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Variation Characteristics of Secondary Vascular Bundles in Pinus massoniana
YANG Chao, FAN Fu-hua, XU Gang
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Objective To reveal the changes of cellular structure, composition and function of secondary vascular tissue in Pinus massoniana during development. Methods The change of morphology, structure, lignin and cellulose in the vascular tissue of P. massoniana were studied by histochemical analysis and cell segregation. Results The vascular cambium gradually enriched cellulose when it differentiated into new phloem and xylem. During the development of phloem, the sieve cells were deformed and lignified, and the proportion of cellulose in phloem decreased. During the development of xylem tracheids from early wood to late wood, the diameter of striated pores decreased, the number of striated pores decreased, the lignification degree of secondary wall increased, the cell lumen area decreased, the proportion of cellulose content decreased, and the choroidal and radial walls thickened. Conclusion The cellular composition and structure of secondary vascular tissues change regularly with development. The intracellular and intercellular transport capacity of xylem cells decrease, while the mechanical strength increases. The secondary phloem lost its ability to transport and its mechanical strength increases.
Effects of Human Intervention on Soil Physical and Chemical Properties of Walnut Forest on Taihang Hillside
LI Xin, LIU Qian-yuan, GUO Wen-fang, WANG Jia-le, LIU Ya-nan, Li Han-cong, Chen Yan-mei
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Objective To explore the impact of human intervention on the physical and chemical properties of the soil of artificial economic forest on mountain slopes, and to provide scientific basis for forest soil restoration and sustainable management. Methods Based on the walnut forests with three intervention methods: unmanaged, clearing of shrubs and grasses, and clearing of shrubs and grasses and fertilizing on Taihang Mountains, the effects of the three interventions on the soil physical and chemical properties of the walnut forest were compared and analyzed through field investigation and laboratory experiments, and principal component analysis was used for comprehensive evaluation of soil quality. Results (1) The physical and chemical properties of soil in walnut forests with different human intervention were significantly different. Soil clay, silt, electrical conductivity, organic carbon, total nitrogen and total phosphorus in the unmanaged forests were the highest, while soil sand and water content were the lowest; The soil clay, silt, electrical conductivity, organic carbon and total nitrogen in the clearing shrubs and grasses were significantly lower than those in the unmanaged forests (p<0.05), while the soil sand and water content were significantly higher than those in the unmanaged forests (p<0.05); The soil clay, silt, conductivity, water content, total nitrogen, total phosphorus and total potassium in the cleared shrub and grass for fertilization were slightly higher than those in the cleared shrub and grass, and the soil sand, pH and organic carbon were slightly lower than those in the cleared shrub and grass. (2) There was a significant correlation between the physical and chemical properties of walnut forest soil in each intervention. There was a very significant negative correlation between soil clay and sand (p<0.01), a significant (p<0.05) or very significant (p<0.01) positive correlation between soil organic carbon and total nitrogen; and the other soil physical and chemical indicators showed different degrees of correlation changes in the internal soil layers of each intervention and drying. (3) There was a certain degree of variation in the physical and chemical properties of walnut forest soil under each intervention. The soil pH showed weak variability, the soil organic carbon and total nitrogen showed medium variability, and the rest of the soil physical and chemical indicators were in the dynamic changes of weak variability and medium variability between the soil layers within each intervention and intervention. (4) soil quality in the unmanaged forests was the best (2.120), followed by> clean shrub and grass fertilization (−0.820) and clean shrub and grass (−1.258)The soil quality in clean shrub and grass fertilization walnut forest was not improved significantly. Conclusion Human intervention significantly affects the physical and chemical properties of soil in walnut forest on Taihang hillside and causes differences in soil quality. Therefore, the regulation and management of human intervention should be paid attention to in the management of walnut forest.
The Variation of Stand Structure with Age and Its Hydrological Effects of Larch Plantation in Liupan Mountains
XU Xiao-qin, YU Peng-tao, WANG Yan-hui, XU Li-hong, YU Yi-peng, LIU Ze-bin
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Objective To study the change of stand structure with age and its hydrological influence, and provide a theoretical basis for forest vegetation construction and management in the semi-arid area, Liupan Mountains. Method The main plantation type -- Larix principis-rupprechtii (Larch) plantation was selected in Diediediegou small watershed in the semi-arid area, Liupan Mountains. Based on daily meteorological data from 1993—2002, both the coupled stand structure model and BROOK90, an ecohydrological model were applied to simulate the variation of stand structures (average tree height, diameter at breast height (DBH), canopy density and leaf area index (LAI)) with plantation age, and then its effects on each water balance component (interception, transpiration, soil evaporation and runoff) were obtained. Result The Larch plantation could be divided into rapid growth period (5~15 years old), slow growth period (15~40 years old) and stable period (over 40 years old) with the increase of age. During the rapid growth period, the average tree height, average DBH, canopy density and canopy LAI increased rapidly with the increase of age, with an average annual growth rate of 0.48 m·a−1, 0.54 cm·a−1, 0.03 and 0.19, respectively. During the slow growth period, the average stand tree height, DBH and canopy density increased slowly, while the LAI increased first and then decreased. But during the stable period, the stand structures did not change significantly. In the fast growth period, the average annual interception and transpiration increased rapidly with the increase of age, and the rate was 1.91 and 24.13 mm·a−1, respectively. Meanwhile, the average annual soil evaporation and water yield decreased rapidly with the increase of age, and the decrease rate was 10.58 and 14.88 mm·a−1, respectively. In the slow growth period, the change of average annual transpiration, soil evaporation and runoff with age slowed down, and tended to be stable when the age was 30 years. The average annual change rates were 0.62, −0.75 and −0.76 mm·a−1, respectively. Conclusion In the semi-arid area of Liupan Mountains, the stand structure of Larch plantations changes continuously when the stand age is less than 30 years, especially less than 15 years, which significantly affectes the eco-hydrological function. And when the stand age is over 30 years old, the stand structure is stable and the water balance components tend to be stable too, which indicates that it is no longer necessary to consider the influence of stand age in the integrated forest-water management.
