Table of Content

20 February 2021, Volume 30 Issue 2

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Variations in vegetation cover and its relationship with climate change and human activities in Mongolia during the period 1982-2015

Jia-meng DU, Gang BAO, Si-qin TONG, Xiao-jun HUANG, Wendurina, Meili, Yu-hai BAO

2021, 30(2):  1-13.  DOI: 10.11686/cyxb2020311

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Dynamics of vegetation change on different spatial and temporal scales in Mongolia were analysed for the period from 1982 to 2015， based on GIMMS NDVI3g data （global inventory monitoring and modeling system normalized difference vegetation index-3rd generation）， climate data， and data on vegetation type from 1982 to 2015. Spatial patterns， trends of change in those patterns， and the main reasons for differences in vegetation type were examined using trend analysis， partial correlation analysis and residual analysis. The average NDVI in Mongolia in the growing season increased gradually from the south to the north across Mongolia over the 34-year period， showed significant latitudinal differences， and decreased as the altitude increased. In the growing season， the NDVI displayed characteristic features in particular time periods， notably a significant increase between 1982 and 1994 and between 2007 and 2015， and a significant decrease between 1994 and 2007. Across the whole of Mongolia， linear regression model indicated an increasing trend in the values of the NDVI during the growing season at the rate of 0.0005 NDVI per year， and changes in the index were closely related to increasing precipitation， with a partial correlation coefficient of 0.74. In the case of spatial distribution， areas with significant increase in vegetation were distributed mainly in the Great Lakes Region in the west， the Hangayn Mountains， the Gobi Altai Mountains， and the northern forest areas. The responses of vegetation to climatic factors varied with the season and the region. On the whole， the NDVI increased in three seasons， and the fluctuation in the NDVI in summer was consistent with that in the growth season， and the fluctuation in the NDVI in summer was consistent with that in the growth season， which was controlled mainly by precipitation， because summer contributes the most to annual productivity. The effect of temperature on the NDVI was marked in spring and autumn. Residual analysis showed that human activities has a major impact on changes in the NDVI， especially in areas with high population density （western alpine areas and central grassland areas of Mongolia）， the decline in the NDVI is obviously caused by human activities.

The impact of different factors on the outcomes of grassland ecological restoration to in China： A Meta-analysis

Xiang JIANG, Jian-xia MA

2021, 30(2):  14-31.  DOI: 10.11686/cyxb2020112

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Grassland covers more than 40% of land area， and grassland ecological degradation has attracted great attention. In recent years， a range of grassland restoration measures have been undertaken in various regions， but the specific recovery effects are undocumented. A total of 86 Chinese and English publications on grassland restoration in China were collected from a publication database for Meta-analysis， and the restoration outcomes in terms of grassland biodiversity and ecosystem services in China were quantitatively evaluated. Through sub-group analysis， the regional location， the grassland type and the degree of grassland degradation prior to the recovery activity， the recovery method， recovery time， recovery area， and the response of each ecological grassland type to the grassland recovery activity were obtained. The results show that the grassland restoration activities have had varying degrees of success in restoring degraded grassland. The recovery time has a major impact on the degree of recovery achieved. The longer the recovery time， the better the recovery effect； Active measures improve the recovery speed of degraded grassland， but natural recovery can restore the grassland to a state closer to that prior to degradation. Grassland restoration in humid regions is generally more successful than in arid regions， while the restoration of temperate grassland is generally better than that of alpine grassland. Moderately degraded grassland provides the most obvious response to improvement activity. In the process of grassland restoration， both the biodiversity and ecosystem services can be restored， but biodiversity restoration is more successful than restoration of ecosystem services.

Effects of alternative fertilizer options on soil CO₂ emission and carbon pool management index in a dryland soil

Xiao-jiao WANG, Li-qun CAI, Peng QI, Ya-zhi Wang, Xiao-long CHEN, Jun Wu, Ren-zhi ZHANG

