Table of Content

20 April 2024, Volume 33 Issue 4

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Effects of grazing exclusion and fertilization on alpine meadow community characteristics and vegetation carbon and nitrogen pools

Rui-min QIN, Si-jia CHENG, Li MA, Zhong-hua ZHANG, Jing-jing WEI, Hong-ye SU, Zheng-chen SHI, Tao CHANG, Xue HU, De-ha-ze A, Fang YUAN, Shan LI, Hua-kun ZHOU

2024, 33(4):  1-11.  DOI: 10.11686/cyxb2023198

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The objective of this study was to determine how two different restoration measures， i.e.， grazing exclusion and fertilization， affect degraded alpine meadows. A field study was conducted to compare the effects of grazing exclusion for various periods （0， 4， 13 yrs） and long-term fertilization （with nitrogen， N， and phosphorus， P） on community characteristics and vegetation carbon （C） and N pools. The results showed that： 1） The species richness index and Shannon-Wiener index decreased significantly with increasing years of grazing exclusion， while Simpson’s index and the Pielou index increased and then decreased. The addition of N and P fertilizers significantly decreased the species richness index and Shannon-Wiener index. 2） Aboveground biomass and root biomass were significantly increased after both 4 and 13 years of grazing exclusion， reaching the maximum at 4 years， whereas litter biomass increased gradually with increasing years of grazing exclusion. The effect of long-term fertilization on biomass was not significant. 3） After grazing exclusion， vegetation C and N stocks increased significantly， with aboveground biomass and root C and N pools being highest at 4 years of grazing exclusion， and litter C and N pools being highest at 13 years of grazing exclusion. Long-term fertilization had no significant effect on vegetation C stocks， and only long-term N addition significantly increased the aboveground biomass N pools. 4） Partial least squares path modeling showed that grazing exclusion and fertilization led to changes in environmental factors that restrained community diversity and promoted the accumulation of plant biomass and vegetation C pools， while fertilization affected vegetation N pools. In summary， grazing exclusion generally restrained species diversity， but promoted community productivity and increased vegetation C and N pools， while long-term N addition had no significant positive effect on species diversity and vegetation C pools， but increased vegetation N pools.

Effects of different utilization methods on community characteristics of primary vegetation of Stipa grandis steppe， Inner Mongolia， China

Xiao-jing SUO, Lei XIANG, He GAO, Xiang-jun YUN, Ba-gen HASI, Jin-rui WU, Wen-cheng DONG, Bo-wei HUA, Jin-yi MOU, Qi WANG

2024, 33(4):  12-21.  DOI: 10.11686/cyxb2023207

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This study explored the effects of different utilization methods on community plant characteristics of Stipa grandis steppe， in order to provide scientific data to assist with the formulation of an optimal utilization system for this grassland. Together with a household survey， plant communities were investigated in S. grandis steppe with three utilization modes： annual mowing， annual grazing and seasonal rotational grazing. We calculated important values and diversity indices to analyze the relationship between plant diversity and biomass. It was found that， 1） The dominant plant groups of S. grandis grassland under the three utilization modes were consistent. 2） There was no significant difference in community species diversity among the three utilization methods， but there was significant difference in functional group species diversity. The species diversity of perennial grasses under mowing was higher than that under annual grazing and seasonal rotation grazing； the species diversity of shrubs and subshrubs under annual grazing was higher than that of annual grazing and seasonal rotation grazing. 3） Above-ground standing crop of annual mowing and seasonal rotation grazing was significantly higher than that of annual grazing. 4） There was a significant positive correlation between plant diversity and biomass under annual mowing and seasonal rotation grazing. In conclusion， mowing and seasonal rotation grazing maintained high species diversity while maintaining high above-ground standing crop， which is conducive to the sustainable use of S. grandis steppe， but the community structure of the two was different and therefore would support different ecosystem functions.

Responses of spatial pattern and driving factors for soil water deficit of desert grassland-shrubland transition sites

Ya-nan ZHAO, Hong-mei WANG, Zhi-li LI, Zhen-jie ZHANG, Yan-shuo CHEN, Rong-xia SU

2024, 33(4):  22-34.  DOI: 10.11686/cyxb2023209

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Shrub encroachment has an important impact on ecosystem structure， function and services， and its adverse impact on soil water has been recognized， but there is still a lack of quantitative assessment and research into its driving mechanisms at a regional scale. In the Ningxia desert steppe， 43 paired sample sites of desert grassland and of shrubland were selected， and a ‘plot compared soil water deficit index’ （PCSWDI） was introduced to evaluate the spatial pattern of soil water deficit and its drivers after the transition from desert steppe to shrubland. Results showed that the soil water content of 0-100 cm and 100-200 cm strata decreased significantly by 27.80% and 57.92%， respectively， after the transition from desert grassland to shrubland. Also， the PCSWDI of shrubland from 0-100 cm was significantly lower than that of desert grassland， indicating that there is no soil water deficit in the 0-100 cm layer of shrubland. Geostatistical analysis showed that the structural variance ratios of the PCSWDI of desert grassland and shrubland were 94.73% and 95.29%， respectively， which indicate strong spatial autocorrelation and were mainly controlled by structural factors. Furthermore， the geographic detector method found that soil water storage， aspect and field capacity were the dominant factors affecting the PCSWDI of the shrubland； The interactive detection showed that the spatial differentiation of the PCSWDI of the 0-100 cm soil layer of shrubland was the result of the interaction of multiple factors. In conclusion， our results show that although there was no soil water deficit in the 0-100 cm soil layer of shrubland， a significant decrease in the 100-200 cm soil water content indicating the depletion of deep soil water was observed. Therefore， vegetation restoration in arid and semi-arid regions must take into account the carrying capacity and water threshold of vegetation， and a nature-based solution may be the main focus of vegetation restoration in the future.

