Table of Content

20 April 2023, Volume 32 Issue 4

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Spatial distribution of ecosystem services in the desert steppe， Inner Mongolia based on ecosystem service bundles

Yu-xia HU, Ji-rui GONG, Chen-chen ZHU, Jia-yu SHI, Zi-he ZHANG, Liang-yuan SONG, Wei-yuan ZHANG

2023, 32(4):  1-14.  DOI: 10.11686/cyxb2022142

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Ecosystem services play an important role in maintaining ecological security， sustainable development and human well-being. In this rresearch， the study area was the desert steppe of Inner Mongolia and a quantitative assessment of water conservation， soil conservation， habitat quality， and recreational potential in 2000 and 2017 was carried out. Their spatial and temporal distribution characteristics and the trade-offs and synergies between services are analyzed and discussed； the dominant service types and spatial patterns of different service bundles are identified. It was found that： from 2000 to 2017， the spatial heterogeneity of various ecosystem services was significant. The high-value areas of water conservation services are mainly concentrated in the southeast and southwest； the high value soil conservation is located in the southwest； the distribution of habitat quality and recreational potential is more random. Various ecosystem services show a mainly decreasing trend； most service pairs show a synergistic relationship， while soil conservation and habitat quality service pairs show a trade-off relationship， and the degree of correlation between service pairs decreases. Ecosystem service bundles are divided into three functional areas of soil conservation， living environment and water conservation and have obvious spatial heterogeneity. In the soil conservation area， the main land use type is unused land， and future management should limit the amount of grazing and seek to influence soil erodibility by changing the surface vegetation cover. The human settlement area， with high grassland cover provides excellent scope for human activities and the coordinated development of multiple industries such as eco-tourism. In the water conservation area， the land use types are mainly grassland with medium cover and grassland with low cover. Future management should focus on water storage and water conservation， adhere to ecological priorities， and pursue ecologically sustainable development in this area.

Remote sensing retrieval of nature grassland biomass in Menyuan County， Qinghai Province experimental area based on Sentinel-2 data

Rui GUO, Shuai FU, Meng-jing HOU, Jie LIU, Chun-li MIAO, Xin-yue MENG, Qi-sheng FENG, Jin-sheng HE, Da-wen QIAN, Tian-gang LIANG

2023, 32(4):  15-29.  DOI: 10.11686/cyxb2022147

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Above-ground biomass （AGB） is an important indicator for evaluating grassland productivity. Accurate inversion of AGB of natural grassland is of great significance for monitoring grassland growth and evaluating the feed balance of forage-livestock. As commonly used remote sensing data （such as Landsat and MODIS） suffer from by many problems caused by low temporal and spatial resolution， it is extremely important to explore Sentinel-2 satellite data with higher temporal and spatial resolution and more spectral bands in monitoring grassland vegetation at county scale. In this study， we used Sentinel-2 satellite remote sensing imagery and the AGB data of Menyuan County， Qinghai Province to construct a grassland biological monitoring system based on random forest （RF）， support vector machine （SVM） and artificial neural network （ANN） methods， to study the spatial and temporal distribution characteristics of natural grassland biomass in Menyuan County from 2019 to 2021. It was found that： 1） The three original bands（B2，B6，B11）and two vegetation indices， inverted red edge chlorophyll index（IRECI），and pigment specific simple ratio chlorophyll index（PSSRa），were the important variables for AGB quantification in natural grassland. Among these，red-edge bands（B5，B6，B7）play an important role in remote sensing inversion of natural grassland AGB. 2） The AGB estimation model based on the RF algorithm was the optimal model（validation set R² 0.72， RMSE 622.616 kg·ha^-1）for natural grassland biomass estimation in Menyuan County， which was superior to the SVM model（validation set R² 0.66，RMSE 698.271 kg·ha^-1）and the ANN model（validation set R² 0.63，RMSE 730.676 kg·ha^-1）. 3） The average value of AGB of natural grassland in Menyuan County from 2019 to 2021 ranged from 3360.26-3544.00 kg·ha^-1. In general， the AGB of grassland in Menyuan County from 2019 to 2021 showed a trend of initially increasing and then decreasing， with a spatial distribution pattern of gradual decrease from the periphery to the middle.

