Table of Content

20 November 2021, Volume 30 Issue 11

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Estimation of vegetation aboveground biomass in the Wei-Ku Oasis based on Landsat 8 OLI images

Dian-dai ZHANG, Xue-mei WANG, Mei ZAN

2021, 30(11):  1-12.  DOI: 10.11686/cyxb2020569

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Estimation of vegetation aboveground biomass in the arid oasis can provide important evidence for evaluating the stability of the oasis ecosystem and estimating regional carbon storage. This research targeted the delta oasis of the Weigan-Kuqa Rivers and used ENVI 5.3 software to preprocess Landsat 8 Operational Land Imager （OLI） image data to survey vegetation aboveground biomass in the study area. We extraced vegetation indices and band factors reflecting aboveground biomass information， combined with measured data from sample plots and used conventional statistical models， multiple stepwise regression and partial least square regression methods to establish an optimal model of vegetation aboveground biomass， so as to reveal the spatial distribution characteristics of vegetation aboveground biomass in this oasis. It was found： 1） There was a extremely significant positive correlation between the 20 selected remote sensing factors and the measured aboveground biomass and the values of the correlation coefficients ranged from 0.5-0.7 （P<0.01）. 2） The optimal estimation models for arbors and shrub aboveground biomass were multiple stepwise regression models. The partial least squares regression models were the best models for estimating the aboveground biomass of herbs and crops. The verification determination coefficients of the model were above 0.6， and the root-mean-square error and mean absolute error were both lower. 3）The vegetation aboveground biomass in the study area was typically within the range of 280-1450 g·m^-2，^{with an area of about 6973.82 ha. Land with low lever aboveground biomass （<65 g·m-2） accounted for about 15.02% of the total land area in the survey area. The ranking of aboveground biomass from high to low for different vegetation categories was： Crops>arbors>shrubs>herbs. For the various vegetation types， the remote sensing estimation model based on the spectral characteristics of ground objects was able to accurately estimate vegetation aboveground biomass in the arid oasis， and carry out remote sensing quantitative inversion of spatial distribution characteristics of its vegetation.}

The characteristics of the soil seed bank in Wuhai and surrounding areas and the relationship with vegetation and soil factors

Chao LUO, Xiao-ping GUO, Chang-dong FENG, Jin-peng YE, Dong-ming XUE

2021, 30(11):  13-28.  DOI: 10.11686/cyxb2020410

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The soil seed bank is the driver of natural vegetation renewal and restoration and is important for ecological restoration in arid desert areas. The aim of our study was to explore the characteristics of the soil seed bank and its relationship with aboveground vegetation and soil factors in arid desert areas. In this research， the study area was Wuhai City， Inner Mongolia， and its surrounding districts and 12 typical habitats and vegetation types within the study area were selected based on factors such as topography， soil， vegetation and degree of disturbance. The characteristics of the soil seed bank and its relationship with aboveground vegetation and soil factors were evaluated based on botanical investigation， persistent and transient soil seed bank sampling in different seasons， germination experiments and analysis of soil physical and chemical properties. It was found that： 1） The average seed bank density in study area was 217-1547 seeds·m^-2， most of which were perennial herbs. The seed density decreased with increase in soil depth. The persistent soil seed bank accounted for 17.34%-64.22% of the total seed bank density. In habitats of intermediate or low disturbance， its proportion was typically more than 40%. 2） The soil seed banks in different habitats and vegetation types differed significantly， while the soil seed banks of adjacent geographical environments were similar. However， the seed bank density and species diversity of intermediate disturbance areas were higher than perimeter zones of low disturbance. 3） The similarity between the soil seed bank and aboveground vegetation in the Xinxing mining area was relatively high， while the composition and structure of the seed bank and vegetation in other areas were quite different. 4） Soil seed bank species showed different clustering in different soil environments. Soil factors only partly explained （typically 30%-40% of data variation） the soil seed bank variation. Soil organic matter and silt content were the most important soil factors affecting the persistent soil seed bank for the 0-5 cm， while clay content and gravel content were also important for the on 5-10 cm soil depth. By contrast， soil total phosphorus and clay contents were the main factors affecting the transient soil seed bank for the 0-5 cm soil depth， while organic matter content and soil bulk density were also important in the 5-10 cm depth. The research provides data on the composition of the topsoil seed bank to support vegetation restoration programs in the Wuhai region.

Effects of biochar and straw on the C∶N∶P stoichiometry of soil， microbes， and extracellular enzymes in an aeolian sandy soil

