Abstract:In order to reveal the function and stress response of CkPHB, we obtained a member of the leucine zipper protein transcription factor (HDZIP Ⅲ) family in Caragana korshinskii, CkPHB gene sequence by designing primer cloning according to transcriptome sequence, and carried out a series of bioinformatics analysis. The tissue localization of CkPHB protein in C. korshinskii leaves was observed by immunohistochemical staining. At the same time, the cloned CkPHB gene was transformed into Arabidopsis thaliana by Agrobacterium tumefaciensmediated method, and the positive overexpression plants were screened for functional verification. The results showed that: (1) the CkPHB gene, a member of the HDZIP Ⅲ family in C. korshinskii was successfully cloned. Its fulllength sequence is composed of 389 amino acids with a molecular weight of 42.83 kD. The protein encoded by CkPHB is hydrophobic and its secondary structure is mainly composed of αhelix. (2) Immunohistochemical analysis showed that CkPHB protein was localized in the xylem region of the vascular bundle of C. korshinskii leaves. (3) Through genetic transformation screening and identification, we finally obtained three T₃ generation plants of C. korshinskii CkPHB gene overexpression line in A. thaliana (CkPHBOE). Compared with wildtype A. thaliana (WT), the CkPHBOE strain of A. thaliana has more developed veins, larger vascular bundle volume and more xylem vessels. The realtime quantitative PCR analysis showed that five genes related to xylem development in CkPHBOE strain (XCP2, CesA7, CesA8, PAL4, F5H) were upregulated compared with WT. (4) The results of drought resistance experiments showed that the survival rate of CkPHBOE strain in A. thaliana was significantly improved under drought conditions. The physiological indexes further supported the above results, indicating that CkPHB overexpression significantly enhanced the drought resistance of transgenic A. thaliana. The research shows that A. thaliana overexpressing C. korshinskii CkPHB gene is more developed and its physiological indexes of resistance are significantly improved, thus enhancing drought resistance, which proves that CkPHB gene plays an important role in promoting leaf vein development and improving plant drought resistance. The results of this study laid a foundation for further studying the drought response mechanism of CkPHB gene in C. korshinskii.

Abstract:ApY₂SK₂ a dehydrin gene from Agapanthus praecox was identified to have the positive protective effect on embryonic cells during cryopreservation. In order to reveal the regulatory mechanism of ApY₂SK₂ response to complex stresses of cryopreservation, a 1 200 bp promoter sequence of ApY₂SK₂ was cloned and analyzed by using Chromosome Walking technique. The results showed that: (1) ApY₂SK₂ promoter contained multiple stress, hormones response and plant embryo developmentrelated cisacting elements. Quantitative Realtime PCR assay suggested that the ApY₂SK₂ promoter had tissuespecific expression pattern, and ApY₂SK₂ gene had the highest expression level in the leaves and fruits of A. praecox. This gene was significantly upregulated response to various stress and ABA treatments. (2) Five different deletion fragments of ApY₂SK₂ promoter were constructed into pBI121 expression vectors, and using Agrobacterium mediated transformation and PCR identification to obtain the A. thaliana T₃ generation transgenic lines. (3) GUS histochemical staining results showed that GUS staining signal were mainly distribute at the whole seedling, and the leaves, flowers and mature fruits of adult transgenic plants. Furthermore, gene transient transformation in leaf epidermis of tobacco test showed that the driver activity of 5 different deletion promoter fragments were significantly different under PEG and ABA treatments. (4) Quantitative determination of GUS enzyme activity suggested that MBS element and ABRE element of the ApY₂SK₂ promoter involved in response to drought and osmotic signals, respectively. The LTR element participates in the low temperature response. Additionally, -1 199 to -262 bp of ApY₂SK₂ promoter contained multiple tandem ABRE cisacting regulators (locate at -373 to -211 bp) that play an important role in response to ABA signaling. This study finally confirmed that ApY₂SK₂ promoter has tissue specific regulatory functions, and some core cisacting elements play a decisive role in regulating the ApY₂SK₂ response to different stresses and hormone signals.