Climate sensitivity of the start of the growing season in spring and the end of the growing season in autumn for vegetation in Inner Mongolia

Kai-feng WANG, Gang BAO, Zhi-hui YUAN, Si-qin TONG, Zhi-gang YE, Xiao-jun HUANG, Yu-hai BAO

2023, 32(4):  30-41.  DOI: 10.11686/cyxb2022274

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The start of growing season （SOS） in spring and the end of growing season （EOS） in autumn are regarded as two important phenological indicators of vegetation growth. However， the sensitivity of these indicators to changes in climate， especially temperature， as well as their differences remain unclear. In this study， MODIS NDVI and meteorological data from 2001 to 2019 were used to calculate the SOS in spring and the EOS in autumn of vegetation in Inner Mongolia at meteorological station- and pixel-scales. In these analyses， the numbers of growing degree-days （GDD） and cooling degree-days （CDD； i.e. DD with mean temperature below the base temperature） were used as temperature indicators that affect the SOS and EOS. These analyses revealed spatial patterns of SOS and EOS and their sensitivity to climate change. It was found that， from 2001 to 2019， the SOS for vegetation in Inner Mongolia usually occurred around d 110-135 （where Jan 1^st=d 1）， and was progressively earlier with time （2.6 d·10 a^-1）. The EOS usually occurred around d 260-280， and showed a weak trend towards later occurrence （0.7 d·10 a^-1）. In 68.1% of the study area the SOS was advanced by GDD accumulation in the period immediately prior and similarly in 56% of the study area EOS was advanced by CDD accumulation in the period immediately prior. Both SOS and EOS were sensitive to precipitation， and the response was mainly positive （i.e. a delay of SOS or EOS）. The results at the meteorological station-scale were basically consistent with those at the pixel-scale. At the meteorological station-scale， the temperature sensitivity of 65% stations was greater at the EOS than at the SOS， and the precipitation sensitivity of 94% stations was greater at the SOS than at the EOS. In the context of climate change， the results of studies on sensitivity are useful for devising sustainable ecosystem management strategies， and have important reference value for phenological simulations and ecosystem climate assessments.

Potential excavation and evaluation of functional oat varieties in winter fallow field of southwest mountainous area

Yi-dan YAN, Ying-ying NIE, Li-jun XU, Xing-fa GAO, Yan-zhang RAO, Xiong RAO, Hong-zhi ZHANG, Cha-shu ZHAO, Yan-ping ZHU, Yu-bo ZHU

2023, 32(4):  42-53.  DOI: 10.11686/cyxb2022330

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In order to screen out oat varieties suitable for adoption and planting in winter fallow fields in southwest mountainous areas， 15 oat （Avena sativa） varieties were trialed in this study and five nutritional qualities of oats： protein， fat， starch， glucan and amino acid content， were analyzed. Grey correlation analysis and cluster analysis were used for multivariate data evaluation. The results were compared with Food and Agriculture Organization of the United Nations/World Health Organization （FAO/WHO） data and other related indicators to explore the potential suitability of the tested varieties for various processed oat products. It was found that the multivariate score for nutritional value of Dingyou No.5 was the best among the 15 oat varieties， making this variety more suitable for large-scale planting. The protein content of Dingyou No. 4 was the highest （170.2 g·kg^-1）， indicating this variety could be used as raw material for high protein oat processed foods such as oat milk and energy bars. Dingyou No.1 had the highest fat content （64.8 g·kg^-1）， and therefore can be used as raw material for high-fat foods such as oatmeal and oat biscuits to meet the dietary needs of people wanting to lose weight. The starch content of Dingyou No.10 was the lowest （388.1 g·kg^-1）， indicating potential use as a raw material of oat processed foods with low glycemic index （GI） such as oat rice and oatmeal to meet the needs of consumers of low GI food. Xiangyan No.13 β-glucan content was the highest （4.33%）， indicating potential for use in health food products designed for the elderly. Comparing the essential amino acid content of oat protein with FAO/WHO data for whole egg protein， the essential amino acid content of Dingyou No.5 was 67.04 g·kg^-1， which was 72.7% higher than that of whole egg protein. This represents a huge advantage for overall nutritional value. These results indicate a potential for fallow fields that have been left unused in winter to be used for growing oats. The nutritional quality of the tested oat varieties was excellent and the market prospects are good. The research results provide important technical data to support utilization of winter fallow fields in China’s southwest mountainous areas， and the development of an oat processing industry and the future manufacture of oat products.