Transcriptome Analysis and Gene Discovery of Abscisic Acid Signaling Pathway in Kandelia obovata under Low Temperature Stress
GUO Jin-min, YANG Sheng, LIU Xing, WANG Jin-wang, WANG Wen-qing, CHEN Qiu-xia
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Objective To understand the molecular mechanism of Kandelia obovata in response to low temperature stress and cultivate new varieties of cold resistance. Method Based on the annual container seedlings of 'Longgang' K. obovata, a cold-tolerant mangrove cultiva, the control group ( CK ) was treated at 15 oC for 12 h and the low temperature group ( LT ) was treated at −5 oC for 12 h. Illumina HiSeq sequencing platform was used for transcriptome sequencing, and the genes related to abscisic acid signaling pathway were discovered. Result The results showed that a total of 148 transcription factors were identified by transcriptome sequencing, which belonged to 25 transcription factor families. Among them, ERF, NAC, WRKY, bHLH, MYB, bZIP, HB-other and MYB-related families contained more genes, which were 17, 14, 12, 12, 10, 9, 6 and 6, respectively. A total of 1 330 differentially expressed genes ( DEGs ) were screened in the differential group, of which 698 ( 52.48% ) were up-regulated and 632 ( 47.52% ) were down-regulated. KEGG pathway enrichment analysis showed that DEGs were significantly enriched in plant hormone signal transduction, phenylpropanoid biosynthesis, galactose metabolism, photosynthesis-antenna protein, and alpha-Linolenic acid metabolism. Among the abscisic acid signaling pathways, KoPYL1, KoABF1, and KoABF2 were up-regulated and KoPP2C1 and KoABF3 were down-regulated, and the expression of these genes was consistent with the qRT-PCR validation results. Conclusion ERF, NAC, WRKY, bHLH, MYB, bZIP, HB-other and MYB-related play an important role in regulating the response of K. obovata to low temperature stress. Phytohormone signal transduction, phenylpropanoid biosynthesis, galactose metabolism, photosynthesis-antenna protein and alpha-Linolenic acid metabolism are important KEGG pathways in K. obovata in response to low temperature stress. KoPYL1, KoPP2C1, KoABF1, KoABF2 and KoABF3 genes in abscisic acid signaling pathway can be used as important candidate genes for future studies on the response of K. obovata to cold stress.
Relationship between Ammonia-Oxidizing Archaea Community Structure and Nitrate Nitrogen Content in Chinese Fir Plantations at Different Generations
CHEN Wen-wen, WANG Shu-zhen, JIANG Yu-jie, ZHOU Chui-fan
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Objective This article aims to analyze the changes of soil available nitrogen content in Chinese fir plantations at different generations, and explore the internal relationship between nitrate nitrogen and the structure and diversity of ammonia-oxidizing archaea community, which provides reference for the effective use of soil nitrogen of plantations and soil quality assessment of Chinese fir forest. Method Four Chinese fir plantations with different generations were selected in Nanping, Fujian Province. High-throughput sequencing technology was used to determine the amoA gene amplified by PCR. Mantel_r correlation analysis, random forest model and partial least squares path model were used to study the relationship between soil available nitrogen content, ammonia-oxidizing archaea community abundance and diversity in different generations. Result The content of nitrate nitrogen (NO3-N), microbial biomass nitrogen (MBN), and the enzyme activity significantly decreased with the increase of continuous cropping generations of Chinese fir. The abundance and diversity of ammonia-oxidizing archaea (AOA) community showed a decreasing trend. Soil available nitrogen content was closely related to ammonia-oxidizing archaea community and enzyme activity, and the abundance and diversity of ammonia oxidizing archaea community was the most important factor affecting nitrate nitrogen content. Conclusion With the increase of planting generation, the abundance and diversity of ammonia oxidizing archaea community decrease to a certain extent. Except for the fourth generation of soil urease and ammonia nitrogen oxygenase enzyme activity increased slightly, soil nitrogen cycle related enzyme activity shows a decreasing trend, resulting in a significant reduction in soil nitrate nitrogen content, which limits the effectiveness of soil nitrogen in continuous cropping Chinese fir plantations.
Effects of 8 Host Young Trees on Growth, Development and Nutritional Efficiency of Hyphantria cunea Larvae
Zhang Shu-man, Fang Jing, Zhao Jia-qi, Wang Kai, Ren Ying-jie, Meng Zhao-jun, Yan Shan-chun
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Objects To explore the adaptability of Hyphantria cunea to different host young trees, scientifically protect trees and prevent and control Hyphantria cunea. Methods Based on eight species of trees widely distributed and planted in Northeast China (Ulmus pumila, Juglans mandshurica, Salix matsudana, Betula platyphylla, Fraxinus mandshurica, Larix olgensis, Albizia kalkora, Tilia amurensis), the growth, development and nutritional effects of H. cunea larvae fed on leaves of different host young trees were measured. Results The survival rate of H. cunea larvae fed on U. pumila and J. mandshurica was the highest, followed by F. mandshurica, S. matsudana and T. amurensis; Feeding on L. olgensis was lower than A. kalkora. The larvae of H. cunea feeding on U. pumila and J. mandshurica had the highest values of weight, body length and head shell width, followed by F. mandshurica and T. amurensis; The feeding rate of A. kalkora was lower than B. platyphylla. The pupation rate and eclosion rate of H. cunea larvae fed on J. mandshurica, U. pumila and F. mandshurica were higher, and the development period was shorter, than T. amurensis; Feeding L. olgensis and A. kalkora could not pupate, and feeding B. platyphylla, A. kalkora and L. olgensis could not eclosion and had a long development period. H. cunea larvae fed the most on U. pumila, J. mandshurica and F. mandshurica, followed by T. amurensis and S. matsudana; The food utilization rate and food conversion rate of larvae feeding on U. pumila and J. mandshurica were at a high level, followed by T. amurensis and F. mandshurica; The larvae fed the lowest amount of A. kalkora and B. platyphylla, and their food utilization rate and food conversion rate were at the lowest level; The results of larval food consumption rate were contrary to their food utilization rate and food conversion rate. Conclusion U. pumila and J. mandshurica are more suitable for the growth and development of H. cunea larvae, followed by F. mandshurica and T. amurensis; However, L. olgensis and A. kalkora are not suitable for their growth; The results show that the H. cunea has different adaptability and nutritional utilization strategies to a variety of hosts.
The Gall Wasps on Common Fagaceae and Three New Record Species from China
PAN Ke-yu, WU Jian-jun, LONG Cheng-peng, QU Ai-jun, WANG Yi-ping
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Objective To understand the gall wasps on Fagaceae plants in China for providing the basis of collection rapid identification and forecast. Method We have conducted an investigation on 9 common Fagaceae with field survey, collecting and lab rearing. Result The result showed there were 15 species of the gall wasps belonging to 8 genera, including 03 new record species in China and 12 known speices. Conclusion The host, distribution range and gall characteristics of various species have been recorded in this paper. The photos of gall characteristics of 12 species have been provided, and the host plants of most gall wasps have been identified.
