The genus Loxocarpus R. Br. sensu lato is the endemic group of Southeast Asia and Sundaland. The species in Loxocarpus exhibit differentiation and diversity in floral organs with similar habits and morphology in vegetative organs and fruits. However， evidence from molecular phylogenies indicates that Loxocarpus sensu lato is polyphyletic. According to correlated morphological characters combined with molecular data， we separated Loxocarpus sensu lato into three genera， including Loxocarpus sensu stricto and two new genera， i.e. Yaoa and Paraloxocarpus. In the present study， the three genera were described with a key to them， and 21 new combinations were proposed.

The formation of Qinghai Province’s geology and geomorphology and the evolution history of natural ecosystem are consistent with those of the whole Qinghai-Xizang Plateau. In order to reveal the distribution patterns of wild seed plants along vertical gradients in Qinghai Province and to provide fundamental data for exploring their adaptive mechanisms to vertical ecological and geographical environments， this study systematically analyzed the elevational distribution patterns of 3 558 plant species in Qinghai Province by integrating literature and herbarium specimen data. The analysis showed that： （1）Plants in Qinghai Province were not randomly distributed in the vertical dimension along the elevational gradient， but can be divided into certain “layer” and “grade” sequences. This was the Layer-Grade system of vertical distribution among plant species established in this paper for the first time. This division was based on the starting elevation of their respective occurrence and upper elevation and the range of vertical heights they extend. （2）Within the scope that by the layers 2 000 m and the grade 4 000 m intersect formation formed intersection sequence， it was the elevation range where plant species were most vertically distributed and most concentrated in Qinghai. （3）All plants with wide vertical height ranges were geographically widespread species； plants with narrow vertical height ranges usually had a narrow geographic distribution as well. （4）The vertical elevation zone of 2 000-4 000 m was the most suitable and most concentrated distribution range and the most prosperous habitat of all kinds of shrubs in Qinghai Province. （5）The range covered four layers （B， C， D， E） starting from an initial elevation of 2 000 m and extending to 3 500 m. Each of these layers extended vertically to an upper elevation of 5 000 m， encompassing 18 multi-grade units. This range represented the most concentrated vertical distribution of plants in Qinghai and can be described as the core zone. （6）Within the same genus， the obvious stepped vertical substitution distribution was one of common and basic survival strategies among plant species in Qinghai. This study had strong theoretical and practical significance and great reference significance for a comprehensive understanding of the elevation distribution characteristics and laws of plants on the plateau surface， and had good guiding value for biodiversity conservation， biological resources development and utilization， species evolution and adaptation in the future.

Structural characteristics of chloroplast genome could reflect the phylogenetic and evolutionary relationships among plants. In this study， the chloroplast genomes of seven species from Tamaricaceae were sequenced and assembled by the Illumina HiSeq platform. Combined with published chloroplast genome sequences from Tamaricaceae and its allies， we conducted comparative analyses of chloroplast genome sequence variation， structural characteristics， relative synonymous codon usage of protein-coding genes， and phylogenetic relationships. The results showed that the ten chloroplast genomes of Tamaricaceae exhibited a quadripartite structure， with a total length ranging from 154 684 bp to 156 178 bp. These chloroplast genomes contained approximately 130 protein coding genes， including 111 non-redundant genes. The GC content and relative synonymous codon usage（RSCU） were consistent with those of typical angiosperm chloroplast genomes. Moreover， we identified 27-54 simple sequence repeats（SSRs） in each genome， which are predominantly composed of A/T bases. Phylogenetic results supported Tamarix austromongolica and Myrtama elegans as members of Myricaria. The results revealed the conserved chloroplast genome structures across the ten Tamaricaceae species， with distinct interspecific variations that offer valuable information for resolving phylogenetic relationships and identifying species within this family.

Compared with traditional breeding method， the doubled haploid （DH） induction technology can effectively shorten the breeding cycle and quickly obtain homozygous lines of trees. Due to the difficulty in inducing DH in trees， it is hard to establish large-scale DH genetic populations， therefore， there are currently few reports on the genetic variation of DH populations in trees. In this study， the growth traits， leaf phenotypes and anatomical characteristics of donor tree of Populus simonii × P. nigra and four DH lines were analyzed. The results showed that the DH lines had obvious growth defects. The height， ground diameter， number of stem nodes， leaf length， leaf width and leaf area of DH lines were significantly lower than those of donor trees. Anatomical analysis of the apical buds revealed distinct morphological differences in the apical meristem growth points between donor trees and DH lines. The observation and analysis of the paraffin sections of the stems and the tissue staining showed that the vascular cambium of DH lines was relatively smaller， the average area of each vessel cell was smaller， and the number of vessel and fiber cells was significantly higher than that of donor trees. This study revealed the defects of DH lines in secondary growth， and will provide a material basis for subsequent research on the function analysis of specific genes and the optimization of breeding strategies.