Abstract:GNOM is a kind of guanine nucleotide exchange factor (GEF) of ADP ribosylation factor (ARF). In order to explore the function of GNOM in stress resistance of Dryopteris fragrans, we cloned DfGNOM and analyzed by bioinformatics. The expression pattern of DfGNOM gene under different plant hormones and stress was analyzed by realtime fluorescent quantitative PCR (qRTPCR). The results provide a basis for further exploring the function of the gene and the stress resistance mechanism of D. fragrans. The results showed that: (1) DfGNOM was obtained with a total length of 4 338 bp. Multiple protein sequence alignment and phylogenetic tree analysis showed that DfGNOM was closely related to Selaginella moellendorffii SmGNOM, and motif analysis showed that the protein contained the sec7 conserved domain. (2) qRTPCR analysis showed that: DfGNOM was expressed in the roots, petioles and leaves of D. fragrans, but the highest expression was in the leaves; the relative expression of DfGNOM was upregulated after IAA treatment; abscisic acid (ABA) treatment decreased the expression level; under NaCl treatment, the trend was “downupdown”; under high temperature and low temperature treatment, the trend was “updownup”. The relative expression patterns of DfGNOM were also different under the treatments of MeJA, ETH and PEG. The results showed that DfGNOM played a regulatory role in the abiotic stress response of D. fragrans.

Abstract:Using Cymbidium faberi and Cymbidium sinense as experimental material, we cloned AGAMOUS (AG) genes by RTPCR, and the tissue expression was studied by realtime fluorescence quantitative PCR (qRTPCR). It was found that: (1) three AG genes were obtained, they belong to MIKC MADSbox gene, and the two AG genes of C. faberi were named as CfAG1 (accession number: MW654188) and CfAG2 (accession number: MW654189). The AG gene of C. sinense was named as CsAG1 (accession number: MW654190). (2) CfAG1 was highly expressed in the gynostemium at fullblossom stage, and moderately expressed in buds at bud stage and ovaries at fullblossom stage. CfAG2 was highly expressed in ovary at fullblossom stage, moderately expressed in gynostemium at fullblossom stage, and slightly expressed in buds at bud stage and petals (including lip petals) at fullblossom stage. The relative expression of CsAG1 gene was the highest in the gynostemium at fullblossom stage, followed by buds at bud stage and ovary at fullblossom stage, and the lowest expression was in sepals and leaves at fullblossom stage. The study indicated that the expression characteristics of CfAG1 and CsAG1 were similar. These three genes are tissuespecific and can regulate the development of gynostemium and ovary. The results provided basic data and scientific basis for the following research on the development and evolution of floral pattern, molecular breeding and new variety breeding of Cymbidium.

Abstract:The QinghaiTibetan Plateau (QTP) is one of the global biodiversity hotspots and renowned for its high level of endemics. Numerous studies have explored the genetic differentiation and evolutionary history of plants in this region, but the large number of Gentiana endemics have been overlooked. Focusing on an annual Gentiana species (G. haynaldii Kanitz) in the QTP, we assessed their genetic structure, divergence and demographic history based on plastid and nuclear DNA sequences in this study. The results showed that: (1) relatively high level of genetic diversity and differentiation was observed in G. haynaldii (cpDNA，F_ST=0.532； ITS，F_ST=0.511). Genetic variance nearly equally occurred among populations or within population. (2) Demographic analyses showed signatures of recent population expansion in G. haynaldii. Species distribution modelling showed stable potential range except slight range expansion from the midHolocene to the present day. (3) Divergence time estimates suggested that the onset of intraspecific diversification generally fell into the Late Pliocene and the Early Pleistocene. The results indicated that the intraspecific divergence in G. haynaldii should be driven by geographical isolation and range fragmentation in glaciations rather than orogeny. This study provides insights into genetic differentiation and evolutionary history of the speciesrich Gentiana as well as alpine plants in the QTP.