Effect of two kinds of tree litter leaf extracts on soil enzyme activities and eco-enzymatic stoichiometry of Axonopus compressus

Lin-xi HUANG, Qian CHEN, Xian-yan ZHANG, Shun YAN, Yun YANG, Pei-yao XIN, Qiong WANG

2024, 33(4):  35-46.  DOI: 10.11686/cyxb2023182

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Matching trees with artificial turf is a common plant configuration scheme in landscaping， but tree litter may affect the growth of understory lawn grass. The aim of this study， therefore， was to explore the allelopathic effects of litter leaf extracts of Koelreuteria paniculata and Prunus serrulata on Axonopus compressus lawn as a preliminarily investigation of the impact of understory vegetation management on the soil quality of A. compressus. Aqueous extracts of K. paniculata and P. serrulata leaf litter were prepared at mass concentrations of 10， 20， and 40 g·L^-1， and applied to A. compressus growing in pots. Hydrolase activity and its stoichiometric changes were determined in the rhizosphere soil of A. compressus treated with the two kinds of litter extracts. It was found that： 1） As the concentration of the K. paniculata extract increased， the activities of β-1，4-glucosidase， β-N-acetylglucosaminidase， and acid phosphatase in the rhizosphere soil of A. compressus initially increased and then decreased， whereasxylase activity initially decreased， then increased， and then decreased. As the concentration of the P. serrulata extract increased， the activities of β-1，4-glucosidase， β-N-acetylglucosaminidase， and xylase in the rhizosphere soil of A. compressus initially decreased and then increased， whereas the activity of acid phosphatase continuously decreased. 2） Correlation analyses showed that the activities of nitrogen- and phosphorus-acquisition enzymes were significantly positively correlated with soil organic carbon （SOC） content； Enzyme carbon∶nitrogen （C∶N） and enzyme carbon∶phosphorus （C∶P） were significantly negatively correlated with total nitrogen （TN） and total phosphorus （TP）， respectively. And enzyme N∶P was significantly negatively correlated with the SOC content. The results of a vector model analysis revealed that the microorganisms in the rhizosphere soil initially had phosphorus limitation characteristics， but treatment with the P. serrulata litter leaf extract alleviated microbial C and P limitation. 3） A redundancy analysis further revealed that SOC， TP content， soil C∶P， soil water content， and pH were the main factors affecting rhizosphere soil enzyme activities and the enzyme stoichiometry of A. compressus. Therefore， in daily management， leaf litter of K. paniculata and P. serrulata should be added to A. compressus turf to improve soil microbial enzyme activities and simultaneously alleviate C and P limitation.

Allelopathic effects of Rhus typhina tillering seedlings on seed germination and seedling growth of three common turf species

Xiao-xi ZHANG, Jia-wei HU, Xing WANG, Jiang-wen LI, Kai-xuan LIU, Ling-su CHEN, Yu-xin DONG, Zi-quan WANG, Jin-qiang CHEN

2024, 33(4):  47-59.  DOI: 10.11686/cyxb2023204

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We aimed to clarify the allelopathic effects of Chinese sumac （Rhus typhina） seedlings on common turf species and the underlying mechanisms of such effects. Three common turf species， namely Trifolium repens， Festuca arundinacea， and Lolium perenne， were cultivated in sand， and were treated with aqueous extracts of the root， bark， and leaf of R. typhina tillering seedlings. Seed germination， seedling growth， and physiological traits such as chlorophyll content， root activity， and antioxidant indexes were measured for all of the turf species. Aqueous extracts of the root， bark， and leaf of R. typhina were prepared at three concentrations： 12.5， 25.0， and 50.0 g·L^-1 （dry weight/volume_water）. A principal component analysis was used to calculate the integrated principal component value （F） based on the allelopathic effects of each extract on each index. These values were then used to assess the comprehensive inhibitory effects of each treatment on each turf species. The results indicated that the allelopathic effects of R. typhina extracts on the turf species were significantly affected by the organ the extract was prepared from， the concentration of the extract， and the type of turf species being treated， and there were significant interactions among these factors （P<0.05）. All T. repens seedlings died after being treated with any of the extracts at any concentration. The seed germination and seedling growth of F. arundinacea were significantly inhibited by the root， bark， and leaf extracts of R. typhina. The effect of the root extract did not change as its concentration increased， but the inhibitory effects of bark and leaf extracts increased as their concentrations increased， with the F value decreasing by 1.07-2.77. The leaf and bark extracts of R. typhina had stronger inhibitory effects on F. arundinacea than did the root extract at the same concentration， with F values 0.98-3.23 lower in the leaf and bark extract treatments than in the root extract treatments. The inhibitory effects of R. typhina root and bark extracts on L. perenne first increased and then decreased as their concentrations increased. However， the inhibitory effect of the R. typhina leaf extract continuously increased as its concentration increased， with the F value decreasing by 1.11. In addition， extracts from all organs exhibited greater inhibitory effects on L. perenne than on F. arundinacea， with F values that were 0.64-2.96 lower in L. perenne than in F. arundinacea. Generally， the leaf extracts had stronger inhibitory effects than the root and bark extracts at concentrations of 12.5 and 50.0 g·L^-1， with F values that were 0.44-1.55 lower in the leaf extract treatments than in the root and bark extract treatments. However， the bark extract had a stronger inhibitory effect than the leaf and root extracts at a concentration of 25.0 g·L^-1， with F values that were 0.51-0.69 lower in the bark extract treatments than in the leaf and root extract treatments. In conclusion， these results show that F. arundinacea is the most suitable of the three tested turf species to be planted under R. typhina， and T. repens should be avoided.