2021, 30(2):  32-45.  DOI: 10.11686/cyxb2020226

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In 2015， the Ministry of Agriculture in China announced a ‘zero increase action plan’ for national fertilizer use， to be implemented by 2020， with the aim of reducing the environmental costs associated with food production. This ‘zero increase’ plan highlights the need to adopt reasonable fertilizer policies with organic materials to alleviate the environmental problems （e.g.， global warming， air pollution， and eutrophication）. Hence， this research aimed to clarify the influence of various fertilization options on soil CO₂ emission and carbon pool management index under different fertilization options. Collection of such data is an essential component of research on carbon sequestration and carbon emission reduction and is also necessary to identify best fertilization practice in unirrigated farming on the Loess Plateau. A long-term field experiment with five fertilization treatments in the Longzhong Loess Plateau was set up in 2012. Fertilization treatments included no fertilizer （CK）， nitrogen fertilizer （NF）， organic fertilizer （OM）， straw （ST）， and organic fertilizer combined with inorganic fertilizer （OMNF）. The annual soil CO₂ emissions， crop carbon emission efficiency （CEE） and carbon pool management index （CPMI） were analyzed in 2018， and the relationships between relevant factors ［soil temperature， moisture content， microbial biomass carbon and nitrogen （MBC， MBN）， readily oxidizable organic carbon （ROOC）， urease and invertase for the soil depth of 0-30 cm］ and soil CO₂ flux were determined by the structural equation model （SEM）. It was found that： 1） Compared with CK， ST， OMNF and OM treatments increased the soil CO₂ flux by 42.72%， 30.82% and 29.79%， respectively， while ST and OM treatments increased the soil CO₂ emission by 36.35%， 32.45%（P<0.05）， respectively， and OMNF reduced carbon emission efficiency by 41.10% （P<0.05）. 2） The OM treatment significantly increased the soil ROOC， MBC， MBN， invertase activity and CPMI in the 0-5 cm soil layer. Compared with CK and NF， the OMNF treatment significantly increased the soil CPMI （0-30 cm） by 127.41% and 99.33% （P<0.05）， respectively. 3） SEM showed that the environmental factors explained in total 53% of soil CO₂ flux， and the factors that had the largest cumulative effect were soil temperature （2.36）， microbial biomass carbon （1.59） and soil moisture content （1.18）. These three factors also indirectly affected soil CO₂ flux. Higher soil temperature promoted increased MBC and invertase activity， and increased MBC further enhanced the rate of change of MBN and ROOC. Overall， OMNF was found to be a sustainable and effective management practice to improve CPMI， maintain microbial activity， increase crop yield， and at the same time also reduce CEE in dryland farming on the Loess Plateau.

Change over time in soil microbial diversity of artificial grassland in the Yellow River source zone

Hua-fang SUN, Xi-lai LI, Li-qun JIN, Cheng-yi LI, Jing ZHANG

2021, 30(2):  46-58.  DOI: 10.11686/cyxb2020105

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This research investigated the characteristics of the soil surface （0-5 cm） microbial community and biological soil crusts （BSCs） in artificial alpine grasslands with a time series of establishment dates （1， 4， 11， 14 and 18 years established） in Maqin County， Qinghai Province. The associated vegetation characteristics were also investigated. It was found that the diversity of surface soil microorganisms increased gradually with the years established， and the diversity indexes （except Simpson’s index） of prokaryotic microorganisms were significantly greater than those of eukaryotic species （P<0.05）. The dominant prokaryotic microorganisms of artificial grassland across the establishment time series were from the phylumProteobacteriaand the genus Gemmatimonas， while the dominant eukaryotic microorganisms were of the phylum Ascomycota and the genus Knufia. The relative abundances of these dominant species differed significantly with years of establishment years. Analysis of the relationship between vegetation characteristics and soil microbes revealed that the number of prokaryotic microbe OTUs （more than 97% of sequences were classified into an operational taxon） was closely related to the vegetation diversity indexes （P<0.01）， and the number of the eukaryotic microorganism OTUs were significantly correlated with vegetation cover and BSCs cover （P<0.01）. The relative abundance of dominant microbial species correlated well with vegetation diversity， especially of eukaryotic microorganisms （P<0.05）. In summary， the data show conclusively that the restoration of artificial grassland vegetation is conducive to the promotion of microbial recovery. However， more time is needed for recovery and stabilization of the soil microbial community than for recovery of the aboveground vegetation.

A study of change in soil characteristics with recovery time in degraded grassland in Minqin

Da-cheng SONG, Li-de WANG, Hao WU, Chun-rong WU, He-ran ZHAO, Sheng-hui HAN, Bao-yi XU

2021, 30(2):  59-68.  DOI: 10.11686/cyxb2020129

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This research investigated soil physical and chemical properties and soil microorganism presence for five sites forming a time series （1， 2， 8， 13， 20 years since cessation of farming） for recovery of degraded grassland in Minqin County， Gansu Province. Soil physical and chemical properties measured included pH， moisture content， sand content， total nitrogen， available potassium and available phosphorus. Soil microbial determinations included comparative abundance of the three main taxonomic groups （bacteria， actinomycetes and fungi）， and soil microbial biomass （carbon， nitrogen， phosphorus） and their correlation. It was found that bacteria were the most abundant soil microorganism， while actinomycetes and fungi were less abundant. With increase in years of recovery， soil sand content， total nitrogen， available potassium， soil microbial biomass carbon， soil microbial biomass nitrogen， soil microbial biomass phosphorus and other indicators showed an initial rise and then a decline trend. For soil moisture content， available phosphorus， bacterial population count， and actinomycete abundance showed a decreasing trend in different degrees. Difference in recovery time did not significantly affect the soil pH or the soil fungal content. There is a certain correlation between soil physical and chemical properties and soil microorganism properties. The results of multivariate evaluation of soil fertility data show that eight years was the time by which key changes were achieved in the recovery of degraded grassland in abandoned farmland areas in Minqin.

