In order to understand the effect of thinning on the structure of Pinus sylvestris var. mongolica plantation in Saihanba Nature Reserve, the diameter structure and spatial distribution pattern of Pinus sylvestris var. mongolica plantations under different tending intensities were studied. The results showed that there was obvious differentiation in the Pinus sylvestris var. mongolica plantation in Saihanba Nature Reserve, and DBH (diameter at breast height) ranged from 2 cm to 34 cm, with a big proportion of small diameter trees. The stands' DBH structure tended to follow the Weibull distribution both before and after the thinning, and the data after the thinning were closer to the Weibull distribution. After thinning, the skewness coefficient of the stands' DBH structure increased, meaning the proportion of trees with bigger DBH increased. On the 4 scales (5 m×5 m, 5 m×10 m, 10 m×10 m, 15 m×10 m), the spatial distribution patterns of Pinus sylvestris var. mongolica plantation were aggregated distribution or random distribution before thinning, and they tended to become random distribution or uniform distribution after thinning. At the same time, the aggregation degree decreased with the increase of thinning intensity. In conlusion thinning not only decreased the density of Pinus sylvestris var. mongolica plantation in Saihanba Nature Reserve but also optimized the stand DBH structure and spatial distribution patterns.

To investigate the comprehensive quality differences of Elaeagnus mollis Diels. plants in three different areas of Shanxi Huxian (D1), Shanxi Xiangning (D2), and Shanxi Yicheng (D3), the correlation analysis method and principal component analysis method were used to comprehensively evaluate the growth traits and fruit traits of seedlings from various sources. The height of the 8-year-old Elaeagnus mollis Diels. trees of the three sources ranged from 4.75 to 5.41 m, the crown breath from 2.44 to 2.48 m, the single-fruit fresh mass from 1.08 to 1.79 the fruit length from 1.75 to 2.09 mm, the fruit width from 1.51 to 2.02 mm, the seed dry mass from 0.84 to 1.18 g the kernel dry mass from 0.29 to 0.49 g, the yield per plant from 0.96 to 1.43 g, the fresh fruit yield per unit crown area from 0.87 to 1.29 g, and the data of D2 were the highest. The ground diameter of the trees from the three sorces ranged from 9.06 to 10.41 cm, new shoots length from 30.25 to 36.88 cm, the kernel percentage from 34.83% to 36.18%, and the data of D3 were the highest. The results of variance analysis showed that the plant height, single-fruit fresh mass, fruit length, fruit width, kernel dry mass, production per plant of D2 were all significantly higher than that of D1 (P<0.05), which were 10.3%, 65.0%, 19.3%, 33.8%, 40.4%, 69.0%, and 49.0% respectively higher than that of D1. The yield of D3 was significantly higher than that of D1 and D2 ( P<0.05), which were 24.0% higher than D1 and 7.4% higher than D2. On the whole, the plant hight, fruit length, kernel dry mass, and kernel percentage were positively correlated with yield per plant, while the single-fruit fresh mass, fruit width and seed dry mass were significantly positively correlated with yield per plant. Three principal components were extracted according to the principle that the eigenvalue was greater than 1, and the cumulative variance contribution rate reached 73.890%. The first principal component reflected the fruit quality traits, with the eigenvalue as 4.843, and the contribution rate as 48.426%. The second principal component reflected the growth traits, with the characteristic value as 1.528, the contribution rate as 15.280%. The third principal component reflected the growth of seedlings, with the characteristic value as 1.018, and the contribution rate as 10.184%. The results of principal component analysis showed that the decreasing order of quality of the Elaeagnus mollis Diels. plants from the three sources was: D2 Shanxi Xiangning (1.2137)>D3 Shanxi Yicheng (1.1032)>D1 Shaanxi Huxian (0.9864). The result indicated: the 8-year-old Elaeagnus mollis Diels. from D2 Shanxi Xiangning had an average single-fruit fresh mass of 1.79 g, kernel percentage of 43.18 % and yield per plant of 1.43 kg. The F value of comprehensive evaluation of D2 ranked the first, so it was the priority for for large-scale planting in the experimental area and adjacent areas. The results of this study can lay a scientific foundation and provide useful reference for the large-scale planting, cultivation and selection of Elaeagnus mollis Diels. in Gansu Province.

