【Objective】 Phytolith-occluded organic carbon (PhytOC) in forest ecosystem is a long-term (decades to millennia) mechanism for sequestrating soil organic carbon and has a vital significance to the global carbon sequestration. This study aims to estimate PhytOC stocks in the forest litter layer under China's subtropical forests. 【Method】 Liters of 5 common types of China's subtropical stands were studied, by collecting litters under forests and samples of 0~10 cm of topsoil. Furthermore, we calculated current litter biomass and determined soil density. The phytolith in the litter and soils were extracted by microwave digestion method,and the phytolith occluded carbon (PhytOC) content in the litter and soils were determined. 【Result】 The SiO₂ contents in the litter under different stands were in the following order: Moso bamboo (Phyllostachys edulis) (152.50 g·kg^-1) > broad leaved (13.96 g·kg^-1) > mixed coniferous and broad-leaved (12.55 g·kg^-1) > Chinese fir (Cunninghamia lanceolata) (7.62 g·kg^-1) > Masson pine (Pinus massoniana) (6.59 g·kg^-1).The phytolith contents in the litters under different forests were in the following order: Moso bamboo (180.20 g·kg^-1) > broad leaved (14.67 g·kg^-1) > mixed coniferous and broad-leaved (11.49 g·kg^-1) > Masson pine (11.36 g·kg^-1) > Chinese fir (5.58 g·kg^-1).The PhytOC contents in the litters under different stands were in the following order: Moso bamboo (4.34 g·kg^-1) > broad leaved (1.07 g·kg^-1) > mixed coniferous and broad-leaved (1.04 g·kg^-1) > Masson pine (0.67 g·kg^-1) > Chinese fir (0.50 g·kg^-1).The current litter biomass under 5 stand types was in the following order: broad leaved (3.20 kg·m^-2) > Masson pine (2.51kg·m^-2) > mixed coniferous and broad-leaved (2.38 kg·m^-2) > Chinese fir (1.88 kg·m^-2) > Moso bamboo (1.45 kg·m^-2). There were strong linear relationships between SiO₂ contents and phytolith contents in the litter under different forest types (R²= 0.940 5, P<0.01), phytolith contents and PhytOC contents in the litters under 5 stands (R²= 0.950 0,P<0.01) as well as occluded carbon contents in phytolith and PhytOC contents in the litters under 5 stand types (R²=0.701 8,P<0.01). The PhytOC stocks in the litter layer under forests of Moso bamboo, Chinese fir, Masson pine, broad leaved, and mixed coniferous and broad-leaved were 0.231, 0.034, 0.062, 0.125, and 0.090 tCO₂·hm^-2, respectively; the PhytOC stocks in 0~10 cm soil layer for Moso bamboo, Chinese fir, Masson pine, broad leaved, and mixed coniferous and broad-leaved stand were 0.492, 0.217, 0.352, 0.362, and 0.448 tCO₂·hm^-2, respectively; 【Conclusion】 The above-mentioned results showed that PhytOC was returned to the soil through litterfall of all the 5 stand types, and the largest PhytOC content in the litter as well as the largest PhytOC stock in litter and the soils was obtained from Moso bamboo. Assuming a litter biomass of 3.6 t·hm^-2a^-1 under Moso bamboo, the PhytOC sequestration rate in the litter layer under subtropical Moso bamboo forest in China's subtropics to be 0.057 tCO₂·hm^-2a^-1. The PhytOC stock data of the litters of 5 stand types provided a scientific basis for evaluation of PhytOC sequestration potentials in China's subtropical forest ecosystem.

【Objective】Growth potential and adaptability of 8 tree species to the harsh coastal environment were assessed in order to provide a reference for species selection for the construction of coastal shelterbelt forest. 【Method】Based on calorimetric measurement, factorial analysis and biomass buildup costs calculation, a comparative analysis was carried out on the strategy of energy use, growth potential and adaptability of each of the 8 species: Tamarix chinensis, Pinus thunbergii, Juniperus chinensis var. kaizuka, Fraxinus chinensis, Populus langfanggensis, Robinia hispida, Robinia pseudoacacia and Amorpha fruticosa, all grown in the coastal areas of Yantai. 【Result】The results showed that carbon content of Pinus thunbergii was the highest among the 8 species, while Tamarix chinensis was the lowest one. In contrast, Tamarix chinensis displayed the highest ash content and Pinus thunbergii the lowest. Pinus thunbergii and Juniperus chinensis showed the lowest nitrogen content and specific leaf area (SLA). Overall, the broad-leaved species were higher than the conifer species (Juniperus chinensis, Pinus thunbergii and Juniperus chinensis) in term of nitrogen content and SLA. The 8 species were divided into 3 groups in terms of ash free calorific values, and the order from the highest to the lowest was: Amorpha fruticosa, Robinia pseudoacacia, Robinia hispida, Pinus thunbergii and Juniperus chinensis as group 1, followed by Fraxinus chinensis and Populus langfanggensis as group 2 and T. chinensis as group 3. The area-based leaf construction costs (CC_area) of the 8 species from high to low is: R. hispida, A. fruticosa, R. pseudoacacia, Fraxinus chinensis, Populus langfanggensis, Tamarix chinensis, Pinus thunbergii and Juniperus chinensis. Correlation analysis showed that the ash free caloric values were very significantly positively correlated with carbon content (P<0.01), but very significantly negatively with ash content (P<0.01). The mass-based and area-based leaf construction costs both displayed a significant positive correlation with ash free calorific value and carbon content of the leaves (P<0.05), and a significantly negatively correlation with ash content (P<0.05). Furthermore, the area-based leaf construction cost showed a very significant negative correlation with nitrogen content and SLA (P <0.01). The results implies that the higher the proportion of carbon-containing compound in per unit of biomass, the lower the energy utilization efficiency and the higher the construction cost of building up the organism; while the higher ash content of the per unit biomass, the higher its energy efficiency and the lower the construction cost of building up. Meanwhile, the high nitrogen content in leaf is useful for the extension of leaf blade, and reduction of energy cost of construction of per unit area of the leaf. 【Conclusion】The comprehensive analysis of the calorific values, construction costs, specific leaf area, leaf ash/carbon and nitrogen content showed that the order for the growth competitiveness of the 8 species from high to low was: Robinia hispida, Amorpha fruticosa, Robinia pseudoacacia, Fraxinus chinensis, Populus langfanggensis, Tamarix chinensis, Pinus thunbergii, and Juniperus chinensis. The order of adaptability was: Tamarix chinensis, Pinus thunbergii, Juniperus chinensis, Fraxinus chinensis, Populus langfanggensis, Robinia hispida, Amorpha fruticosa and Robinia pseudoacacia. Tamarix chinensis should be taken as the front line plant, followed by Juniperus chinensis and Pinus thunbergii as the second line and Populus langfanggensis and Fraxinus chinensis as the third line in building up the coastal shelterbelt forest in Yantai region. Robinia pseudoacacia, Amorpha fruticosa and Robinia hispida should be planted behind the shelterbelt forest.

