96° to 122°, with total area was 3.367 9×10⁶ km². The high suitable zone was in Qinba Mountain, eastern Sichuan Basin, eastern Yunnan-Guizhou Plateau, Wuling-Wushan Mountain and Wuyi Mountain. Area of high suitable zone would decrease, while that of medium suitable zone would increase under scenarios RCP4.5 and RCP8.5. The mean centers will move to low latitude area in the futre under scenarios RCP4.5 and RCP8.5, and the centroid under RCP8.5scenario has the longest moving trajectory and the largest change range among three climate scenarios. So, the prefect forecast of Maxent model has important guiding significance for optimizing A. deliciosa planting pattern in China.

Abstract:In order to understand the dynamic change of soil respiration rate and it’s response to meteorological factors, soil respiration rate of Eucalyptus urophylla×E. grandis plantation in Leizhou Peninsula was measured by using LI-8100A Soil carbon flux automatic measurement system. The results indicated that soil respiration rate of E. urophylla×E. grandis plantation changed distinctly from March 2016 to February 2017, showing single peak curve with the maximum at May, 2016 and minimum at February, 2017, respectively. The mean soil respiration rate was (2.34±0.70) μmol m^-2s^-1. According to the correlation coefficient, the influencing factors on soil respiration rate was ordered as soil temperature > air temperature > atmospheric pressure > photosynthetical active radiation > vapor pressure deficit > soil moisture. Furthermore, the principal component analysis showed that the variation of heat energy caused by temperature and photosynthetical active radiation and that of moisture caused by soil moisture were the main effect factors on soil respiration rate. The meteorological factors model was reliable due to 94.0% variation of soil respiration rate can be explained by regression analysis. The cumulative annual CO₂ flux of soil surface in E. urophylla×E. grandis plantation was estimated as 893.31 g C m^-2a^-1. The temporal variation of soil respiration could be fully explained by coupling effect of meteorological factors.

Abstract:In order to understand the effect of human disturbance on Castanopsis fargesii secondary forest community in Bifengxia, the species diversity and soil physiochemical properties of C. fargesii community under human disturbances at different degree were studied by using typical plots methods. The results showed that there were 148 vascular species in community, belonging to 60 families and 106 genera. With intensifying disturbance, the diversity indices in tree and herb layer increased at first and then declined, and the species diversity in shrub layer was the highest. The dominant species in tree layer were C. fargesii and Cunninghamia lanceolata, and the shrub layer is rich in species with many dominant species, and the dominant species number in herb layer was in the order of middle disturbance > slight disturbance > severe disturbance. There were significant correlation among the contents of soil organic carbon, soil potassium and soil moisture and the level of species diversity (P<0.05). Therefore, it was suggested that the species diversity and soil quality of C. fargesii community in Bifengxia could be promoted under middle disturbance and the contents of soil organic carbon, soil potassium and soil moisture had related significantly with species diversity.

Abstract:In order to investigate the photoprotection mechanism in young leaves of dominant tree species of subtropical forest in summer, three mid-successional species, i.e. Schima superba, Castanopsis fissa and C. chinensis, and three late-successional species, i.e. Machilus chinensis, Cryptocarya chinensis and C. concinna, grown on 100% (FL) and 30% (LL) of full sunlight, respectively, the leaf phenotype, anthocyanins content, photosynthetic pigment content, antioxidant capacity, flavonoids content, phenols content and restoration efficiency of the maximum photochemical efficiency (Fv/Fm) of young or mature leaves of six dominant trees were analyzed. The results showed that young leaves of dominant tree species at two successional stages had lower chlorophyll content (Chl a+b) and Chl a/b than mature leaves, but light protects substances were more than mature leaves. Young leaves of mid-successional species exhibited higher anthocyanins content and total antioxidant capacity (TCA) but lower contents of flavonoids and total phenols than those in late-successional species. Young leaves of both successional species grown in FL demonstrated higher contents of anthocyanins, phenols, flavonoids, TCA and restoration capability of Fv/Fm than those grown in LL. In addition, Fv/Fm of young leaves with anthocyanins restored faster after exposed to weak light. Therefore, it was suggested that photosynthetic capacity is negative correlated with photoprotection potential. Anthocyanins play an important role in photoprotection of young leaves in mid-successional species, whereas young leaves of late-successional species are mainly photoprotected by antioxidant compounds (flavonoids, total phenols).