Abstract:In order to understand the genetic background and genetic relationship of 148 S. tuberosum of tetraploid potato at home and abroad, the whole genome was resequenced through the thirdgeneration highthroughput sequencing method. Using SNP as molecular markers, genetic similarity coefficient as indicator and pedigree information, we analyzed the genetic diversity of the population by using a combination of population structure and cluster analysis. The results showed that: (1) 1 209 969 highquality SNP loci were obtained after effective filtering and screening. The number of SNP loci clearly located at the chromosome level was 1 192 472, accounting for 98.55%. Except for chromosome 11, which has no loci distribution, chromosome 5 has the most, Chromosome 7 is the least. (2) The genetic similarity coefficients among various breeds ranged from 0.784 to 0.958, with an average of 0.842, mainly concentrated in the range of 0.800 to 0.880, with 10 604, accounting for 97.5%. (3) The structure analysis showed that 148 materials were divided into 6 groups, 36 varieties with Q value> 0.6, accounting for 24.3%. Among varieties with a relatively single genetic background, 16 varieties bred in North China accounted for 44.4%. 13 foreign varieties accounted for 36.1%, and the two together accounted for 80.5%, indicating that the genetic components of bred varieties in North China and foreign varieties have a higher percentage of genetic components than other regional varieties. (4) The results of cluster analysis showed that 148 potato varieties were divided into 3 groups. The varieties of ‘Zhongshu Series’, ‘Longshu Series’ and ‘Jizhangshu Series’ clustered together have a certain geographic region, and other varieties of different geographic origin. The interlaced distribution of potato varieties shows that the differences in breeding areas are not necessarily related to genetic relationships. Breeding units frequently introduce each other, and there are gene exchanges between different areas during the selection and breeding of new varieties. The results of structure analysis and cluster analysis are basically consistent and mutually verify. Studies have shown that most S. tuberosum have a high genetic similarity, and the genetic background is not rich enough. It is urgent to introduce new germplasm in breeding to broaden the genetic basis.

Abstract:The study adopts the method of conventional tableting of 5 Convallarieae species. The shapes, chromosome number and karyotype of the observation analysis, and comprehensively collect all the Convallarieae has reported a total of 81 of the 253 published of chromosomes, through comprehensive statistics, reconstruction of phylogenetic tree, between the Convallarieae was studied and the subordinate relations between the systems, to reveal the relationship between species and the trend of origin and evolution. The results showed that: (1) the results of cytological experiments showed that the chromosome number of 4 species of Convallarieae was 2n=38, except for Aspidistra elatior, which was 2n=36, and all of them were diploid, and the asymmetry karyotype was Stebbins 2C. The variation range of the asymmetry coefficient As.K% was from 65% to 69%, but the karyotype formula was different. (2) The chromosome number of most species is 2n = 38, while that of some species in Aspidistra is 2n = 36; according to the variation of chromosome length, the karyotypes were mainly divided into unimodal and trimodal. The statistical results show that the group with chromosome 2n=36 usually has one more pair of medium chromosomes and two less pairs of small chromosomes than the group with chromosome 2n= 38, which may be due to the fusion of two small pairs of chromosomes into a pair of medium chromosomes. (3) The latest phylogenetic tree of Convallarieae based on four chloroplast gene fragments (rbcL, matK, psbatrnH and trnLF) and nuclear gene ITS showed that Convallarieae was divided into three clades. The Ⅰ clade was located in the base of the whole clades and was the first to be differentiated from the ConvallariaSpeirantha clades and the chromosome number is x=19; the Ⅱ clade is the RhodeaReineckia clades, and the chromosome number is x=19; the Ⅲ clade is the TupistraAspidistra clades and the chromosome number is x=18 or 19. Based on the analysis of chromosome cardinality and karyotype of Convallarieae, the low number x=18 of Convallarieae evolved from x=19 through chromosomal fusion or loss. It is speculated that the karyotype evolved from a relatively symmetrical unimodal to an asymmetrical trimodal. This study provides cytological evidences to reveal the evolutionary relationships between genera and species within Convallarieae.

Abstract:The feature of a new type of ventilatory structure in vascular plant named as the “raised pore” in Christensenia assamicas leaves were observed by using paraffin section and SEM for the first time. The results showed that: (1) the raised pore was comprised of around 20 strip cells, like a raised upsidedown bowl on the outer epidermis under leaves, massive microvilli are distributed on the intine of the raised part, and there is a round hole on the top that cannot be opened or closed which diameter is about 240 μm; (2) The photosynthetic cells liked tubular branches are contained in the air chamber under the raised pore and massive microvilli are distributed on them; (3) With the transition from the air chamber to the leaf vein, microvilli gradually changed into microfibrils and striplike plaques; (4) The appearance of the raised pore is similar with hepaticas single stomata of bryophytes, but cell differentiation is more complicated than the latter. It is considered that the raised pore is a kind of ventilatory structure in vascular plant with the largest diameter found so far, can neither be opened nor closed, and has high efficiency in terms of gas metabolism and special defense function. It may be related to the morphological evolution of hepaticas single stomata of bryophytes.