Adaptability evaluation of different oat varieties introduced in the Hulunbuir region

Hong-fei LI, Bang-wei ZHOU, Miao ZHANG, Shu-nan SHI, Zhi-jian LI

2024, 33(4):  60-72.  DOI: 10.11686/cyxb2023247

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In order to select high-quality Avena sativa varieties suitable for cultivation in the Hulunbuir region， eighteen oat germplasm lines were tested for their regional adaptation at this site. Because of spatial variation in the field planting environment at the test site， a randomized complete block test design was adopted. Production performance traits measured for the tested germplasm lines included nutritional quality and agronomic traits. A gray correlation analytical method was used to generate a multivariate trait score for the tested varieties， in order to provide information on adaptability of the tested oat varieties in this region. All tested oat varieties reached maturity， with the crop cycle period ranging from 76 to 109 days. The development of all tested germplasm lines showed a pattern of “slow-fast-slow” growth rate. For the tested oat varieties， the vegetative yield gradually increased till the grain filling stage. The variety Galileo had the highest hay yield （13.18 t·ha^-1）， followed by Tianyan No.3 （12.32 t·ha^-1） ， Baylor （12.25 t·ha^-1）， these three being significantly higher than other varieties （P<0.05）. The heights of Baylor （120 cm） and Tianyan No.3 （117 cm） were significantly higher than other oat varieties tested （P<0.05）. Fuyan No.1 had the highest fresh∶dry weight （4.98） and Baiyan No.7 had the lowest stem∶leaf （1.74）， indicating that these two varieties would have better palatability. Fuyan No.1 had the highest crude protein content （13.46%）， and Fuyan No.2 had the lowest neutral detergent fiber and acid detergent fiber contents， indicating enhanced nutritive value for these two cultivars. Grey correlation analysis shows that oats grown in this area should be selected with traits such as high fresh∶dry weight， large leaves， thick stems， high crude protein content， and high vegetative yield. Tianyan No.3， Galileo and Fuyan No.2 were the top-ranked varieties for overall performance and could be promoted as excellent varieties for cultivation in the Hulunbuir region.

Phenotype and genetic variation analysis of forward and reverse hybrid progeny from different oat crosses

Ping MU, Ji-kuan CHAI, Wei-juan SU, Hai-long ZHANG, Gui-qin ZHAO

2024, 33(4):  73-86.  DOI: 10.11686/cyxb2023183

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In order to clarify the phenotypic and genetic variation differences of F₁ and backcross hybrid progenies in oat （Avena sativa）， crosses were made in this study between four oat varieties： Forage （F709）， 709 （709F）， Molass （ML2） and Longyan No. 2 （L2M）. Molecular identification of hybrid F₁ plants was conducted by simple sequence repeat （SSR） and their phenotypic differences were compared. The genetic variation and diversity of the F₂ generation were also analyzed. It was found that 32 from 37 （86.5%） of F₁ plants were identified as true hybrids based on SSR. True hybrid rates of up to 88.9% were obtained for the Forage and 709 crosses， and rates of up to 84.2% were obtained for Molass and Longyan No.2. The cross mode significantly affected hybrid phenotype. The flag leaf width of F709-F₁ was 19.4% narrower than that of 709F-F₁. The grain number of the main panicle of ML2-F₁ was 12.2% less than that of L2M-F₁. The genetic variation of the F₂ population was remarkable. Significant differences were observed in the F₂ genetic variation coefficient （G_cv）， generalized heritability （H_b） and relative genetic progress （ΔG_t） of the same trait in F₁ and backcrosses. Among the F₂ population， plant height had the lowest G_cv （4.50%-10.27%） and higher H_b （33.12%-85.41%） while tiller number and effective tiller number had the greatest relative genetic progress. The H_b of peduncle length of the F₂ population from Forage and 709 was the lowest （14.13% for the F₁ cross and 23.81% for the backcross）， with the least relative genetic progress. Significant G_cv and H_b differences between the F₁ and backcrosses， were observed for grain number of the main panicle with values of 7.09% and 22.54%， respectively in F709-F₂， and 19.03% and 66.01% in the backcross._{The leaf number of the F2 population from Molass and Longyan No.2 had the highest Hb （99.53%）， indicating little environmental effect. The Hb of flag leaf width of ML2-F2 was 9.07%， and ΔGt was 2.79， while in L2M-F2， Hb was 30.23% and ΔGt was 9.77. Ten polymorphic SSR primers resulted in 73.5% polymorphism rate in the F2 population. Actual heterozygosity （0.35-0.99） was much higher than the expected heterozygosity. The Nei’s gene polymorphism and Shannon index were 0.29-0.50 and 0.53-0.71， respectively， indicating an obvious segregation and greater variation with great selection potential.}