【Objective】 Microbial biomass carbon and nitrogen are an important "source"or "storeroom" for vegetation's requirements. They are important index of comprehensive evaluation of soil quality or fertility, and also sensitive early-warning indicators of soil ecosystem. This study aims at providing a scientific basis for converting farmland to forests and making decisions of forest management, and providing basis for further study on the C and N cycle and greenhouse gas emission at forestland. 【Method】 Seasonal dynamics of soil microbial biomass C and N and their contribution rates to soil nutrition pools in the Robinia pseudoacacia plantation land with tree ages of 10-year-old (RP10) and 43-year-old and naturally restored vegetation (NRV) were studied and compared to those of the farmland (FL) in the rocky mountain region of northern China. 【Results】 Microbial biomass C and N of all lands were sharply decreased with increasing soil depth. Seasonal dynamics of microbial biomass C and N contents were different significantly among all these lands. Soil microbial biomass C and N contents in 0-20 cm soil layer of FL, NRV, RP10 and RP43 were 251.94, 290.68, 150.66, 197.34 mg·kg^-1and 30.95, 46.46, 36.55, 45.27 mg·kg^-1, respectively. Soil microbial biomass C and N contents of NRV were much higher than that of other lands, 1.15, 1.93, 1.47 times, and 1.50, 1.27, 1.03 times of that in FL, RP10 and RP43, respectively. Microbial biomass C and N contents in 0-20 cm soil layer in RP43 were significantly higher than that of RP10 (1.31 and 1.24 times, respectively), indicating an increase with forest age. Seasonal dynamics of microbial biomass C-N ratio were different significantly among all lands, and the seasonal means of FL, NRV, RP10 and RP43 were 8.64, 6.26, 4.12 and 4.36, respectively. Soil microbial biomass C-N ratio of RP10 and RP43 were 0.48 and 0.50 times of that of FL, 0.66 and 0.70 times of NRV. The average contribution rates of soil microbial biomass C to soil organic carbon in FL, NRV, RP10 and RP43 were 1.88%,2.00%,1.54% and 1.24% in 0-20 cm soil layer, respectively, and the contribution rates of soil microbial biomass N to soil total nitrogen were 1.21%, 5.44%, 3.55% and 2.26%. A significantly positive correlation was found between soil microbial biomass C and N, and they were also significantly positively correlated with soil content of total N, organic matter and available potassium. In addition, soil microbial biomass C was also significantly positively correlated with soil ammonium-N content. Microbial biomass in soil, especially microbial biomass N, could be enhanced with increasing forest age of R. pseudoacacia to significantly elevate the soil biological fertility. Based on the comparison of soil microbial biomass C and N content and its contribution to soil N pools among the different lands, we can conclude that the naturally restored vegetation was more conducive to the recovery of soil microbial structure and function and could improve the biological activity of soil.

【Objective】 This study analyzed prediction accuracy of empirical best linear unbiased predictor(EBLUP), and effects of previous observations, age interval of observations and prediction span on prediction accuracy, based upon height data from 79 dominant trees of ponderosa pine in British Columbia, Canada. 【Method】We randomly selected 49 trees for fitting mixed-effects models and 30 trees for validating EBLUP. The base models were Richards, Logistic, and Korf. Fit statistics, AIC, BIC and Loglik, were used as evaluation criteria, and mean squared prediction error (MSPE) for analyzing effects of previous observations, age interval of observations and prediction span on prediction accuracy. We used the nlme function in R for model fitting, and the IML procedure in SAS for analyzing EBLUP prediction. To isolate the effect of one factor, we kept two other factors fixed.【Result】Fitting results showed the Logistic model had the best criteria among the three models of under investigation, indicating that it was the best-fitted model and was chosen for EBLUP prediction analysis. In the analysis of EBLUP prediction, we first introduced how to use EBLUP to predict random effects associated with a stand through a detailed example. Data from six trees, which deviated significantly from population-mean growth process, were used to present relationships among individual growth, population-mean growth, and adjusted values given by EBLUP. The results indicated that EBLUP prediction could fully follow individual growth process, given that there were multiple previous observations with long-enough age intervals. EBLUP analysis results also presented the number of previous observations, age interval of observations and prediction span significantly affected prediction accuracy. MSPE decreased as the number of previous observations increased, particularly when observations separated long enough in age so that they could give more efficient growth information. With respect to prediction span, prediction accuracy decreased as prediction span extended further away from the ages at which observations were obtained. 【Conclusion】 We concluded that EBLUP could be taken as the second stage of a two-stage fitting process. The first stage was used to estimate fixed model parameters, whereas the second stage to predict random effects associated with a stand on the basis of parameter estimators obtained in the first stage, and then to predict the height growth process of the stand.

【Objective】 Zinc finger proteins containing B-box (BZF) play important roles in regulating growth and development, and response to stresses in plants. Light stress has a significant impact on the growth and development of bamboo. Studies on protein sequence of BZF and expression profiles of BZF genes in Phyllostachys edulis and fluorescence parameters of transgenic plants with over expressed PeBZF 4 were conducted in order to reveal the response and regulatory mechanisms of BZF genes in bamboo under high intensity of light.【Method】Homologous gene alignment method was used to obtain bamboo BZF sequences from BambooGDB directly. The analysis and comparison of gene and protein, the prediction of acting elements, protein functional domains, hydrophilicity and hydrophobicity of proteins were performed using special software and online public platform. Real-time quantitative PCR was used for the analysis of gene expression in different tissues, and the changes of gene expression in leaf after the treatments of high intensity of light (1 200 μmol·m^-2s^-1) and darkness. The over expression vector of PeBZF 4 was constructed and transferred into Arabidopsis thaliana mediated by Agrobacterium tumefanciens. The phenotype of transgenic plants was observed directly and the fluorescence parameters were measured using IMAGING-PAM.【Result】Four homologue BZF genes were obtained from BambooGDB, and designed as PeBZF 1, PeBZF2, PeBZF3 and PeBZF4 respectively. Cis-acting element analysis showed that four PeBZFs all had light-responsive cis-acting regulatory elements and light responsive elements, but the light-responsive elements were different, including MNF1 and Sp1 in PeBZF 1, I-box, Sp1 and boxⅡin PeBZF 2, GT1-motif, MNF1 and Sp1 in PeBZF 3 and PeBZF 4. The analysis of protein structure showed that the proteins encoded by these genes all contained two B-box domains and CHC3H2 binding motif, indicating that they were B-box zinc finger proteins. Tissue specific expression indicated that the levels of these PeBZFs were obviously different in leaf, sheath, stem and root, among which the highest level of PeBZF 1 and PeBZF3 was found in leaf, and that of PeBZF 2 and PeBZF 4 was in sheath. All the expression of these PeBZFs were inhibited by high intensity of light (1 200 μmol·m^-2s^-1). The expression of PeBZF 2 and PeBZF3 showed a gradual downward trend with the extension of irradiation time, while that of PeBZF 1 and PeBZF4 raised slightly after 1 h treatment compared with 0.5 h treatment, followed by a rapid decline. The expression of PeBZF 1, PeBZF2 and PeBZF3 were significantly inhibited by darkness, while that of PeBZF 4 was significantly upregulated about 3.2 times of that in control. The actual photosynthetic efficiency (Y(Ⅱ)) and non-photochemical quenching (NPQ) of transgenic plants with over expressed PeBZF 4 were higher than those of wild type.【Conclusion】 There were four different B-box-type zinc finger protein genes expressed constitutively in Ph. edulis, the expression changes of 4 genes under high intensity of light and dark treatments suggested that they were involved in regulation of light response to stress. The values of Y (Ⅱ) and NPQ increased in transgenic plants with over expressed PeBZF 4, indicating that PeBZF 4 could improve the thermal dissipation capability and photochemical efficiency of transgenic plants. This result indicated that BZF might be associated with bamboo resistance to light stress.