Effects of soil pH on soil carbon， nitrogen， and phosphorus ecological stoichiometry in three types of steppe

Jing-jing ZHANG, Zun-chi LIU, Chuang YAN, Yun-xia WANG, Kai LIU, Xin-rong SHI, Zhi-you YUAN

2021, 30(2):  69-81.  DOI: 10.11686/cyxb2020108

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Soil acidity or alkalinity is one of the most important physico-chemical features of the soil， and affects the ecological stoichiometry of soil carbon， nitrogen， and phosphorus through its impact on physical， chemical and biological processes of an ecosystem. Accordingly， the soil pH in grassland ecosystems has changed as a result of climate change and human activities for decades or even centuries. Existing studies have generally focused on the changes in soil nutrients in response to grazing， fertilization， and altered temperature or precipitation. It remains unclear how ecological stoichiometry of soil carbon， nitrogen and phosphorus in various categories of steppe responds to changing soil pH. In this study， three types of steppe （i.e. desert， typical and meadow steppe） with a range of pH values were selected and their soil acidity or alkalinity was altered through manipulative experiments by adding sulphuric acid or sodium hydroxide. We found that： 1） The soil pH values of the 0-10 cm layer in both desert and typical steppes were significantly higher than in meadow steppe. However， the soil pH values of the 10-30 cm layer in all three types of steppe were not significantly different. The values of soil organic carbon， total nitrogen and phosphorus， as well as the ratios of soil carbon to nitrogen， nitrogen to phosphorus and carbon to phosphorus in desert steppe were lower than in typical and meadow steppes. The soil total nitrogen in typical steppe was significantly higher than that in meadow steppe for the 10-30 cm layer. The ratio of carbon to nitrogen in the 0-10 cm layer in meadow steppe was significantly higher than in typical steppe. 2） For the 0-10 cm layer， the addition of acid significantly increased the soil organic carbon， the ratios of carbon to nitrogen and carbon to phosphorus in desert steppe. Soil organic carbon and the ratio of nitrogen to phosphorus in desert steppe， and soil total nitrogen and phosphorus in typical steppe were also significantly reduced by the addition of alkali. In contrast， the addition of alkali enhanced the ratio of soil carbon to phosphorus in desert steppe. For the 10-30 cm layer， the addition of alkali increased the ratio of soil carbon to nitrogen in desert steppe， but it decreased total nitrogen and the ratio of nitrogen to phosphorus in typical steppe. The ratio of carbon to phosphorus also declined in meadow steppe after adding alkali. 3） Soil organic carbon， total nitrogen， and the ratios of carbon to phosphorus and nitrogen to phosphorus at the 0-10 cm soil layer in desert steppe were negatively correlated with soil pH values. The correlations between soil pH and ecological stoichiometry of soil carbon， nitrogen and phosphorus did not differ significantly in typical steppe or in meadow steppe. These results indicate that the ecological stoichiometric characteristics of soil carbon， nitrogen and phosphorus in the three studied steppe types were affected by changing soil pH in the order： desert steppe>typical steppe>meadow steppe. The surface soil was more sensitive to the change in acidity or alkalinity than the subsoil. The similarities and differences of the results between variance and correlation analyses reflected the different effects of soil pH on the three types of steppe in short and long-term adaptation to a changing acidic or alkaline environment. Therefore， in the context of changes in soil pH caused by climate change and anthropogenic activities， grassland ecosystems are likely to adjust their soil pH during the restoration and reconstruction of soil degradation， in order to ensure a nutrient balance and cycling.

Effects of simulated drought on plant phenology and productivity in an alpine meadow in Northern Tibet

Wen-rong LUO, Guo-zheng HU, Ganjurjav H, Qing-zhu GAO, Yan LI, Yi-qing Ge, Yu LI, Shi-cheng HE, Luo-bu DANJIU

