Table of Content

20 December 2023, Volume 32 Issue 12

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Ecological value and its spatiotemporal dynamic patterns of grassland in China

Jia-hui LI, Lin HUANG, Jiang-wen FAN

2023, 32(12):  1-13.  DOI: 10.11686/cyxb2023058

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As China’s largest terrestrial ecosystem and one of the important natural resources， grasslands provide a series of ecosystem services which contribute to human well-being. However， there are still wide expanses of grassland suffering from various degrees of degradation， and requiring urgent conservation and restoration action to improve their quality， function and stability. Accounting of grassland ecological value provides an effective means to monitor the changes in and assess the combined importance of multiple grassland ecosystem functions. This study analyzed the spatiotemporal evolution of grassland ecological value in China from 2000 to 2020. It then assessed the spatiotemporal dynamics of the value of key ecological services of grasslands， including windbreak and sand fixation， water conservation， forage supply and carbon sequestration. Next， adaptation strategies for optimizing and enhancing the grassland ecological value in China were proposed. It was found that in 2020， the ecological value of China’s grassland was 2.47×10⁴ billion CNY， and the value was 7.6 million CNY·km^-2， among which the value per unit area of windbreak and sand fixation and species richness maintenance were relatively high， accounting for 27.3% and 25.8% of the total， respectively. In the past 20 years， more than 90% of China’s grassland area has shown an increasing trend in ecological value. This applies especially to grassland located on the eastern Qinghai-Tibetan Plateau， the northern Loess Plateau， and the eastern and central parts of Inner Mongolia indicate a rapid growth. Moreover， the sum of grassland ecological values of Mongolia， Tibet， Qinghai， Sichuan and Xinjiang accounted for about 67.4% of China’s total ecological value. In the past 20 years， Shaanxi， Beijing， Ningxia， Tianjin， and Shanxi showed a relatively high growth rate in grassland ecological value （>65%）. Finally， China’s grasslands were divided into three categories and twelve subcategories， based on grassland protection and restoration strategies focusing on different key ecological services. Our study offers significant insights for assigning various protection and restoration priorities to achieve sustainable growth in grassland ecological value.

Species selection for no-tillage reseeding in grassland restoration based on plant-soil feedback

Mei-qi GUO, Lin LIU, Jing-ying JING, Gao-wen YANG, Ying-jun ZHANG

2023, 32(12):  14-23.  DOI: 10.11686/cyxb2023041

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As the proportion of more nutritious forage species with good palatability in grassland is reduced or such species become absent due to grassland degradation， reseeding improved forages is an effective way to rapidly restore degraded grasslands. The selection of reseeding species is the primary factor affecting the success of reseeding. In this study， a method for selecting species for no-till reseeding restoration of degraded grassland was tested， using a typical grassland in Inner Mongolia with different degrees of degradation as the experiment site. Soil from degraded grassland patches was also retrieved for a growth test of potential species for reseeding， then the total biomass （Tb） and response to soil factors of each species were measured. Species were then selected for reseeding based on plant-soil feedback （PSF） and Tb， with preference given to species with positive or neutral feedback to the reseeded species and with non-significant differences in Tb between grassland plant patches. It was found that： Lightly degraded grassland with Leymus chinensis as the dominant species was best reseeded with Medicago falcata and Bromus inermis， lightly to moderately degraded grassland with Stipa capillata as the dominant species was best reseeded with L. chinensis， moderately degraded grasslands with Artemisia frigida as the dominant species were best reseeded with Lespedeza bicolor， and heavily degraded grasslands with Potentilla acaulis as the dominant species were best reseeded with Agropyron cristatum， which is not sensitive to changes in soil properties. This study is the first to establish a universal method for selecting species for replanting degraded grasslands， providing theoretical support for no-till reseeding restoration techniques for degraded grasslands both in China， and abroad.