The botanical characteristics and germination traits of Artemisia hedinii seeds from two natural populations in Tanggula Town（TGL） and Yuegai Town（YG） of Qinghai Province were investigated， and functional traits such as morphological characteristics， seed viability， water absorption rate， and water content were determined， and the effects of constant temperature， alternating temperature， and gibberellin（GA₃） treatments on seed germination traits were studied using germination rate， germination energy， and germination index as indicators. Additionally， conventional chromosome squashing technique and karyotype analysis were employed to reveal differences in chromosome karyotype characteristics between the two populations. The results showed that A. hedinii seeds were flat and slender， with 1 000-seed mass of 0.121 2 g（YG） and 0.090 1 g（TGL）， respectively， and seeds reached water saturation after 24 hours of imbibition. Temperature was a critical factor affecting seed germination， under the optimum germination temperature （25 ℃）， the germination rate exceeded 85%； a low temperature（5 ℃） led to no seed germination， while a high temperature（35 ℃） reduced the germination rate to the values less than 72%， the appropriate temperature and GA₃ treatments significantly improved germination indices. GA₃ could alleviate the inhibitory effect of high temperature on germination to a certain extent but had no effect on inhibition of low temperature. The chromosome number of A. hedinii was 18， with a basic chromosome number of 9， and the karyotype formula was 2n=2x=18m， karyotype type was 1A， and chromosome was symmetrical. The chromosome length ratio， average arm ratio， and karyotype asymmetry index of the Tanggula Town population were all higher than those of the Yuegai Town population. In conclusion， temperature was an important factor regulating A. hedinii seed germination. The optimal germination temperatures for both populations were constant 25 ℃ and variable temperature 25 ℃/15 ℃， and GA₃ could effectively promote seed germination under high-temperature conditions. A. hedinii was a diploid plant with 18 stable and symmetric chromosomes， and heterogeneous environment might play a significant role in the chromosomes evolutionary direction of A. hedinii， driving the chromosome karyotype evolution in specific directions.

Camellia fascicularis，as a National Class II Key Protected Plant and a wild plant with extremely small populations in Yunnan Province， scientific guidance is urgently required for its population reconstruction and conservation. In this study， simplified genome sequencing method using Hyper-seq technology was used to evaluate and analyze the genetic diversity， population genetic structure and screen core germplasm among 133 accessions collected from three wild populations（Hekou， Mengzi and Maguan） and two ex situ conservation populations（Kunming Arboretum and Wenshan Arboretum）. The results revealed that genetic diversity of C. fascicularis was high， an average expected heterozygosity（H_E） was 0.232 6， an average observed heterozygosity（H_O） was 0.365 9， and an average nucleotide diversity（P_i） was 0.372 5. The genetic diversity of the ex-situ conservation populations（KMSMY and WSSMY） was slightly lower than that of the MG population and higher than those of the MZ and HK populations， but the H_E， H_O and P_i values of both ex-situ conservation populations did not reach 90% of the species-level benchmark. Genetic structure analysis showed that 133 individuals from five populations were categorized into four clusters， the MG and KMSMY populations showed more complex genetic structure and backgrounds. Population genetic differentiation showed that the degree of genetic differentiation among populations was very high（F_st=0.410 3）. In conclusion， 27 core germplasms were extracted from 133 germplasms based on genetic distance， which effectively represented the genetic diversity of C. fascicularis. This study first analyzed the genetic characteristics of C. fascicularis at the genomic-level， providing crucial theoretical foundations for formulating in situ conservation strategies， optimizing the ex situ preservation protocols and implementing scientific population reconstruction for this endangered species.