2021, 30(2):  82-92.  DOI: 10.11686/cyxb2020099

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This research aimed to elucidate the effects of drought events on the phenology and productivity of the plant community in Tibetan alpine meadow. A rainfall interception experiment comprising drought treatments imposed early or late in the growing season （SE and SL， respectively） was carried out in alpine meadow of Northern Tibet， over two years （2016-2017）. Results showed that： 1） The plant phenology had a contrasting response to SE and SL drought treatments. Plant phenology of key species was more sensitive to SE. SE significantly delayed plant green update， and led to a shorter growing season and reproductive duration （P<0.05）， while SL had no significant effect on plant phenology. 2） Biomass of the plant community and different functional groups decreased under the drought treatments. Community biomass decreased by 62.9% （P<0.05）. The height and coverage of the community was suppressed by drought， while the response of height and coverage differed between grasses and forbs. 3） Community height and biomass were significantly positively correlated with the growing season and reproductive duration （P<0.05）. The results indicate that the productivity of alpine meadow grassland was regulated by phenology in response to drought， mainly through the impact on plant height. Moreover， the responses to drought varied between different functional groups， and suggest that increasing and intensified drought may lead to change in the community structure of alpine meadow.

Growth of Elymus nutans in saline saline-alkali soil amended with calcium silicate slag： Performance and mechanism

Zhen-lian FAN, Yang-jie JIA, Yuan FAN, Hui-ping SONG, Zheng-jun FENG

2021, 30(2):  93-101.  DOI: 10.11686/cyxb2020319

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Saline-alkali soil management is an issue of worldwide concern. Desulfurization gypsum is one of the common saline soil amendments. Silica-calcium slag is a by-product of aluminum extraction from fly ash. It is rich in calcium， silicon and other elements， which enhance the saline-alkali resistance of plants. Therefore， silica-calcium slag has the potential to improve saline-alkali soil after flue gas desulfurization. Silica-calcium slag at 0， 10， 25 and 50 g·kg^-1 soil， and 50 g·kg^-1 soil desulfurization gypsum as a comparison were applied as treatments mixed into saline-alkali soil in pot experiments to explore the effects on the growth of Elymus nutans. It was found that silica-calcium slag improved the growth of E. nutans in saline-alkali soil. The weight per plant of E. nutans was increased by a factor of 0.4-1.6， the total plant biomass per pot was increased by a factor of 2.8-6.8， the root length by 3.16%-40.21% and the plant height by 9.07%-17.35% after the application of silica-calcium. The treatment with 50 g·kg^-1 silica-calcium slag applied was the best. Moreover， the performance of 50 g·kg^-1 silica-calcium slag was also better than that of 50 g·kg^-1 soil desulfurization gypsum in plant growth. The possible mechanisms were as follows： 1） Incorporating silica-calcium slag and desulfurized gypsum significantly reduced the soil pH， which could improve the physical and chemical properties of soil and alleviate the alkali stress to plants. 2） Silica-calcium slag increased the absorption of Ca and Si by plants， which are beneficial for resisting salt and alkali stresses. 3） Silica-calcium slag helped the plants to absorb more potassium and reject more sodium to improve the osmotic pressure of plant cells， increasing the intracellular K∶Na balance， thus reducing the harm from saline-alkali stress. This study shows that silica-calcium slag can effectively improve the properties of saline-alkali soil and promote the growth of E. nutans， providing a new option for the utilization of coal-based solid wastes and the improvement of saline-alkali soil in northern China.

Effects of coupling of drip irrigation water and fertilizer on yield and quality of alfalfa in the yellow river irrigation district

Bai-ping SHA, Ying-zhong XIE, Xue-qin GAO, Wei CAI, Bing-zhe FU

2021, 30(2):  102-114.  DOI: 10.11686/cyxb2020095

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This research explored the effects of water and fertilizer and their interaction on the growth and nutritional quality of alfalfa under drip irrigation. The design incorporated four water supply treatments （W₁， W₂， W₃， W_4，） and five fertilizer treatments （F₁， F₂， F₃， F₄， F₅）， and used a split-plot ANOVA design to analyze the alfalfa growth rate， hay yield and nutritional quality under the various combinations of water and fertilizer application. It was found that optimal irrigation and fertilization significantly increased the alfalfa plant height， growth rate and number of branches， enhanced hay yield and improved the nutrient status. Increasing the amount of irrigation decreased the irrigation water use efficiency， and the yield response to fertilizer increments increased initially and then decreased with successive water increments. Similarly， increasing the amount of fertilizer applied decreased the yield response to further fertilizer increments， while the irrigation water use efficiency increased initially and then decreased with successive fertilizer increments. Based on the Grey correlation and a ‘fuzzy similarity priority ratio evaluation’ analysis， it was concluded that the plant height， growth rate， and number of secondary branches contributed strongly to hay yield， and the number of primary branches and leaf to stem ratio contributed weakly to hay yield. The W₃F₂ combination of water and fertilizer gave the highest hay yield （19832 kg·ha^-1） and protein content （19.27%）， and also a comparatively high irrigation water use efficiency （3.8 kg DM·m^-3 water） and fertilizer partial productivity （146.9 kg DM·kg^-1）. A regression optimization model showed that the optimal range of water and fertilizer for alfalfa production under drip irrigation was an irrigation amount of 6000-6500 m³·ha^-1， and a fertilizer application rate of 250-320 kg·ha^-1.