Effects of salt stress on water use efficiency and osmotic adjustment of seedlings of different triticale strains

Yi-yin ZHANG, Xue-ying LI, Bin WANG, Ke-chen SONG, Jian LAN, Hai-ying HU

2024, 33(4):  87-98.  DOI: 10.11686/cyxb2023184

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In this study， we compared water use efficiency and the osmotic adjustment system among seedlings of 10 different triticale strains （SD， X-520， X-516， J-46， JIN， HN， T-11， T-9， T-5 and XJ） under salt stress. The salt-stressed group was grown in soil irrigated with salt water to reach a total salt content of 0.6% NaCl， and the control group was grown in soil with normal irrigation. The effects of salt stress on the growth， water use characteristics， and contents of osmotic adjustment substances in triticale were determined， and the different triticale strains were ranked on the basis of their salt tolerance. These analyses provided a theoretical basis for the evaluation of salt-tolerant triticale varieties in Ningxia. It was found that salt stress inhibited the normal growth of triticale， and promoted its water use efficiency and the accumulation and transfer of osmotic adjustment substances. Under salt stress， the highest value for plant height was in X-520， followed by X-516， and the highest values for tiller number and aboveground biomass were in SD. The stable carbon isotope （δ¹³C） contents were more in SD， X-520， and X-516 （-27.33， -27.40， and -27.39， respectively） than in the other triticale strains. The highest contents of proline， soluble protein， and starch were in SD. Correlation analyses showed that δ¹³C was significantly positively correlated with relative water content and the contents of organic osmotic adjustment substances， root sodium ions， and leaf potassium ions. The strains were ranked from most to least salt tolerant， as follows： SD>X-520>X-516>J-46>JIN>HN>T-11>T-9>T-5>XJ. Therefore， SD， X-516， and X-520 were identified as potential breeding materials to generate new triticale strains suitable for cultivation in saline-alkali land in Ningxia.

Meta-analysis of the effects of mycorrhizal fungi on plant leaf physiology

Lu-ping MA, Zhao-yong SHI, Wen-jing WEI, Shuang YANG

2024, 33(4):  99-109.  DOI: 10.11686/cyxb2023189

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Leaves are important plant organs， and their contents of nutrients， photosynthetic pigments， soluble sugars， and soluble proteins， as well as the activities of various enzymes， are important parameters that characterize their physiology. Photosynthesis and transpiration are important indicators of physiological activity in leaves. Mycorrhizal fungi are soil microorganisms that form symbioses with the vast majority of plants， and they can affect leaf physiology. For this study， we selected the most widely distributed arbuscular mycorrhizal fungi （AMF） and evaluated their effects on plant leaf physiology by conducting a Meta-analysis. Most previous studies have focused on investigating the physiological functions of a single plant inoculated with one AMF. To address this issue， we used a quantitative research method and a Meta-analysis to build and analyze a database of 152 relevant papers. These analyses allowed us to evaluate the impact of AMF on plant leaf physiology， and explore the effects of AMF at different classification levels. According to the results reported in the literature， AMF significantly increased the contents of nitrogen， phosphorus， potassium， calcium， magnesium， and zinc in leaves by 12.6% to 26.3%； Increased contents of chlorophyll， chlorophyll a， and chlorophyll b by 16.3%， 12.1%， and 11.1%， respectively； And increased the contents of soluble sugars and soluble proteins by 34.8% and 18.4%， respectively. Various AMF also increased the activities of enzymes in leaves， including peroxidase （by 31.3%）， superoxide dismutase （by 17.8%）， catalase （by 23.3%）， polyphenol oxidase （by 59.1%）， and phenylalanine ammonia lyase （by 65.3%）. As a result， AMF increased the net photosynthetic rate and transpiration rate of leaves by 27.7% and 31.1%， respectively. The results of this Meta-analysis show that different taxa （family， genus， species） of AMF have different effects on leaf physiology. These findings represent a systematic evaluation of the impacts of AMF on leaf physiology， highlight the functional diversity of AMF， and provide a practical basis for screening efficient AMF to improve leaf physiology.