【Objective】 Tung oil extracted from tung tree (Vernicia fordii) kernels has extremely high economic value. Tung oil contains α-eleostearic acid up to 70 percent. However, there are some difficulties in screening enzyme genes involved in α-eleostearic acid metabolism of tung tree due to very few studies being carried out on plant α-eleostearic acid metabolism pathway. Studies on metabolism pathway of α-linolenic acid, the isomers of α-eleostearic acid, were more in-depth and provide an example for analyses of metabolism pathway of α-eleostearic acid. This study was aimed to provide a theoretical basis for explaining the mechanism of α-eleostearic acid metabolism of tung tree through identifying α-linolenic acid metabolism pathway based on transcriptome data of tung tree kernels. It was also intended to largely accelerate the processes of genetic improvement and molecular breeding of tung tree through regulating gene expression profiles and developing molecular markers tightly linked to them. 【Method】 This study compared transcriptomes of tung tree kernels of 3 different oil synthesis stages using RNA-Seq technology and subsequently obtained a lot of differentially expressed Unigenes which can be classified into 128 metabolic pathways. Through GO classification and pathway enrichment analysis, the metabolism pathway of α-linolenic acid was identified and the expression profiles of related genes were analyzed. 【Result】 A total of 58 439 non-redundant Unigene with a 200-3 000 nucleotide-length were identified by RNA-Seq of tung tree kernel RNA of stages I-III. Accounting for 70.3 percentage of all non-redundant Unigenes, a total of 41 059 Unigene sequences could be matched to public database. Non-redundant Unigenes with different sequence length possessed different matching efficiency in alignments against sequences obtained from database. The longer the sequence was, the higher the matching efficiency would be. The matching efficiency of sequences with length greater than 2 000 bp was up to 98.28% whereas the matching efficiency of sequences with 500-1 000 bp and 100-500 bp length was decreased to 78.86% and 48.99%, respectively. Accounting for 0.47 percentages of all non-redundant Unigenes, a total of 105 Unigenes in 3 transcriptome data were enriched into α-linolenic acid metabolism pathway. Each pair-wise comparison of 3 transriptome data identified numbers of differentially expressed Unigenes and some of them were involved in α-linolenic acid metabolism pathway. Through alignment against KEGG database, 105 Unigene sequences were found to correspond to fourteen key enzyme genes involved in α-linolenic acid metabolism. These key enzyme genes were observed to have homologous genes in other species. Expression profiles showed that genes related to anabolism were generally up-regulated whereas genes related to catabolism were generally down-regulated during oil synthesis stage. 【Conclusion】 This study elucidated α-linolenic acid metabolism pathway of tung tree based on its kernel transcriptome data. Furthermore, key enzyme genes involved in α-linolenic acid metabolism were identified and their expression profiles were analyzed. The results of this study play important roles in enlightenment of the follow-up studies.

【Objective】The dust on the surface of the leaves of trees can reflect the around environmental pollution in a certain extent. With the increasing of the degree of atmospheric pollution, the harm of haze weather becomes more severe. Therefore, haze becomes a high-profile word in modern society. Haze is mainly formed by atmospheric particles floating and crowding in the air. Atmospheric particles fall on the leaf surfaces through dry or wet deposition. After that, the foliar dust formed. The foliar dust has an impact on the spectra reflection of the leaves of trees and the plant physiological ecology. In this paper, we explored the relationship between foliar dust contents and reflection spectra of Euonymus japonicas. The prevention control strategy of haze and the correct remote sensing inversion were also introduced.【Method】The leaves of Euonymus japonicus growth at the academy of forestry were used as raw materials. The collecting leaves were fresh-keeping and took to indoors quickly. The weight of the leaves before and after cleaning was tested using a 1/10 000 high precision electronic analytical balance. The differences of the weight are the weight of the foliar dust. The reflection spectrum of the leaves before and after cleaning was measured using a FieldSpec3 Portable NIR spectrometer produced by the company of ASD (Analytical Spectral Device) of USA. The differences of the reflection spectrum were compared and analyzed. The differences of leaf reflectance before and after cleaning, and the first derivative spectrum and red edge parameter characteristics were compared and analyzed. The differences of leaf spectral reflectance between different amounts of dust was also compared, The relation model between foliar dust content and leaf spectral reflectance was established.【Result】Spectral reflectance of leaves before and after cleaning the dust is different. In the range of 520-560 nm, the leaf reflectance of dust leaves was higher than that of clean leaves. While in the range of 760-850 nm, the leaf reflectance of dust leaves was less than that of clean leaves. The reflectance spectra of different foliar dust content is difference. The results suggest that the leaf spectral reflectance of Euonymus japonicus increased with the increasing of foliar dust content in visible band. However, the spectral reflectance decreased in near infrared region. No changes were found in red and yellow edge position, blue edge slope, and blue edge area. Compared with the clean leaves, the blue edge position of the dust leaves increased, the slope of yellow and red edge of the dust leaves decreased, the area of yellow and red edge of the dust leaves decreased. The R² value of prediction model of foliar dust content being built with red edge index is the largest (0.716). A certain relationship between foliar dust content and spectrum were existed.【Conclusion】The foliar dust increased the reflectance in visible light wave band, but decreased the reflectance at near infrared region. Certain correlation with leaves internal structure may exist. We can predict leaf surface dust content in a certain precision range by taking red edge index (SDr) as parameter. Simple ratio index is positively correlated with the content of foliar dust. The interference of spectrum detection by foliar dust has been preliminary quantitative discussed in this paper, which supplied a reference method for the future evaluation of foliar dust impact on the spectral reflectance and establish a modified model.