Analysis of Tannin of Chinese Gallnut by UHPLC– QTOF–MS Analysis of Tannin of Galla Chinensis by HPLC– QTOF–MS
NI Bing-bing, LIU Hong, YU Li-yang, ZHANG Guo-yun, HE Cai-yun, ZHANG Jian-guo
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Objective To develop an effective method for characterizing tannin of Chinese gallnut by ultra-performance liquid chromatography–quadrupole time of flight mass spectrometry (UHPLC–QTOF–MS), and analyze the fragmentation behavior of gallotannins. Methods High temperature and ultrasonic–assisted methods were implemented for extracting phenolic compounds from Chinese gallnut, and the fragmentation pathway of gollotannins were characterized by MS/MS spectrometry. Results A total of 20 compounds were identified, including 14 gallotannins, 2 gallagyl esters, 3 phenolic acids, and 1 flavanol. Gallotannins with molecular mass higher than 1500 Da were not identified when high temperature 121 ℃ was used as extract method, while they were successfully detected by the ultrasound extract method, including 1–O–galloyl–βD–glucose to 14–O–galloyl–βD–glucose. Under the conditions of ultrasonic power of 1 500 W and extraction temperature of 65 ℃, more gallotannin isomers were identified. The MS/MS spectrum showed that gallotannins were mainly decomposed by the loss of glucoside, gallic acid, galloyl, H2O and carboxyl. Conclusion In the study, UHPLC–QTOF–MS technology coupled with ultrasonic extraction methods have been proved to determine gallnut tannin comprehensively and efficiently. The identification of gallnut tannin and the analysis of their fragmentation mechanism can provide a reference for research on the chemical composition of other plants rich in tannin.
Selection of High Efficient Fungi for Litter Degradation in Firebreak Belt
Xu Ming
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Objective To screen and optimize the strain and apply it to the degradation of dead leaves of landscape tree species in forest firebreak belt for recycling of dead leaves and forest fire prevention. Method The highly degrading strains were screened out by the degradation methods of leaf strips of tree species in color bio-fireproof forest belt and the degradation weight loss methods. The highly degrading strains and their combinations were selected by the experimental analysis of the degradation weight loss effect of the highly degrading strains and their combinations. In addition, their degradation rules on the dead branches and leaves were analyzed. Result Through the degradation experiments of 11 strains on deciduous leaves and dead branches and leaves of 12 colorful landscape trees in the firebreak belt, Postia Placenta (Pp),Trichoderma Koningii (Tk1) and Polystictus versicolor (Pv) were found to have strong degradation ability and weight loss effect. The weight loss of Sassafras tsumu, Photinia × fraseri and Schima superba were 54.3% ± 2.3% and 62.1% ± 3.3% respectively. Conclusion Pp + Pv, Pv + Tk1 and Pp + Tk1 have significant degradation effect on the tree species in the forest firebreak belts, which can be widely used as in the forest firebreak belts in the south of Jiangsu Province.
Average Tree Height-Diameter Models of Cunninghamia lanceolata in China Based on Continuous Forest Inventory Plot Data
NIU Si-yuan, LIU Peng-ju, LEI Xiang-dong, REN Yi, GAO Ying
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Objective Based on the national permanent forest plots, the basic average tree height - diameter models of Cunninghamia lanceolate was established by province for predicting tree height . Methods There was a total of 23 239 samples distributed in 15 provinces in this study.. Eighteen candidate base growth equations were used to fit height-diameter relationship in each province. The coefficient of determination (R2), mean absolute error (MAE), mean relative error (MRE) and root mean square error (RMSE) combing with the residual plots were used for model evaluation. In addition, the 5-fold method was used to test the optimal model in each province. Result The best height-diameter model in each province was not the same. The best model for Chinese fir in Sichuan, Yunnan, Chongqing, Shanxi, Zhejiang, Jiangxi, Hunan and Guangxi was the Mitscherlich equation. For Jiangsu, Anhui, Henan and Fujian, the best model was the Hossfeld equation, And for Guangdong, Hubei and Guizhou, the best model was hyperbolic equation, Logistic equation and Gompertz equation, respectively. The R2 of the model ranged from 0.602 to 0.807, MAE ranged from 0.94 to 1.53 m, MRE ranged from −4.72 to −2.93%, RMSE ranged from 1.23 to 2.00 m, and MPE ranged from 0.50 to 2.77. These models performed well and had biological significance, which indicated that these models could be used as the basic height-diameter models of C. lanceolate plantation in each province Conclusion height-diameter models of C. lanceolate distributed in 15 provinces are developed in this study, which simulates well the average tree height of C. lanceolate in each province, and can be used as basic models of height-diameter for C. lanceolate plantation in each province in China.
Effects of Arbuscular Mycorrhizal Fungi Inoculation and Different Forms of Nitrogen Addition on Soil Nitrogen and Phosphorus Contents and Enzyme Stoichiometry in the Rhizosphere of Chinese Fir Seedlings
LEI Mei, GAN Zi-ying, TAN Shi-guang, SONG Xiu-ling, SHANG-GUAN Han-ting, QIU Qing-yan
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Objective To understand the influences of arbuscular mycorrhizal fungi (AMF) inoculation and different forms of nitrogen (N) addition on soil nitrogen (N) and phosphorus (P) nutrients, soil N and P enzyme activities and their enzyme stoichiometry in the rhizosphere of Chinese fir (Cunninghamia lanceolata) for providing theoretical basis of sustainable management of Chinese fir plantations. Method In the present study, a pot experiments were carried out to investigate the AMF inoculation (G. mosseae, Gm) and different forms of N (NH4 + -N, NO3-N) addition on soil N and P nutrients, related enzyme activities and their stoichiometry of one-year-old Chinese fir seedlings. Result The results showed that: (1) AMF inoculation increased soil available P content, but decreased the NO3-N, NH4 + -N, DON and total P content. Compared with NH4 + -N treatment, AMF under NO3-N treatment had more significant effect on soil N and P nutrients (P<0.05). (2) AMF inoculation and different forms of N addition increased the activities of soil acid phosphatase (AP), urease (URE), and N-acetyl-β-D glucosidase (NAG). Inoculation of AMF under NH4 + -N treatment was more conducive to improve urease activity, and inoculation of AMF under NO3-N treatment was more conducive to improve N-acetyl-β-D glucosidase activity; (3) AMF inoculation reduced the ratios of soil URE: AP, PRO: AP and NAG: AP (p<0.05), and the decrease of soil URE: AP, PRO: AP stoichiometry under NO3-N treatment was higher than that under NH4-N treatment.. Conclusion AMF inoculation can improve soil P availability, and increase the transfer of soil available N to the plants by increasing the activities of nitrogen and phosphorus-related enzyme in the soil and reducing the stoichiometry of nitrogen and phosphorus-related enzyme to maintain soil N and P balance. Moreover, the effects of NO3-N treatment on soil nitrogen and phosphorus balance is larger than that under NH4 + -N treatment.