Abstract:We studied the effect of variable temperature treatment on flower bud differentiation of Crocus sativus in order to provide theoretical basis for early flower bud differentiation. The bulb of C. sativus was treated by threestage variable temperature treatment ［20 ℃25 ℃20 ℃ (T₁), 20 ℃30 ℃25 ℃ (T₂), 25 ℃35 ℃25 ℃ (T₃), 25 ℃30 ℃25 ℃ (CK₁) and 25 ℃25 ℃25 ℃ (CK₂)］. The differentiation of flower bud was observed by paraffin section technique. The contents of starch, soluble sugar, soluble protein, endogenous auxin IAA, gibberellic acid (GA) and activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) were measured. The results show that: (1) the corm of C. sativus treated with T₁ started flower bud differentiation earlier than other groups, the length and growth of flower bud of C. sativus treated with T1 were better than other groups, and the first flowering time of C. sativus treated with T₁ was more than one week earlier than that of control group. (2) T₁ treatment could promote the accumulation of soluble sugar, soluble protein and other nutrients, and increase the activities of SOD, POD and CAT. In addition, T₁ treatment could effectively regulate the contents of endogenous IAA and GA. The results showed that the change of external temperature could also indirectly regulate the synthesis and transportation of nutrients, antioxidant enzymes and plant hormones in Crocus sativus bulbs, thus affecting the dormancy and flower bud differentiation of plants, and ultimately regulating the flower bud differentiation and flowering. The appropriate threestage variable temperature treatment (20 ℃25 ℃20 ℃) could effectively regulate the initiation and duration of flower bud differentiation of Crocus sativus.

Abstract:To understand flower bud morphological differentiation and related physiological biochemistry changes of Syzygium cumini, provide the basis for controlling the quantity of flower and cultivation management, we observed the morphological characteristics of flower buds by frozen section and scanning method, and the related physiology indexes were determined by anthrone colorimetry, coomassie brilliant blue G250 and enzymelinked immunosorbent in this experiment. Results indicated that: (1) the flower bud morphological differentiation of S. cumini could be divided into seven periods: inflorescence primordium differentiation period, floret primordium differentiation period, sepal primordium differentiation period, petal primordium differentiation period, stamen primordium differentiation period, pistil primordium differentiation period and stamen and pistil formation period. (2) During the flower bud morphological differentiation of S. cumini, the length of flower bud showed a “fastslow” growth trend and the width showed a “fastslowfast” growth trend. (3) As for the changes of nutrient and endogenous hormone contents in flower bud, total soluble sugar decreased firstly and then increased, the content of protein rose significantly. (4) During the flower bud morphological differentiation of S. cumini, the content of GA₃ was extremely low, while ABA, IAA and ZT rose, the ratios of ABA/GA₃ and ZT/GA₃ increased while ABA/IAA decreased. In conclusion, during the seven periods of flower bud morphological differentiation of S. cumini, a massive accumulation of carbohydrate and protein, low concentration of GA₃, high concentrations of ZT, ABA, IAA, ABA/GA₃ and ZT/GA₃ contribute to the flower bud morphological differentiation.