The research of the coupling effect of water and nitrogen on the photosynthetic physiology of Acer truncatum seedlings can provide a scientific basislay a scientific foundation for the water and fertilizer management of A. truncatum seedlings, which is beneficial to the development of A. truncatum industry. In this study, one-year-old A. truncatum seedlings were used as materials, and a two-factor completely randomized pot experiment was conducted with three water gradients of 10%~20% (W1), 40%~50% (W2), and 70%~80% (W3) of field capacity (FC), and four nitrogen gradients of 0 g/plant (N0), 2 g/plant (N1), 4 g/plant (N2), and 6 g/plant (N3) of nitrogen fertilizer. The photosynthetic parameters, chlorophyll content, and chlorophyll fluorescence parameters of A. truncatum seedlings under different water and nitrogen treatments were measured to analyze their variation and reveal the influence mechanism of water and nitrogen coupling on the photosynthetic physiology of A. truncatum seedlings. The results showed that water and nitrogen coupling had a significant impact on the photosynthetic physiology of A. truncatum: (1) The overall trend of Pn, Gs, Ci, and Tr of A. truncatum seedlings showed an increase increased with the increasinge of soil water content, while iWUE and LS showed the opposite trend; the effect of nitrogen application on the photosynthetic parameters of A. truncatum was more complex, with the highest Pn of 8.84 μmol/(m²·s) in the W2N2 treatment. (2) Water and nitrogen had a significant impact on the actual photochemical efficiency of photosystem II (ΦPSII), and non-photochemical quenching coefficient (qN) of A. truncatum seedlings, while there was no significant effect on the maximum photochemical efficiency of photosystem II (Fv/Fm) and photochemical quenching coefficient (qP). (3) Soil moisture is the main influencing factor of chlorophyll content in A. truncatum leaves. With the increase of soil moisture content, the total chlorophyll content of A. truncatum leaves increasesd, the chlorophyll a/b ratio decreasesd, and the proportion of chlorophyll b significantly increasesd. (4) Pn of A. truncatum was significantly positively correlated with Ci, Gs, Tr, Fv/Fm, and Chl, and significantly negatively correlated with iWUE and LS. In conclusion, increasing soil water content can significantly improve the photosynthesis of A. truncatum seedlings. When the soil water content is low, water is the dominant factor affecting the photosynthetic physiology of A. truncatum. When the soil water content is at a medium-to-high level, its photosynthetic physiology is jointly determined by water and nitrogen. This conclusion can provide theoretical reference for the establishment of water and fertilizer management system for A. truncatum seedlings.

In order to understand the function of MdMTA under drought stress, long-term drought treatment was conducted using wild-type apple GL-3 and MdMTA-interfering transgenic apples (RNAi) as materials to explore the role of apple RNA methylation transferase MdMTA in long-term drought stress. The results showed that: (1) Under drought stress, the growth potential of MdMTA RNAi transgenic plants RNAi #1 and RNAi #4 was significantly decreased compared with GL-3, leaf area was decreased by 12.9% and 10.3% compared with GL-3, stomatal number was decreased by 17.2% and 19.0% compared with GL-3. (2) Under drought stress, CAT activity of MdMTA RNAi transgenic plants RNAi #1 and RNAi #4 decreased by 16.8% and 22.0% compared with GL-3, POD activity decreased by 24.8% and 21.0%, and H₂O₂ content increased by 30.4% and 22.3%, O^2- content increased by 14.3% and 24.8%. (3) Under drought stress, the photosynthesis of MdMTA RNAi transgenic plants RNAi #1 and RNAi #4 was significantly inhibited. Compared with GL-3, the net photosynthetic rate decreased by about 16.9% and 17.0%, respectively. Stomatal conductance, intercellular CO₂ concentration and transpiration rate were also significantly lower than GL-3. In conclusion, interference with the expression of MdMTA could cause greater damage to apple plants than wild-type GL-3 under long-term drought stress, suggesting that MdMTA played an important role in the process of long-term drought stress in apple.