Variation and Seasonal Difference of Corilagin Content in Leaves of Acer truncatum Bunge, Acer buergerianum Miq. and Acer paxii Franch.
SU Ya-jing, LU Yi-zeng, QIAO Qian, SUN Zhong-kui, WU Chong, YAN Yu, CHENG Tian-tian, ZHANG Lin, FENG Zhen
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Objective To determine the content of corilagin in leaves of Acer truncatum Bunge, A. buergerianum Miq. and A. paxii Franch. Methods The ultra-performance liquid chromatography (UPLC) were used. XBridge C18 (4.6 × 150 mm, 3.5 µm) was used as the chromatographic column, and 0.4% formic acid aqueous solution and methanol as the mobile phase with the flow rate of 0.3 mL·min−1, the column temperature of 25 ℃, the detection wavelength of 270 nm, and the injection volume of 2 μL. Results The leaves of A. truncatum Bunge, A. buergerianum Miq. and A. paxii Franch. contained corilagin. There were significant differences in the content of corilagin among different tree species. The content in A. buergerianum Miq. was the highest, followed by A. paxii Franch. and A. truncatum Bunge. There were also significant differences in the content of corilagin among different varities. Among the four varieties of A. truncatum Bunge, ‘Lvbaoshi’ reached the highest value of 0.607 9 mg·g−1, the average content in ‘Xingwang’ among the four cultivars of A. buergerianum Miq. was the highest, and ‘Qianlihong’ had the highest value (6.888 7 mg·g−1) in October, and the highest valuein A. paxii Franch. ‘Lulv’ was 2.664 0 mg·g−1. In addition, there was also a big difference in the content of corilagin at different harvest times. The highest values of A. truncatum Bunge and A. paxii Franch. mostly appeared in May and June, and the best harvesting time of A. buergerianum Miq. was in October. Conclusion This is the first time for revealing that there is corilagin in the leaves of A. truncatum Bunge, A. buergerianum Miq. and A. paxii Franch., among which A. buergerianum Miq. is more suitable as the raw material for extracting corilagin, and A. truncatum Bunge and A. paxii Franch. can be used as candidate resources.
Spatial Distribution Characteristics of Soil Soluble Nitrogen Component in Hippophae rhamnoides Plantation with Different Stand Ages in Loess Hilly Region
ZHAO Man-xing, MA Wen-quan, ZHANG Xia, MA Zhou, BAI Er-lei, NAN Guo-wei
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Objective To investigate the spatial distribution characteristics of soil soluble nitrogen component in Hippophae rhamnoides L. subsp. sinensis Rousi plantation with different stand ages in loess hilly region. Methods Based on the Hippophae rhamnoides plantation with three different stand ages of5-year-old, 15-year-old and 20-year-old were selected in Jinding Town of Zhidan County, soil samples were collected in 0-10 cm, 10-20 cm and 20-30 cm soil layers, and seasonal dynamic variation of the proportion of soil soluble nitrogen component were analyzed. The grassland was treated as control. Results With the extension of the recovery years, the content of soil soluble nitrogen components in the Hippophae rhamnoides plantations increased. For soil nitrate nitrogen and soluble organic nitrogen (SON), there were significant differences between Hippophae rhamnoides plantations in 20 years and 5 years, while there was no significant difference between grassland and Hippophae rhamnoides forests in 5 years. There was no significant difference in soil ammonium nitrogen among different restoration years. The soil nitrate nitrogen and SON showed the same trend, with 20-year-old>15-year-old> grassland>5-year-old. For the ammonium nitrogen, soluble organic nitrogen in forests with 15-year-old was the largest, followed by 20-year-old,5-year-old, and grassland, and the average content of ammonium nitrogen in the surface layer was the lowest. There was no significant difference in soil soluble nitrogen components among different soil layers. Soil nitrate nitrogen was the highest in summer and the lowest in winter or autumn. Ammonium nitrogen was the highest in summer or autumn, and the lowest in winter. SON was higher in spring and winter than in summer and autumn. The proportion of SON, nitrate nitrogen and ammonium nitrogen in total soluble nitrogen was 80.3%, 10.2% and 9.5% respectively. The proportion of SON in total soluble nitrogen of Hippophae rhamnoides forests with different years was higher in spring and winter than in summer and autumn, and most of nitrate nitrogen and ammonium nitrogen were higher in summer and autumn than in spring and winter. Conclusion In the loess hilly area of northern Shaanxi, Hippophae rhamnoides plantations can effectively improve soil soluble nitrogen components. With the increase of forest age, the soil nitrogen accumulation increases.
Genetic Analysis of the Fruit and Oil Related Traits on Hybrid Offspring of Nested Mating of Camellia oleifera
CHAI Jing-yu, WANG Kai-liang, YAO Xiao-hua, TENG Jian-hua, LIN Ping
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Objective To Select the optimal parent and parental combination for improving breeding efficiency and maximize genetic gain in oil-tea hybrid breeding. Method In this study, 11 fruit and oil related traits were detected in the intraspecific and interspecific hybrid progeny in nest design, including weight of single fruit, seed rate of fresh fruit, kernel rate of dry seeds, oil content of kernel and seven kinds of fatty acid content in the oil. The general combining ability (GCA) of female parent and special combining ability (SCA) of hybridized combination were analyzed. The genetic control modes for 11 traits were analyzed. Result There were highly significant differences in 11 traits among 12 families. These differences mainly caused by paternal effects at the level of P < 0.01, and only the differences of stearic acid and linoleic acid content were affected by maternal effects at the level of P < 0.05. The GCA and SCA of the parents were comprehensively analyzed. The intraspecific hybridization ‘Changlin No.4’ × ‘Changlin No.23’ showed better combining ability in weight of single fruit, seed rate of fresh fruit, kernel rate of dry seeds, oil content of kernel and oleic acid content in oil. The interspecific hybridization of Camellia oleifera and C. meiocarpa ‘Changlin No. 53’ × ‘Xiao No.3’ had a better performance on weight of single fruit, palmitic acid, linoleic acid and linolenic acid content. The cross of ‘Changlin No. 53’ × ‘Xiao No.2’ had advantages in seed rate of fresh fruit, kernel rate of dry seeds, oil content of kernel and oleic acid content. The analysis of genetic effect showed that stearic acid, oleic acid and linoleic acid content were mainly controlled by additive genetic effect, while the other eight traits were mainly influenced by non-additive genetic effect. The heritability of 11 economic traits of per plant was greater than that of families. The breeding strategy of selecting excellent individual plants within the full-sib families should be adopted in the cross breeding of C. oleifera. Conclusion The economic traits of C. oleifera are mainly controlled by inheritance, and less affected by environment. Weight of single fruit, seed rate of fresh fruit, kernel rate of dry seeds, oil content of kernel, palmitic acid, palmitoleic acid, linolenic acid and cis-11-eicosenoic acid content were mainly controlled by non-additive gene effect, and the influence of additive gene effect is relatively low. In interspecific hybridization, SCA evaluation of hybridized combination should be given priority. In this study, we explored the parental allocation and genetic effects of interspecific hybridization between C. oleifera and C. meiocarpa, which laid a theoretical foundation for guiding interspecific hybridization breeding of C.oleifera.