The stoichiometric characteristics of Alternanthera philoxeroides with different invasive degrees and their comparison with the coexisting species Gomphrena celosioides

Ju-hong WANG, Ze-xuan XU, Wen CHEN, Hui ZHU, Long-jun HUANG, Jia-wei LI

2021, 30(2):  115-123.  DOI: 10.11686/cyxb2020286

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Invasion by alien species affects the diversity level and the stability of ecosystems. This study explored the nutritional strategy and successful invasion mechanism of Alternanthera philoxeroides with different degrees of invasion （mild， moderate， and heavy invasion） by measuring carbon （C）， nitrogen （N）， phosphorus （P） contents and their stoichiometry of soils， plant organs and comparing these with a coexisting species， Gomphrena celosioides. It was found that： 1） The element contents in soils increased with alien species invasion. The available phosphorus （AP） content in soil with heavy invasion is higher than the other habitats； 2） N and P contents of A. philoxeroides organs in the three invasive degrees were the leaf>roots and stems， indicating that the elements N and P were more allocated to the leaves； 3） N content in organs， and P content in leaves of A. philoxeroides were significantly higher thanthatof G. celosioides， showing that alien species have strong absorption and utilization of the elements N and P； 4） The C∶P and N∶P ratios of A. philoxeroides leaves were significantly lower than those of G. celosioides， indicating that the growth rate of the invasive species， A. philoxeroides， was higher than that of the companion. The N∶P ratio in roots and stems of A. philoxeroides was greater than G. celosioides. It indicates that invasive plant A. philoxeroides by absorption and utilization of resources， and rapid growth of aboveground parts increases competitiveness， and further expansion.

Effects of different seed coating formulations on seed germination and seedling growth of Lespedeza davurica

Li-rong TONG, Shun-gang NI, Ya-nan ZHOU, Juan WANG, Fang-shan XIA

2021, 30(2):  124-134.  DOI: 10.11686/cyxb2020357

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Based on original research on a seed coating formulation for Lespedeza davurica， in this experiment a fungicide （carbendazim， 50% wettable powder）， water retaining agent （super absorbent polymer， SAP）， filling materials （corn stalk powder） and other coating materials were selected as ingredients for further testing and modification of the recipe. The tests were conducted with L. davurica cv. “Jinnong No.1” and studied the effects of different formulations on seed germination and seedling growth of L. davurica. The results showed that carbendazim to seed ratio 1∶60 effectively solved the problems with seed decay and inactivation during seed germination. SAP at a range of concentrations was used as a water-retaining agent in the coating formulation， and 5% SAP was found to provide optimum efficacy. At this concentration of SAP， water was effectively held， and the seed vigor was the strongest with the highest germination index. In addition， 5% SAP also resulted in a higher emergence rate and seedling growth rates in a greenhouse emergence test， indicating better seedling vigour. Adding corn stalk powder to the coating formulation was also beneficial. A range of powders of different fineness were tested. Among these， fine corn stalk powder （able to pass a 75 μm sieve） resulted in a better germination status then the others tested and enhanced seedling biomass accumulation. The 1000-seed weight of the coated seeds was 2.3 times that of the naked seeds， and the coated seed diameter was close to 2 times that of the naked seeds. The tested seed coating formulation was therefore suitable for industrial production and mechanical seeding.