【Objective】 Urban greening trees are an important part of city greening. They purify the atmosphere by capturing the particulate matter, especially in the arid region cities which frequently suffer from dust storms. To reduce the impact of air pollution on people and the ecological environment of the cities, greening tree species which have strong dust retention ability and are suitable to arid conditions should be chosen to the urban greening. In this study, the dust retention ability of several common greening tree species in Aksu, Northwest China, was examined to find out the appropriate species. 【Methods】 Dust retention capacity of Platanus acerifolia, Populus alba var. pyramidalis, Ulmus densa, Fraxinus bungeana, and Salix babylonica were examined in this study; The dust was washed from the leaf surfaces and then weighed by Electronic Scales with an accuracy of 1μg (PTX-FA-210, Shanghai); The individual leaf area was measured by using a Laser Leaf Area Meter (CI-203, USA). Data were subjected to ANOVA with multiple comparisons by using SPSS (version 15.0, Software Co., USA), with the level of significance set at P<0.05. 【Results】 The maximum dust amount per unit leaf area differed among the five tree species and four functional areas, Pl. acerifolia (13.5±0.90 g·m^-2) > P. alba var. pyramidalis (12.1±0.87 g·m^-2) > U. densa (9.21±0.77 g·m^-2) > F. bungeana (7.11±0.43 g·m^-2) > S. babylonica (6.96±0.24 g/m²). In the different areas, the dust retention amount showed the descending order as follows, Industrial area (IA) > Transportation area (TA) > Residential area (RA) > Clean area (CA). Our results also showed that in any case ( IA,TA, RA, CA) the leaves at 1 m height retained the most dust and the leaves at 4 m height retained the least dust. Dust retention amount per plant of the five species also differed from each other, Pl. acerifolia (2.6 kg) > P. alba var. pyramidalis (1.7 kg) > F. bungeana (1.4 kg) > U. densa (0.4 kg) > S. babylonica (0.2 kg). 【Conclusions】 The industrial area (IA) was obviously the most severely dust-polluted area and the clean area was the least dust-polluted area. The greatest amount of dust in IA suggested that a greater amount of atmospheric pollutants emitted in the industrial area was locally generated. The smallest amount of dust in CA meant that the dust generated from the urban settings did not significantly affect the suburban area and also lent a support that the dust was not from large-scale atmospheric processes. The dust retention amount per leaf area and per plant of Pl. acerifolia and P. alba var. pyramidalis was higher than other examined species, thus they could be the priority in urban greening.

【Objective】 The "One Hundred Mile Azalea Forest" is the largest Rhododendron forest in China so far. Rhododendron agastum is an important protected species in the natural reserve "One Hundred Mile Azalea Forest" in Guizhou province, and has important ecological, scientific and cultural value. 【Method】 In field investigations in a forest of Rh. agastum, we found that there were a 1ot of litter but rare seedlings in the forest. Aiming at this problem, the effects of litter coverage on seedling regeneration of Rh. agastum communities were investigated in the One Hundred Mile Azalea Forest. The physical effects of litter coverage on seed germination and seedling growth were investigated in artificial simulation experiments in which different seed-sowing positions and different thicknesses of litter were applied. The biochemical effect of litter on seed germination was investigated by irrigating Rh. agastum seeds with litter leachates that were prepared by extraction of litter with diethyl ether, ethyl acetate, or n-butanol. 【Result】 Our results indicated that a thick litter layer suppressed seedling regeneration under natural conditions. The maximum seedling number was observed for litter less than 4 cm thick, and the number of seedlings gradually decreased with increased litter thickness. Sowing patterns and litter depth had a significant influence on the germination and seedling emergence. The seed germination rate of the control (without litter) was highest. Seeds sown on the litter surface had much lower germination rate or failed to germination. With the increase of litter thickness, the seed germination rate and seedling emergence rate decreased. No matter which kind of extract processing of three kinds of leachates, high concentrations inhibited seed germination, most notably for the diethyl ether fraction at the concentration of 12 mg·mL^-1. In this concentration, the germination rate and seedling height of Rh. agastum were decreased by 83.0% and 68.8%, respectively, with the embryo root growth completely stopped. These present results suggested that litter would have a physical and allelopathy effect. The litter appeared to act as a physical obstacle that prevented seedlings from rooting, and also impeded their growth. Furthermore, the litter led to low-light conditions that suppressed seed germination. Allelochemicals present in the litter also inhibited seed germination and seedling formation, which was evidenced by the fact that the litter extractions by using diethyl ether, ethyl acetate, and n-butanol contained 29, 16, and 4 allelochemicals, respectively by gas chromatography-mass spectrometry. 【Conclusion】 Thus, in Rhododendron forest tending management, reasonably cleaning up litters could promote the natural regeneration of Rh. agastum seedlings.

【Objective】 Honey peach (Prunus persica) fruits are highly perishable and rapidly lose quality after harvest. To explore an effective and safe storage technique and the preservation mechanism of the fruits, the effect of short-term N₂ treatment in combination with the modified atmosphere package (MAP) on overall quality, reactive oxygen species (ROS) metabolism and energy level in honey peach fruits (cv. Hujingmilu) during storage were investigated. 【Method】 Honey peach fruits were pretreated with pure N₂ for 6 h in glass jars, and packaged with 0.02 mm polyethylene film. Fruits without any treatment were used as control. All fruits were stored for 30 days at (1±1) ℃ and at 85% ~ 90% relative humidity and subjected to subsequent shelf life at (25±1) ℃. The decay index solidity, content of total soluble solids (TSS), ascorbic acid (Vc) and H₂O₂, superoxide anion (O₂^.-) production rate, activities of superoxide dismutase (SOD), catalase (CAT) and lipoxygenase (LOX), membrane permeability, malondialdehyde (MDA) content, contents of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) and energy charge (EC) were analyzed during the cold storage and shelf life. 【Result】Results indicated that contents of ATP and ADP in the control fruit decreased rapidly in 10 days of cold storage. Both SOD and CAT activity were observed to have a decrease during the whole cold storage and subsequent ripening of the control fruits while th O^·-₂ production rate, H₂O₂ content and MDA content increased significantly, leading to increase in membrane lipid peroxidation level and the damage degree of the membrane integrity. Compared with the control, short-term N₂ treatment in combination with MAP treatments effectively reduced decay index as evidence in showing that the decay index was only 55.56% of the control on day 4 of shelf life. Furthermore, the application of short-term N₂ treatment in combination with MAP effectively increased contents of ATP and ADP content and EC value, enhanced activities of CAT and SOD, delayed increases in both O^·-₂ production rate and H₂O₂ content and reduced MDA content and membrane permeability. Thus the treatments maintained the nutritional quality during low temperature storage and subsequent shelf life at room temperature. Correlation analysis showed that EC value was very significantly negatively correlated with O^·-₂ production rate (R²=0.971 2), H₂O₂ content (R²=0.974 6) and membrane permeability (R²=0.967 8). These results suggested that short-term N₂ treatment in combination with MAP treatments maintained high energy level and antioxidant levels, delayed the accumulation of ROS and alleviated the process of membrane lipid peroxidation, thereby delaying the ripening and senescence and maintaining the quality of honey peach. 【Conclusion】 Thus, the extension of shelf life of honey peach by short-term N₂ treatment in combination with MAP might be due to the improvement of energy status and antioxidant properties, and alleviation of membrane damage.