Analysis of traits related to seed yield and nutrient utilization in the Kentucky bluegrass germplasm in Gansu

Xue HA, Jin-qing ZHANG, Fang-xu BAI, Xiang-rong MA, An-qi WANG, Hui-ling MA

2023, 32(4):  54-67.  DOI: 10.11686/cyxb2022168

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In this study， we analyzed traits related to seed yield and the ability to utilize various minerals in six wild germplasms of Poa pratensis （Kentucky bluegrass） from Gansu. The overall aim of this research was to provide a research basis and theoretical reference to improve the use of this plant， generate new germplasm， and identify wild Kentucky bluegrass varieties that can utilize certain minerals. The coefficients of variation of 11 seed yield-related traits and eight traits related to mineral elements ranged from 4.46% to 50.88%. The coefficients of variation for sodium content， calcium content， and the number of seeds on branches were all greater than 40.00%， indicative of wide variability. Correlation analyses showed that the seed yield of wild Kentucky bluegrass was positively correlated with inflorescence length； number of branches； number of florets on spikelets； number of seeds on branches； number of seeds on spikelets； and spikelet seed setting rate. The mineral elements were ranked from highest average content to lowest， as follows： K>Mg>Ca>Na>Mn>Zn>Fe>Cu， and there were complex correlations among the different elements. The results of clustering and principal component analyses showed that the comprehensive ranking of wild Kentucky bluegrass germplasm in Gansu based on 19 traits was Qinzhou>Lanzhou>Longxi>Gannan>Qingshui>Longnan， and the first two， middle two， and last two germplasms each formed one category. Therefore， the material from Qinzhou performed best in terms of the numbers of florets on spikelets， seeds on branches， seeds on spikelets， seeds on inflorescence， spikelet seed setting rate， and thousand grain weight. The Qinzhou strain of Kentucky bluegrass was therefore identified as a good parental material for breeding research. These results provide a theoretical basis and basic data for further research on germplasm resource classification， genetic characteristics， internal relationships among traits， and on the selection， utilization， and improvement of traits in wild P. pratensis.

Adaption to the Plateau climate in Qinghai of 39 silage maize varieties cultivated in different ecological regions of China

Li-li ZHU, Ye-meng ZHANG, Wan-cai LI, Ya-li ZHAO, Xiang LI, Zhi-guo CHEN

2023, 32(4):  68-78.  DOI: 10.11686/cyxb2022148

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The objective of this research was to identify silage maize varieties adapted to the Plateau climate in Qinghai from among 39 maize varieties cultivated in different ecological regions in China. We planted these varieties in experimental field plots. Principal component analysis and grey correlation analysis were used to provide a multivariate ranking based on agronomic traits， yields and nutritional analysis of the 39 maize varieties. The 39 varieties were sourced from 10 ecological regions recognized in the national maize variety system. It was found that the agronomic characters， biological yields and nutritional ingredients of eight varieties， including Jindan No.73， Jingjiu silage 16 and Keda 101 of the middle and late mature spring maize type region in North East China； Yu silage 23 of the middle-mature spring maize type region in North East China， Qinyu 58 and Qingqing 300 of the tropical and subtropical maize type region， Tunyu 168 of the northwest spring maize type region， and Zhongyu 335 of the southwest spring maize type region， ranked in the top 10 based on the two analysis methods， indicating that the overall performance of these varieties was better than the others. Hence these 8 varieties can be recommended as suitable for planting in Qinghai.

Effects of selenium on metabolic transformation and morphogenesis in different varieties of alfalfa during the germination stage

Shi-min ZHANG, Jiao-yang ZHAO, Hui-sen ZHU, Kai WEI, Yong-xin WANG

2023, 32(4):  79-90.  DOI: 10.11686/cyxb2022141

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This research explored the effects of exogenous selenium on the metabolic transformations of sugar and nitrogen， germination indicators and morphogenesis in seeds of different varieties of alfalfa （Medicago sativa） during the germination stage. Five sodium selenite concentrations （0， 0.3， 0.6， 1.2， 2.4 mg·L^-1） were applied to M. sativa cv. Gannong No.3， DS310FY and M. sativa cv. Zhongmu No.5 seeds. The germination rate， phenotype， physiological indicators and selenium content of the treated seeds were determined after 10 days of culture， and multivariate and correlation analyses were used to explore the relationship between various physiological indicators and the phenotypic traits， so as to identify the most suitable selenium concentration and potentially define a methodology for producing selenium fortified materials. It was found that the reducing sugar content， soluble sugar content and germination potential of DS310FY and M. sativa cv. Gannong No.3 seedlings were all significantly higher than those of the control under 0.6 mg·L^-1 selenium treatment for 4 d （P<0.05）. The reducing sugar content， nitrate reductase activity， germination rate and germination index of DS310FY and M. sativa cv. Gannong No.3 seedlings were all significantly higher than those of the control under 0.3 and 0.6 mg·L^-1 selenium treatment for 10 d （P<0.05）， while the maximum values of epicotyl length of M. sativa cv. Gannong No.3 seedlings and total amino acid content， vigor index， epicotyl length， hypocotyl length， and fresh weight per plant of DS310FY alfalfa seedlings were all significantly higher after selenium application than in the control （P<0.05）. In addition， 0.3 mg·L^-1 selenium treatment also significantly increased sucrose content， germination rate and hypocotyl diameter of M. sativa Zhongmu No.5 seedlings compared to the control （P<0.05）. Correlation analysis and variation trend of each indicator showed that the accumulation and transformation of sugar in alfalfa seedlings mainly promoted the development of the hypocotyl， while the accumulation and transformation of nitrogen mainly promoted the elongation of the epicotyl and the increase in plant fresh weight. Therefore， increased sugar conversion efficiency after selenium application mainly promoted the germination of alfalfa seeds， while increased nitrogen conversion efficiency mainly promoted the morphological establishment of the seedlings. In conclusion， the overall performance of metabolic transformation and morphogenesis of DS310FY alfalfa during germination was best under 0.6 mg·L^-1 selenium treatment and this treatment also provided selenium nutrient fortification.