To investigate the mechanism and the principle in the resistance to the Plagiodera versicolora in Salix triandra, Four different but related willow species were selected as the test materials,which included the insect-resistant group represented by three clones of S.triandra and three non-insect-resistant groups represented by S.babylonica,S.caprea and S.matsudana. The Plagiodera versicolora adults and larvae were fed with leaves treated with the differential metabolites Catechin solution, Salicylic acid solution, Gallic acid glucose solution, Neophesperidin solution and Eupatilin solution to explore the mechanism of resistance to the Plagiodera versicolora in Salix triandra. The results showed that: (1) The Plagiodera versicolora showed mortality after consuming leaves treated with Eupatilin solution: The average survival rate of adults was 83.33% after 24 h and 40% after 48 h. The average survival rate of larvae was 80% after 24 h and 35% after 48 h. (2) None of the leaves treated with other solutions caused death of Plagiodera versicolora: After 24 h and 48 h, the survival rate of adults and larvae was 100% without any mortality. (3) After feeding Plagiodera versicolora to leaves treated with the five differential metabolite solutions screened by combining the results of transcriptome and metabolome analyses, only the Eupatilin solution caused Plagiodera versicolora death. Eupatilin might be an important reason for the resistance of Salix triandra to Plagiodera versicolora. Therefore, it was speculated that the mechanism of insect resistance of S. triandra was related to the secondary metabolite-Eupatilin.

Plants harmed by herbivorous insects can produce a large amount of toxic chemical defense substances to enhance their resistance. In order to explore the role of Streltzoviella insularis larval gut bacteria in overcoming the defense substances of Fraxinus chinensis, the verbascoside content of F. chinensis (infested and uninfested) phloem were determined by High-performance liquid chromatography. The effect of verbascoside on the S. insularis was studied through artificial diet mixing verbascoside. The traditional culture techniques and 16S rDNA high-throughput sequencing technology were adopted to study the effect of antibiotics on the gut bacteria of S. insularis larvae. In vivo and in vitro experiments were carried out to study the degradation effect of the larval gut bacteria on verbascoside. The results showed that: (1) The content of verbascoside in the F. chinensis phloem was increased due to the harm of S. insularis larvae; (2) Verbascoside not only inhibited the growth of larvae, but also had a toxic effect on larvae; (3) Antibiotics can completely eliminate the larval gut bacteria; (4) It was found that the gut bacteria of the S. insularis larvae can degrade verbascoside, among which Serratia sp. (G9) and Myroides sp. (G17) had the strongest effect, the degradation rate reaching to 100%.

In this study, we screened and isolated a cellulase-producing strain Gibbsiella acetica SGA from the gut of the Apriona germari larvae using CMC-Congo red staining method, and conducted morphological identification, molecular biological identification, and optimization of fermentation conditions. Through single-factor experiments, optimal cultivation conditions for the strain were determined, including a 24-hour incubation period, initial pH of 7, 5% inoculum size, 100 mL liquid volume, a cultivation temperature of 32 ℃,14 g/L glucose as the carbon source, and 6 g/L yeast extract as the nitrogen source. Orthogonal optimization experiments established the best ratio of glucose at 1.4%, yeast extract at 0.6%, liquid volume at 50%, and pH at 6. Under these optimized fermentation conditions, the CMC enzyme activity of SGA reached 203.24 μg/h/mL, representing a 1.35-fold increase compared to the initial culture conditions. This research lays a foundation for the future application of the G.acetica SGA strain, facilitating the diversification of cellulose-degrading microbial resources.