Abstract:Alfalfa, the perennial legume forage, soil salinization is becoming a yield limiting factor of it. ‘Zhongmu No.1’, as one of the Alfalfa, was used as the material in this study. Based on the screening test of salt stress and melatonin, salt (150 mmol/L NaCl) and melatonin (30, 50, 80 μmol/L MT) separate and combination treatment were selected. The effects of exogenous melatonin on the growth characteristics, membrane permeability, osmotic regulation and effects of antioxidants enzymes and photosynthetic indexes were shown in this article. The results showed that: (1) the growth of alfalfa seedlings was significantly inhibited by salt stress, but not affected by various concentrations of melatonin. All melatonin treatments effectively alleviated the damage caused by salt stress to the growth of alfalfa, and the effect of 150 mmol/L NaCl+ 80 μmol/L melatonin treatment (NaCl + MT2) was the best, the seedling foot length, the root fresh weight and root dry weight increased significantly by 34.52%, 41.93% and 19.61% compared with salt stress treatment, respectively. (2) Salt stress significantly increased the permeability of cell membrane system and the degree of membrane lipid peroxidation of alfalfa seedlings. The relative conductivity and MDA content of seedling leaves treated with NaCl + MT2 were significantly lower than those treated with salt stress by 27.18% and 30.24%, respectively. At the same time, the relative water content in seedling leaves was significantly increased, but the proline content was significantly reduced, exogenous melatonin effectively alleviated the damage of cell water loss and cell membrane under salt stress. (3) The activities of POD and SOD in the leaves of NaCl + MT2 seedlings were significantly higher than those of salt stress treatment by 31.45% and 41.41%, respectively. However, the CAT activities had no significant change. Exogenous melatonin could significantly enhance the activities of POD and SOD in the leaves of alfalfa seedlings, improve the scavenging ability of reactive oxygen species and reduce the peroxidation damage induced by salt stress. (4) Salt stress significantly inhibited the photosynthetic efficiency of alfalfa seedlings, while the net photosynthetic rate, stomatal conductance and transpiration rate of seedlings treated with NaCl + MT2 increased by 30.27%, 45.1% and 42.15%, respectively compared with salt stress. It was found that salt stress significantly increased the accumulation of reactive oxygen species in alfalfa seedling leaves, reduced the activities of antioxidant enzymes, and reduce its photosynthetic efficiency. Exogenous melatonin promoted the growth of alfalfa seedlings by improving its antioxidant capacity and photosynthetic efficiency, so our study provides a theoretical basis for improving alfalfa salt tolerance and reforming saline alkali land.

Abstract:In this study, the full red fruits of six big fruit type Ziziphus jujuba Mill. varieties (‘Junzao’, ‘Zanxindazao’, ‘Jingudazao’, ‘Hamazao’, ‘Jinzandazao’ and ‘Xinzhengdamaya’) cultivated in Xinjiang were used as research objects. We observed the pericarp tissue structure, measured the cell wall components and metabolismrelated enzyme activities, analyzed the changes in the expression of extension protein genes. And then, we analyzed the fruit cracking difference of them. In order to find the internal regular pattern that causes the fruit cracking difference. The result might be providing a theoretical basis for the cultivation and introduction of varieties resistant to fruit cracking. The results showed that: (1) ‘Junzao’, ‘Zanxindazao’, and ‘Jingudazao’ are the fruit cracking varieties, while ‘Hamazao’, ‘Jinzandazao’ and ‘Xinzhengdamaya’ have better fruit cracking resistance. (2) The cuticle thickness of the six varieties were significantly different from each other, and ‘Jinzandazao’, ‘Hamazao’ and ‘Xinzhengdamaya’ were larger than others. while the epidermal thickness was not different. There were significant differences in the cavity/pulp area rank from low to high, which were ‘Hamazao’ < ‘Xinzhengdamaya’ < ‘Jinzandazao’< ‘Junzao’ < ‘Jingudazao’ < ‘Zanxindazao’. (3) The contents of cellulose, protopectin, soluble pectin, and the activities of cellulase and pectin were all different among the six cultivars. Among them, the content of protopectin in crack resistant cultivars ‘Jinzandazao’, ‘Hamazao’ were significantly lower than that of other cultivars, this means that there is a correlation between the propectin content and the cracking rate. While the change trend of cellulose content and cellulase activity is basically constant, so there no correlation was found between the other indices and their cracking rates. (4) The expression levels of ZjEXP11 and ZjEXP12 in the pericarp of the fruit cracking resistance varieties were significantly lower than those in the fruit cracking varieties. Therefore, this study speculated that the expression level of ZjEXP11 and ZjEXP12 in the pericarp were correlated with the fruit cracking. In summary, There are significant differences in fruit cracking of Xinjiang big fruit type jujube among cultivars. compared with the cracking sensitive cultivars, the cracking resistant cultivars had thicker cuticle and epidermal layer, smaller pulp cavity area, lower propectin content and lower expression level of ZjEXP11 and ZjEXP12.