Functional characterization of the role of SbER10_X1 in regulating photosynthesis and biomass of sorghum forage

Jia-cheng ZHENG, Jie YU, Fan LI, Xiao-yi HUANG, Jie-qin LI, Hai-zhou CHEN, Xin WANG, Qiu-wen ZHAN, Zhao-shi XU

2023, 32(4):  91-100.  DOI: 10.11686/cyxb2022173

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The objective of this study was to functionally analyze SbER10_X1 in terms of its role in regulating the photosynthesis and biomass of sorghum. We generated SbERex lines overexpressing the sorghum SbER10_X1 gene and SbERin lines with the target gene silenced. From the transgenic lines， we selected SbERex 5 and SbERin 6 line for observations of stem cell size， determination of phytohormone contents in the main stems， analyses of photosynthesis-related parameters， and measurement of biomass-related traits in 2 consecutive years， and compared these attributes with those of the wild type （WT）. Compared with the WT， SbERex 5 showed a higher gibberellin content in the stem and markedly decreased abscisic acid content， leading to a significant enlargement of stem cells and increased plant height. The SbERin 6 line showed a significantly reduced gibberellin content and increased abscisic acid content in the stem， but the stem cell size was unchanged. Compared with the WT， the SbERex 5 line showed significantly increased photosynthetic rate and water-use efficiency， which contributed to significant increases in plant height， number of tillers， leaf area， grain yield， and biomass per plant. All these characteristics showed slightly lower values in SbERin 6 than in WT. These results suggest that SbER10_X1 affects phytohormone synthesis， increases sorghum cell size， enhances photosynthetic capacity， and effectively improves the biomass production of forage sorghum.

Genome-wide identification of members of the TCP gene family in Melilotus albus and their expression patterns under drought stress

Yan-peng LI, Na WEI, Qing-yan ZHAI, Hang LI, Ji-yu ZHANG, Wen-xian LIU

2023, 32(4):  101-111.  DOI: 10.11686/cyxb2022167

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Melilotus is an important forage and green manure legume crop in northern China. It plays an important role in grass husbandry and ecological and economic construction in this region， and in greater China. Drought stress is an important factor affecting the distribution and yield of Melilotus. It is important to screen and characterize genes that regulate the response of Melilotus to drought stress to understand the drought resistance biology of this genus. The TCP （teosinte branches1， cycloidea， proliferating cell factory） family of transcription factors is specific to plants， and its members are known to play important roles in regulating the response to drought stress. The aim of this study was to identify members of this gene family in Melilotus and explore their biological functions in response to drought stress. In this study， the TCP gene family in Melilotusallbus was systematically identified at the whole-genome level using bioinformatics methods. Further analyses revealed details of TCP gene structures， phylogeny， chromosome locations， and expression patterns under drought stress. The genome of M. albus contained 18 MaTCP genes， which were unevenly distributed on six chromosomes. In a phylogenetic analysis， the 18 MaTCP genes were grouped into two subfamilies： TCP-P and TCP-C. The TCP-P subfamily contained only PCF branches， while the TCP-C subfamily contained CYC/TB1 and CIN branches. All of the 18 MaTCP genes contained a highly conserved bHLH domain and had similar conserved motifs and gene structures within the same subfamily， but members of the TCP-P family had four fewer amino acids in their bHLH domain. Analyses of the transcriptome data obtained for M. albus under drought stress revealed two MaTCP genes （MaTCP2 and MaTCP15） that may be related to the drought stress response. Quantitative reverse-transcription polymerase chain reaction analyses confirmed that， under drought stress simulated by a polyethylene glycol treatment， the transcript levels of MaTCP2 increased significantly in the root of M. albus， while the transcript levels of both genes in the leaf peaked at 3 h of the simulated drought treatment. These results confirmed that both genes are involved in the drought response in M. albus. The results of this study lay the foundation for further research on the drought response of Melilotus， and will be useful for generating Melilotus varieties with enhanced drought resistance through genetic engineering.