Due to anthropogenic drainage and climate change, The groundwater level of Zoige Peatland has generally decreased due to anthropogenic drainage and climate change, and there are different drainage durations and microhabitat differences,which may have significant effects on the changes of plant communities in the peatland. In order to accurately evaluate the response of plant communities in peatland to different drainage duration and microhabitat differences, two types of peatlands with short drainage duration (S) and long drainage duration (L) were selected in this study. 12 peatlands with different microhabitats (in terms of slope location and ditch distance) were selected, and the nearby undrained peatland (NS) on the middle slope was used as the control. The change of plant community was compared. The results showed as follows: 1) Compared with NS, the average above-ground biomass of the two peatland types (S and L) with long drainage duration increased, while plant diversity, total coverage, species richness and evenness decreased. The above-ground biomass of Gramineae and Cyperaceae plants increased gradually, while that of Caltha scaposa and Cremanthodium brunneo-pilosum plants decreased gradually. 2) Compared with S, the total above-ground biomass and total plant coverage of L plants decreased significantly, the richness and evenness of plant species decreased, and the plant diversity increased. 3) Plants in different microhabitats of the peatlands responsed differently to the response of plants to the same drainage duration was different in different microhabitat of peatland: from the bottom to the middle to the top of the slope, the total biomass, total coverage and species richness gradually decreased along the slope from bottom to top, while the diversity and evenness gradually increased. From far-ditch to near-ditch peatlands, there was no significant difference was shown in above-ground biomass, but the total coverage and species richness decreased gradually, while the diversity and evenness increased gradually. 4) Multivariate analysis of variance showed that drainage duration only had a significant effect on the total plant coverage, while microhabitat had a significant effect on total plant coverage, evenness and diversity, and the collaboration of drainage duration and ditch distance had a significant effect on plant community evenness. Therefore, different drainage durations have a significant impact on plant communities in peatland, and plant communities in different microhabitats have different responses to the same drainage duration. Drainage duration and microhabitat may affect the carbon input of peatland by changing the biomass and species composition of plant communities in peatland.

In order to explore the distribution and optimal habitats for the wild Hesperis oreophila in Hebei Province, the environments of two populations in Saihanba and Wuling Mountain were investigated, and the correlation between habitat conditions and biological characteristics was analyzed. The results showed that: (1) Both populations were distributed in meadows, woodlands and roadsides; Compared with the Saihanba population, the Wuling Mountain population had a higher average distribution altitude, more precipitation in the wettest season, and a smaller average distribution density. Conversely, the Saihanba population had a higher forest coverage, higher environmental humidity, and more fertile and loose soil; The pH value of the Saihanba population was significantly reduced by 9.37% compared with that of the Wuling Mountain population, and the contents of organic matter, alkaline hydrolyzed nitrogen, available phosphorus, available potassium were significantly reduced by 25.88%, 38.08%, 50.85%, and 29.60%, respectively. (2) The coefficients of variation of leaf and branch number of plants in different plots of Saihanba population were higher than 70%, and the coefficient of variation of leaf and branch number of plants in different plots of Wuling Mountain population were 54.29% and 72.93%, respectively; Compared with the Wuling Mountain population, the average number of leaves and branches increased by 29.84% and 61.00%, while the average flower diameter and flowering number decreased by 11.11% and 23.95%, respectively; Compared with the two populations, the variation of flower color in the Wuling Mountain population was greater, and the coefficient of variation (absolute value) of a^* and b^* exceeded 30%. The mean L^* value of leaves in the Saihanba population was significantly increased by 4.99%. (3) Correlation analysis showed that habitat factors such as mean temperature in the hottest season, precipitation in the wettest season, light, soil moisture and soil available phosphorus were significantly correlated with plant phenotype and relative content of chlorophyll. Based on the results of habitat survey and correlation analysis, the growth of this species was better in the fertile soil and humid environment.

In order to investigate the inheritance pattern of ploidy in the offspring of crosses between Ulmus macrocarpa and tetraploid Ulmus pumila and their differential metabolites from the parents, heterozygous triploid U. pumila offspring obtained from crosses between diploid U. macrocarpa and tetraploid U. Pumila and their parents were used for ploidy identification by flow cytometry, and metabolite differences between parental and heterozygous triploid U. pumila offspring were analyzed by non-target metabolomics. The results showed that:(1) The filial generation obtained by hybridization were allotriploid. (2) There were significant differences in the number and content of the different metabolites between the elm heterozygous triploids and the parents. A total of 121 metabolites were screened, including cis-aconitic acid, D-glucuronic acid and phosphoserine the content which were higher than those of the parents; Cortexolone, (R)-pantolactone and mannobiose were lower than those of the parents; And the contents methyl eugenol, versicolorone and tocainide were between those of the parents, which were intermediate to those of the parents. (3)The metabolic mechanisms that differentiate heterozygous triploid U. pumila from its parents mainly lied in the fatty acid metabolic pathway and the phenol propane biosynthetic metabolic pathway. The major metabolites of heterozygous triploid U. pumila differed significantly from those of the parents, and the quantity and content of metabolites were closely related to their phenotypic, physiological and abiotic stress resistance.