Response of Chestnut Quality of 'Yanshanzaofeng' to Climate Factors in Different Cultivation Areas
FAN Xiao-yun, GUO Su-juan, JIANG Xi-bing, LI Yan-hua
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Objective To explore the key climate factors affecting the quality of 'Yanshanzaofeng' chestnut in different cultivation areas and establish the key climate factors evaluation system of 'Yanshanzaofeng' cultivation for providing theoretical basis for the scientific planting and introduction of 'Yanshanzaofeng'. Methods Based on 'Yanshanzaofeng' planted in eight different growing areas, the correlation and regression analysis were carried out between nut quality indexes and climate factors, and the nonlinear regression equation between nut quality indexes and key climate factors was constructed. Results The results showed that the cross diameter (33.63 mm), longitudinal diameter (26.98 mm), fruit shape index (0.73) and single grain weight (10.86 g) of 'Yanshanzaofeng' in Jinhua cultivation area were higher than those in other cultivation areas. The soluble sugar content (19.01%) and amylopectin/amylose ratio (1.69) in qianxi cultivation area of Hebei province were higher than those in other areas. The key climate factors affecting the quality of 'Yanshanzaofeng' nuts were temperature, light and water, and the daily range of average temperature in growing season had the greatest influence on the quality of nuts. The nut quality of 'Yanshanzaofeng' was the best in the ecological area with a daily average temperature difference of 25.89℃ in the growing season. The optimal value of quality indexes were soluble sugar 25.63%, amylopectin/amylose ratio 1.93, protein 8.32%. Conclusion Climatic conditions such as longer sunshine duration, higher average temperature and greater diurnal range of average temperature in growing season are conducive to the formation of sweet and waxy quality of 'Yanshanzaofeng'.
Analysis of Complete Chloroplast Genome Sequences and Phylogenetic Evolution of Zanthoxylum armatum‘Jiuyeqing’
LIU Xia, SUN Chong, HUANG Qin-qin, LIU Hao-wen, Huang Feng-ting, CHEN Ze-xiong
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Objective To reveal the structural characteristics and phylogenetic relationships of the chloroplast genomes of Zanthoxylum armatum ‘Jiuyeqing’, and provide reference for identifying germplasm resources, breeding new varieties and the genetic analysis among varieties of the genus Zanthoxylum. Method The total DNA of Z. armatum ‘Jiuyeqing’ was extracted using a modified CTAB method. High-throughput sequencing was performed using the BGISeq-500 platform, the chloroplast genome was assembled by SPAdes v3.13.0 software, the whole chloroplast genome information of Z. armatum ‘Jiuyeqing’ was annotated by GeSeq software, and the structural characteristics, repetitive sequences, codon preference and phylogenetic relationship were analyzed. Result Z. armatum ‘Jiuyeqing’ was a typical tetrad structure with a full-length sequence of 158 558 bp, encoding 133 genes. 19 tandem repeats were detected, 49 long repeat sequences, 70 simple sequence repeat (SSR) were detected. A total of 26 398 codons (excluding stop codons) were detected in the protein-coding gene of the chloroplast genome of Z. armatum ‘Jiuyeqing’, and there was a strong A/T base preference at the third base of the codon. Conclusion The complete chloroplast genome sequences of Z. armatum 'Jiuyeqing' was firstly assembled for the study. The results of phylogenetic analysis show that the genus Zanthoxylum is a monophyletic group, and the Z. armatum 'Jiuyeqing' is closely related to Z. simulans. The results of the study enrich the genetic information of Zanthoxylum and improve important references for Zanthoxylum germplasm resource evaluation, molecular breeding, development of cpSSR molecular markers, and genetic diversity research.
Genome-wide Identification and Expression Analysis of BpAMT Gene Family in Betula platyphylla
Yang Hai-xin, Liu Xiao-ying, Zhan Ya-guang, Fan Gui-zhi
, Available online  
Abstract:
Objective To identify AMT gene family members in Betula platyphylla and analyze the expression pattern of AMT genes. Method Bioinformatics methods were used to identify the family genes and real-time fluorescence quantitative analysis of gene expression. Result 9 AMT genes were identified from the B.platyphylla genome and divided into two subfamilies, AMT1 and AMT2, named BpAMT1.1-1.4 and BpAMT2.1-2.5; These BpAMT proteins contained 384-522 amino acid residues with isoelectric points ranging from 4.61 to 8.16, and all of which were located on the plasma membrane and organelle membrane; The genes of BpAMT family were distributed on 5 chromosomes unevenly, and there were tandem duplication among the members. BpAMTs’ expression patterns had specificity in different tissues, showing a leaf>root>stem trend; At the same time, KNO3, NH4Cl, MeJA, GA3, ABA, CdCl2 and diurnal variation could affect the expression of BpAMT gene, and the response of members differed under different treatments. Conclusion 9 BpAMT genes are identified and divided into two subfamilies. BpAMT gene plays an important role in regulating nitrogen uptake, transport and in response to hormone signals or abiotic stress. These results lay a foundation for further analysis of the function of BpAMT gene in growth and resistance to stress in B.platyphylla.
Age-independent Dominant Height Growth Model for Pinus massoniana Plantation
ZHANG Ke-xin, LIU Xian-zhao, GUO Hong, LIU Dan, LEI Yuan-cai
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Abstract:
Objective An age-independent theoretical growth equation was constructed to predict the dominant height of Pinus massoniana plantation when the age was unknown or not an effective influence factor. Methods Based on the four theoretical growth equations of Hossfeld IV, Lundqvist-Kolf, Richards and Schumacher, an age-independent dominant height model of Pinus massoniana was constructed by using the difference form of hidden age factors, and the free parameters were expressed as a function of site index. Results Among the four basic theoretical growth models, the age-related dominant growth model of Pinus massoniana plantation established by Richards model performed the best. The fitting accuracy of age-independent models was higher than that of age-related models, and the age-independent dominant growth model of Pinus massoniana plantation established by Richards model and Korf model performed the best. When the site index was introduced to the model, the fitting accuracy of Hossfeld model improved most obviously, and when K was set as a variable parameter, the age-independent dominant high growth model was the best. Conclusion When the forest of different age or age is difficult to obtain, the theoretical growth model independent of age can predict the growth of dominant height. After the functional relationship between site index and free parameters is replaced in the model, the accuracy of the model is improved and the model can be better applied to predict stand growth.