Isolation and growth-promoting characteristics of rhizobacteria producing indole-3-acetic acid from the rhizosphere soil of Kalidium foliatum

Xin-yu CHENG, Ji-lian WANG, Mairiyangu·Yasheng, Ming-yuan LI

2024, 33(4):  110-121.  DOI: 10.11686/cyxb2023205

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Plant growth-promoting rhizobacteria that are able to produce indole-3-acetic acid （IAA） are useful for the development of high-efficiency microbial fertilizers. In this study， IAA-producing rhizobacteria were isolated from the rhizosphere soil of Kalidium foliatum growing in the Kizilsu Kirgiz Autonomous Prefecture of Xinjiang by culturing on selection media. The isolates were identified on the basis of 16S rDNA PCR-restriction fragment length polymorphisms and their 16S rDNA gene sequences. The effects of strains with a strong ability to produce IAA on the germination of maize and wheat seeds were determined. Furthermore， their effects on the growth of maize and wheat seedlings （plant height， stem diameter， aboveground dry weight） under saline-alkali stress were verified in pot experiments. A total of 67 isolates were screened， and their IAA production capacity ranged from 16.65 to 71.63 mg·L^-1. Among all the strains， PM14 and PM18 showed the highest IAA production capacity. In addition， strains PM14 and PM18 were capable of phosphorus solubilization and nitrogen fixation. On the basis of 16S rDNA gene sequence and phylogenetic analyses， the isolates were divided into six genera， of which Enterobacter was the dominant genus. Both PM14 and PM18 promoted seed germination， but there were significant differences in the promoting effect on seed germination between low- and high-concentration groups （P<0.05）. After inoculation with PM14 or PM18， the plant height， fresh weight， aboveground dry weight， stem diameter， and root dry weight of maize seedlings were increased by 4.7%-37.2%， 28.8%-94.5%， 15.8%-157.9%， 4.4%-35.5%， and 23.5%-82.4%， respectively， but there was no significant effect on chlorophyll content. The plant height， stem diameter， fresh weight and aboveground dry weight of wheat seedlings were increased by 9.5%-33.1%， 13.0%- 49.6%， 57.4%-112.8%， and 71.4%-114.3%， respectively， after inoculation with PM14 or PM18. Except for an inactivated culture of PM14， all other treatments had positive effects on root dry weight， with increases ranging from 52.8% to 69.0%. However， none of the treatments significantly affected chlorophyll content. In summary， IAA-producing plant growth-promoting rhizobacteria improved the resistance of wheat and maize plants to salt-alkali stress， which is of great significance for the development of microbial fertilizers suitable for cultivating crops in salt- and alkali-affected areas.

Differences in phosphorus acquisition characteristics and rhizosphere properties among different hairy vetch genotypes

Dan-na CHANG, Zi-ying CHEN, Mei HAN, Zheng-peng LI, Qing-biao YAN, Shuai-lei LV, Guo-peng ZHOU, Xiao-feng SUN, Wei-dong CAO

2024, 33(4):  122-134.  DOI: 10.11686/cyxb2023208

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Hairy vetch （Vicia villosa） is one of China’s most important fertilizer and forage dual-purpose green manure crops. In this study， we investigated differences in phosphorus （P） acquisition and rhizosphere properties among different genotypes of hairy vetch to provide baseline knowledge about phosphorus utilization in hairy vetch. A pot experiment was carried out in Xining city， Qinghai Province， testing two factors： Hairy vetch cultivars and phosphate fertilizer types. Two P-efficient and two P-inefficient hairy vetch cultivars were screened in a field test. The phosphate fertilizers were calcium superphosphate and rock phosphate， and the control had no phosphate fertilizer added. We analyzed P uptake， soil P fractions， soil organic acid contents， root acid phosphatase （RACP） and soil acid and alkaline phosphatase activities （ACP and ALP）， and the abundance of genes encoding soil acid and alkaline phosphatases （phoC and phoD） at the full-bloom stage of hairy vetch. The results showed that the ranges of total P-uptake and P-utilization rates of hairy vetch cultivars were 7.45-46.07 mg·pot^-1 and 7.12%-22.49%， respectively. The total P-uptake and P-fertilizer utilization rates were significantly higher in P-efficient cultivars than in P-inefficient cultivars， by 0.91%-61.20% and 12.52%-60.25%， respectively. Compared with P-inefficient cultivars， P-efficient cultivars contained higher proportions of labile P and moderately labile P and lower proportions of stable P. The proportions of labile P and moderately labile P in P-efficient cultivars were 6.14-26.14 times higher and 1.04-1.54 times higher， respectively， than those in P-inefficient cultivars. The proportion of stable P was 2.92-7.91 times higher in P-inefficient cultivars than in P-efficient cultivars. Soil total organic acid and oxalic acid contents， and the activities of RACP， ACP， and ALP were significantly higher in P-efficient cultivars than in P-inefficient cultivars by 117.45%-254.60%， 19.40%-50.75%， 16.37%-146.40%， 6.19%-104.19%， and 6.16%-35.06%， respectively. The abundance of phoC and phoD was 1.07-2.58 times higher and 1.46-3.64 times higher， respectively， in P-efficient cultivars than in P-inefficient cultivars. Linear regression analyses showed that soil total organic acid and oxalic acid contents and RACP and ACP activities were significantly positively correlated with soil labile P （determination coefficients of 0.40， 0.46， 0.13， and 0.19， respectively）， but significantly or very significantly negatively correlated with stable P （determination coefficients of 0.75， 0.58， 0.41， and 0.49， respectively）. In summary， compared with the P-inefficient cultivars， the P-efficient hairy vetch cultivars showed stronger abilities to acquire insoluble P and had higher P-uptake and P-fertilizer utilization rates. The P-efficient hairy vetch cultivars acquired immobile P by increasing organic acid （mainly oxalic acid） contents and phosphatase activity， accompanied by increased abundance of phoC and phoD genes in the soil， which in turn increased the proportions of labile P and moderately labile P and promoted P absorption and utilization.