Jiao SUN, Jin-xiu LIANG, De-jie KONG, Xin-nian GUO, Yong-dong WEI, Tao ZHOU

2021, 30(11):  29-39.  DOI: 10.11686/cyxb2020407

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In this research straw or biochar were added to a sandy soil located at Helanshan East Road in Ningxia Province and the stoichiometric characteristics of soil， microorganisms and extracellular enzymes were analyzed to provide a scientific basis for farmland nutrient regulation and sustainable soil utilization. The experiment comprised seven treatments； a control， straw added at 3.5， 7.0， or 10.5 t·ha^-1， or biochar added at 3.4， 6.8， or 10.2 t·ha^-1. All plots received a standard base fertilizer dressing of 330 kg·ha^-1 elemental N， 46 kg·ha^-1 elemental P and 75 kg·ha^-1 elemental K. Our results demonstrated that the content of soil C， P， available N （AN） and available P （AP） increased significantly with increase in the rate of straw or biochar added， and addition of biochar was superior to addition of straw on an equal carbon basis. However， returning straw and biochar to the field had no significant influence on soil N content. Soil C/N， C/P， N/P and AN/AP ranged from 10.1-10.9， 7.4-8.2， 0.70-0.75 and 2.7-3.4， respectively. Additionally， both soil N/P and AN/AP exhibited a significant positive correlation with the quantity of straw returned， but a significant negative correlation with the quantity of biochar returned. The contents of microbial biomass carbon （MBC）， microbial biomass nitrogen （MBN） and microbial biomass phosphorus （MBP） after biochar addition were higher than those after straw treatment on an equal carbon basis， while the stoichiometric ratios for C∶N， C∶P and N∶P of soil microorganisms and extracellular enzymes were significantly higher after straw addition than those after biochar addition to the field. Finally， correlation analysis revealed that after addition of straw， soil AN was significantly positively correlated with β-glucosidase （BG）， L-leucine aminopeptidase （LAP）， β-acetylgucosaminidase （NAG）， MBC， ［BG+α-D-cellobiohydrolase （CBH）］∶β-acetylgucosaminidase （AKP）， （NAG+LAP）∶AKP and MBN∶MBP， but negatively correlated with AKP. After addition of biochar to the field， soil AP was significantly positively correlated with BG， CBH， LAP， NAG， MBC， MBN， （BG+CBH）∶AKP， but negatively correlated with MNC∶MBN. Taken together， these findings highlight that addition of biochar to the field increased soil nutrient content and microbial biomass， whereas returning straw to the field was conducive to maintenance of soil nutrient balance.

Effects of the ant species Formica aquilonia on soil seed banks in mountain meadows

Zhao-bi CHE, Peng-fei XU, Ya-ya GUO, Jia-min CAO, Xing-yu HUANG, Han-jun YANG, Wei-hua LU

2021, 30(11):  40-51.  DOI: 10.11686/cyxb2020401

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The aim of this research was to clarify the influence on soil seed banks of the ant species Formica aquilonia， whichis widely distributed in mountain meadows. Our study measured the composition of soil seed banks for 0-10 cm and 10-20 cm soil depths at the site of F. aquilonia nests， and at various distances from the nests. The influence of the soil environment on the species distribution of seed banks was also evaluated. It was found that for any given distance from ant nests， seed number and species number in the soil seed bank at 0-10 cm depth were significantly higher than at 10-20 cm. A total of 28 species belonging to 28 genera and 12 families， with the majority being from the Poaceae， were found in the soil seed bank at the center of ant nests. At depths of 0-10 cm and 10-20 cm at the nest center， the germination numbers of Plantago depressa， Agrostis turkestanica， Bromus inermis， Dactylis glomerata and Poa pratensis in the soil were significantly higher than at other sample points （P<0.05）. Perennial herbs were the plant type found in highest numbers in the soil seed bank. Again， the number of perennial herb seeds was significantly higher （P<0.05） at the nest center than at other sample points at both soil sampling depths. There was a significant positive correlation between nest size and seed number at the nest center （P<0.01）. With increasing distance from the nest center， the Shannon-Wiener diversity index， Marglef richness index， Pielou evenness index and Simpson dominance index values of the soil seed bank all exhibited a V-shaped pattern of change at both soil depths， with the species diversity index being lowest at 100 cm from the ant nest. Redundancy analysis indicated that soil available phosphorus was the main factor affecting the distribution of the soil seed bank in this area. The data show that F. aquilonia collect seeds from the surrounding environment and transport them to their nests， and so increase the seed number found at the nest site. This activity affects the spatial distribution of the soil seed bank in the nest surrounds， and causes spatial heterogeneity of the species distribution in the soil seed bank.

Effect of soil moisture and plant density on vegetative propagation traits and biomass of Elymus nutans

Ling-ling WANG, Kunduzay·Turgun, Guang-fei MENG, Zheng-gang GUO

2021, 30(11):  52-61.  DOI: 10.11686/cyxb2020424

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Elymus nutans， a good quality forage， produces daughter plants through vegetative asexual propagation in the alpine region. However， it’s unclear whether interaction between plant density and soil moisture has an influence on the subterranean vegetative propagation of E. nutans. In this study， a pot experiment was carried out to analyze the pattern of change in subterranean vegetative propagation （ramet numbers， rhizome length and underground bud number per plant） and biomass of E. nutans under different combinations of soil moisture and plant density. There were three soil moisture treatments： 30% of field capacity （W₁）； 50% of field capacity （W₂） and 80% of field capacity （W₃）， and three plant densities （4， 8， and 12 plants·pot^-1； R₁， R₂ and R₃， respectively）. This study showed that with increase in soil moisture， ramets per plant at first increased and then decreased， whereas rhizome length， numbers of underground buds per plant， aboveground and belowground biomass and total biomass all increased. With increase in plant density， ramets per plant， rhizome length， numbers of underground buds per plant， aboveground and belowground biomass and total biomass all decreased. Significant interaction effects between soil moisture and plant density were observed for ramets per plant， rhizome length， numbers of underground buds per plant， aboveground and belowground biomass and total biomass. Based on the results of this study， the optimal treatment for development of rhizome length， numbers of underground buds per plant， and aboveground and total biomass was W₃R₁， while for ramets per plant and belowground biomass the optimal treatment was W₃R₁. This indicates that in management of E. nutans cultivated grassland， soil moisture should be considered when determining the ideal plant density.