The aim of this study was to explore the characteristics of self-incompatible behavior between pollen and stigma during self-pollination of jujube（Ziziphus jujuba）. The effects of different sample drying methods on jujube ‘Junzao’ flower stigma samples were compared by scanning electron microscopy（SEM）， and the technical parameters of SEM acceleration voltage and sample working distance were systematically optimized respectively. The results showed that high-clarity and high-resolution microscopic images of jujube flower stigma papillae cells were obtained by using CO₂ critical point drying and optimized parameters of SEM working distance with 5.4-10.8 mm and acceleration voltage of 3.0 kV. Based on the optimized SEM system，the microstructure of jujube ‘Junzao’ stigmas and pollen-stigma interactions after self-pollination（‘Junzao’בJunzao’）and cross-pollination（‘Junzao’בQingjian Suanzao’）were observed respectively. The results indicated that the pistil of jujube was a “bifurcate” type of pistil，the stigma surface was composed of clusters of papillae cells，the diameter of individual papillae cell was 10-18 μm. There were no significant differences in the adhesion，hydration，germination and growth of pollen on the stigma between self-pollination and cross-pollination. Further observations using fluorescence microscopy revealed that self-pollinated pollen tubes grew to 1/2 style channels and showed swelling and curling，while the cross-pollinated pollen tubes grew to the bottom of the style， indicating that jujube had a typical gametophytic self-incompatibility. This study systematically elucidated the dynamic characteristics of pollen-stigma recognition and pollen tube growth in self-incompatible jujube， which had important scientific value and application significance for understanding the reproductive characteristics of jujube and the guidance for practical hybrid breeding.

To establish a high quality variety screening system for Rhododendron， seven Rhododendron species from the azalea germplasm bank of Yunnan Agricultural University were taken as materials， and their ornamental values were evaluated by Analytic Hierarchy Process， and the drought resistance was evaluated through the determination of physiological indexes under drought stress， and cross-compatibility of high-quality species was evaluated by the cross-breeding and fertility tests. The results showed that R. × pulchrum ranked first for its compact plant shape， high flower and leaf fullness， and garden application potential. R. simsii had the highest ornamental score for its flowers， but a small number of flowers in each inflorescence， small leaves， and defoliation in winter， ranking the second. R. delavayi had the highest overall ornamental score， but relatively low potential for garden application， ranking the third. The drought resistance was ranked as R. × pulchrum > R. simsii > R. dauricum > R. vialii > R. delavayi > R. molle > R. decorum. The optimal group among seven hybrid groups was R. delavayi × R. simsii， because the fruit setting rate was 27.3%， and seed germination rate was 100.0%. However， no hybrid offspring was obtained from the hybrid combination of R. × pulchrum either as the male or female parent. In conclusion， the ornamental value and drought resistance of R. × pulchrum was the best， and the ornamental value and drought resistance of R. simsii and R. delavayi were the second， and the hybrids were compatible.

In order to provide experimental basis for palynological and taxonomic studies of Orchidaceae， pollen morphological characteristics of 13 wild orchids from 10 genera in Mount Emei were investigated and compared by light microscopy and scanning electron microscopy. The results indicated the rich diversity of pollen morphology of wild orchids in Mount Emei， and the pollen morphology of species from three genera， Holcoglossum， Odontochilus and Rhomboda were demonstrated for the first time. The properties of pollinium （granular， waxy）， texture （granular pollinium， separable pollinium，hard pollinium）， number （2，4，8）， morphology （e.g.， horseshoe shaped， crescent-shaped， obovoid， spherical， oblanceolate， clavate， etc.）， surface structure （smooth but uneven， granular， rough， stripy， laminated， etc.） of pollinia， as well as the pollen dispersal units （tetrahedral pollen， massulae， pollinium） and their exine ornamentation （foveolate， fine reticulate， pitted， coarse reticulate， fine punctate， smooth， etc.） varied greatly among genera， while the pollen morphological characteristics of different species within the same genus shared certain features， but there were also specificities. There were significant differences in surface structure of pollinia and exine ornamentation of pollen dispersal units among the four species of the genus Calanthe. The results showed that pollen morphological characteristics was an important basis for identifying closely related species within and between genera of Orchidaceae. There was strong differentiation of orchids in Mount Emei， with a high proportion of endangered and endemic species. Therefore， it is necessary to strengthen research on the diversity of pollen characteristics of wild orchids in this area.