Abstract:To ascertain the mechanism of ion osmosis adjustment adapted to saline soil habitat, we studied the absorption and distribution of the main mineral cations in roots, branches and leaves of E. moorcroftii trees with the age of one to twelve. Result showed that: (1) the Ca²⁺ accumulation of the tree was the highest (13.79 g/kg), K⁺ was the next (5.92 g/kg), Na⁺was the lowest (1.00 g/kg). With the increasing of tree age, the Na⁺ content in the roots, the K⁺, Ca²⁺ and Mg²⁺ contents in the branches and leaves had the rising trend, while K⁺ content had the opposite trend. The accumulation of Na⁺ in the root of the higher age grade trees were significantly bigger than that of the lower and middle age grade ones. (2) The K⁺/Na⁺ of the tree was higher (15.36) than the Mg²⁺/Na⁺ (12.25) and the Ca²⁺/Na⁺ (10.51). The K⁺/Na⁺ of the root and branch decreased, while it increased in the leaf. (3) With the increasing of tree age, the selective transport coefficients of K⁺ and Mg²⁺ from the soil to the root, and K⁺, Mg²⁺ and Ca²⁺ from root to branch, as well as K⁺ and Mg²⁺ from root to leaf showed the straight upward trend. (4) The Na⁺ content in the soil had an extreme significant positive correlation with the Na⁺ content in the root (0.687,P<0.01), and a significant positive correlation with the K⁺ content in the leaf (0.605 P<0.05). The K⁺ content in the soil had a significant and extreme significant positive correlation with the K⁺ in the leaf and Na⁺ in the root respectively (0.544, 0.676), and had a significant negative correlation with the Mg²⁺ in the root (-0.499). E. moorcroftii maintained the ion balance and adapted to saline soil habitat through accumulating Na⁺ in the root and selective absorpting the K⁺, Mg²⁺ and Ca²⁺ in the branch and leaf.

Abstract:Under the natural high temperature environment in summer of Xinjiang, taking the barren stalk, ear seed setting rate and relative seed setting rate as the main evaluation indexes, we coupled with the yield and main agronomic traits, to identify and evaluate the heat tolerance of 26 maize inbred lines for 2 consecutive years. Combined with the local high temperature and dry climate characteristics, we established a set of heat tolerance identification and evaluation system, which is helpful for heat tolerance improvement and breeding new varieties of maize in China. The results showed that: (1) there were great differences in the empty stem rate, ear setting rate, relative seed setting rate and heat tolerance of different maize genotypes. Among them, GW5F, GW4F, GW7F and PH6WC had the strongest heat tolerance. Under high temperature stress, the empty stem rate was the lowest, and the ear seed setting rate and relative seed setting rate were the highest; Secondly, 8 inbred lines such as PHBA6 and Xinzi 351 had better yield and comprehensive performance under high temperature stress. Other inbred lines were sensitive to high temperature. (2) High temperature stress led to a serious decline in maize ear traits. Ear weight, rows per ear and grains per row were most seriously affected. (3) The correlation between yield and main agronomic traits was quite different between years or materials, and the correlation between ear weight and yield was the highest. (4) Taking the relative seed setting rate as the main assessment criteria, the tested materials can be divided into two categories by hierarchical clustering. GW5F, PH6WC and GW4M were clustered into the first group. The second group contains three subgroups; Six inbred lines such as Ji 63 and Mo17 were clustered into the first subgroup; 6 inbred lines such as PHBA6 and LH82 were clustered into the second subgroup; 11 inbred lines such as Zheng 58 and Xinnongyu 6390M were clustered into the third subgroup. In summary, four inbred lines with extremely high temperature tolerance were identified, which can be used for basic research and genetic improvement of maize heat tolerance. 8 inbred lines with strong heat tolerance were mostly local inbred lines in Xinjiang, which have a wide genetic basis, adapt to the local high temperature, and were excellent heatresistant breeding materials.