【Objective】Rhododendron hybridum is a famous ornamental species with flowers and tree crowns. The species has beautiful flowers with gorgeous flower colors, and long florescence, thus, it is a common urban afforestation tree species and indoor potted flowers. R. hybridum belongs to the weak light plant. In this study, we investigated the tolerance mechanism of Rhododendron to weak light to find the suitable light intensity for its growth, so as to provide theoretical basis for cultivation production. 【Method】A series of pot experiments were conducted to study the effects of weak light on physiological characteristics and leaves' submicroscopic structure of R. hybridum with different intensity treatments of low light (16 000,12 000,8 000,4 000 and 500 lx). 【Results】 The results indicated that in all of the treatments, the amount of leaves and blooms increased with the treatment time of days, but the amount was fewer with the decreased light intensity. The leaves gradually lost green and turned red, leaf margin became shrunk and withered with the decreased light intensity. R. hybridum grew best at the light intensity of 12 000 lx. The content of chlorophyll overall showed a rising trend when the light intensity was above 8000 lx, but gradually reduced when the light intensity was less than 8 000 lx. After 90 days, the chlorophyll contents under less than 8000 lx were significantly lower than that before the treatment(P<0.05). The photosynthetic rate of all treatments decreased significantly first, then rising, and declined subsequently, and was directly proportional to the light intensity by the end of the experiment. The malondialdehyde (MDA) contents increased fastest, and the activity of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) all decreased significantly over treatment time when the light intensity was 500 lx. From 4 000 lx to 8 000 lx light intensity, the MDA contents gradually increased but the soluble protein contents, CAT, POD and SOD activities didn't drop very much. The MDA contents increased slowest, and the decrease in soluble protein contents, CAT, POD and SOD activities was lowest from 12 000 to 16 000 lx light intensity. As the light intensity receded, the ultrastructure of R. hybridum leaves was steadily damaged: the number of chloroplasts decreased; the structure of chloroplast was seriously damaged gradually; the degree of cavity in chloroplasts increased; and the structure of cell organelles were also broken. When light was over 8 000 lx the cell structure was relatively normal. With the light intensity at 8 000 lx and lower, the chloroplast number decreased, thylakoid structure began to fuzzy, plastid balls and starch granules enlarged. Under 4 000 lx light intensity, part of chloroplast membrane was damaged, grana lamellas were blurring, plastid balls and starch granules obviously increased and enlarged. Under the light intensity of 500 lx, the cell membrane began to collapse, chloroplast membrane was heavily damaged, grana lamella disintegrated and only had a small amount of unordered lamella structure, the degree of inanition was serious, some cells even became empty cells.【Conclusion】 Based on the comprehensive analyses of various indexes, we draw a conclusion that R. hybridum is able to tolerate the low light intensity of 4 000 lx, however a suitable light intensity for R. hybridum growth is between 12 000-16 000 lx.

Defoliations by leaf/needle-feeding insects can cause significant losses of tree growth, biomass, and carbon storage. Potential effects of artificial defoliations at 0%, 25%, 50% and 75% levels to mimic the defoliator damages on biomass and chlorophyll contents of the poplar (Populus simonii×P. nigra) and larch (Larix gmelinii) seedlings at 5, 10, 15, 20 and 25 days after each treatment were investigated in the current study. Our results showed that there were no significant differences among the treatments in the plant height and root length (P > 0.05) for both tree species, except that 50% larch seedling needle removal resulted in a significant increase of root length (P < 0.05). Fresh and dry weights of the poplar seedling roots and whole seedling biomass in the three defoliation treatments were significantly lower than those of the untreated control, whereas the fresh and dry weights of the poplar seedling stems were not different among the treatments and the control. Fresh and dry weights of the larch seedling root, stem and whole seedling biomass in either defoliation group were significantly lower than those in the control group. Defoliations of poplar leaves resulted in different levels of increase in chlorophyll contents ("a" > "b"). Significant increase of chlorophyll contents already occurred at 5th day after the defoliation, with the 75% level being significantly higher than the control and the two lower levels (25% and 50%) for both chlorophyll "a" and "a"+"b" (P<0.05). At 10th day after the defoliation, chlorophyll "a" and "a"+"b" contents of 25% and 75% defoliations were significantly higher than that of the control, and were not different among the treatments. At 15th days after the defoliation, there were no differences in chlorophyll contents among the treatments and the control (P>0.05). At 20th day after the defoliation, chlorophyll "a", "b" and "a"+"b" contents of 50% defoliation were significantly lower than those of 25% defoliation and control; and slightly lower (but not significantly) than those of the 75% level. At 25th day after the defoliation, there were no differences in chlorophyll contents between each treatment and the control (P>0.05). Chlorophyll contents of the 50% defoliation level were significantly higher than those of 25% defoliation treatment, and slightly higher (but not significantly) than those of the 75% level.. In contrast to the poplar leaves, the chlorophyll "b" content was higher than chlorophyll "a" in the larch needles. The chlorophyll contents of larch needles at 25% and 75% defoliation levels showed a pattern of increase-decrease-increase; i.e. increased after the fifth day, decreased after the 10th day, and further decreased to a level similar to the control on the 15th day; its content levels increased again after the 20th day, and reached back to control level at 25th day after the treatments. The larch needle chlorophyll contents in the 50% defoliation group were lower than that of the control at 5th, 15th, and 20th days of the defoliations; the contents at 5th and 20th days were even lower than those in 25% and 75% defoliation groups; the contents at 10th day were not different significantly from the control and 25% and 75% defoliation groups. At 25th day after the 50% defoliation, chlorophyll contents in the larch needles were significantly higher than those of control and 25% and 75% defoliation groups. Our results showed that defoliations have significant impacts on carbon sequestration and photosynthetic physiological responses of both poplar and larch seedlings. Increasing the chlorophyll contents and improving the photosynthesis efficacy (per unit area) should compensate the decreases of carbon sequestration and biomass loss caused by the defoliations to some degrees, and polar seedlings seemed to show a stronger compensation ability than do the larch seedlings.

【Objective】 Guizhou province of China is one of the most typical karst regions in the world, at the same time, its fire disturbance is highly representative in the national forest fires. With the fragile karst environment plus severe forest fire disturbance, the fire prevention is particularly important and urgent in the Karst mountain regions of Guizhou province. Among the many fire prevention measures, the biological firebreak with its versatile, and long-term advantage, has attracted much attention of scholars and managers. The primary task of biological firebreak is to select the appropriate pyrophyte (the plants with good fire resistance). However, there is few study focus on the pyrophyte selection for karst mountain regions. On the other hand, with regard to pyrophyte selection, there is no uniform evaluation method up to now. It's necessary to select appropriate fire-resistant tree species which are also suitable for growing in karst mountain regions,【Method】we investigated 9 common tree species from karst mountain regions of northwest Guizhou. Based on the measurements of four leaf traits (benzene-alcohol extract content, ash content, ignition time and heat value) during fire prevention period, we used the Principal Component Analysis (PCA), combined with the Weighted-Technique for Order Preference by Similarity to an Ideal Solution (W-TOPSIS), to analyze the fire resistance. 【Result】The Viburnum foetidum var. ceanothoides' s and Castanea seguinii' s benzene-alcohol extractive content were 2.12 and 1.97 times higher than Murica nana' s; The ash content of M. nana'sand V. foetidum var. ceanothoides' were the highest, and Castanea seguinii's, Vaccinium pseudorobustum's and Ligustrum quihoui's were the lowest; The ignition time of L. quihoui, Castanea seguinii and Cotoneaster glaucophyllus var. glaucophyllus were the longest, and Puracantha fortuneana, Cunninghamia lanceolata and Rhododendron simsii were the shortest; The highest heat value were Castanea seguinii's, V. pseudorobustum's and Ligustrum quihoui's, followed by Cunninghamia lanceolata's, Cotoneaster glaucophyllus var. glaucophyllus's and Pyracantha fortuneana's, and Myrica nana's was the lowest; the indicator of greatest impact on fire resistance was ignition time, followed by extractive content, and then ash content, and, heat value was the smallest. The fire resistance order of the nine tree species was as follows: Myrica nana > Vaccinium pseudorobustum > Ligustrum quihoui > Cotoneaster glaucophyllus var. glaucophyllus > Castanea seguinii > Viburnum foetidum var. ceanothoides > Rhododendron simsii > Pyracantha fortuneana > Cunninghamia lanceolata. 【Conclusion】The result suggests that the integration of PCA and W-TOPSIS is suitable to assess the fire resistance of plants. The Myrica nana, Vaccinium pseudorobustum and Ligustrum quihoui are suitable to be planted in the study region as high fire-resistant tree species.