In order to screen the appropriate conditions for colchicine to induce polyploidy of Pyrus calleryana, germinating seeds were treated with colchicine by soaking method, and the effects of different concentrations and treatment time on seed germination, seedling formation and mutagenesis were studied. The tetraploid mutant plants were identified by phenotypic observation, stomatal characteristics and chromosome count. The results showed that: (1) Colchicine inhibited the germination and seedling formation of P. calleryana; With the increase of treatment concentration and the extension of treatment time, the seed germination rate and seedling formation rate decreased gradually, and the mutagenesis rate increased first and then decreased. Treatment with 0.8% colchicine had the best induction effect for 36 h, and the tetraploid induction rate was 35%. (2) The chromosome count in root tip showed that the number of tetraploid chromosomes was 2n=4x=68, and the number of stomata and guard cells increased and the density decreased. (3) Compared with diploid plants, tetraploid plants were shorter at first and then grew taller, having thicker stems, larger, darker and thicker leaves, and there were significant differences in physiological and biochemical indexes.

In order to establish a mature Primula × pubescens tissue culture system, the method of tissue culture and rapid propagation was adopted, the effects of different culture media, different plant growth regulator types and concentration ratios on callus induction and differentiation, adventitious bud proliferation and rooting culture were studied by using Primula × pubescens leaves as explants, and the vitrification phenomenon in the tissue culture process was restored. The results showed that: (1) The optimal callus induction medium was MS+6.0 g/L agar+30.0 g/L sucrose+1.2 mg/L NAA+1.5 mg/L 6-BA, the induction rate could reach 96.67%, and the callus was green and compact in texture. (2) The most suitable medium for callus differentiation was MS+6.0 g/L agar+30.0 g/L sucrose+0.5 mg/L NAA+2.0 mg/L 6-BA, and the differentiated clumps of buds grew robustly. (3) The optimal adventitious bud proliferation medium was MS+6.0 g/L agar+30.0 g/L sucrose+0.5 mg/L NAA+0.2 mg/L 6-BA, the proliferation rate could reach 70.33%, and the seedlings were green and vigorously grown. (4) The most conducive medium for rooting-induced was MS+6.0 g/L agar+30.0 g/L sucrose+0.2 mg/L NAA, with a rooting rate of 70.67%, and the roots were thick and not easy to fall off. (5) The recovery effect of 0.5 g/L activated carbon or 3.0 mg/L AgNO₃ vitrified seedlings was the best in medium.

In order to fully explore the ornamental value of the landscape forest resources of Saihanba National Forest Park, optimize horizontal patch pattern of the autumn landscape forest in Saihanba, studying the color quality and influence factor of autumn landscape forest, 25 representative landscape forest pictures were selected by drone aerial photography in Saihanba, and using BIB-LCJ method to design questionnaire to evaluate autumn landscape quality. Color Impact and ArcGIS software were used to quantify color processing and divide color patches to analyze the color elements that affects the landscape quality in autumn. The results indicated that: (1) Based on the beauty value, Saihanba autumn landscape level above grade Ⅲ was 56%. (2) Color elements with significant correlation with beauty value were ranked by contribution size, the negative index was largest patch index>background proportion; The positive index was division index> patch evenness index>saturation index>main color comparison>lightness index>color uniformity index>hue index. (3)The dominant hue ratio was 57.85%, saturation index was 0.25, lightness index was 0.44, maximum patch index was 18.58%, and division index was 0.85. The color patches were broken and even. The beauty value of Mongolian oak - spruce mixed forest with background ratio of 21.76% was the largest. In conclusion, Saihanba landscape aesthetic quality was relatively beautiful. Division index, patch evenness index and largest patch index have a significant influence on the landscape color quality in the study area.