Identification of the alfalfa SAUR gene family and its expression pattern under abiotic stress

Hao LIU, Xian-yang LI, Fei HE, Xue WANG, Ming-na LI, Rui-cai LONG, Jun-mei KANG, Qing-chuan YANG, Lin CHEN

2024, 33(4):  135-153.  DOI: 10.11686/cyxb2023235

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SAUR （small auxin up-regulated RNA） is a category of auxin gene in plant early response， involved in a series of biological processes such as plant growth and development and abiotic stress response. The SAUR gene family has been systematically identified and analyzed in Arabidopsis thaliana， rice （Oryza sativa）， cotton （Gossypium spp.） and other species， but the research on the SAUR gene family in alfalfa（Medicago sativa）， the most important leguminous forage in the world， has not been carried out. In this study， a total of 433 MsSAUR gene family members were identified in the reference genome of alfalfa using bioinformatics methods， and their genome location， gene structure， promoter cis-acting elements and expression patterns in different tissues were analyzed. Meanwhile， using transcriptome data of alfalfa under different abiotic stresses， it was found that five MsSAUR gene family members responded to drought stress， 11 responded to salt， 19 responded to cold and 12 responded to alkali stress. MsSAUR14/94/254 could respond to drought and salt stress simultaneously， and MsSAUR297 could respond to drought， salt and alkali stress simultaneously. MsSAUR306 can respond to drought， salt and cold stress simultaneously. The results of this study can provide important candidate genes for the creation， using genetic engineering， of new germplasm with high yield and resistance.

Identification and expression pattern of the WRKY transcription factor family in Medicago sativa

Xian-yang LI, Hao LIU, Fei HE, Xue WANG, Ming-na LI, Rui-cai LONG, Jun-mei KANG, Qing-chuan YANG, Lin CHEN

2024, 33(4):  154-170.  DOI: 10.11686/cyxb2023214

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WRKY transcription factors are one of the largest gene families in plants and play important roles in plant growth and development as well as in abiotic stress processes. Currently， members of the WRKY gene family have been extensively studied and analyzed in a variety of plant species. However， the alfalfa （Medicago sativa） WRKY transcription factors have not been identified and analyzed at the genome-wide level. In this study， we systematically identified alfalfa WRKY gene family members and analyzed their expression patterns under different stress treatments. We showed that a total of 198 WRKY transcription factors were unevenly distributed across 32 chromosomes in alfalfa， with chromosome 7 having the largest number. The phylogenetic tree results show that the WRKY gene family members can be divided into three groups. Among these WRKY transcription factors， 42 responded to salt stress， 7 to alkali stress， 19 to cold stress and 37 to drought stress， and MsWRKY154 and MsWRKY166 were found to respond to both salt， drought， and cold as well as alkali stress. The results of this study provide a foundation for the intensive investigation of the biological function of WRKY transcription factors in alfalfa， and can also provide valuable information for molecular breeding in alfalfa.

Chloroplast genome assembly and phylogenetic analysis of Pholidota chinensis and Pholidota cantonensis

Bao-cai LIU, Xue-bo HU, Wu-jun ZHANG, Yun-qing ZHAO, Ying-zhen HUANG, Jing-ying CHEN

2024, 33(4):  171-185.  DOI: 10.11686/cyxb2023192

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Pholidota chinensis and Pholidota cantonensis are rare and endangered epiphytic orchids. Little is known about their chloroplast genome sequences and phylogeny， so the aim of this study was to reveal their chloroplast genome characteristics and phylogenetic relationships. Young leaves of domesticated P. chinensis and P. cantonensis were collected in May 2022， and DNA was extracted and then sequenced using the Illumina sequencing platform. Bioinformatic analyses revealed that the chloroplast genomes included repetitive sequences and quartet boundaries， and showed codon biases. Chloroplast DNA sequences from related species were downloaded from the NCBI for genome comparison and phylogeny analyses. The chloroplast genomes of P. chinensis and P. cantonensis were 159122 bp （37.41% GC content） and 158798 bp （37.47% GC content） in length， respectively. They both included a large single-copy region （LSC）， a small single-copy region （SSC）， and an inverted repeat sequence （IRa/IRb）. The relative synonymous codon usage of UUA encoding leucine reached 1.90 in P. chinensis and 1.91 in P. cantonensis. The chloroplast genome of P. chinensis had 44 simple sequence repeats， 47 scattered repeats， and 26 tandem repeats. The chloroplast genome of P. cantonensis had 32 simple sequence repeats， 25 scattered repeats， and 30 tandem repeats. The quartet boundaries and covariance of the six species in the Pholidota showed no large block variations， but some nucleotide polymorphisms were detected. Genes including trnK-UUU， trnQ-UUG， and rpl16 were identified as candidate genes for molecular markers of these species. A systematic analysis clarified that， although P. chinensis and P. cantonensis are in the genus Pholidota， they are more closely related to Bulleyia yunnanensis and Coelogyne fimbriata， and are located on the same branch of epiphytic orchids in the phylogenetic tree. The inversion of large segments of the chloroplast genome might be one of the reasons for the different growth habits of members of the Orchidaceae， and their ability to adapt to different habitats. The results of this study reveal the characteristics of the chloroplast genomes of P. chinensis and P. cantonensis， and provide new information about the relationship between their phylogeny and growth habits. These findings lay the foundation for further research on the classification of members of the Orchidaceae， as well as for molecular marker development and other related research.