【Objective】The objective of this study is to evaluate the effect of three common methods on the DPPH radical scavenging activity and the rate of extraction of Litsea cubeba from the dry fruit. GC-MS analysis was carried out to perform the correlation between chemical composition and antioxidant activity of extracts.【Method】The antioxidant extracts of Litsea cubeba were obtained using liquid-liquid extraction (with ultrasonic assisted or magnetic assisted), SFE (CO₂ super-critical fluid extraction) and steam distillation extraction. The antioxidant activities of the extracts were measured by a free radical scavenging method using 1,1-diphenyl-2-picrylhydrazyl (DPPH). The GC-MS analysis of Litsea cubeba extracts were carried out with added 1,4-dibromobenzene which served as an internal standard. Peak area normalization was used to get the relative amount of main compounds in the respective extracts.【Result】Results demonstrate that the oil has significant antioxidant activity. The natural antioxidants are most effectively extracted by employing liquid–liquid extraction. The ultrasonic assisted liquid-liquid extraction exhibiting the highest oil yields of 26.34%, while magnetic agitation extraction showed highest antioxidant activity of 31.22 mg·mL^-1 (IC₅₀). The antioxidant activity of supercritical carbon dioxide extraction is 56.95 mg·mL^-1. Steam distillation showed lowest antioxidant activity of 64.95 mg·mL^-1. More than 122 compounds were identified by GC-MS analysis, including 12 kinds of fatty acids, 16 kinds of terpenes, 18 kinds of oxygenated terpenes, and other trace compounds including alkenes, alcohols, ketones, and alkanes from these extracts. GC-MS results show that the main components of the oil of Litsea cubeba from dried fruit are saturated fatty acid such as lauric acid, unsaturated fatty acids such as 9-Octadecenoic acid,9,12-Octadecadienoic acid and various terpenes and oxygenated terpenes such as α-pinene, β-pinene, limonene and citral. The fatty acid content of liquid-liquid extraction was 53.51%-66.61%, apparently higher than 17.64% of CO₂ supercritical fluid extraction (SFE) and 8.1% of steam distillation. Meanwhile, the steam distillation and SFE get abundant terpenes and oxygenated terpenes with 29.37% and 17.69%, respectively, which were apparently higher than liquid-liquid extraction with 6.49%-9.75%.【Conclusion】Liquid-liquid extraction with magnetic assisted extraction made a apparently positive affect on the antioxidant activity and the highest compounds of unsaturated fatty acid. Meanwhile, ultra-sonic assisted enhance the yield of oil. The oil extracted by steam distillation rich in terpene compounds and showed lower antioxidant activity (64.95 mg·mL^-1). In addition, HPLC grade citral exhibited the lowest antioxidant activity of IC₅₀ values of 74.33 mg·mL^-1. Thus, we can make a legitimate inference that antioxidant biological activity has been mainly attributed from fatty acid composition (in particular unsaturated fatty acid) rather than terpenes or oxygenated terpenes.

【Objective】In general, forest biomass shows a notable variation with slope variables, such as slope direction and slope position, etc., especially in the arid or semi-arid regions where the precipitation is limited and the redistribution of soil water is remarkable. Up to now, it is hard to conveniently and accurately measure the biomass for the whole slope. In this study, the emphasis was placed on quantification of the variation of forest biomass along the slope and its spatial pattern. And considering the scale effect, a method of assessing forest biomass of a whole slope up-scaling from a certain plot was derived, providing technical support for improving forest management and implementing intensive tending. 【Methods】 Methods To achieve the objectives, two representative slopes (a half-shady slope and a shady slope) covered by 27-year-old Larix principis-rupprechtii plantation were chosen in the small watershed of Diediegou within the semi-arid region of Liupan Mountains, Northwest China. On each slope, six plots each with an area of 20 m×20 m were set up along the slope topdown. The aboveground biomass was measured in mid-July of 2012. In the analysis, the "horizontal distance from the slope top" was used as a variable to quantify the variation of the forest biomass along the slope, and also the relationship between the biomass of a certain plot and the average of the whole slope. 【Results】The average aboveground biomass was 52.36 t·hm^-2 on the half-shady slope, 18.16% lower than that on the shady slope. The variation range was 42.50 t·hm^-2 on the half-shady slope, 14.71% higher than that on the shady slope, indicating a stronger impact on half-shady slope than on the shady slope. On the other hand, the variation trend of aboveground biomass was similar on both slopes, i.e., the aboveground biomass increases gradually from top down, reaches the maximum at the lower part (half-shady slope) or middle-lower part (shady slope), and thereafter decreases till the slope foot. This is probably due to the redistribution of soil water on the slope. Along the increasing horizontal distance (x, m) from the slope top, the moving averages of aboveground biomass over the slope section (y, t·hm^-2) increased gradually, with the relation of y=2×10^-7x³－7×10^-5x²+0.067 5x+30.838 (R²=0.995 7) for the half-shady slope, and y=－2×10^-7 x³－8×10^-5x²+0.121 9x+40.875 (R²= 0.999 8) for the shady slope. The moving average of aboveground biomass increased by 4.92 t·hm^-2 for each 100 m of horizontal distance from the top on the shady slope, 21.66% less than the average of 6.28 t·hm^-2 on the half-shady slope. This indicates that the spatial scale effect on the aboveground biomass exists on both slopes, however, it was weaker on the wetter shady slope than that on the half-shady slope. Furthermore, the ratios of aboveground biomass at a certain plot to the slope average (Y) varies nonlinearly along the relative distance of plots from slope top (X, m), which can be expressed as Y=－7×10^-8X³ +4×10^-5X²－2.2×10^-3X+0.643 2 (R²=0.932 1) for the half-shady slope, and Y=－1×10^-8X³+1×10^-6X²+3×10^-3X+0.620 4 (R²=0.973 9) for the shady slope. With these relations, the average of aboveground biomass for the whole slope can be up-scaled from plot at a certain slope position. 【Conclusion】In this semi-arid mountainous region, the variation of forest biomass along the slope positions follows a pattern of unimodal type, which is mainly due to the redistribution of soil water on the slope. And it is good to quantify the variation of forest biomass and its spatial scale effect by using the "horizontal distance from the slope top" as a spatial variable. Based on the work above, a convenient and accurate calculation of forest biomass of the whole slope was obtained.