To explore the main physiological and biochemical factors affecting the dormancy release of seeds， the seeds of P. polyphylla var. yunnanensis were used as materials， and the phenotypic changes of embryos were observed by stereomicroscope. Five typical stages（S1， spherical embryo； S2， short cylindrical embryo； S3， conical embryo； S4， torpedo embryo； S5， budding） were screened out， respectively. Physiological and biochemical methods and ELISA were used to determine the nutrient content， enzyme activity and plant hormone content in the seeds at each stage. The results showed that the embryo rate was finally（66.50±6.22）%； the water absorption rate was 76.54%. The main nutrient of P polyphylla var. yunnanensis seeds was starch. During the germination process， the contents of starch， free amino acids and activity of glucose-6-phosphate dehydrogenase（G-6-PDH） showed a decreasing trend； the content of soluble sugar showed a trend of decreasing first， then increasing and then decreasing again； the activities of peroxidase（POD）， malate dehydrogenase （MDH） and content of gibberellin A₃（GA₃） showed a trend of increasing first and then decreasing； the contents of gibberellin A₄（GA₄） and indole-3-acetic acid（IAA） showed a trend of decreasing first and then increasing， superoxide dismutase（SOD） activity increased significantly in S5 stage， catalase（CAT） activity showed a trend of M type fluctuation， abscisic acid（ABA） content showed a trend of ‘decreasing-increasing-decreasing-increasing’. The embryo rate was significantly positively correlated with SOD activity， and significantly negatively with G-6-PDH activity and free amino acids content. GA₃ content was significantly positively correlated with CAT activity， GA₄ content was significantly positively correlated with contents of starch and amino acids（P<0.01）， while IAA content was significantly negatively correlated with soluble sugar content（P<0.01）. The dormancy type of P. polyphylla var. yunnanensis seeds was morphological and physiological dormancy； and the development status of embryo was closely related to the fluctuation of physiological and biochemical indexes. The increases in contents of soluble sugar， free amino acid， GA₃ and GA₄， GA₃/ABA and IAA/ABA， and activities of SOD， POD and CAT were all helpful to the release of seed dormancy.

Highland barley is a grain crop adapted to alpine environments and plays a crucial role in agricultural sustainability and ecosystem stability．To elucidate the dynamic changes in endophytic bacterial communities in highland barley seeds across growth stages，seed samples from four varieties were collected and analyzed using 16S rRNA high-throughput sequencing．Alpha diversity was assessed using Shannon，Simpson，Chao1 and ACE indices，and community composition and its succession across growth stages were analyzed．The results showed that the diversity of endophytic bacterial communities in highland barley seeds remained relatively stable among varieties but significantly decreased during the grain-filling stage．Proteobacteria was the dominant phylum at all growth stages，with other dominant phyla including Bacteroidota，Firmicutes，and Actinobacteriota．The relative abundance of these phyla varied significantly with growth stages and exhibited variety-specific characteristics．Acinetobacter was the dominant genus at the seed stage，Bacillus and Pseudomonas prevailed during the grain-filling stage，and Flavobacterium and Lactobacillus were most abundant at maturation．The results also indicated that genotype significantly influenced the structure of endophytic bacterial communities，resulting in compositional differences among varieties．The community composition and diversity characteristics at different developmental stages suggest that endophytic bacteria may play crucial promotive and protective roles in the growth and development of hulless barley by facilitating nutrient acquisition， synthesizing plant growth hormones， enhancing tolerance to environmental stresses， and suppressing pathogenic microorganisms， thereby providing a scientific basis for further elucidation of their ecological functions and molecular regulatory mechanisms.