Analysis of metabolic pathways and differentially expressed genes of Trifolium pratense responding to waterlogging stress

Pan-pan SHANG, Bing ZENG, Ming-hao QU, Ming-yang LI, Xing-yun YANG, Yu-qian ZHENG, Bing-na SHEN, Lei BI, Cheng YANG, Bing ZENG

2023, 32(4):  112-128.  DOI: 10.11686/cyxb2022139

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Waterlogging stress is an important abiotic stress that affects plant growth， development and distribution， and research on plant waterlogging stress is key to addressing plant production management under extreme heavy rainfall in recent years. Trifolium pratense is a high-quality legume forage， but is poorly tolerant to waterlogging， and long-term waterlogging can lead to root rot and death. In order to investigate the molecular response mechanism of T. pratense under waterlogging stress， the transcriptome was sequenced from seedling leaves of the waterlogging-tolerant variety “Hong Long” at 0， 8 and 24 h using an Illumina high-throughput sequencing platform， and the sequenced data were compared with the reference genome for differentially expressed genes （DEGs） and functional annotation. The results showed that， compared with the control 0 h， “Hong Long” had 5065 DEGs after 8 h of waterlogging stress， among which 2442 genes were up-regulated and 2623 genes were down-regulated； After 24 h of waterlogging stress， there were 9022 DEGs， among which 4279 genes were up-regulated and 4743 genes were down-regulated. The gene ontology （GO） enrichment results showed that DEGs were mainly enriched in terms of metabolic process， cellular process， biological regulation， cell and catalytic activity； The kyoto encyclopedia of genes and genomes （KEGG） enrichment results showed that DEGs were significantly enriched in pathways such as plant hormone signal transduction， plant-pathogen interaction， carbon metabolism and glyoxylate and dicarboxylate metabolism， in which antioxidant enzymes such as peroxidase and formic dehydrogenase were highly expressed in the glyoxylate and dicarboxylate metabolism pathways. This study also found that the differentially expressed AP2/ERF， WRKY， bHLH， NAC， bZIP and other important transcription factors also played important roles in the response of T. pratense to waterlogging stress. Finally， the expression pattern of DEGs was verified by qRT-PCR and found to be consistent with the RNA-Seq results， confirming the accuracy of the sequencing results. In this study， functional annotation， metabolic pathways and transcription factors of DEGs were analyzed based on the transcriptome information， which provided a preliminary understanding of the molecular response mechanisms of T. pratense to waterlogging stress and provided basic data and theoretical direction for the subsequent functional mining of candidate genes.

The use of the tRNA-sgRNA/Cas9 system for gene editing in perennial ryegrass protoplasts

Jia-ming YAO, Huan-huan HAO, Jing ZHANG, Bin XU

2023, 32(4):  129-141.  DOI: 10.11686/cyxb2022180

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Transfer RNA （tRNA） can link multiple sgRNAs （single-guide RNAs） to form a polycistronic gene， which then combines with a CRISPR/Cas9 （clustered regularly interspaced short palindromic repeats/CRISPR-associated gene 9） expression vector to form a polycistronic tRNA-sgRNA/Cas9 （PTG/Cas9） system for multiple gene editing. The PTG/Cas9 system has been used to alter sgRNAs transcript levels and improve multi-target editing efficiency in rice （Oryza sativa）. To efficiently edit target genes in perennial ryegrass （Lolium perenne）， we generated two CRISPR intermediate vectors with tRNAs to provide a fast and flexible PTG/Cas9 vector construction method. To verify whether the PTG/Cas9 system effectively edits genes in the perennial ryegrass genome， we introduced the PTG/Cas9 plasmid into perennial ryegrass protoplasts by PEG 4000-mediated transformation. Then， we extracted DNA from protoplasts and amplified the target sequences to determine whether they had been edited successfully. The gene editing efficiency was about 6.7%. These results show that the PTG/Cas9 system can be used for gene editing in the ryegrass genome， and provide the basis for further genetic research on， and breeding of perennial ryegrass.