Physiological mechanism of NaHS priming improvement of seed vigor in naked oat

Jian-xin LIU, Rui-rui LIU, Hai-yan JIA, Ting BU, Na LI

2021, 30(2):  135-142.  DOI: 10.11686/cyxb2020127

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Hydrogen sulfide （H₂S） plays an important role in the germination of crop seeds. This research explored the role of an exogenous H₂S donor， NaHS， as a priming agent for increasing seed vigor and its physiological mechanism. Naked oat seeds were used as the test material， and primed with different concentrations of NaHS （0， 50， 100， 200， 400， 800 and 1600 μmol·L^-1） for 18 h and with 800 μmol·L^-1 NaHS for different times （6， 9， 12， 15， 18， and 21 h）. The germination potential （GP）， germination rate （GR）， germination index （GI）， vitality index （VI） and seedling dry weight （DW） were analyzed to determine the appropriate NaHS priming concentration and priming time. Compared with non-priming of seeds， the effects of 800 μmol·L^-1 NaHS priming for18 h on H₂S production， storage substance content and active oxygen metabolism of seeds were studied. The results showed that 800 μmol·L^-1 NaHS priming for 18 h could significantly increase the GP， GR， GI， and VI of naked oat seeds， but had no significant effect on DW. NaHS priming had no significant effect on the starch， soluble sugar， soluble protein， reduced ascorbic acid （ASA）， dehydroascorbic acid （DHA） contents， ASA/DHA， and ascorbic peroxidase activity of seeds， but significantly increased H₂S and oxidized glutathione （GSSG） contents， cytochrome oxidase （COX）， superoxide dismutase， catalase and peroxidase activities by 113.5%， 14.4%， 103.3%， 6.1%， 112.0% and 120.5%， respectively； Decreased α-amylase and β-amylase activities and superoxide anion， hydrogen peroxide， malondialdehyde， reduced glutathione （GSH） contents， GSH/GSSG and plasma membrane relative permeability by 39.8%， 53.6%， 34.7%， 36.1%， 37.6%， 29.2%， 38.1% and 11.9%， respectively. These results indicate that NaHS priming may increase the H₂S content of the seeds， thereby regulating the antioxidant system and activating COX activity， reducing the damage caused by reactive oxygen species to the plasma membrane， enhancing cell aerobic respiration metabolism， and improving the vitality of naked oat seeds.

Transcriptome analyses of functional genes in young leaves and roots of Giant Juncao

Jing ZHOU, Si-qi CHEN, Wen-jiao SHI, Fu-lin YANG, Hui LIN, Zhan-xi LIN

2021, 30(2):  143-155.  DOI: 10.11686/cyxb2020326

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Giant Juncao （Pennisetum giganteum）is a Poaceous C₄ plant that grows to more than 3 m in height， with high biomass and a well-developed fibrous root system making it ideal for use in waterway， soil and sand stabilization， and as a wind shelter. In order to investigate transcriptome information of Giant Juncao grass， high-throughput Illumina sequencing was conducted on tissues of young leaves and roots， gene expression profiles of leaves and roots were compared， and differentially expressed genes （DEGs） were identified. A total of 210806 transcripts and 150336 unigenes were de novo assembled with an average length of 760 bp and 642 bp， respectively. A total of 88765 unigenes were annotated from at least one of the following databases： Nr， Nt， Swiss-Prot， KOG， GO， KEGG and Pfam. Comparing the young leaf and root tissues， 5735 DEGs were detected， of which 3435 were upregulated and 2300 were downregulated unigenes. GO function analysis showed that upregulated DEGs were mainly involved in electron transport， carbohydrate metabolism， and metal ion binding， while downregulated DEGs included those related to metabolic processes， catalytic activity， and small molecule metabolic processes， among others. KEGG pathway enrichment analysis identified a total of 120 metabolic pathways， among which the DEGs involved in carbon fixation of photosynthetic organisms showed the highest level of enrichment and DEGs involved in biosynthesis of secondary metabolites were the most abundant. Two DEG transcription factors， bHLH and WRKY， were identified as the main regulators of differential gene expression in leaves and roots. This study has greatly enhanced the transcriptomic information available for Giant Juncao， provided a valuable data resource for future molecular biology research， and established a theoretical foundation for improvement of Giant Juncao varieties.

Effects of dietary NDF∶NFC ratio on growth performance， nutritive digestibility， ruminal fermentation characteristics and methane emissions of Holstein heifers

Li-feng DONG, Xiu-zhu YANG, Yan-hua GAO, Bin-chang LI, Bei WANG, Qi-yu DIAO

2021, 30(2):  156-165.  DOI: 10.11686/cyxb2020117

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The present study examined the effect of different dietary neutral detergent fiber/non-fibrous carbohydrate （NDF^{∶NFC） levels on growth performance， nutrient digestibility， ruminal fermentation and methane （CH₄） emissions of Holstein heifers. The objective was to obtain the CH₄ emission data and CH₄ conversion factor （CH₄-E/gross energy intake） under the current production system， to provide scientific evidence and references to develop mitigation strategies. Forty-five 15-month-old Holstein heifers in healthy condition were selected and randomly assigned to three groups， with 15 animals in each group： low NDF∶NFC group （NDF∶NFC=0.60）， medium NDF∶NFC group （NDF∶NFC=0.75）， and high NDF∶NFC group （NDF∶NFC=0.90）. The experiment lasted 70 d with a 14 d adaptation period and 56 d measurement period. It was found that： 1） increasing the dietary NDF∶NFC levels significantly decreased dry matter intake （DMI）， organic matter intake （OMI）， average daily gain （ADG）， DM and crude protein （CP） digestibility （P<0.05）. 2） Increasing the dietary NDF∶NFC levels significantly increased total VFA concentration， acetate content （%） and acetate∶propionate ratio， but significantly decreased propionate content （%） （P<0.05）. 3） Increasing the dietary NDF∶NFC levels significantly increased enteric CH₄， methane energy （CH₄-E）， CH₄∶metabolizable body weight， CH₄∶DMI， CH₄∶OMI， CH₄∶NDF intake （P<0.05）. The CH₄ conversion factor significantly increased when dietary NDF∶NFC levels increased （P<0.05）. 4） Several prediction equations were developed using body weight， feed intake， nutrient content， or NDF∶NFC. Among these， an equation developed using DMI and NDF intake had highest R2 value of 0.77. It is thus concluded that the increasing dietary NDF∶NFC decreased growth performance， nutrient digestibility， and ruminal propionate concentration， but significantly increased enteric CH₄ emissions and CH₄ conversion factors of Holstein heifers.}