Abstract:In order to understand the effect of light intensity on the agronomic properties and quality traits of two-year-old notoginseng (Panax notoginseng), the agronomic properties, anatomical structure, biomass accumulation and allocation, as well as saponins accumulation in P. notoginseng were studied by using artificial shade method. The results showed that biomass accumulation of P. notoginseng was the biggest under 13.5% of full sunlight. The content of total saponin was the highest under 9.2% of full sunlight, while the saponin content per plant was big under 13.5% of full sunlight. The leaf and stem biomass accumulation of P. notoginseng enhanced with the light transmittance decreasing. When the light transmittance increased, the thickness of leaf epidermis, sponge tissue, palisade tissue and the leaf increased for reducing light capture. Therefore, the growth, biomass and saponin accumulation of P. notoginseng would be improved under light transmittance from 9.2% to 13.5% of full sunlight.

Abstract:In order to understand the effect of arbuscular mycorrhizal fungi (AMF) on growth and photosynthetic physiology of Betula alnoides, four clone seedlings were inoculated with six arbuscular mycorrhizal fungi (AMF) and grown in greenhouse, and then seedling growth, photosynthetic parameters, chlorophyll contents and fluorescence parameters were investigated. The result showed that all six AMFs could form symbiote with seedlings of B. alnoides clones. After inoculated with Glomus intraradices (AMF5) and G. mosseae HUN03B strain (AMF3), the seedling growth, net photosynthetic rate, water use efficiency, chlorophyll contents and fluorescence parameters were significantly enhanced (P<0.05), indicating that affinity of AMF5 and AMF3 with clones was obviously better than that of other AMFs. There were no significant differences in inoculation rate among four clones, but the promotion effect of AMF inoculation on growth and photosynthetic physiology of FB4 and BY1 were obviously better than those of FB4+ and A5. Therefore, the optimal AMF strains were AMF5 and AMF3 for B. alnoides, which would provide theoretical foundation to its mycorrhizal seedling cultivation.

Abstract:In order to understand the response of Calendula officinalis seedlings to mixed neutral salt stress, the growth and photosynthetic physiology of seedlings was studied under stressed with NaCl∶Na₂SO₄ at mole ratio of 9∶1. The results showed that the balance of active oxygen metabolism and the integrity of cell membrane structure were maintained by enhancing activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and decreasing content of malondialdehyde (MDA) in leaves of C. officinalis seedlings under lower than 100 mmol L^-1 salt concentration, which could maintain normal photosynthesis and growth of seedlings. When salt concentration was more than 200 mmol L^-1, the activities of SOD, POD and CAT decreased rapidly, and content of MDA increased rapidly, which significant influnced on photosynthetic capacity and growth. Therefore, the threshold salinity of C. officinalis seedlings to mixed neutral salt stress was 100 mmol L^-1, the seedlings could maintain normal metabolic balance by regulating protective enzyme system.

Abstract:In order to explore the light saturation point of blueberry (Vaccinium darrowixV. corymbosum) leaves in Wenzhou area, the light-response curves of electron transport rate and photosynthesis of blueberry cultivars ‘O’neal’ and ‘Misty’ under shading and full sunlight were fitted by four models, such as modified rectangular hyperbolic model (model I), rectangular hyperbola model (model Ⅱ), nonrectangular hyperbolic model (model Ⅲ) and exponential equation model (model IV). The results showed that the light response curves could be fitted well by the model I. The fitted values of light saturation point by model I were close to measure values, however, those fitted by model Ⅱ, model Ⅲ and model IV were lower than measure values. The light saturation points of ‘O’neal’ were 656.32-806.17 (full light) and 605.83-756.22 μmol m^-2s^-1(shading); and those of ‘Misty’ were 1 034.63-1 641.25 (full light) and 933.09-988.18 μmol m^-2s^-1(shading). In conclusion, the two blueberry cultivars were semi-heliophyte.