Transcriptome analysis-based bermudagrass root RNA sequencing data under drought stress

Shuo LI, Pei-ying LI, Zong-jiu SUN, Wen LI

2024, 33(4):  186-198.  DOI: 10.11686/cyxb2023193

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The root system is the most important organ of bermudagrass in response to drought stress， and the molecular mechanism of its response to different degrees of drought needs to be further clarified. In this study， two bermudagrass genotypes with contrasting drought-resistant （C138） and drought-sensitive （C32） properties， were sampled under normal irrigation （soil relative water content is 80%-90% of the field capacity）， moderate drought （50%-60% of field capacity） and severe drought （20%-30% of field capacity）. From transcriptome sequencing with the Illumina High-throughput sequencing platform， 43581 Unigenes were obtained， 33025 of which were annotated. Compared with normal irrigation， there were 7537 genes differentially expressed in C138 under moderate and severe drought， comprising 1164 up-regulated and 6373 down-regulated， while in C32， there were 4304 up-regulated and 2427 down regulated unigenes. Top20 GO enrichment analysis found that C138 was mainly enriched in oxidoreductase activity， carbohydrate metabolism and cellulose binding under moderate stress； C138 was mainly enriched in phosphate metabolism and protein phosphorylation under severe stress， and C32 was mainly enriched in peroxidase activity and oxidative stress response. KEGG Pathway enrichment analysis found that C138 was mainly enriched in glutathione metabolism， phenylpropyl biosynthesis and the nitrogen metabolism pathway， while C32 was mainly enriched in oxidative phosphorylation， tricarboxylic acid cycle， ribosomal enzymes and carbon metabolism pathways under moderate stress. Under severe drought stress， C138 was mainly enriched in glutathione metabolism， arachidoic acid metabolism and the ribosomal enzyme pathway， while C32 was mainly enriched in the glutathione metabolism and phenylpropyl biosynthesis pathways. Overall， the gene expression response to moderate drought stress in bermudagrass was mainly related to oxidative response. Severe drought stress was mainly related to the Ca²⁺ pathway， abscisic acid signaling pathway， and glutathione metabolism. Thus， glutathione metabolism might be the main KEGG pathway affected in response to drought in bermudagrass. Moreover， compared with C32， C138 had more calcium-dependent protein kinase-related gene expression in response to drought stress and thus had stronger drought resistance. In conclusion， glutathione metabolism and MYB transcription factor-related genes may be critical for drought resistance in bermudagrass and from this work are indicated as the first choice for investigation in a drought-stress gene study.

Effects of dietary supplementation with kudzu vine on apparent nutrient digestibility， intestinal development， and intestinal digestive enzyme activities in growing meat rabbits

Cheng-fang GAO, Lei SANG, Shi-kun SUN, Dong-jin CHEN, Jin-xiang WANG, Xi-ping XIE

2024, 33(4):  199-209.  DOI: 10.11686/cyxb2023180

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We investigated the effect of dietary supplementation with kudzu vine （Pueraria lobata） on the growth and quality of meat rabbits. A total of 200 weaned Ira rabbits with similar body weight （0.88±0.13 kg） at 35±2 days of age were randomly divided into four groups with five replicates in each group and 10 rabbits in each replicate. The rabbits were fed with diets containing 0 （Group A）， 15% （Group B）， 25% （Group C）， and 35% （Group D） kudzu vine， where Group A was the control group. The experiment consisted of a 7-day pretest period， followed by a 42-day trial period. Starting from day 36 of the trial period， a 7-day digestion and metabolism test was conducted to analyze the apparent digestibility of nutrients in the diets of meat rabbits. Intestinal development and the activities of intestinal digestive enzymes were determined and analyzed at the end of the test. A conventional nutrient analysis was conducted for kudzu vine. It was found that： 1） The apparent digestibility of nutrients （dry matter， crude protein， crude fiber， neutral detergent fiber， acid detergent fiber， acidic lignin， ether extract， and galacturonic acid） by meat rabbits was higher in the treatment groups than in the control group. The apparent nutrient digestibility was highest in Group D （35% kudzu vine）， and it was significantly higher than that in Group B （15% kudzu vine） and the control group （P<0.05）. 2） The activities of cellulase， hemicellulose， and pectinase in the cecum of meat rabbits were higher in the treatment groups than in the control group. The activities of these enzymes were highest in group B （15% kudzu vine）， and were significantly higher than those of their counterparts in the control group （P<0.05）. 3） Dietary supplementation with kudzu vine had no effect on the relative length of the stomach and small intestine of meat rabbits （P>0.05）. However， the relative length of the cecum， relative weight of the cecum， relative weight of the stomach， and relative weight of the small intestine were significantly higher in Groups C and D （25% and 35% kudzu vine， respectively） than in the control group （P<0.05）. 4） Dietary supplementation with kudzu vine increased the villus length of the jejunum， ileum， and duodenum， villus length/crypt depth （V/C） ratio， and the mucosal thickness of meat rabbits， and decreased the crypt depth. Compared with the control group， Group D （35% kudzu vine） showed significantly higher values （P<0.05） for villus length of the ileum and duodenum，lower values for the crypt depth of the jejunum and ileum， and significantly higher values （P<0.05） for the V/C ratio of the jejunum and ileum. Therefore， dietary supplementation with 35% kudzu vine is optimal for Ira meat rabbits.