Comparative analysis of meat production traits， meat quality， and muscle nutrient and fatty acid contents between Ziwuling black goats and Liaoning cashmere goats

Ji-qing WANG, Ji-yuan SHEN, Xiu LIU, Shao-bin LI, Yu-zhu LUO, Meng-li ZHAO, Zhi-yun HAO, Na KE, Yi-ze SONG, Li-rong QIAO

2021, 30(2):  166-177.  DOI: 10.11686/cyxb2020199

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Liaoning cashmere goats have been used since 1990 for crossbreeding to improve Ziwuling black goats in Qingyang， Gansu province. However， little is known whether there are differences in fatty acid and muscle nutrient contents of the two breeds that may affect the crossbreeding outcomes for Ziwuling black goats. To provide the theoretical information for use in crossbreeding improvement for Ziwuling black goats， differences between the two goat breeds in meat production capacity， meat quality， and the contents of muscle nutrients and fatty acids were analyzed. In this study， five healthy nine-month-old Ziwuling black goats and five Liaoning cashmere goats reared under the same management conditions were slaughtered to measure the carcass traits， including meat quality， fatty acid contents and muscle nutrient composition of the longissimus dorsi muscle， foreleg and hind leg muscles. The results showed that Ziwuling black goats had lower carcass weight， dressing out percentage， net meat weight， net meat production rate， rib-eye area， GR （grith rib） value， shear force and drip loss than those of Liaoning cashmere goats （P<0.05）. However， the average meat lightness， chroma value， pH₁ and pH₂₄ in Ziwuling black goats were higher than those of Liaoning cashmere goats （P<0.01）. Measurement of muscle nutrient composition revealed that the contents of water and crude ash of muscle in Ziwuling black goats were higher than Liaoning cashmere goats （P<0.05）， but the contents of intramuscular fat and crude protein were lower than Liaoning cashmere goats. Eleven saturated fatty acids （SFAs）， ten polyunsaturated fatty acids （PUFAs） and six monounsaturated fatty acids （MUFAs） were detected in muscle of both goat breeds， which mainly comprised palmitic acid， stearic acid， linoleic acid， cis-11， 14-eicosadienoic acid and oleic acid. The contents of SFA， PUFA， n-3 PUFA， n-6 PUFA and the PUFA∶SFA ratio in Ziwuling black goats were higher than Liaoning cashmere goats （P<0.01）， but the MUFA content was lower than Liaoning cashmere goats （P<0.01）. The results indicate that Liaoning cashmere goats had higher meat production capacity， but muscle from Ziwuling black goats had better meat quality and muscle nutritional composition， as well as a healthier fatty acid profile.

Distribution of alfalfa in the Ming and Qing Dynasties and the underlying driving factors

Shuang LIU, Fu-ping HUI

2021, 30(2):  178-189.  DOI: 10.11686/cyxb2020120

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Based on the investigation of alfalfa records in Chinese ancient books and Chinese local records， it is found that the adoption of alfalfa across China shows two totally different faces. On the one hand， identification of alfalfa in the ancient records is relatively simple and clear， and the evolution of alfalfa flower color from yellow to purple is relatively clear. On the other hand， identifying alfalfa in local records is more complex as in a large number of cases there are misnomers， and alfalfa is often confused with other plant species. The appearance of the modern Chinese name Mùxu is actually a useful indicator of the adoption and spread of alfalfa in China. Based on the quantitative analysis of alfalfa records in local chronicles， it can be inferred that alfalfa in the Ming and Qing Dynasties was mainly distributed in the northwest， North China and Jianghuai， while it was also distributed in the middle and lower reaches of the Yangtze River， the southeast coast and the southwest frontier. Using knowledge of social and economic factors in the Ming and Qing Dynasties， we can draw three conclusions. First， the establishment and reorganization of military garrisons the Ming and Qing Dynasties resulted in alfalfa spread in the border areas and along the grain transport routes because alfalfa was used to feed horses. Secondly， during recovery programs in natural disaster areas， there was often widespread promotion by local officials of the planting and utilization of alfalfa， because as well as being an animal feed， alfalfa could be used as a vegetable by poor farmers and by the poor in the cities. Finally， the simple cultivation requirements of alfalfa made it a convenient crop for farmers to grow， thus incentivizing ongoing adoption of alfalfa and spread of its use. After the middle period of the Qing Dynasty， alfalfa was widely used to treat saline-alkali land in Hebei and Shandong， and the rotations of alfalfa with other crops were quite sophisticated. In short， the broad spectrum of knowledge embodied in the agronomy of alfalfa use has formed an agricultural system in its own right， which in the Ming and Qing Dynasties became established as the norm for local practice in many parts of China.