【Objective】 The provenances trial was to select high productivity, good stability of Fraxinus mandshurica provenances for Dailing, Lushuihe and Maoershan where the trials were established and adjacent areas. 【Method】20 provenances of F. mandshurica were used to study the phenotypic variation in tree height (H), diameter at breast height (DBH) and volume (V) at the age of 14 by analysis of variance and multiple comparisons for single site and three sites. Stability of performance was assessed with regression coefficients (b_i) of the joint regression analysis of Eberhart & Russell. Finally, geographic variation was analyzed with trend surface. 【Result】 1) The results showed that there were statistically significant (P<0.01) differences in H, DBH, and V among different sites and provenances, and also significant in site× provenance interaction. At Lushuihe site, the top provenances were Hailin (7.55 m), Dailing (7.34 m) and Lushuihe(7.05 m) in terms of H, Hailin (6.13 cm) and Lushuihe (5.47 cm) in terms of DBH, and Hailin (14 909 cm³) in terms of V. In terms of H(7.62 m), DBH(6.79 cm) and V(16 747 cm³) together, Wuchang was selected at Maoershan site. Xinglong (5.67 m), Linjiang (5.65 m) and Dongfanghong (5.61 m) were selected in terms of H, Linjiang selected in terms of DBH(5.07 cm) and V(7 984 cm³) at Dailing site. For all three sites, provenance Wuchang was selected in terms of H(6.35 m), Linjiang in terms of DBH(5.35 cm), Hailin(10 546 cm³), Wuchang(9 857 cm³) and Linjiang(9 818 cm³) in terms of V. 2) The stability analysis showed the provenances of Youhao, Linjiang, Xifeng, Dailing, Wangqing and Tangwanghe had an average stability, the provenances of Xinglong, Lushuihe, Hengren, Hailin, Wandianzi, Suiling and Sanchazi had a high stability, the provenances of Huinan, Maoershan, Fangzheng, Dongfanghong, Zhanhe, Huanan and Wuchang had a low stability. 3) Geographic variation analysis showed that the effect of latitude was greater than that of longitude on the growth of F. mandshurica, the volume of the provenances along the direction from northwest to southeast was larger than the others. 【Conclusion】It was found that the selection at 14-year-old was closer to the selection at 6-year-old than to the selection at 2-year-old, indicating that provenances selection was not stable if it was made too early. The results provide a useful basis for germplasm management and genetic improvement of F. mandshurica.

【Objective】 Camellia oleifera is one of the four famous woody plants for edible oil in China. Camellia oil is a high quality and edible oil, mostly composed of unsaturated fatty acids (UFA), such as oleic acid and linoleic acid, and the average UFA content in Camellia oil is above 90%. But oil content of oil-tea seeds is low and vulnerable to adverse environmental conditions, restricting rapid development of the Camellia oil industry. Cloned pivotal genes from C. oleifera can be used as a biotechnological alternative for improving the molecular breeding of C. oleifera. Malonyl-CoA:ACP transacylase is one part of the fatty acid synthase (FAS Ⅱ) complex, which is responsible for transferring the malonyl group from malonyl-CoA to the holo-acyl carrier protein (ACP). Malonyl-ACP, the product of this enzymatic reaction, is the key building block for de novo fatty acid biosynthesis.【Method】 Seeds of the variety C. oleifera 'Huashuo' were used for RNA extraction, and a full-length cDNA of malonyl-CoA:ACP transacylase gene in seeds was cloned using RACE technique. Transcriptome data and expression profiles of C. oleifera seeds were used for bioinformatics analysis of the gene. Normal techniques of digestion and connection was used to construct prokaryotic expression vector, and the α-ketoglutarate dehydrogenase(KDH)-coupled assay system was used to detect the enzymatic activity of the expressed product.【Result】The cDNA of CoMCAT was 1 867 bp with an open reading frame of 1 131 bp encoding 376 amino acids. It was named as CoMCAT (GenBank accession number: KJ910337). Sequence analysis showed that the protein encoded by CoMCAT had a chloroplast transit peptide of 58 amino acids and contained two highly conserved motifs of 'GQGXQ' and 'GXSXG' which were respectively located on malonyl-CoA binding site and ACP binding site. The BL21 (DE3) bacteria harboring pET30a-CoMCAT was induced to express the recombinant protein which was about 40 kDa. The enzymatic activity of the recombinant CoMCAT was 2.384 U·μg^-1 under the optimum condition at 30 ℃ with pH 7.0.【Conclusion】 The molecular cloning of the CoMCAT gene and its bioinformatics analysis, and expression characteristics in prokaryotic cells are first reported study of C. oleifera seeds. The results not only enriches the C. oleifera gene bank of MCATs, but lays an essential foundation for further study of the gene function and molecular genetic breeding in C. oleifera.

【Objective】The high rooting efficiency of Norway spruce cuttings has important significance on promoting its superior clones breeding. The change of rooting characters, endogenous hormones and phenolics content in the rooting process of Norway spruce cuttings were studied in order to explore the effect of different endogenous hormone and polyphenols in cuttings on rooting and provide scientific theory basis for mechanism research of Norway spruce cutting propagation. 【Method】 In the present study, Norway spruce shoot cuttings from mixed clones of 5-year-old trees were taken as the experimental material, whose callus formation and root development were investigated after cutting for 30, 40, 50, 55, 60, 65, 70, 75, and 70 d; as well as cuttings needles (after 0, 37, 45, 67, and 72 d) and cuttings base or basal callus (after cutting for 45, 67, and 72 d) were analysised endogenous hormones and polyphenols content. 【Result】The results showed that 55% shoot cuttings had formed callus in 30 d, which had finished in 50 d after planting. The period of 50~75 d after planting was fastigium of callus differentiation and adventitious root information, the rooting percentage was 90%, the average number of root was 10.7. After which, the number of root remain the same, but the root was kept growing and the index of root effect was continue rising. The content of indoleacetic acid (IAA),zeatin /gibberellin (ZT/GA₃) reduced at 37 d after planting, 28.79% and 52.35% respectively. whereas, the value of gibberellin (GA₃),ZT/IAA,GA₃/IAA increased, 55.02%, 32.78% and 67.97% respectively. During the period of callus formation (37~45 d), IAA and GA₃ reduced 25.75% and 40.91% respectively; ZT/GA₃,ZT/IAA and GA₃/IAA increased, 39.32%,23.75% and 20.41% respectively. In the rooting induced period (45 ~67 d), the value of IAA,ZT/GA₃ increased, IAA increased from 61.7 to 79.8 ng·100 g^-1. while, the value of GA₃, ZT/IAA and GA₃/IAA reduced 16.27%, 24.86% and 35.26% respectively. The level of ZT was about 80 ng·100 g^-1 until 67 d after planting, which was decreased to 55.6 ng·100 g^-1 at 72 d. p-hydroxybenzoic acid (PHBA) level showed elevatory trend before 37 d, increased from 2.23 to 7.19 ng·100 g^-1, which showed decrease trend after callus formation and reduced to 4.16 ng·100 g^-1. Catechin (CA) and total phenolic acid (TPA) level both showed decrease trend in the rooting process. The change trend of endogenous hormones and polyphenol compounds in needles were the same as those in cutting base phloem. Endogenous hormones and polyphenols produced in young leaves and buds and transported to stem base and other parts. Therefore the content of endogenous hormones and polyphenol compounds in needles were much higher than that in cutting base phloem. Especailly for the level of IAA at 67 d, IAA level of needles (79.8 ng·100 g^-1) was 4.58~7.52 times higher than that of stem base (17.4 ng·100 g^-1). 【Conclusion】 In rooting process of shoot cuttings in Norway spruce, endogenous hormones and polyphenol jointly promoted callus differentiation and adventitious roots formation. The IAA level increased and GA₃, ZT, and polyphenols decreased during the adventitious root formation period. Endogenous IAA was the main endogenous hormone for promoting adventitious root formation, endogenous GA₃, ZT and polyphenol inhibited of adventitious root formation.