Effects of cold-season green manure on soil biochemical properties and the microbial community in a Castanea henryi orchard， China

Fen-sheng CHENG, Long-hui YOU, Jin-lin YU, Hui-chang XU, Hui-ming YOU, Sen NIE, Jian-min LI, Gong-fu YE

2021, 30(11):  62-75.  DOI: 10.11686/cyxb2021177

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This research evaluated the benefits of green manure for soil quality recovery， compared with traditional clear tillage and chemical herbicide application methods， in a Castanea henryi orchard in the typical red soil hill region of Fujian. A randomized block design was adopted， with each block having an area of 0.3-0.5 ha. The experiment site was cleared of natural weeds， then two grass species （Vulpia myuros， Mode₁； Lolium perenne， Mode₂） and a legume species （Vicia villosa， Mode₃） were trialed as green manure crops， and compared with glyphosate （CK₁） and clear tillage treatments （CK₂）， with three replicates of each. After 2 years， the physical and chemical properties of soils in the three green mature and the two CK treatments in the C. henryi orchard were analyzed. It was found that： 1） Compared with the clear tillage and glyphosate spraying treatments， the contents of alkali-hydrolyzable nitrogen， available phosphorus and available potassium in soils of Mode₁， Mode₂ and Mode₃ green manure crops were significantly increased， and the Mode₁ observe values was the highest， which ware 74.14， 156.87 and 234.76 mg·kg^-1， respectively. The soil porosity of the Mode₂ treatment was the highest， at 56.03%. The sucrase activities in soil of the Mode₁ and Mode₂ were significantly increased， with values of 32.29 and 26.87 U·g^-1， respectively. 2） The dominant bacterial groups shared by soils of all five treatments were Actinobacteria， Proteobacteria， Chloroflexi and Acidobacteria， with relative abundances of 24.9%-28.9%， 20.9%-28.8%， 13.7%-18.6% and 10.8%-12.9%， respectively. The dominant fungal groups shared by the five treated soils were mainly Ascomycetes and Basidiomycetes. 3） Compared with the clear tillage treatment， the Chao1 index and Shannon index of the bacterial community in the three green mature treatments were increased， while the fungal presence was decreased. 4） Compared with clear tillage and glyphosate spraying， the relative abundance of Proteobacteria， Bacteroides and Presence of Firmicutes in the soil of the three green manure treatments was decreased， while presence of bacteria of the phyla Chloroflexi and Planctomycetes was increased. The green manure crops promoted the transformation of the soil bacterial community from fast growth to slow growth. 5） Non-metric multidimensional scaling analysis of bacterial and fungal communities in the five treatments showed that the degree of differentiation of the soil fungal community was higher than that of the bacterial community. 6） Correlation analysis and redundancy analysis showed that the green manure crops increased soil invertase and catalase activities and alkali-hydrolyzable nitrogen content； the glyphosate treatment increased soil carbon：nitrogen ratio， and the clear tillage treatment changed fungi-related dominant groups by reducing soil water content. In summary， short-term green manure plantings in C. henryi orchards improved soil physical and chemical properties and enzyme activities to various degrees. Green manure， clear tillage and glyphosate treatments each resulted in a unique soil fungal community.

Effects of different densities of Brandt’s voles on communities of mycorrhizal fungal in the typical steppe of Inner Mongolia

Rong-rong LIU, Ping WANG, Xin-ling DAI, Ke-yu CHEN, Guo-liang LI, Xin-rong WAN, Bao-ming JI

2021, 30(11):  76-86.  DOI: 10.11686/cyxb2021113

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Brandt’s vole （Lasiopodomys brandtii） is the main rodent in typical steppe grassland of Inner Mongolia， China. Its activities can change the composition and diversity of plant communities and the physical and chemical properties of soil. It follows that Brandt’s vole activity could potentially affect the community composition and diversity of arbuscular mycorrhizal fungi （AMF）， one the of most important groups of soil microbes living in association with the majority of grassland plant species. However， little is known about the influences of Brandt’s vole activities on AMF. To investigate the effect of rodent activities on the community structure and composition of AMF， we conducted field sampling from plots treated with different densities of rodents （initial numbers of rodents per plot were 12， 24 and 48 for low， medium and high rodent densities， respectively） in Maodeng Ranch， Xilinhaote， Inner Mongolia. AMF communities in soil samples were analyzed with Illumina sequencing， and root mycorrhizal colonization rate and hyphal density were evaluated using a standard grid intersect method. 1） A total of six families and nine genera of AMF were identified in soil samples， among which the dominant genus was Glomus. 2） High density treatment of Brandt’s voles reduced plant biomass， vegetation cover， community richness and plant diversity， and reduced soil moisture and pH， but increased soil nitrate content and reduced AMF richness and diversity， root colonization rates and hyphal length density in soil. 3） Hyphal length density was positively correlated with the richness and diversity of plant communities， and with pH and moisture， but negatively correlated with nitrate content. AMF colonization was positively correlated with plant diversity， pH and moisture， but AMF diversity was positively correlated with soil pH and moisture. Operational taxonomic unit abundance of AMF was positively correlated with plant diversity and moisture. 4） Non-metric multidimensional scaling and permutational MANOVA analyses showed that AMF community structure differed between low-density and high-density rodent treatments and that NO₃^- and pH were the main factors driving the changes in AMF community composition. Based on these findings， we conclude that high density of Brandt’s voles will lead to a decrease in plant community biomass and diversity and soil nutrient content， and these changes will in turn lead to a significant decrease in AMF community diversity， which may accelerate the degradation of typical steppe.