Redefining “grassland” in Grassland Law of China

An ZHAO

2021, 30(2):  190-198.  DOI: 10.11686/cyxb2020135

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The current Grassland Law of China defines grassland with the words “the grassland referred to in this Law refers to natural grassland and artificial grassland”. This paper reviews the different definitions of grassland from different disciplinary perspectives， including botanical， ecological， ecosystem and human ecology considerations， and holds that the definition of ‘grassland’ in current grassland law is archaic and too narrow， both from ecological and legal viewpoints. A definition of ‘Grassland’ should at least refer to natural grassland， artificial grassland， and grassland ecosystems， including the natural environment and human activities. Morover， the definition of ‘Grassland’ needs to break through the legal relationship in traditional jurisprudence. That is， the relationship between human and nature （quasi human） will rise to a new category of legal relationship. It is pointed out that it is necessary to review the guiding ideology of Grassland Law from the perspective of the theory of ecosystem management and related legislation.

Effect of early nutrition intervention on rumen microflora development in young ruminants

Jian-bo ZHANG, KAO Ren-qing DING, Ze-yi LIANG, Ahmad Anum-ali, Mei DU, Juan-shan ZHENG, Xue-zhi DING

2021, 30(2):  199-211.  DOI: 10.11686/cyxb2020102

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The presence of a normal and stable rumen microflora is an important indicator of rumen health in ruminants. It also plays an important role in the development of rumen morphology， microbial colonization， regulation of immune function， and resistance to invasion by exogenous pathogenic factors. Recent studies have shown that the composition of rumen microbes in neonatal ruminants is relatively simple. However， different microbial communities begin to colonize and occupy different niches during early rumen development， so nutritional interventions at this point may result in the formation of specific microbial communities and may have lasting effects. Such interventions provide a better long-term strategy for further improving ruminant productivity and health. In this paper， the latest research findings on early nutrition intervention in the development of the rumen microecological system are reviewed in detail from the following three perspectives： Exploring the development of rumen morphology and function of young ruminants， the factors affecting the early rumen microbial community colonization and the selection of a ‘window period’ for intervention， and brief analysis of the immune interaction between host and microbial communities. This information would help in the improvement of the performance of ruminants through early nutrition intervention to meet the global challenge of animal husbandry， as well as improvements in straw fiber utilization and the control of methane emission.

Stocking rate effects on stoichiometric characteristics of the steppe grassland pioneer species Stipabreviflora and its underlying soil

Mei XIONG, Ji-rong QIAO, Yang YANG, Feng ZHANG, Jia-hua ZHENG, Jian-xin WU, Meng-li ZHAO

2021, 30(2):  212-219.  DOI: 10.11686/cyxb2020116

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We investigated the effect of stocking rate （Control， CK； Lightly grazed， LG； Moderately grazed， MG and Heavily grazed， HG） on carbon （C）， nitrogen （N）， phosphorus （P） and their stoichiometry for the pioneer species Stipa breviflora （Sb） and its underlying soil for the 0-20 and 20-40 cm depths in desert steppe grassland. Stocking rate had no significant effect on N， P content and no effect on C∶N∶P stoichiometry in Sb foliage， but C content in Sb foliage significantly increased with increase in stocking rate （P<0.05）. Soil N， P and C∶N∶P values for the two soil layers were significantly （P<0.05） affected by stocking rate， except for soil C∶N from 0-20 cm. Those differences between C∶N∶P ratios were mainly caused by the changing of soil N and P content， and these effects for the two soil layers were somewhat random with no consistent pattern across stocking rates. The stoichiometry of Sb foliage was not affected by changes in soil stoichiometry. Grazing decreased the Sb P and soil C content， but this effect was decreased by increased stocking rate. Compared with CK， HG markedly changed the characteristics of soil N， P and C∶N and of Sb foliage C and C∶N. The increasing of soil depth showed greater impact on soil P， N∶P and C∶P under MG.