China is one of the distribution centers of Ribes L. plants in the world. In order to reveal the characteristics of species diversity and distribution patterns of Ribes L. in China， and to explore its relationship with environmental factors， the field surveys， specimen identification and data analysis were conducted. The results showed that： （1）There were 56 species of wild Ribes L. plants in China， belonging to six subgenera： subgenus Grossularia， subgenus Ribes， subgenus Berisia， subgenus Coreosma， subgenus Hemibotrya and subgenus Grossularioides.（2）Wild Chinese Ribes L. plants were mainly distributed in the southwest， northwest and northeast regions， the northwest region had the highest species richness， with 34 species belonging to five subgenera， followed by the southwest region with four subgenera and 30 species， and the northeast region had six subgenera and 16 species. （3）The vertical distribution patterns of wild Ribes L. plants in China were remarkable， and the elevation of the concentrated distribution of Ribes L. gradually increased with the decrease of latitude. In the higher elevational northeast region， Ribes L. plants were distributed in the elevation range from 700 to 2 100 m， and concentrated in the elevation range of 700 to 1 500 m. In the middle elevation northwest region， Ribes L. plants were distributed in the elevation range of 1 000 to 3 000 m， and concentrated in the elevation range of 1 000 to 2 000 m. In the lower elevation southwest region， Ribes L. plants were distributed in the elevation range of 2 500 to 5 000 m， and concentrated in the elevation range of 2 500 to 4 000 m.（4）There were 25 endemic species of the Ribes L. in China， including 19 species in the southwest， 15 species in the northwest， none in the northeast， and three endemic species in other regions of China. The distribution of regional endemic species of the Ribes L. was obvious， with 12 species in the southwest， nine in the northwest and eight in the northeast， respectively. No common species were found in the southwest， northwest and northeast regions. In conclusion， the species composition of the Ribes L. in China showed a distinct geographic distribution pattern， the species composition varied in different regions， and this study revealed the species diversity characteristics and distribution pattern of the wild Ribes L. plants in China.

Based on the establishment of species list and geographical distribution database， the species diversity and geographical distribution pattern of wild Impatiens in Sichuan Province were studied. The species composition， endemicity， geographical distribution pattern in Sichuan Province were analyzed through systematic literature retrieval， specimen textual research and field investigation respectively， and the hot spot area of Impatiens distribution were determined by screening algorithm. The results showed that a total of 108 wild species （including one variety） of Impatiens were recorded in Sichuan Province by April 2025， distributed in 82 counties， with 94 species endemic to China and 41 species endemic to Sichuan Province. The vertical distribution was most abundant at the elevation of 2 000~2 500 m. Nine hot counties， including Emeishan City， Mianning County， Muli County， Kangding City， Shimian County， Yanyuan County， Jiulong County， Jinchuan County and Zhaojue County were screened， which contained 80.55% of the wild Impatiens in Sichuan Province. Sichuan Province was characterized by diverse geomorphologic types and well-developed river systems， the distribution of Impatiens had high species diversity and regional endemicity. The study clarified and improved the species diversity of Impatiens in Sichuan Province， and provided the reference for protection， development and utilization of endemic germplasm resources.

In order to clarify the competitive influence of rare and endangered plant Ammopiptanthus mongolicus， this study selected the ecotone between A.mongolicus and Zygophyllum xanthoxylum， and used Hegyi single tree competition model to analyze the intraspecific and interspecific competition relationship by investigating 25 target trees of A.mongolicus. The results showed that intraspecific and interspecific competition intensity of A.mongolicus accounted for 5.09% and 94.91% of the total competition intensity（341.32）， respectively， indicating that the competition of A. mongolicus was mainly derived from interspecific competition. There were many competing tree species of A.mongolicus in the ecotone， and the competition intensity from high to low was Artemisia xerophytica， Caragana brachypoda，Z.xanthoxylum，Oxytropis aciphylla， A.mongolicus， Reaumuria trigyna， Krascheninnikovia ceratoides， Reaumuria soongarica， Potaninia mongolica， Asparagus gobicus. The relationship of the interspecific competition index and the total competition index with the crown width of A.mongolicus was approximately subject to the power function relationship， and the competition intensity decreased with the increase of crown width of target trees. When the crown width of target trees was less than 1.0 m， the competitive pressure was greater， and the obtained model could well reflect the competitive intensity of A.mongolicus.