A digital image analysis of seed phenotypic traits of 132 Lespedeza accessions

Zheng-yu YANG, Zhong-jie LU, Mao ZHANG, Rui DONG

2021, 30(11):  87-97.  DOI: 10.11686/cyxb2020413

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Lespedeza is an important forage legume species. In order to understand the genetic diversity of seed phenotypic traits in Lespedeza populations， digital image information was captured and collated for 132 Lespedeza accessions of 16 species， including Lespedeza juncea， Lespedeza cuneata， Lespedeza capitata and Lespedeza bicolor， among others. Seven seed morphological characteristics including seed length （SL）， seed width （SW）， length to width ratio （SL∶SW）， perimeter （Pe）， seed thickness （ST）， hilum length （HL）， and 100-seed weight （SY） were evaluated. Data were analysed using REML analysis in GenStat and a pattern analysis method that combines cluster analysis and principal component analysis. Significant differences （P<0.05） were found in most seed traits among the 132 Lespedeza accessions and all accessions of L. juncea. Except for the traits SL∶SW in L. capitata and L. bicolor， and the traits SL∶SW and Pe in L. cuneata， there were significant differences among accessions in all traits. For all 7 measured seed traits， the variability between seeds within accessions was greater than 5%， with the highest being 61.95%， and the lowest 5.42%. The R values of SY， ST and Pe of the 132 accessions and 4 species were all greater than 0.9， indicating strong genetic stability and that data can be used as a reference index for breeding. This research provides a good database for use in classification， germplasm resource improvement and genetic diversity research in the Lespedeza genus.

The effects of grass hedgerow roots on shear strength and scouring resistance of root-soil complexes in the purple soil region

Xiao-hong LIU, Yun CHEN, Zhe-hao YAN, Han TANG, Jiao-jiao QIANG, Yue QI, Yi-zhi DU

2021, 30(11):  98-107.  DOI: 10.11686/cyxb2020420

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Vegetated contour strips have significant effects on soil and water conservation on slopes， and the plant roots play a very important role. To explore the soil conservation properties of their root systems， we planted strips of two legumes （Dolichos lablab and Medicago sativa） at the Southwest University， Chongqing and the shear strength and scouring resistance of root-soil complexes were tested. To identify factors affecting mechanical properties， we imaged roots in grayscale， tested root chemical composition and mechanical properties and subjected data to correlation analysis. It was found that： 1） More than 90% of the root-soil complexes of M. sativa and D. lablab had a root diameter of less than 1.0 mm. The cellulose content of M. sativa complexes was significantly higher than that of D. lablab. The root length density， root surface area density and root volume density， and shear strength of complexes of D. lablab were more than those of M. sativa. 2） For the same diameter， the average maximum tension and tensile strength of D. lablab root complexes （19.76 N and 32.70 MPa， respectively） were more than those of M. sativa （14.32 N， 26.66 MPa）. The root diameter was positively correlated with ultimate maximum tension by a power function， and negatively correlated with tensile strength by power function. 3） The root systems of the two legume vegetation strips significantly （P<0.05） improved the cohesion and resistance， especially D. lablab vegetation strips. The average cohesion of D. lablab complexes was 22.88 kPa， which was 71.06% higher than that of the CK. And the scouring coefficient of D. lablab complexes was 19.00 L·g^-1， 2.60 times of that of the CK. 4） Principal component analysis showed that the root system traits that most affected the shear strength and scouring resistance of root-soil complexes were root length density， hemicellulose content and maximum tension. The comprehensive score of root-soil complexes of D. lablab vegetation strips was higher than that of M. sativa. In summary， the shear strength and scouring resistance of root soil complexes of D. lablab vegetation strips were better than those of M. sativa strips

Comprehensive evaluation of drought resistance of 15 oat varieties at the seedling stage

Dou-dou LIN, Gui-qin ZHAO, Ze-liang JU, Wen-long GONG

2021, 30(11):  108-121.  DOI: 10.11686/cyxb2021219

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This research evaluated the physiological response to drought stress of 15 different oat varieties at the seedling stage and used multivariate analyses of data for multiple traits to develop drought resistance indexes. Oat seedlings at the two-leaf growth stage in sand culture were stressed with nutrient solution containing 15% PEG. Antioxidant enzyme activity， malondialdehyde concentration， osmolyte levels， chlorophyll content， water use efficiency and relative conductivity of oat seedlings were measured at 0， 7 and 14 days of stress. Correlation analysis and principal component analysis were used to develop drought resistance indexes of the oat varieties， and cluster analysis and the membership function method were used to evaluate their drought resistance. It was found that： with increasing duration of drought stress， the antioxidant enzyme activity of the oat seedlings initially increased and then decreased； malondialdehyde content， osmolyte content and relative conductivity increased with increasing stress duration， while water use efficiency and chlorophyll content decreased significantly （P<0.05）. There was a good correlation between the 10 drought resistance indexes， with the correlation coefficient as high as 0.97. Principal component analysis showed that under drought stress， measures indicating the status of the plasma membrane system， photosynthetic factors and osmotic adjustment of the oat seedlings could be used as multivariate indexes to evaluate drought resistance， and the 15 tested oat varieties could be clearly separated into two distinct groups of differing drought resistance through scores for the first principal component. Cluster analysis further divided the tested varieties into four subgroups with different drought resistance. In particular， six varieties （Mengyan No.1， Qingyin No.1， Dingyan No.2， DA92-2F4， Qingyan No.1， Bayan No.5） displayed strong drought resistance. The cluster results also showed that the drought resistance of oat accessions from Northwest China （Gansu and Qinghai） was stronger than those from Northeast China （Jilin） and North China （Hebei）. Based on the multivariate score （D） for drought resistance from subordinate function analysis， the oat materials with the strongest drought resistance were Qingyan No.1 （0.829）， Qingyin No.1 （0.744） and DA92-2F4 （0.728）， while Longyan No.3 （0.208）， Bayan No.6 （0.240） and Zhangyan No.4 （0.241） had relatively weak drought resistance. The results of each evaluation method were consistent， but the multivariate evaluation system based on multi method correlation analysis was the most accurate and reliable. The results provide data on oat drought resistance to support selection and breeding decisions， and a methodology for generating a drought resistance index.