Identification of MicroRNAs during Seed Germination and Its Response to PEG and NaCl Stresses
Wang Xiao-jing, Wang Tao, Yang Kai, Li Lu-bin
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Objective To identify microRNAs (miRNAs) and reveal its expressional pattern in seed coat rupture stage of Moso bamboo seeds (Phyllostachys edulis) under different drought and salt stresses. Methods Polyethylene glycol (PEG6000) and NaCl were used to simulate drought and salinity stress, respectively. Small RNA libraries were separately built for Moso bamboo seeds germinated under H2O, 10% PEG, 15% PEG, 50 mmol·L−1 NaCl and 100 mmol·L−1 NaCl, and the seeds were all sampled at seed coat rupture stage. High throughput sequencing and bioinformatics analysis were used to explore the expressional pattern of miRNA. Results A total of 246 known miRNAs and 262 novel mature miRNAs were identified in this study. The most abundant miRNAs in seed coat rupture stage of Moso bamboo was miR166, followed by miR159, miR6478, miR319, etc. According to miRNA target prediction, MIR396 family owned the largest number of target genes, and ph02gene13935 (GAMYB) could to be regulated by 28 miRNAs of MIR159, MIR319 or MIR396; A total of 181 differentially expressed miRNAs (DEmiRNA) were identified in six comparison groups; Compared with control group, in 10% PEG, 15% PEG, 50 mmol·L−1 NaCl and 100 mmol·L−1 NaCl treatments, phe-miR171e-5p, phe-miR3630-3p, phe-miR171e-5p and phe-miR159a were differentially expressed respectively with highest expressional level in known miRNAs; The target genes of DEmiRNA were significantly enriched in different GO and KEGG pathways; Ten DEmiRNAs were verified by qPCR, and the overall trend of qPCR results was consistent with the sequencing data. Conclusion In seed coat rupture stage of moso bamboo, there exhibit high accumulation of known miRNAs such as miR159, miR6478, miR319 in all control and four treatment groups, which may play a conservative regulatory role in Moso bamboo seed germination. Compared with the control group, phe-miR171e-5p, phe-miR3630-3p, phe-miR171e-5p and phe-miR159a 1 are differentially expressed in 10% PEG, 15% PEG, 50 mmol·L−1 NaCl and 100 mmol·L−1 NaCl, respectively, which can respond to PEG or NaCl stress during seed coat rupture stage of Moso bamboo.
Effects of PagWOX11/12a Gene on Stem Growth and Development of Populus alba × P. glandulosa
Wen Shuang-Shuang, Wang Liu-Qiang, Lu Meng-Zhu
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Objective To analyze the effect of PagWOX11/12a gene on the growth and development of poplar for further research on the regulation mechanism of this gene in woody plants. Method Bioinformatics methods and software were used to construct phylogenetic evolutionary tree, sequence alignment and biochemical characterization analysis. Tissue-specific expression patterns were analyzed by qRT-PCR. The phenotype of poplar after specifically suppressed the expression of PagWOX11/12a was analyzed by using transgenic plant 35S::PagWOX11/12a-SRDX (DR). Result PagWOX11/12a gene could encode a protein with 255 amino acids, which was expressed in different tissues of 84K. The phenotypic analysis of DR transgenic plants showed that inhibiting the expression of this gene could reduce the length of phloem cells, pith cells and xylem fiber cells, inhibit internode elongation, and significantly reduced plant height compared with non-transgenic 84K. Conclusion PagWOX11/12a gene participates in regulating the height growth of poplar by affecting the elongation of internodes. This study provides a reference for further revealing the regulatory mechanism of PagWOX11/12a gene involved in the growth and development of poplar.
Community composition and ecological functional analysis of the endophytic microorganisms in Eucommia ulmoides seeds
ZHANG Qing-Qing, DONG Chun-Bo, SHAO Qiu-Yu, LU Ying-Xia, DONG Xuan, LIANG Zong-Qi, HAN Yan-Feng
, Available online  
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Objective To reveal the microbial community composition and diversity in Eucommia ulmoides seeds and enrich the related microbial resources. Methods In this study, the diversity of endophytic microorganisms in E. ulmoides seeds was analyzed by traditional culture method and high-throughput sequencing technology, and functional annotated by FAPROTAX and FUNGuild database. Results A total of 40 fungi strains (3 phyla and 11 genera) were isolated from E. ulmoides seeds, and the dominant genus was Aspergillus (30%); 142 bacterial strains (1 phylum, 6 genera) were isolated, of which Solibacillus was the dominant genus (47.18%). Through high-throughput sequencing, 141 fungal OTUs were obtained belonging to 6 phylum and 101 genera; 442 bacterial OTUs were obtained belonging to 24 phylum and 313 genera. At the genus level, the dominant fungi were Apiotrichum (31.28%) and Debaryomyces (26.07%); The dominant bacterial genera were Pseudomonas (16.66%) and Lactobacillus (9.68%). The results of functional annotation showed that fungi mainly degraded organic matter, promoted the growth of host plants and the absorption of soil nutrients by host, improved soil microbial community structure and Pathogen community. The bacteria mainly consisted of chemoheterotrophic, heterotrophic, fermentation. and nitrogen fixation bacteria. Conclusion E. ulmoides seeds carry a variety of probiotics and potential phytopathogens, which have important effects on plant growth and development. In addition, a number of beneficial functional bacteria were isolated in this study, which will provide microbial resources for the subsequent artificial control of seed microbiome to enhance plant health.