In terrestrial angiosperms， the balance between water supply and consumption is primarily regulated through the coordination of leaf veins and stomata， with epidermal cells playing a significant role in this process. However， research on Nymphaeaceae species remains very limited. In this study， seven species of Nymphaeaceae and six species of terrestrial herbaceous plants were selected as materials. Through quantitative analysis of floral and leaf anatomical traits， the intraspecific variation within Nymphaeaceae and the differences in floral and leaf characteristics between the two plant groups were examined. The results indicated that flowers of Nymphaeaceae plants exhibited larger stomatal size， epidermal cells size， and a higher vein density than leaves， whereas leaves displayed greater stomatal density， epidermal cell density， and stomatal index. The anatomical traits of Nymphaeaceae flowers were similar to those of terrestrial herbaceous flowers， except for epidermal cell size. However， the epidermal cell density and stomatal density of leaves were significantly higher than those of terrestrial herbs， while stomatal size， epidermal cell size， vein density and stomatal index were notably lower than those of the terrestrial herbs. The stomatal density of Nymphaeaceae flowers had no correlation with either epidermal cell size or floral vein density； in leaves， epidermal cell size had a negative correlation with stomatal density， and no significant association was found between stomatal density and leaf vein density. Principal component analysis revealed that， compared to terrestrial herbaceous plants， Nymphaeaceae flowers had an advantage in epidermal cell density； meanwhile， leaf trait spaces were completely separated， with Nymphaeaceae leaves exhibiting higher epidermal cell density and stomatal density. In conclusion， the flowers of Nymphaeaceae exhibited the traits similar with terrestrial herbs， likely due to their water-retaining characteristics， while the decoupling of stomata and veins in leaves reflected adaptive evolution in the aquatic environment. These findings provided the valuable foundation for further research on water-use characteristics and environmental adaptation mechanisms in aquatic plants.

Exploring the impact of climate warming on water use efficiency（WUE） of treesis significant for understanding the responses of tree carbon-water coupling to climate warming. In 2004， Larix gmelinii seedlings grown in four sites along temperate gradient（e.g.， Tahe， Songling， Sunwu and Dailing） simulating climate warming were transplanted to a common garden（Mao’ershan） near the natural edge of this species’ range. In August 2022， in the common garden and four different transplanting sites， the instantaneous water use efficiency（WUE_i） and intrinsic water use efficiency（WUE_g） were measured using the gas exchange method， and long-term water use efficiency（WUE_L） was calculated via carbon-13 isotope abundance to explore the effects of different simulating climate warming magnitudes on WUE of L. gmelinii. The results showed that both WUE_i and WUE_g significantly increased， with an increase of 33.37%， 38.84%， 42.06% and 58.76% for WUE_i， and an increase of 15.94%， 18.47%， 20.84% and 39.10% for WUE_g of L. gmelinii under the simulated climate warming by transplantation from the sites Tahe， Songling， Sunwu and Dailing， respectively. The WUE_L significantly increased by 16.92% and 30.56% for Songling and Tahe， respectively. The increasing rate of WUE_i， WUE_g and WUE_L showed positive linear correlations with the warming magnitude. Both WUE_i and WUE_g showed significant and similar site differences in the common garden and among the transplanting sites， while WUE_L showed significant differences only among the transplanting sites. WUE_i was sensitive to all the warming magnitudes， but WUE_L was sensitive only to the high warming magnitude. Therefore， the warming magnitude and the determining methods should be taken into consideration in tree WUE responses to climate warming.

The aim of this study was to explore the effects of variations in rainfall on the growth and C， N， P stoichiometric characteristics of Fraxinus malacophylla seedlings， which could provide a theoretical basis for the application of F. malacophylla seedlings in karst vegetation restoration. In this study， two-year-old F. malacophylla seedlings were used as materials， and the treatments with 40% increased rainfall， 40% reduced rainfall， natural rainfall， and 5- and 10-day rainfall intervals were set， and the responses of seedling biomass and C， N， P stoichiometric characteristics were investigated， respectively. The results showed that both extending the rainfall interval and reducing rainfall significantly inhibited biomass accumulation of seedlings， roots， stems， and leaves， whereas increasing rainfall had an opposite effect. Leaf C and P contents significantly increased（P<0.05）， whereas leaf N content significantly decreased under the increased rainfall（P<0.05）. Under the reduced rainfall， the contents of C， N， and P in roots， C and P in stems， C and N in leaves significantly decreased at a five-day rainfall interval（P<0.05）. The contents of C， N， and P in roots， stems， and leaves significantly decreased at a 10-day rainfall interval（P<0.05）. Under the conditions of reduced and natural rainfalls， the leaf N∶P ratio was greater than 16， indicating that the growth of seedlings was limited by P. Under the increased rainfall， the leaf N∶P ratio ranged from 14 to 16， indicating that the growth of seedlings was limited by both N and P. The above results revealed that F. malacophylla seedlings responded to rainfall changes by regulating the biomass accumulation and C， N， P stoichiometric characteristics in organs. The findings could provide a scientific basis for restoration of vegetation in Karst regions and for the cultivation and management of F. malacophylla.