Physiological mechanism of exogenous cysteine application alleviation of lanthanum stress in naked oats

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

2021, 30(11):  122-131.  DOI: 10.11686/cyxb2020428

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The rare earth element lanthanum （La） as a heavy metal can cause stress damage to crops at high concentrations. In order to explore the mitigative effect of exogenous cysteine （Cys） on La stress in naked oats （Avena nuda） and its physiological mechanism， the effects of spraying Cys （0.0， 0.5， 1.0， 2.5， 5.0 mmol·L^-1） at heading stage on the metabolism of reactive oxygen species （ROS） and osmotic regulation in leaves of naked oats under 400 mg·kg^-1 La stress， were studied in a pot experiment. Measurements made included agronomic yield traits and the absorption and accumulation of La at crop maturity. It was found that the increase in superoxide anion content in naked oat leaves under La stress was alleviated by spraying 0.5-2.5 mmol·L^-1 Cys. Spraying 0.5-5.0 mmol·L^-1 Cys significantly alleviated increase in hydrogen peroxide and malonaldehyde contents in leaves of naked oat under La stress， and improved the shoot biomass， grains per spike， grain weight per spike， and grain yield of naked oats， but had no significant effect on plant height and 1000-grain weight. Spraying 0.5-5.0 mmol·L^-1 Cys significantly reduced the activities of superoxide dismutase and peroxidase， and ascorbic acid and carotenoid contents， and increased ascorbic acid peroxidase activities， glutathione and phytochelatin contents in leaves of naked oats under La stress. Spraying 0.5 and 1.0 mmol·L^-1 Cys significantly increased catalase （CAT） activity， while spraying 2.5 and 5.0 mmol·L^-1 Cys significantly decreased CAT activity. Spraying 0.5-5.0 mmol·L^-1 Cys significantly alleviated the decrease of soluble protein and soluble sugar contents in naked oat leaves under La stress， and further improved the proline content. Spraying 2.5 mmol·L^-1 Cys had the best effect. With increase in the spraying concentration of Cys， the enrichment capacity and absorption and accumulation of La in root， stem and leaf of naked oat under La stress were significantly increased， by 4.5%-41.3% and 4.4%-41.2%， respectively， but there was no significant effect on the transport of La to different parts of the naked oat plant. The above results showed that although exogenous Cys increased the absorption and enrichment of La in naked oats， the oxidative damage to cells and inhibition of agronomic yield traits caused by La stress was alleviated by regulation of the ROS scavenging system and promotion of the accumulation of osmoregulatory substances， thus enhancing the tolerance of naked oats to La stress.

Screening of superior lactic acid bacteria from natural Lolium multiflorum silage and their effects on silage quality

Jie YUAN, Ran-ran MA, Wen-jie ZHANG, Neng-xiang XU, Ran-ran ZHAO, Hong-ru GU, Cheng-long DING

2021, 30(11):  132-143.  DOI: 10.11686/cyxb2021064

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The aim of this study was to isolate superior lactic acid bacteria （LAB） strains suitable for Italian ryegrass silage fermentation. LAB were isolated from naturally fermenting Italian ryegrass and strains with rapid growth rate and high acid production efficiency were identified and selected. Subsequently the physiological and biochemical characteristics of these strains were analyzed and we then investigated the influence of these strains on the quality of Italian ryegrass silage. Using the traditional plate culture method， 180 strains of LAB were isolated from naturally fermenting Italian ryegrass silage in this study. Among them， five strains of LAB grew rapidly and had strong acid production ability. These five strains grew well in MRS liquid medium with a NaCl concentration of 3.0%， temperature of 15-35 ℃ and pH of 3.5-7.0. According to 16S rRNA gene sequence alignment and identification， four of the strains （designated PR_LAB_9， PR_LAB_34， PR_LAB_67 and PR_LAB_86） were Lactobacillus plantarum， and a fifth （PR_LAB_76） was Pediococcus pentosaceus. The growth curve and acid production ability of these five strains were determined. All these five LAB strains were able to reproduce and produce acid in 12 hours， and strain PR_LAB_76 had faster growth rate and better acid production efficiency in 24 h than the other four LAB strains. Fermentation quality， nutrient composition and microbial counts of Italian ryegrass ensiled without or with the five LAB strains were also investigated in the present study. All five LAB strains improved the quality of Italian ryegrass silage， including significant reduction in the pH， ammonia nitrogen content and dry matter loss， and increase in the water soluble carbohydrate concentration of ensiled forage. The dry matter content， crude protein content， lactic acid content and LAB counts in the group treated with PR_LAB_76 were significantly higher， and the pH value and yeast counts in the PR_LAB_76 treated silage were significantly lower than those of the four groups treated with other LAB strains. In conclusion， P. pentosaceus PR_LAB_76 was identified in this study as a superior inoculum for industry use in the production of Italian ryegrass silage.