Effects of light and N:P ratio on photosynthetic characteristics in seedlings of three typical tree species
XIANG Wang, CHENG Xiang-Rong, XU Hai-Dong, LIU Jiang-Wei
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Objective To study the response of photosynthetic characteristics of different ecological tree species to light and nutrient supply for providing a scientific basis for plantation cultivation. Method The seedlings of Quercus acutissima, Phoebe bournei, and Schima superba were used. This study included two light intensities (natural full light and 45% full light) and three N:P ratios (N:P=5, N:P=15, N:P=45). We measured the changes of Photosynthetic fluorescence parameters, and seedlings’ height, seedlings’ ground diameter to study the changes of plant photosynthetic characteristics in different environments, and analyze the relationship between seedling growth and photosynthetic parameters. Result (1) Compared with the full light treatment, the shading treatment decreased the light saturation point (LSP) and the maximum net photosynthetic rate (Pnmax) of Q. acutissima, and increased the Pnmax of S. superba. but had no significant effect on Pnmax of P. bournei. Under the two light treatments, ertilization increased the LSP and light compensation point (LCP) of P. bournei and S. superba, but the effects of fertilization on the shading LSP and LCP of Q. acutissima were less. (2) Shading significantly reduced the quantum yield of regulated energy dissipation of PSⅡ [Y(NPQ) ] of Q. acutissima, P. bournei and S. superba, and significantly increased the photosynthetic electron transport rate (ETR). Under the full light treatments, fertilization generally increased the effective quantum yield of PSⅡ [Y(II) ] and ETR of Q. acutissima, P. bournei and S. superba, but decreased Y(NPQ) . Under the shading treatments, fertilization significantly increased Y(II) and ETR of P. bournei, while Y(II) and ETR of Q. acutissima increased significantly when the N:P supply ratio was 5. Y(II) and ETR of S. superba increased significantly when the N:P supply ratio was 15. (3) Compared with the full light treatment, shading significantly increased the contents of chlorophyll a, chlorophyll b, chlorophyll a + b and carotenoid of Q. acutissima, P. bournei and S. superba. Under the two light treatments, fertilization significantly increased the photosynthetic pigment content of Q. acutissima, S. superba and P. bournei (only full light treatment). (4) Regardless of light or shading, fertilization generally increased the relative growth rates of seedling’s height and ground diameter of the three tree species, and there was a positive correlation between the growth and photosynthetic pigment. Conclusion Photosynthetic characteristics and growth of Q. acutissima, P. bournei and S. superba are affected by the interaction of light and fertilization. The effect of nitrogen and phosphorus fertilization on seedling growth under different light intensities depends on nitrogen and phosphorus supply ratio and tree species.
Transcriptome Analysis of Sonneratia apetala Root in Response to Salt Stress
LIANG Rui-tao, HAN Wei-dong, YANG Shao-xia, CHEN Bei-bei
, Available online  
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Objective To lay a molecular basis for functional verification experiment and genetic breeding of tree salinity tolerance, the genetic mechanisms was explored, and salt-related genes were identified for Sonneratia apetala Buch.-Ham. Method In this study, the root tissues were collected from a 1-year-old S. apetala treated with 500 mmol•L−1 NaCl for 0 (control group) and 10 d (treatment group). Then transcriptome sequencing and bioinformatics analysis was performed based on the three-generation full-length transcriptome dataset of S. apetala. Result (1) Compared with the control group, 14401 genes were differentially expressed after salt treatment, of which 7153 were up-regulated and 7248 were down-regulated. (2) GO analysis found that a total of 11068 differential genes were annotated in 47 GO items. (3) For KEGG enrichment analysis, a total of 6189 differential expression genes were enriched to 134 pathways, of which 14 were significantly enriched (P-value <0.01, Q-value <0.05). (4) Further functional annotation analysis of the differentially expressed genes revealed a total of 89 genes was potential salt-related candidate genes. Among these, 24, 22, 19, 10 and 14 genes encoded enzymes or functional proteins referred to antioxidation, osmotic adjustment substances, plant hormones, protein kinase and transcription factors, respectively. Conclusion Genes relating to active oxygen scavenging, osmotic regulation, plant hormones, protein kinases and transcription factors participate in the regulation of salt stress adaptation in S. apetala.
Response of Radial Growth of Larix griffithii to Temperature and Precipitation Fluctuation in Tibet Shergyla Mountain
YU De-shui, LU Jie, ZHANG Meng, ZHANG Xin-sheng
, Available online  
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Objective To study the response of radial growth of Larix griffithii Hoof to temperature and precipitation based on the annual ring core of L. griffithii collected in the Shergyla Mountain. Method The standard chronology was established by using the tree chronology method combined with TASP-Win and ARSTAN programs. Pearson and bootstrap calculation methods were used to analyze the correlation between ring width index and temperature and precipitation from 1961 to 2020. Result There were significant differences in radial growth before and after temperature fluctuation. Before the temperature fluctuation, the radial growth was positively correlated with the average temperature in January and June of the year and August of the previous year (P< 0.05). It was positively correlated with the average precipitation from September to October and December of the previous year and negatively correlated with that in August of the previous year. And It was significantly positively correlated with the relative humidity from January to December (P< 0.01). After the temperature fluctuation, the radial growth was negatively correlated with the average temperature from March to December and positively correlated with the precipitation in August and June of the previous year. Conclusion The climatic conditions in Southeast Tibet are extremely special. The uneven hydrothermal conditions caused by climate fluctuations is the main reason for the radial growth change of L griffithii. AThe short-term change of temperature in the non-growing season also has a significant indigenous impact on the radial growth of trees.