Effects of Epichloë endophyte and field management practices on the abundance and diversity of the soil fungal community

Yuan-yuan JIN, Zhen-jiang CHEN, Tian WANG, Chun-jie LI

2023, 32(4):  142-152.  DOI: 10.11686/cyxb2022154

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Endophytic fungi in grasses affect soil chemistry and microbial communities in host plant habitats by affecting above-ground plant litter decomposition and root exudation. However， few detailed data are available on whether the effects of Epichlo? endophyte on the habitat soils of host plants are mainly caused by endophyte-mediated plant litter decomposition or root metabolism. In this study， the chemical properties and the abundance and diversity of the soil fungal community in endophyte-infected （E+） and -free （E-） sample soils were determined after three cycles of mowing with different treatment practices （mowing and return to the field， mowing and removal， and natural growth）. It was found that： 1） Endophyte fungi increased organic carbon， ammonium nitrogen and nitrate nitrogen in the soil of E+ sample plots under the treatment of mowing back to the field， and significantly increased ammonium nitrogen content in the naturally growing soil of the host plants. 2） Epichlo? endophyte significantly increased the alpha diversity of the soil fungal community under the treatment of mowing and return to the field， while beta diversity differed significantly among the three treatments. 3） Epichlo? endophyte and management practices affected the abundance and diversity of the soil fungal community directly， or indirectly by affecting soil chemical properties （organic carbon， carbon to nitrogen ratio and nitrate nitrogen）. In summary， both decomposition of above-ground plant parts and root metabolism mediated by endophyte infection affect soil chemistry and the abundance and diversity of soil fungal community， with endophyte-mediated decomposition of above-ground parts having a stronger effect than root metabolism.

Effects of green-waste mulching treatments on plant growth and the soil bacterial community

Zheng-jun SHI, Song PAN, Shi-xiu FENG, Feng-jun YUAN

2023, 32(4):  153-160.  DOI: 10.11686/cyxb2022177

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In this study， we determined the effects of green-waste mulching treatments on plant growth and the soil bacterial community. The experiment consisted of five treatments ［single cover （T₁）， spraying with urea （T₂）， spraying with avermectin （T₃）， drying （T₄） and semi-composting （T₅）］ and a control （CK）， consisting of bare soil without mulch. It was found that compared with CK， the treatments resulted in increased plant height， stem diameter， biomass， and nitrogen content， and these increases were significant in the T₃ and T₄ treatments （P<0.05）. The highest contents of phosphorus and potassium in plants were in the T₁ treatment. Green waste mulches reduced the soil pH and increased the soil nutrient contents to varying degrees. The highest contents of soil organic matter and available phosphorus （AP） were in the T₁ treatment. The highest content of available nitrogen （AN） in soil was in the T₄ treatment， and was 1.02-2.49 times higher than that in other treatments. The highest content of available potassium in soil was in the T₃ treatment. The results of high-throughput sequencing analyses showed that the number of soil bacteria and Shannon’s index were highest in the T₁ treatment， and were 11.16% and 4.63% higher than their respective values in CK. The treatments and CK were ranked， from highest soil Chao1 index to lowest， as follows： T₄>T₁>CK>T₃>T₅>T₂. The dominant bacterial phyla in soil were Proteobacteria and Acidobacteria， and the dominant families wereKoribacteraceae and Sphingomonadaceae. The results of a redundancy analysis showed that AN and AP were the key factors affecting the soil bacterial community. In conclusion， green waste mulching treatments can effectively promote plant growth and regulate soil physical and chemical properties， and affect the soil bacterial community to some extent. The results of this study also confirmed that the application of avermectin， drying， and semi-composting can enhance the efficacy of mulching with green-waste to varying degrees.

Culturable seed-borne bacteria of lucerne imported from Europe and North America and their pathogenicity to plants and animals

Zhen-fen ZHANG, Rong HUANG, Bo YAO, Wang-dong ZHANG, Cheng-de YANG, Xiu-rong CHEN

2023, 32(4):  161-172.  DOI: 10.11686/cyxb2022311

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To explore the diversity of seed-borne bacteria of imported alfalfa （Medicago sativa） and their pathogenicity to animals and plants， 34 samples of lucerne seeds imported from North America and Europe were collected and analyzed. After Petri-dish isolation and culture， 39 seed-borne bacterial isolates were obtained. The taxonomic status of the bacterial isolates was determined through observations of phenotypic characteristics and 16S rDNA amplicon sequencing. Twenty-one representative strains with potential pathogenicity were selected for evaluation in a plant model （alfalfa， M. sativa） and an animal model （mouse， Mus musculus）. Petri-dishes test and pot experiments were performed to study the impact of the bacterial isolates on alfalfa plants. The mouse infection model consisted of intraperitoneal injection of a bacterial suspension （10⁹ CFU·mL^-1） at a dose of 0.1 mL·10 g^-1. We found that the alfalfa seeds harbored a diverse community of bacteria. These bacterial isolates were grouped in 39 morphospecies that corresponded to three phyla and 15 genera. Out of 39 isolates， 24 （61.54%） were Gram positive and 15 （38.46%） Gram negative. Among them， Firmicutes was the predominant phylum observed in all groups and Bacillus was the dominant genus. The results of pathogenicity tests showed that bacterial strain GCKH （Rhodococcus sp.） was only pathogenic to alfalfa while ZSR17 （Acinetobacter sp.）， ZSR25 （Escherichia sp.）， and R1 （Massilia sp.） were pathogenic to mice. Notably， ZF1 （Erwinia sp.）， ZS3 （Erwinia sp.）， CQ10 （Pantoea sp.）， and ZS6 （Pantoea sp.） could cause disease in both alfalfa and mouse hosts， indicating that they are potential co-pathogenic bacteria capable of cross-kingdom infection. The results provide a preliminary overview of the taxonomic status of seed-borne bacteria carried by lucerne seeds imported from Europe and America and the potential harmfulness of these bacterial strains. These findings lay a theoretical foundation for the integrated management and prevention of the invasion and transmission of the plant-pathogenic， animal-pathogenic， or co-pathogenic bacteria on forage seeds that have the potential to cause infections in plants and animals.