Abstract:In order to construct regeneration system from embryogenic callus of Anthurium andreanum, the tender leaves and petioles of 3 cultivars were used as explants, the effects of medium, plant growth regulator combination and illumination condition on embryogenic callus induction and plant regeneration were studied. The results showed that the optimum medium for embryogenic callus induction was modified MS₃+1.5 mg L^-1 2,4-D+0.5 mg L^-1 KT+4% sucrose+2% glucose+0.25% Phytagel. The embryogenic callus induction rate had obvious difference among cultivars and explants, showing in the order of ‘Pink Champion’ > ‘Robino’ > ‘Champion’, and leaves > petioles. The embryogenic callus induction rate of ‘Pink Champion’ leaves could reach up to 57.9%. The optimum medium for embryoid differentiation was 1/2 modified MS_a+2% sucrose+0.25% Phytagel. The embryoid differentiation rate derived from leaves of ‘Pink Champion’ could reach up to 31.6%, and had not significant differences cultured under light and dark. The survival could reach up to 100% after transplanted plantlets.

Abstract:In order to construct the rapid propagation system in vitro of Iris hexagona, the effects of medium and plant growth regulators on induction, proliferation and rooting of adventitious buds were studied by using young rhizome as explant. The results showed that the rhizome was sterilized for 13 min with 0.1% HgCl₂. The optimum medium for induction was MS+1.5 mg L^-1 6-BA+0.5 mg L^-1 NAA+30 g L^-1 sucrose+7.5 g L^-1 agar, and that for adventitious bud proliferation was MS+0.5 mg L^-1 6-BA+0.2 mg L^-1 NAA+0.3 mg L^-1 KT+30 g L^-1 sucrose+7.5 g L^-1 agar. The rooting rate of plantlets could reach up to 100% cultured on MS+1.5 mg L^-1 IBA+ 30 g L^-1 sucrose+7.5 g L^-1 agar. The survival of plantlets could reach up to 100% transplanted on humic soil or perlite+peat soil+vermiculite (1∶2∶1) as substrate.

Abstract:The lichen genus Coenogonium belongs to Coenogoniaceae, Ostropales, Ostropomycetidae, Lecano- romycetes, Ascomycota, Fungi, mainly distributed in tropics and subtropics. Ten species of Coenogonium were reported, including a species, C. disjunctum, as new record to China. Each species is described and discussed in detail, and the key to the genus and the photos of the new record species are presented. It is the first systematic study on Chinese Coenogonium, which can provide the basic information for the taxonomy of lichenized fungi.

Abstract:One new species, Dichroa fistulosa from Guangdong Province, China, is described and illustrated, which belongs to genus Dichroa, Hydrangeaceae. The species possesses hollow stems, which is unique in the genus. It resembles D. mollissima, but can be distinguished by its indumentum of leaves. It is also similar to D. philippinensis in gross appearance, but the shape and serration of leaves are quite different.

Abstract:In order to identify the original plants of traditional Chinese medicine Xihuangcao, the development of glandular trichomes on the leaves of Isodon lophanthoides var. lophanthoides was observed under light and electron microscopes. The results showed that there were two types of glandular trichomes, capitate and peltate glandular trichomes. The capitate glandular trichome was colorless and transparent, composed of one basal cell, one stalk cell and a head with one or two secretory cells, while the peltate glandular trhichome was red, composed of one or two basal cells, one stalk cell and a head with 4-8 secretory cells. The glandular trichomes were formed by second successive periclinal divisions of the initial cell, and because of the different meristematic state of stalk cell and apical cells, they developed into two types, capitate and peltate. The ultrastructural structure of glandular trichomes showed that plastid, golgi and the endoplasmic reticulum (RER) were the main secretory and transport organelles. When the peltate glandular trichomes matured, the subcuticular spaces were full of secretions. The characters of secretions might determine glandular trichomes color of I. lophanthoides var. lophanthoides.