Effects of resveratrol supplementation in the perinatal diet on production performance， blood indexes， and transcript abundance of genes encoding inflammatory factors in goats

Jie ZHAO, Heng-guang CHEN, Xiao-meng PEI, Hao YU, Yin-ying XU, Da-gan MAO

2024, 33(4):  210-220.  DOI: 10.11686/cyxb2023190

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The aim of this experiment was to study the effects of resveratrol in the perinatal diet of goats in terms of growth performance， blood indexes， and the transcript levels of genes encoding inflammatory factors. Eighteen multiparous Subai female goats at 129 days of gestation （21 days prior to expected parturition） were divided into a control group （basal diet） and a Res group （supplemented with resveratrol at 400 mg·kg^-1 dry matter intake）. Blood was collected 15 days before （d_-15） and 0 （d₀） and 15 （d₁₅） days after parturition， and the productive performance， blood indexes， and transcript levels of genes encoding inflammatory factors were determined. The pre-test period was 1 week and the formal test period was 4 weeks. It was found that the Res treatment did not significantly affect ewe feed intake， lamb birth weight， body size， or daily weight gain. The feed intake significantly changed between before and after parturition （P=0.023）， and ewes in both groups had the lowest feed intake on the day of parturition. In terms of biochemical indexes， the Res treatment significantly affected d₀ non-etherized fatty acid levels， and the time×Res interaction was significant （P<0.05）. The Res treatment tended to affect total cholesterol （TC） （P=0.093）， but did not significantly affect triglyceride levels. In both groups， the triglyceride levels differed significantly between before and after delivery （P=0.002）. The Res treatment did not significantly affect high density lipoprotein levels， but there was a trend towards an effect of the Res×time interaction （P=0.055）. Neither low density lipoprotein nor glucose levels showed significant changes （P>0.05）. In terms of antioxidant indexes， the Res treatment significantly increased superoxide dismutase activity on d₁₅ （P<0.05）， and there was a tendency for Res treatment to affect the total antioxidant capacity （P=0.078）. However， the Res treatment did not significantly affect glutathione peroxidase activity or the malondialdehyde content （P>0.05）. In terms of immunity indexes， the Res treatment significantly affected the immunoglobulin A level on d₀ （P<0.05） and the immunoglobulin M levels on d₀ and d₁₅ （P<0.05）， but there was no significant change in the immunoglobulin G level during the test period （P>0.05）. The Res treatment led to significantly decreased transcript levels of TNFα and IFNγ on d₁₅ （P<0.05）， but there were no significant changes in the transcript levels of Nrf2， HO-1， IL-1， and IL-6 （P>0.05）. Our results show that addition of resveratrol to the diet of perinatal ewes affects free fatty acid levels in the blood， enhances their antioxidant performance， and reduces their inflammatory response to a certain extent.

Evaluation of rodent control quality in grassland in China based on an entropy weight TOPSIS model

Ding YANG, Jiao JIN, Jing-hao LI, Zhi-peng WANG, Yuan-bo HAO, Ning DING, Lu CHEN

2024, 33(4):  221-230.  DOI: 10.11686/cyxb2023063

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Grassland is a complex socio-economic ecological composite system and a valuable resource providing many ecosystem services. However， due to climate change and excessive human usage， grassland has become more and more vulnerable to ecological instability in recent years. One problem needing to be addressed is the control of rodent populations in grassland. Poisoning of rodents has also reduced the populations of natural predators， both by effects of the poison directly， and depriving natural predators of food indirectly. The result has often been a serious rebound of rodent populations after initial control by poisoning， therefore， emphasis is now moving towards ‘green’ control of rats allowing them to exist in the ecosystem without population explosion events. It is urgent to develop new models to refine and evolve this new approach to rodent control. In response to that need， we developed an objective TOPSIS （technique for order preference by similarity to an ideal solution） model to examine the status of rodent control across 14 provinces， accounting for 99% of grassland area of China. Of the 14 provinces， six were classified as major grassland provinces with 95% of China’s grassland between them， and the other eight as minor grassland provinces. The results showed that rodent eradication program evaluation scores were highest for investment in prevention and control， followed by scores for outcomes， with scores for infrastructure and organizational development the lowest. From 2019 to 2021， the overall score across the three areas evaluated was generally low， rating as is average or poor. Interestingly， minor grassland provinces performed significantly better than major grassland provinces in the overall evaluation. This study provides objective data for adjusting resource allocation for improved outcomes in the process of grassland rodent management and prevention of harmful population explosion events.