Impact of heat stress on growth rate， serum antioxidant properties， and rumen flora in weaned lambs

Ai-yu LIU, Chao WANG, Zhan-jun WU, Shou-pei ZHAO, Li-chen ZHAO, Xiao-yu LI, Wei-tao ZHANG, Le-tian WANG, Yu-hong GAO

2023, 32(4):  173-182.  DOI: 10.11686/cyxb2022249

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Heat stress （HS） has affected the efficiency and development of the sheep industry. This study investigated the growth performance， serum antioxidant properties， and rumen microbiota in weaned lambs under HS conditions using an environmental control chamber. Twelve weaned lambs were randomly allocated into two groups and raised in two chambers with one lamb per pen. The chamber of the control group was maintained at 21.5 ℃ and 60% humidity， while the HS chamber was maintained at 33.5 ℃ and 60% humidity. The entire experiment lasted for 14 days， and the growth rate， serum antioxidant enzyme activities， heat stress proteins （HSP）， and rumen flora diversity were measured at the end of the experiment. It was found that： 1） Under HS conditions， the daily feed intake and daily weight gain of lambs decreased （P<0.05） by 28.38% and 41.12%， respectively， compared with those in control group， while the feed/gain （F/G） increased by 33.13%. 2） The serum antioxidant properties of lambs decreased under HS conditions. The total antioxidant capacity， catalase， or superoxide dismutase （SOD） activity decreased （ P<0.05） under HS， while the levels of malondialdehyde increased （P≤0.05）. Moreover， compared with the control group， the serum HSP content in the HS group increased （P<0.05） by 1.19 times for HSP60， 1.47 times for HSP70， and 1.39 times for HSP90. 3） The diversity and abundance of rumen flora were affected by the HS conditions； The Shannon index and Simpson index both decreased （P<0.05）， while the relative abundance of Bacteroidetes or Proteobacteria increased （P<0.05）. In particular， Bacteroidetes abundance increased by 76.47% compared with the control group. However， the abundance of Actinobacteria or Firmicutes decreased （P<0.05）. In addition， under HS， the abundance of Prevotella_1 in the rumen increased by 326.28% （P<0.05）， and the abundance of Selemonas_1 decreased by 84.21% （P<0.05）， compared with the control. In summary， HS affected growth rate， serum antioxidant properties， and rumen microbe community structure of the lambs. The results from this study provide data to help understand and relieve sheep affected by HS in commercial production.

Effects of tree shading on physiological indexes， lactation performance， and blood physicochemical parameters of dairy cows housed in a shed

Li-chen ZHAO, Xiao-fang WANG, Xin-nian ZHAO, Yong-liang LI, Ya-nan WANG, Man FENG, Yu-hong GAO, Jian-jun GUO