To explore the species composition， floristic geographical components， and diversity characteristics and patterns of change in the herbaceous communities of waterfalls in Dehang Geological Park， three herbaceous communities of waterfalls were used as materials， and the importance values， floristic geographical components， species α and β diversity， nutritional traits， reproductive traits， and phylogenetic diversity were analyzed respectively， and the basic data of plant diversity in waterfall habitats was provided. The results indicated that a total of 85 species from 66 genera and 35 families of herbaceous plants were identified， and Aster ageratoides， Strobilanthes oligantha， Pilea notata and Pilea sinofasciata were the dominant species. The geographical distribution types were consistent with the floristic characteristics of the East Asia， with more tropical components in Dalongdong and a less proportion in Xiannvtan. In terms of alpha diversity， Shannon-Wiener and Simpson indices of plants in Dalongdong were higher， but the Pielou index was the lowest； beta diversity indices were consistent， with the highest value occurred between Dalongdong and Liusha Waterfall， and the lowest value occurred between Liusha and Xiannvtan Waterfall. The life habits were predominated by perennial herbs， with medium-sized， simple， papery， unlobed， and serrated leaves. There were differences in leaf arrangement and pubescence； reproductive traits were mainly characterized by bisexual flowers， terminal and axillary， dry fruits， and wind-dispersed seeds， with flowering periods concentrated from May to August and fruiting periods from August to October， and differences in inflorescence type. The herbaceous communities exhibited a clumped distribution， with environmental filtration being as a primary factor influencing community structure. The herbaceous community in the Dehang waterfalls exhibited unique diversity characteristics compared to the other communities.

In the context of climate change intensification and increasing limitation of arable land， improving drought tolerance in forest trees has emerged as a critical breeding goal. However， achieving enhanced stress resistance without compromising growth and biomass production remains a major challenge. In this study， transgenic 84K poplar （Populus alba×P. glandulosa ‘84K’） lines constitutively overexpressing PagPYL4 gene， an abscisic acid（ABA） receptor gene， were developed， and their physiological and growth responses were evaluated under drought stress. The results showed that under the influence of exogenous ABA， the overexpression of PagPYL4 gene significantly altered stomatal aperture in plants. Under short-term drought treatment， compared with the wild type， the overexpression of PagPYL4 gene reduced water loss and improved drought tolerance； however， it also inhibited stomatal conductance and photosynthetic rate， leading to a significant decrease in growth rate of plant height and ground diameter. Our findings demonstrated that while PagPYL4 overexpression effectively enhanced drought resistance， its indiscriminate activation can impose substantial growth penalties. This highlighted the importance of spatially and temporally regulated gene expression strategies to balance stress resilience and biomass productivity in future tree breeding programs.

Birch（Betula platyphylla）， as a perennial woody plant， is difficult to obtain homozygous plants and families due to its long growth cycle and complex genotype， which leads to slow progress in its breeding work. Double haploid breeding technology is a breeding method that has emerged in recent years. It only requires two generations to obtain homozygous plant families. Therefore， double haploid breeding technology can greatly shorten the process of forest breeding and obtain homozygous families， while the discovery and application of the DMP gene has opened up a new research direction in doubled haploid breeding. This article aimed to study the BpDMPs gene family in birch， and revealed its physicochemical properties， protein structure， systematic evolution， gene structure， chromosome distribution， and potential functions in the growth and development process of birch through bioinformatics analysis； to identify the birch DMP gene with haploid induction function in the gene family through expression pattern analysis， and verify the gene function through Arabidopsis complementation experiments. The bioinformatics analysis results showed that birch contained 14 gene family members， distributed on six chromosomes. Phylogenetic analysis showed that 14 genes in the BpDMPs gene family belonged to five branches. The predictive analysis of cis-acting elements in the promoter of the BpDMPs gene family showed that the promoter contained response elements related to growth and development， hormone metabolism， stress response， and so on. The qRT-PCR results showed that there were significant differences in the expression levels of BpDMPs in various tissues of birch， with BpDMP2 and BpDMP7 having higher expression levels in the stamens. Through Arabidopsis complementation experiments， it was demonstrated that the BpDMP7 gene can replenish the phenotype of Arabidopsisdmp8dmp9 mutant grain sterility. This article provided basic information for further studying the functions and regulatory mechanisms of the BpDMPs gene family， and offered a new perspective for understanding the roles these genes play in plant growth， development， and environmental adaptation processes.