Identification， evolution and expression analysis of the CCoAOMT family genes in Medicago sativa

Qian MA, Qi YAN, Zheng-she ZHANG, Fan WU, Ji-yu ZHANG

2021, 30(11):  144-156.  DOI: 10.11686/cyxb2020429

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Alfalfa （Medicago sativa） is a forage legume with high feed quality widely cultivated all over the world. It contains lignins that play an important role in stress resistance of alfalfa. However， lignin seriously affects the nutritional value of alfalfa because it is difficult for livestock to digest. Therefore， it is necessary to breed alfalfa varieties with low lignin content. Caffeoyl CoA O-methyltransferase （CCoAOMT） is a key enzyme in the lignin synthesis pathway. In this study， the members of CCoAOMT gene family in the alfalfa genome were identified by bioinformatic methods， and the gene structure， chromosome location， phylogeny and gene expression were analysed. It was found that there were 44 MsCCoAOMT genes in the alfalfa genome. These genes were distributed on 16 chromosomes with tandem duplication， among which 36 （82%） MsCCoAOMT genes contained 5 exons. A phylogenetic tree was constructed and showed that MsCCoAOMT family genes can be classified into 5 groups. In addition， ten conserved motifs were found by predicting the motif of MsCCoAOMT protein with MEME software. qRT-PCR results indicated that most of MsCCoAOMT genes were tissue-specific in their expression. Our results provide reference information for the genetic improvement of alfalfa and development of lines with low lignin content.

Cloning and salt-tolerance analysis of MsWRKY11 in alfalfa

Ru-yue WANG, Wu-wu WEN, En-hua ZHAO, Peng ZHOU, Yuan AN

2021, 30(11):  157-169.  DOI: 10.11686/cyxb2020426

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MsWRKY11 was cloned from the cDNA of Medicago sativa， andtransgenic lines of over expressed MsWRKY11 （MsWRKY11-OE） in alfalfawere obtained by transplanting PHB-MsWRKY11-Flag expression vector into alfalfa. The effect of MsWRKY11 on alfalfa tolerance to salt stress was studied by treating transgenic lines and wild type （WT） with 0 or 250 mmol·L^-1 NaCl. The results showed that MsWRKY11 was closely related to Medicago truncatula WRKY11， and the expression of MsWRKY11 was upregulated by addition of NaCl， salicylic acid and jasmonic acid. The growth rates （aboveground biomass and height）， peroxidase activity， catalase activity and ratio of K⁺/Na⁺ were increased in MsWRKY11-OE lines compared with WT， meanwhile the Na⁺ content， relative conductance， malondialdehyde content and superoxide anion content were decreased in MsWRKY11-OE lines under salt stress. The expression of salt-tolerance related genes， including MsNHX1， MsSOS3， MsAPX， MsGRX， MsNAC and MsP5CS were upregulated under salt stress. Also， the expression of those genes was higher in MsWRKY11-OE lines than in the WT under salt stress. These results indicate that MsWRKY11 was involved in the maintenance of K⁺/Na⁺ homeostatic status and stimulation of peroxidase activity under salt stress， and through these mechanisms enhanced the salt-tolerance of alfalfa.

Effects of vitamin B complex on intestinal microflora composition and gut epithelial structure in growing goats

Chen WU, Zhi-hao YAO, Wen-qing MEI, Yu-yan FENG, Qu CHEN, Ying-dong NI

2021, 30(11):  170-180.  DOI: 10.11686/cyxb2020562

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The aim of this study was to explore the effects of vitamin B complex on intestinal microflora composition and intestinal morphology and structure in growing goats. Ten four-month-old female goats with similar body weight （12.60±1.28 kg） were randomly divided into a control group （CON） and a group treated with vitamin B complex （VB）. Goats in the CON group were fed a basal diet （n=5）， and goats in the VB group were fed with the basal diet supplemented with vitamin B complex （n=5）. The experiment comprised an adaptive feeding period of two weeks and a treatment period of 11 weeks. Throughout the experiment， all goats were provided free access to water. At the end of the experiment， the microflora composition of cecal and colonic contents was analyzed by 16S rRNA sequencing， and the intestinal epithelial morphology structure and expression levels of related genes and proteins expression were detected. Compared to CON， VB supplementation did not alter the α diversity index obtained by bacterial taxonomic analysis （P>0.05）. At the phylum level， Firmicutes and Bacteroidetes were the dominant bacteria in the intestines of the goats. Compared to CON， there was a tendency for the abundance of Bacteroidetes in the cecum of the VB group to increase （0.05<P<0.10） and for the abundance of Spirochaetes to decrease （0.05<P<0.10）. At the taxonomic order level， the abundance of Solirubrobacterales and Streptomycetales in the cecum of goats in the VB group was significantly decreased （P<0.05）. At the taxonomic family level， the abundance of Christensenellaceae， Streptomycetaceae， Solirubrobacteraceae in the cecum and Christensenellaceae in the colon of goats in the VB group was significantly decreased （P<0.05）. At the genus level， the abundance of Lachnoclostridium in the cecum of goats in the VB group was significantly increased （P<0.05）， while the abundance of Bacillus， Nocardioides in the cecum and unidentified_Christensenellaceae and unidentified_Gammaproteobacteria in the colon of goats in the VB group was significantly decreased （P<0.05）. Compared to CON， intestinal villus height （P<0.01）， crypt depth （P<0.05） and the ratio of villus height/crypt depth （V/C， P<0.05） of the jejunum in the VB group were significantly increased； and the intestinal crypt depth of the ileum was significantly decreased （P<0.05）. Real-time PCR results showed that Occludin （P<0.05）， EGFR （P<0.01）， MKI67 （P<0.05） and CCND （P<0.05） mRNA expression was significantly up-regulated in colonic epithelium of the VB group， and ZO-1 protein expression was also significantly up-regulated （P<0.05）. It is concluded that dietary supplemention with vitamin B complex increased the abundance of certain probiotics and reduce the abundance of harmful bacteria in the cecum and colon of growing goats. Dietary supplementation with VB also promoted the growth of intestinal villi and improved intestinal structure. The observed changes from VB supplementation would benefit animal welfare and growth.