Investigation of Arbuscular mycorrhizal fungi (AMF) in several alpine oak understory forests in the subalpine zone of the Hengduan mountains
Li Hong-bo, Huang Yao-hua, Kang Ding-xu, Wu Jian-rong, Ma Huan-cheng, Chen Shi
, Available online  
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Objective To clarify the taxonomic status of AMF spores under the oak forest in the subalpine belt of the Hengduan Mountains. Method Six samples of alpine oak root enclosures and root systems were selected from different parts of the subalpine belt of the Hengduan Mountains, and AMF spores in the soil were selected by wet sieving sedimentation method. AMF-specific primers were used to amplify the 18SrRNA gene of the ITS region, which was identified by combining morphological and molecular biological means, and the phylogenetic relationships were constructed to infer their affinities. Result The results showed that AMF spores and root cloning consequences of alpine oak in Sichuan and Tibet were the genus Paraglomus. And the consequence of AMF cloning on the root surface and the AMF in soil of alpine oak in Shangri-La showed that AMF could exist in the inter-roots of alpine oak plants. These AMF were the genus Glomus. In addition, only one AMF was found in the root envelope and inter-root soil of alpine oak forest in different sampling sites, suggesting that AMF might have a symbiotic relationship with alpine oak. Aniline blue pigment staining result showed obvious arbuscular and vesicle structures in roots. In addition, the AMF spores under the Alpine oak forest differentiated during the evolution and were between the taxonomic status of Paraglomus and Glomus, and there were differences in AMF in Tibet, Sichuan and Shangri-La, Yunnan. Conclusion AMF generally exists in the pure understory root rhizosphere and inter-root soil of alpine oak in the subalpine belt of the Hengduan Mountains, which provides a theoretical reference for understanding the formation and evolution of AMF in the understory of alpine oak in the subalpine belt of the Hengduan Mountains
Physiological and transcriptomic analysis of Catalpa bungei seedlings in response to saline-alkali stresses
Gao Xin-qiang, Wang Xiao-yan, Jiao Wei, Wang Jing, Zheng Li-yue, Wang Dan-ning, Wang Xing-yun, Hou Li-jiang, Shang Zeng-zhen, Liu Yan-zhen
, Available online  
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Objective To explore the physiological and molecular mechanism of saline-alkali tolerance in Catalpa bungei, we studied the influence of different saline-alkali stress on the growth, photosynthetic and physiological indicators of C. bungei seedlings combing with transcriptome sequencing. Methods Pot experiment was used to study the different responses of biomass, photosynthetic and physiological indicators of C. bungei seedlings to different saline-alkali stress. Illumina high-throughput sequence technology was used to sequence the transcriptome, and the effect of saline-alkali stress on transcriptional level was analyzed by bioinformatics. Results Under different saline-alkali stress, the damage degree of leaves was Na2CO3>mixed saline-alkali>NaCl. Net growth of plant height and stem diameter, fresh weight and dry weight of overground part and root, biomass, root-shoot ratio were all significantly suppressed with increasing saline-alkali concentration. But the growth stress index decreased with increasing concentration. Contents of MDA and relative conductivity both rose to varying degrees with increasing concentration. SOD enzymatic activity, contents of soluble sugar and Pro, contents of total chlorophyll and photosynthetic rate increased firstly and decreased then with increasing concentration. Transcriptome sequencing generated a total of 60.4Gb of raw data. Finally, we obtained 55 793 Unigenes after assembling, of which 29 534 (52.93%) Unigeneswere annotated. Through differentially expressed genes (DEGs) analysis, 1 779, 2 835 and 4 059 DEGs were screened from three comparison groups (CK vs NaCl, CK vs Na2CO3 and CK vs mixed saline-alkali) respectively. GO functional enrichment analysis of these DEGs indicated that they were significantly enriched in integral component of membrane, intrinsic component of membrane, catalytic activity, isoprenoid metabolic and biosynthetic process, oxidoreductase activity. KEGG functional enrichment analysis of these DEGs indicated that they were significantly enriched in phenylpropanoid biosynthesis, starch and sucrose metabolism, plant hormone signal transduction, terpenoid backbone biosynthesis and arginine biosynthesis. Moreover, the most abundant differentially expressed transcription factors (TFs) were bHLH, ERF, MYB-related, NAC, C2H2, WRKY, MYB and bZIP families. Conclusion C. bungei mainly resists from saline-alkali stress by accumulating contents of soluble sugars and Pro, improving SOD enzymatic activity and photosynthesis, but all of them show the phenomenon of "low promotion and high suppression", indicating that it has a certain threshold value. C. bungei common responses to saline-alkali stress by regulating biological processes and metabolic pathways including component of membrane, catalytic activity, isoprenoid metabolic and biosynthetic process, phenylpropanoid biosynthesis, starch and sucrose metabolism, plant hormone signal transduction, and interacting with TFs. This study provides a scientific theoretical basis for deeply studying the physiological and molecular mechanisms of saline-alkali tolerance in C. bungei.
Investigation and Analysis on Host Species and Their Resistance Substances to Bacterial Bark Canker of Populus × euramericana
LI Yong, CHANG Ju-pu, GUO Li-min, SUN Shang, YANG Xu-qi, PIAO Chun-gen
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Objective To investigate and analyze the host species of bacterial canker of Populus × euramericana, the disease-resistant varieties and the possible disease-resistant substances they contain. Method The host of the pathogen and the resistant varieties were determined by field investigation and inoculation tests. The content of active substances in the bark of disease-resistant and susceptible varieties was analyzed by HPLC. Result The hosts of bacterial pathogen of P. × euramericana canker are P. deltoides, P. × euramericana and Salix matsudana. P. × euramericana cl. 'Zhonglin 46', P. deltoides cl. '2025', P. × euramericana cv. '2001', P. deltoides cl '313', P. deltoides 'Zhonghe-1' and P. deltoides '16-09' were highly susceptible to the bark canker disease; P. × euramericana 'Yukang 1' and P. deltoides '16-10' were highly resistant varieties, P. deltoides '131', P. deltoides '03-59', P. deltoides '02-212' and P. deltoides '03-34' were resistant varieties. Hybrid willows and Salix babylonica are resistant to the pathogen, and Salix × aureo-pendula can be affected, but do not cause serious disease. The HPLC analysis showed that the contents of catechol, benzoic acid and chlorogenic acid in the bark of resistant and highly susceptible poplar varieties were significantly different. The catechol and catechin increased when the hosts were infected by Lonsdalea populi. Conclusion In this study, the host species of bacterial canker of P. × euramericana are determined, and resistant and highly susceptible poplar varieties are screened. It is showed the catechol and catechin are important compound for host to defense the pathogen infection. The results will be helpful to the control of the bacterial disease of poplar.
Effects of Castanopsis kawakamii Forest Litter on Seed Germination of Pinus massoniana
JIA Mei-hua, WANG Zhe, LIU Jin-fu, JIN Meng-ran, HE Zhong-sheng, XING Cong, SHI You-wen, SHEN Cai-xia
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Objective To understand the effect of litter of Castanopsis kawakamii natural forest on the competitive intensity of regeneration of Pinus massoniana. Method The allelopathic effects of litter extract of natural forest with different concentration and decomposition degree on seed germination and radicle growth of P. massoniana were studied. Result (1) The main factor affecting the germination of P. massoniana seeds was the degree of litter decomposition. Compared with the blank control, the litter of undecomposed layer and fully decomposed layer had no significant effect on the germination of P. massoniana seeds; the semi-decomposed layer inhibited the germination rate and germination index and promoted the germination potential. (2) The main factors affecting the growth of radicle were the concentration and action time of litter extract, and the effect of undecomposed layer on the whole radicle growth period of P. massoniana seeds was enhanced with the decrease of concentration, but increased with the decrease of concentration, and the promoting effect was the strongest at the concentration of 1 ≤ 100, and the effect of semi-decomposition layer was promoted by low concentration and high concentration, and the intermediate concentration was inhibited by the undecomposed layer. The fully decomposition layer showed promoting effect as a whole, and the promoting effect decreased with the decrease of concentration. (3) Correspondence analysis showed that different decomposition degree-concentration had no significant effect on seed germination of P. massoniana, but had significant correlation with radicle growth. Conclusion The result proves that the litter extract of different decomposition degree has a weak promoting or inhibiting effect on the seed germination of P. massoniana, promotes the growth of radicle at low concentration, and promotes the regeneration of P. massoniana, which will intensify the interspecific competition in the forest, and lead to the inhibition of the natural regeneration of C. kawakamii.