Abstract:The ecological stoichiometric of soil carbon (C), nitrogen (N), and phosphorus (P) is an important basis to reflect the process of ecosystem change. This study selected Caragana tangutica, Berberis diaphana, Potentilla fruticosa, Caragana jubata and Salix gilashanica which lived in northern piedmont of the central Qilian Mountain as object, to determine the contents of soil C, N and P by field investigation and sampling, analyze the vertical distribution characteristics of soil C, N and P contents and their ecological stoichiometry in different shrub communities, and discuss the coupling relationship among the indexes. It could provid a theoretical basis for the relationship between soil and plant nutrients and the restoration and reconstruction of degraded vegetation in Qilian Mountain. The results showed that: (1) the mean contents of soil C, N and P were 45.29, 3.85, 0.70 g/kg, respectively, which were higher than the national average levels. (2) According to the correlation analysis, soil C and N presented extremely significant positive correlation (P<0.01), but there was no significant correlation between soil C and P or between soil N and P, Furthermore, C and N showed almost synchronous variation. (3) The contents of soil C and N in the surface layer were higher than those in the lower layer, while there was no significant difference in soil P between soil layers in all shrub types. The contents of soil C and N showed an inverted pyramid distribution pattern with the deepening of soil layer in different shrub types, but the changes of soil P were not consistent with the deepening of soil layer in different shrub types, and the effect of soil layer on soli P was not significant. (4) The mean soil C∶N, C∶P and N∶P ratios were 11.29, 66.99 and 5.67, respectively, which were all below the national level. The soil C∶P and N∶P showed a decreasing trend with the deepening of soil layer to different degrees in all shrub types, but the change rule of soil C∶N was different with the deepening of soil layer in all shrub types. (5) Soil C, N and C∶N, C∶P, N∶P had extremely significant quadratic function relationship (P<0.01), but the relationship between soil P and C∶N, C∶P, N∶P was not significant. According to the research, the soil C∶N and P content have high stability (3.99% and 2.66%), whereas the C∶P and N∶P are important indicators for determining nutrient limitation. The soil of shrub community is mainly restricted by N element in northern piedmont of the central Qilian Mountain.

Abstract:To clarify the living conditions and development trend of the Populus euphratica population in the desert hinterland natural oasis, we analyzed the influence of the difference in groundwater depth condition on the age structure and renewal succession of the P. euphratica population. We selected the P. euphratica forest in the Daliyabuyi Oasis, lower reaches of the Keriya River, as the research site. The age structure characteristics were analyzed and the update dynamics on the sequence were predicted by classifying the age structure and groundwater depth gradient as well as quantifying the individual competitiveness. The results show that: (1) the age structure of the P. euphratica population in Daliyabuyi Oasis has a weak growth trend as a whole, but there are great differences among different habitats, and the updating capability of P. euphratica in most areas is relatively weak. (2) There is a power function relationship between individual competitiveness and age structure, the competitive relationship that can be maintained becomes more simple and the proportion of young stands with lower competitiveness decreases with the increase of groundwater depth. (3) The normal renewal succession of the P. euphratica population can be ensured when the water depth is less than 6 m, while the groundwater depth more thant 6 m will make the P. euphratica population lose the component of young forest, and showing an obvious declining trend.

Abstract:In this study, the P. tabuliformis plantation community in the Zhongtiao Mountain was used as the research object, contribution of understory subassemblages of different samples to the distribution pattern of community species richness has been studied, and the key species that affect the distribution pattern of species richness in the regions community have been identified. This study will provide a theoretical basis for the conservation of regional species diversity. The results show that: (1) the distribution pattern of understory species frequency in this area is obviously to the right, and there are obvious differences in species richness in different samples. (2) The contribution of common species to the distribution pattern of community richness is greater than that of rare species. (3) The most common species explained 88.4% of the species richness pattern of the entire community (P<0.01), while the rarest species only explained 24.5% (P>0.05). After removing the rarest species, the most common species can explain 90.8% of the remaining species (P<0.01), while after removing the most common species, the rarest species can only explain 48.6% (P<0.01). (4) When there are more common species in the subassemblage, the higher the correlation between the subassemblage and the richness distribution pattern of the full assemblage. (5) Forsythia suspensa, Philadelphus pekinensis, Smilax stans, Adenophora wawreana and Lonicera chrysantha contribute the most to the distribution pattern of community species richness, and not the more common species contribute more to the community richness pattern. (6) Species with low interspecific associations with more frequent species contribute more to the distribution pattern of community species, but this explanation does not apply in respect of rare species. In the process of protecting the species diversity of P. tabuliformis plantations, we should not only focus on common species and ignore rare species.