2023, 32(4):  183-196.  DOI: 10.11686/cyxb2022178

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In this experiment， tall trees were planted on the west side of a cowshed to shade sunlight from the west in summer. Three hundred and sixty dairy cows with similar health， body condition， and parity ［lactation days （185±25）， parity （2.5±0.5）， milk yield （31.02±1.25 kg）］ were randomly assigned to two groups. The two groups were housed in cowsheds with the same building structure and a south-north orientation. Poplar trees with a height of 15 m （crown length of 6 m， lower crown width of 0.8 m， and upper crown width of 0.3 m） were planted outside the west gable of one shed （shed-shaded）， and the other shed was left unshaded with no trees planted outside （control shed）. This study was carried out through three stages； The early hot season in May， the hot season from July to August， and late-hot season in October. The physiological and behavioral parameters of the cows， their milk yield， and nutrient digestibility of feed consumed were measured at all stages， and whole blood and serum biochemical parameters were measured throughout the experiment. It was found that： 1） Shading positively affected dairy cows in the hot season， but had little effect in the early and late stages of hot season. Shading reduced the ambient temperature in the shed during the hot season. The average daily temperature was 0.99 ℃ lower in the shaded shed than in the control shed， and the temperature was 1.13 ℃ lower in the shaded shed than in the control shed between 09：00 and 20：00 （P<0.05）. 2） During the hot season， the respiratory rate of cows in the shaded shed was 8.21% lower than that of cows in the control shed （P<0.05）， and the proportion of cows lying down in the shaded shed was increased by 7.42%. 3） Shading also improved nutrient digestibility of feed consumed in the hot season， with dry matter intake increased by 9.81% （P<0.05） and milk yield increased by 4.69% （P<0.05） for cows in the shaded shed compared with those in the control shed. The crude protein， neutral detergent fiber， and acid detergent fiber contents were also improved， with increases of 12.80%， 9.87%， and 19.40%， respectively， for cows in the shaded shed compared with those in the control shed. 4） The number of white blood cells， the lymphocyte ratio， the and platelet volume in whole blood were significantly higher in cows in the shaded shed （P<0.05） than in those in the control shed in the hot season， while the hematocrit and number of platelets were significantly lower in cows in the shaded shed （P<0.05）. In both the hot season and late-hot season， shading also increased the serum glucose and total protein contents （P<0.05） and decreased the serum cortisol content （P<0.05）. In summary， planting trees on the west side of cowsheds can effectively reduce the ambient temperature inside the shed， thereby relieving heat stress in cows during the hot season and improving their lactation performance. The results of this study provide a reference for improving productivity by managing greening and shading on farms.

Review of grass seed pelletizing in ecological restoration

Yuan MA, Xiao-li WANG, Yan-long WANG, Yu-shou MA, Hai-peng CUI

2023, 32(4):  197-207.  DOI: 10.11686/cyxb2022152

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Ecological environmental management is a strategic direction proposed by China in order to protect and build a healthy ecological environment and achieve sustainable development. Ecological restoration of degraded grassland and historical mine sites is one of the important tasks of ecological environment management in China. At present， the management difficulties in the degraded areas are mainly related to seed germination and seedling growth. Seed pelletizing as a seed management technology plays an important role in promoting seed germination， enhancing seedling emergence and improving seeding establishment capacity. By combining seeds with formulated powder applied through pelletizing machines， different types of pelletized seeds were developed that improved the contact surface between soil and seeds and improved the seed survival environment， so providing improvement in seed establishment to ensure successful ecological restoration outcomes. Based on a large amount of literature and patents related to seed pelletizing， this study reviews seed pelletizing materials， including fillers， binders and active ingredients， that can be used in ecological restoration fields such as alpine grassland degradation management， alpine mine restoration and pastureland rehabilitation. This work provides technical data for the development of high quality seeds and a successful grass seed industry in China.

Progress in research on the effects of grazing on grassland litter decomposition

Ao JIANG, Lu-huai JING, Tserang-donko MIPAM, Li-ming TIAN

2023, 32(4):  208-220.  DOI: 10.11686/cyxb2022160

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Grazing， as one of the major land-use types in grassland ecosystems， regulates litter decomposition through altering the soil environment， biotic and abiotic factors， and litter quantity and quality， thus affecting nutrient cycling and energy flow. However， there is still much to learn about how grazing affects litter decomposition in grasslands and the microbial mechanisms related to this process. In this study， we conducted a bibliometric analysis and literature review to provide an overview of research on grazing and its effects on litter decomposition. The progress and deficiencies of research on the effects of grazing on litter decomposition in grasslands were clarified from three aspects， i.e.， the soil environment （e.g.， soil moisture， soil temperature， bulk density， light， and pH）， microbial activity （e.g.， community structure， nutrients， and home-field advantage）， and litter quality （plant community structure， plant diversity， and litter quality）. We summarized the results of studies on the effects of grazing-induced changes in litter decomposition on nutrient cycling. On the basis of our findings， we propose several future research directions： 1） Construct a network of long-term experiments in which grazing intensity is manipulated； 2） Explore the mechanisms by which grazing affects the litter decomposition of roots with varying diameters； 3） Determine the effects of grazing on mixed-species litter decomposition； 4） Identify the key processes and mechanisms by which grazing affects litter decomposition from a systematic perspective that integrates plant-litter-soil and environment-microorganisms； and 5） Determine the synergistic effects of grazing and global change on litter decomposition. This study provides a scientific basis for understanding how global change will affect litter decomposition and the mechanisms underlying the maintenance and sustainable development of ecosystem services in grasslands.