Waterlogging stress, one of the most important abiotic stresses, has induced a huge losses of poplar woody products in plain river network area of China. In order to elucidate flood-tolerance mechanism of poplar, two poplar species Populus deltoides ‘Lux’ ex I-69/55 (flood-tolerant) and P. simonii (flood-susceptible) were adopted as the materials to investigate influences of waterlogging stress on cell structure of primary roots. The flooding treatment was conducted on seedlings of the two species with height of 90-100 cm for 14 days, followed by 3 days drainage and recovery. During the study, phenotype of all the seedlings was observed every day, and root segmentsat 2.0-3.5 cm from the root tip of fine roots of the two species were sampled on day 0,1,3,7 and 14 of waterlogging stress. Responses of anatomy and ultrastructure of these roots to waterlogging stress were investigated by using methods of paraffin section and transmission electron microscope. Results showed: 1) Decreased stem growth, retarded leaf initiation and development, chlorosis and abscission of leaves, as well as development of hypertrophied lenticels all occurred in both of the two species under flooding treatment. With the waterlogging stress prolonged, most hypertrophied lenticels of P. simonii turned brown and became rotten, whereas they maintained normal fine in P. deltoides ‘Lux’ ex I-69/55. At the end of the study, survival rate of the latter were five times that of the former. 2) Waterlogging stress induced formation of aerenchyma in the primary root of the two species. Comparing to P. simonii, P. deltoides ‘Lux’ ex I-69/55 formed its aerenchyma slower. On the 3^rd day of waterlogging stress, some cortical cells began to collapse and formed few irregular small cavities in roots of P. simonii. After flooded for seven days, more serious collapse, continuing increase and enlargement of cavities, as well as loose structure were observed in cortical cells of root of P. simonii. Whereas, in P. deltoides ‘Lux’ ex I-69/55, the cortical cells displayed only slight collapse and few irregular small cavities on the 7^th day of waterlogging stress. Till day 14 of flooding treatment, much more cortical cells collapsed and fused into numerous irregular big cavities in P. simonii, which resulted in separation between cortical cells and pericycle cells. However, the structare in P. deltoides ‘Lux’ ex I-69/55 still maintained the relative integrity. 3) After flooded for three days, obvious plasmolysis occurred in cortical cells of root of P. simonii, accompanied with destruction and decrease of mitochondria, endoplasmic reticulum and Golgi apparatus, as well as disappearance of starch grain and increase of osmophores. On the 7^th day of flooding treatment, P. simonii displayed more serious plasmolysis and severe destruction in mitochondria and other organelles in root cortical cells. Whereas, normal cortical cells and numerous organelles were still observed in root of P. deltoides ‘Lux’ ex I-69/55 root, except for slight plasmolysis. By day 14 of waterlogging stress, cracked cell wall, as well as seriously destroyed and decreased mitochondria were observed in cortical cells of root of P. simonii roots, and nucleus and other organelles were not found. Whereas, P. deltoides ‘Lux’ ex I-69/55 still had complete cell structure and numerous organelles, especially mitochondria. These results indicated that normal hypertrophied lenticels, fine aerenchyma, as well as numerous structural stable mitochondria played a vital role for poplar under waterlogging stress.

【Objective】 Dendrolimus punctatus is the most serious pest of coniferous forest in China, and it mainly damages Masson pine (Pinus massoniana), a dominant and local native tree species that is widely distributed in south China. It was found that the outbreak of D. punctatus is regular, and according to different outbreak frequencies of D. punctatus, the Masson pine forest were differentiate into non-outbreak area, occasional outbreak area, and frequent outbreak area. However, the function of physiological characters of Masson pine from different area during D. punctatus outbreak was unclear. Plant volatiles are important byproduct of trees and can mediate many important ecological processes. 【Method】 To test the needle volatile emission characters of Masson pine at different area, and explore the correlations between needle volatile emission and D. punctatus out break frequency, we selected three classical D. punctatus outbreak area, non-outbreak area in Baiyun tree farm, occasional outbreak area in QingShan tree farm, and frequent outbreak area in Shaoping tree farm, to identify and compare the composition of their needle volatiles. All these tree farms are located at Pingxiang City, Guangxi Province, China. 【Resuts】 Our results indicated that the volatiles of Masson pine needles are mainly composed of S-α-pinene, R-α-pinene, myrcene, R-β-Pinene, S-β-pinene, (+)-3-carene, α-terpinene, (+)-limonene, (-)-limonene, γ-terpinene. However, the component ratio of these volatiles from non-outbreak area in Bai Yun tree farm, occasional outbreak area in Qing Shan tree farm, and frequent outbreak area in Shao Ping tree farm are significantly different. According to the emission characters, these volatiles are distinguished into four types. The first type includes R-α-pinene and myrcene, whose emission quantities are negatively correlated to the outbreak frequencies of D. punctatus; the second type includes S-β-pinene, γ-terpinene, and (+)-3-carene, and reverse to the first type, the emission quantities of these volatiles are positively correlated to the outbreak frequencies of D. punctatus; the third type includes R-β-Pinene and (+)-limonene, whose emission quantities are significantly different among different areas, but not correlated to the outbreak frequencies of D. punctatus; the last type, including S-α-pinene, (-)-limonene, and α-terpinene didn't show significant differences among different areas. 【Conclution】 Combining our results with previous researches about behavior response of D. punctatus to different pine needles volatiles, we deduced that the compositions of pine needle volatile chemicals may influence the outbreak of D. punctatus. Furthermore, natural enemies are important controlling factors of Dendrolimus, the attractive effect of pine needle volatiles may be different among different areas, we mean that the volatile mixtures from non-outbreak area in Bai Yun tree farm and occasional outbreak area in Qingshan tree farm may attract more natural enemies of D. punctatus, and then influence the outbreak of D. punctatus. These results provided solid bases for further usages of plant volatiles to repel D. punctatus or attract their natural enemies.

Cultivar ‘Liaofu 1’ was breeded by seedling breeding and clone selection. Its parent is Hippophae rhamnoides. Mongolica ‘Chuyi’ that was introduced from Russia. ‘Liaofu 1’ has no or few thorns, the 100-berry weight is above 60 g, the average stem fruit yield ranges from 2 to 4 kg at full fruit stage, and the fruit yield per unit area can reach to 6 000 kg/hm².