Abstract:This paper uses space instead of time to lay out typical plots in P. massoniana plantations of different ages in Mengguan Forest Farm in Guizhou Province. Shannon and Levins formulas, Pianka formulas are used to analyze the niche dynamics of dominant species in shrubgrass communities at different development stages. The results showed that: (1) the important values of the same dominant species is different in different forest stands. The important value of Quercus aliena in the 8a and 18a forest stands are 50.89% and 47.32%, respectively, and the important value of Myrsine africana in the 28a forest stands is 50.49% and for 36a, the important value of Smilax china is 50.62%, and the important value of Dicranopteris dichotoma always ranks first in each developmental stage. (2) Q.aliena and S.china have an absolute advantage in the niche width, Vaccinium bracteatum and Castanea seguinii increase in niche width with increasing age, and D.dichotoma niche width increases with the increase in stand age. Microlepia marginata and Deyeuxia arundinacea show a trend of first increasing and then decreasing with the increase of stand age. There is no absolute positive or negative relationship between the importance values of shrub and grass and the width of niche. The same species adapts to the environment and resources in different periods. The utilization capacity is different. (3) Q. aliena and S. china, M. africana and C. seguinii, Stenoloma chusanum and M. marginata, D. arundinacea and Arthraxon hispidus and other species pairs show strong similarities in ecological or biological characteristics. Species with large niche width values are not synchronized with other species niche overlap values.

Abstract:Map of spatial distribution of genera was made by the county and Hamamelidaceae of China in ArcGIS software, number of every patch, area and perimeter were gotten from the maps. Shape indices, largest patch indices, Simpsons evenness indices and Shannons evenness indices were calculated. The characteristics of geographical distributions of each genus in Hamamelidaceae of China can be quantitatively analyzed. It provided the basis for the protection, development and utilization of Hamamelidaceae resource. Results showed that: (1) Chunia, Parrotia, Tetrathyrium, Fortunearia, Hamamelis and Mytilaria are monotypic genera. The total area of the first three genera is small and the distribution is narrow, while the total area and distribution range of the last three genera are larger than the first three genera; Disanthus, Sinowilsonia, Rhodoleia, Eustigma, Semiliquidambar, Exbucklandia, Altingia, Sycopsis, Distylium, Loropetalum, Corylopsis and Liquidambar are multiple genera. When area of genus increases, distribution range of genus basically increases. And the multiple genera are twice as many as the monotypic genera. (2) Total area and largest patch area of Liquidambar are the largest, which can reflect spatial distribution and characteristics of Hamamelidaceae in China. (3) Spatial distribution of all genera in Hamamelidaceae of China is disjunction. Chunia, Distylium, Loropetalum and Liquidambar have the main distribution area. Fortunearia, Hamamelis, Mytilaria, Sinowilsonia, Semiliquidambar, Exbucklandia, Altingia， Sycopsis and Corylopsis have main and secondary area. Parrotia, Tetrathyrium, Disanthus, Rhodoleia and Eustigma are all scattered area.

Abstract:This article reports and records a new distribution of Orchidaceae plants that has never been discovered in Sichuan—Calanthe tsoongiana T. Tang & F. T. Wang. According to the records of East Asian Cymbidium genus, the original distribution area of Shrimp Orchid was in West Tianmu Mountain and Guizhou Province. The type specimen of Shrimp Orchid is from West Tianmu Mountain, Zhejiang. This article is the first record of Shrimp Orchid in Beichuan County, Sichuan Province.

Abstract:This article reports a new record of Aquilegia yangii Y. Luo & L. Li, distributed in the Tongtianhe National Forest Park, Feng County, Shaanxi Province. The report expanded the distribution area of this species eastward to the Qinling area of Shaanxi Province, enriching the distribution records of new plants in Shaanxi Province, and providing evidence for the study of species diversity in the Qinling area.