Feed nutritional value and silage processing properties of Caragana microphylla

Hong-jiao HU, Xin-ping LIU, Tong-hui ZHANG, Yu-hui HE, Ming-ming WANG, La-mei ZHANG, Shan-shan SUN, Li CHENG

2021, 30(11):  181-190.  DOI: 10.11686/cyxb2020421

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Caragana microphylla is one of the key available ruminant feed resources in the Inner Mongolia Autonomous Region， and its industry utilization is still in the development stage. There is therefore an urgent need to explore suitable feed processing technologies for this forage. In this study， C. microphylla herbage samples at florescence （A₁）， fruit stage （A₂） and at the end of the growing season （A₃） in Horqin Sandy Land were ensiled with different amounts of added molasses ［no addition （C₀）， 10 g·kg^-1（C₁）］ and silage inoculant bacteria ［no addition （B₀）， 0.02 g·kg^-1 （B₁）， 0.04 g·kg^-1 （B₂）， 0.06 g·kg^-1 （B₃）］. Samples of C. microphylla herbage for the three growth periods were collected before ensiling as controls （CK₁， CK₂， CK₃）. The optimal silage processing technology was selected by evaluating the nutritional value of different C. microphylla silages. The results showed that， except for phosphorus （P） content， the nutrient contents of C. microphylla before ensiling differed significantly between growth periods， with the ranking being： A₃>A₁>A₂. The effect of silage inoculant bacteria on the nutritive value of C. microphylla was greater at fruit stage and the end of the growing season than at florescence， while the effects of molasses were greater at florescence， and there was almost no interaction between them. After ensiling， the content of each C. microphylla silage displayed no obvious pattern of difference between different growth periods. The optimal silage processing methodology was A₂＋B₁＋C₀ （harvest at fruit stage， add 0.02 g·kg^-1 silage inoculant bacteria， but no added molasses） and the weight ranking of nutritive value indexes was crude protein （CP）>crude fiber （CF）>crude ash （Ash）>acid detergent lignin （ADL）>phosphorus （P）>nitrogen free extract （NFE）>crude fat （EE）>calcium （Ca）. Compared with the three controls， CP， EE， NFE and Ash contents of C. microphylla were enhanced by use of the optimal silage technology identified above， and the increases were 15.70%， 1.79%， 28.16% and 5.59%， respectively. At the same time， the contents of CF and ADL were decreased by 40.65% and 11.83%， respectively. This study provides technical advice on methodology for ensiling Caragana roughage in arid and semi-arid areas of northern China to provide a non-conventional feed source. This development is expected to be of great significance for promoting adoption of regional sand-fixing plants in the reclamation and utilization of environmentally delicate sites to develop the animal breeding industry.

Synergistic effect of oregano essential oil and organic cobalt on degradation characteristics of silage maize stalks and rumen fermentation of sheep

Xiong-xiong LI, Ting JIAO, Sheng-guo ZHAO, Wei-na QIN, Xue-mei GAO, Zheng-wen WANG, Jian-ping WU, Zhao-min LEI

2021, 30(11):  191-202.  DOI: 10.11686/cyxb2020414

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Five animals from a cross between male small tail Han sheep and female native ibex （second generation）， about 10 months of age and （45±5） kg weight， fitted with permanent rumen fistula were used in this research. Treatments comprised four additives： Carrier （Car）， carrier+essential oil （CarEO）， carrier+cobalt （CarCo） and carrier+essential oil+cobalt （CarEOC） inserted into the rumen different sheep via the fistulae， with a fifth sheep having no additives as control （CK）. A Latin square design was used for 5 rounds of tests and the nylon bag method was used to determine the nutrient degradation dynamics of maize straw silage at 0， 6， 12， 24 and 48 h， and to explore the effects of the different additives on the rumen fermentation characteristics of the sheep. It was found that the dry matter degradation rate （DMD）， crude protein degradation rate （CPD）， neutral detergent fiber degradation rate （NDFD） and acid detergent fiber degradation rate （ADFD） of silage maize stalks in each treatment group increased with increasing rumen degradation time and reached their maxima at 48 h. After adding CarEOC， NDFD and ADFD of silage maize stalks added at 48 h were numerically higher than CK， but the difference was not significant （P>0.05）. Compared with CK， the DMD of silage maize stalk was increased after addition of CarEO， CarCo and CarEOC， with the DMD and CPD increased by 3.33% and 3.89%， respectively， at 48 hours after addition of CarEOC. After 24 and 48 h degradation， CPD differed significantly （P<0.05） between CarEOC and CK. None of the additive treatments significantly affected the pH of sheep rumen fluid （P>0.05）， but after addition of CarEOC， the rumen fluid pH and NH₃-N showed a trend of initial decrease followed by an increase. However， there was no obvious change in NH₃-N after adding CarEO. Under the CarEO and CarEOC treatments， the total volatile fatty acid， acetic acid， propionic acid， and butyric acid levels in the rumen fluid showed a tendency of initial increase， then decrease， and finally increase， especially for the CarEOC treatment. These results were interpreted as indicating that the addition of CarEO and CarEOC were beneficial to rumen microbial activity. After adding Car in this experiment， none of the rumen degradation indexes differed significantly from those of CK at any of the sampling times （P>0.05）. Based on grey correlation multivariate analysis， the correlation value of the degradation quality and fermentation characteristics of silage maize stalks in the rumen was CarEOC>CarCo>CarEO>Car>CK， indicating that CarEOC promoted the degradation of fiber compounds in the rumen of sheep， and could therefore be used as a green feed additive to promote more efficient use of roughage resources as feedstuffs for sheep in commercial meat production systems.

Effect of cutting height and nitrogen fertilizer rate on yield and nutritive value of whole-plant mulberry （Morus alba）

Hong-lin WANG, Yan-chun ZUO, Xu YAN, Xiao-kang ZHOU, Jing KOU, Xi-zhi YANG, Jun-ying GUO, Jun PU, Hao-ren ZHANG, Zhou-he DU

2021, 30(11):  203-211.  DOI: 10.11686/cyxb2020490

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In this study， a two-factor randomized block experiment was conducted to determine the yield， botanical characteristics， and nutritive value of a forage mulberry cultivar （Morus alba cv. Chuansisang-1）. Treatments comprised different cutting heights （H₁： 70 cm， H₂： 90 cm， and H₃： 110 cm） and nitrogen fertilization rates （N₁： 138 kg N·ha^-1， N₂： 207 kg N·ha^-1， and N₃： 276 kg N·ha^-1） in Northeast Sichuan， South China. Feeding value of the forage mulberry under the different treatments was evaluated in order to provide data support promotion and utilization of forage mulberry as an animal feed. It was found that herbage yields increased with age under each treatment， and the treatment combination H₂N₃ had the highest herbage yield. Cutting height and nitrogen application rate both had significant effects on the yield， botanical characteristics， and nutritive value of forage mulberry. Cutting height was the main factor affecting the botanical characteristics of forage mulberry， and there were also significant （P<0.05） cutting height×nitrogen fertilization rate interaction effects on herbage yield， single-branch weight， and nutritive value. At the same cutting height， the herbage yield， and neutral detergent fiber of N₃ treatment were the highest， and the crude protein content was higher in N₂ than in N₁ or N₃， and the herbage yield， the number of leaves on main branches and single plant weight were largest under the H₂ treatment. The contents of neutral detergent fiber and acid detergent fiber increased with increase in cutting height. Crude protein and ash contents were highest at H₂， and crude fat content initially increased and then decreased across the three cutting heights. The feeding value of ‘Chuansisang-1’was evaluated using a multivariate subordinate function analysis and the optimal treatment combination was found to be H₂N₃ （i.e. a cutting height of 90 cm and nitrogen application rate of 276 kg N·ha^-1）.

Studies on multiple intercropping effects and quality of autumn sown triticale and sweet sorghum in central Gansu Province

Dan-dan CHANG, Xu WANG, Xin-hui TIAN, Wen-hua DU

2021, 30(11):  212-220.  DOI: 10.11686/cyxb2020417

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This research explored the optimal planting configuration when intercropping autumn sown triticale and sweet sorghum in central Gansu Province. The experiment was conducted in 2017-2018 at Lanzhou， Gansu Province， utilizing a three-factor split-split plot design. Main plots contained Gannong No.2 triticale； Sub-plots contained intercropped triticale and sweet sorghum， and varieties of sweet sorghum （Dajiang 1000 and Dajiang 505） were the sub-sub plot factors. Parameters measured included the number of branches， plant height， forage yield and nutritional quality for the autumn sown triticale； While for sweet sorghum， plant height， number of leaves， leaf length and width， stem diameter， forage yield and nutritional quality were determined and analyzed. It was found that the optimum planting practice for intercropping triticale and sweet sorghum was to sown triticale （variety Gannong No.2） in autumn at 30 cm row spacing with every three row left blank， and to sow the blank row in sweet sorghum （Dajiang 1000） in the summer of the following year. Triticale and sweet sorghum were harvested at flowering and heading stages respectively， and the annual total fresh and hay yields at this site in the central region of Gansu Province were， respectively， up to 136.52 and 38.52 t·ha^-1.

Current status of research on Vicia villosa var. glabresens as indicated by a bibliometric analysis using the China National Knowledge Infrastructure （CNKI） database

Li-jun GU, Ting-yu DUAN

2021, 30(11):  221-228.  DOI: 10.11686/cyxb2020404

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This study investigated the development of literature from 1972 to 2019， and the current state of knowledge relating to Vicia villosa var. glabresens， using CiteSpace as a bibliometric tool. It was found that the number of publications on V. villosa var. glabresens has grown rapidly over the study period. Key words with a high frequency of occurrence were ‘Green manure’， ‘Production’， ‘Lolium multiflorum Lam.’ and ‘Grass meal’. The journal with the largest number of publications on this crop was Sichuan Animal Husbandry and Veterinary Science， followed by Pratacultural Science and Guizhou Animal Husbandry and Veterinary Science， with article numbers of 10， 8 and 8， respectively. Several authors， including Xinkang Ling， Zaichun Xu， and Chongyi Kuang have published multiple articles on V. villosa， but the majority of authors have only single or occasional publications. At present， the research foci are forage and green manure uses， but in addition for ecological restoration， V. villosa var. glabresens has shown potential for development and utilization.