Correlation between vegetation biomass and soil fractal characteristics and soil moisture at different elevations in the Helan Mountains

Ye-yun HUANG, Kai-yang QIU, Ya-chao ZHU, Ying-zhong XIE, Wang-suo LIU, Yi YANG, Si-yao WANG, Lu-yao CUI, Ping-an BAO

2023, 32(12):  24-35.  DOI: 10.11686/cyxb2023050

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This research investigated the vertical variation of vegetation biomass， soil fractal characteristics and soil moisture content in arid and semi-arid mountain ecosystems， and investigated the correlation between vegetation biomass， fractal characteristics and soil moisture， in typical vegetation zones at different elevations in the Helan Mountains. Vegetation biomass， soil fractal characteristics and soil moisture content and the vertical variability of these parameters were analyzed by one-way ANOVA and Pearson correlation analysis. It was found that： 1） The herb biomass and shrub biomass did not show a linear trend with elevation； The maximum value for shrub vegetation biomass occurred at a shallow mountain scrub sampling site designated QSGC and the maximum value for herbaceous vegetation biomass occurred at a subalpine scrub sampling site designated YGSGC， with better vegetation conditions and higher vegetation productivity. 2） The soils in Helan Mountains were comprised mainly of powder-sized and very fine sand particles， and the soil texture became finer as the elevation increased. 3） Soil moisture content increased significantly with elevation， but was slightly lower at a sampling site designated QHYS and characterized by presence of Qinghai spruce. 4） Correlation analysis showed that annual precipitation and soil clay content were the factors most strongly associated with vegetation biomass. Overall， vegetation biomass， soil fractal characteristics， and soil moisture content in the vegetated Helan Mountains were found to be affected by the combined effects and influences of several environmental factors， showing obvious spatial heterogeneity. This study provides important information about the spatial variation patterns of vegetation biomass in Helan Mountains and apparent causative factors. Such information will assist planning of the restoration of degraded vegetation in the Helan Mountains and will provide reference data for planning the rational use of vegetation and soil resources in the Helan Mountain ecosystem.

Changes in soil phosphorus fractions and their causes under alpine meadows with different degradation status in Zoigê

Zhi-qiang YANG, Dan LIU, Xiao-qin LIAO, Dan-yang CHEN, Xiao-yan SONG, Yang LIU, Chang-ting WANG

2023, 32(12):  36-46.  DOI: 10.11686/cyxb2023054

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This research investigated the variation in soil phosphorus content in alpine meadows of different degradation status， using the Hedley sequential fractionation method. Soil phosphorus fractions were measured for undegraded （UD）， lightly degraded （LD）， moderately degraded （MD）， severely degraded （SD）， and extremely degraded （ED） alpine meadow sites in Zoigê， and the environmental factors influencing soil phosphorus fractions were also explored. It was found that： 1） On the whole， the HCl extractable phosphorus （HCl-P） dominated soil phosphorus fractions in the alpine meadow， and the content of the dilute HCl extractable inorganic phosphorus （DHCl-P_i）， concentrated HCl extractable inorganic phosphorus （CHCl-P_i） and concentrated HCl extractable organic phosphorus （CHCl-P_o） together accounted for more than 50% of the total phosphorus （TP）. 2） All categories of soil phosphorus fraction showed a decline trend with increased degradation. Compared with the undegraded meadow， the H₂O extractable phosphorus （H₂O-P）， NaHCO₃ extractable inorganic phosphorus （NaHCO₃-P_i） and NaHCO₃ extractable organic phosphorus （NaHCO₃-P_o） of ED soil were decreased （P<0.05） by 92.51%， 89.57% and 85.10%， respectively， in the 0-10 cm soil horizon. Only NaHCO₃-P_o decreased significantly （by 80.32%） in the 10-20 cm horizon of ED soils. The NaOH extractable inorganic phosphorus （NaOH-P_i）， NaOH extractable organic phosphorus （NaOH-P_o）， CHCl-P_o and residual-P in the 0-20 cm soil horizon decreased with increased degradation and were lowest in ED soil， with values of 12.15， 7.09， 21.14 and 26.48 mg·kg^-1， respectively. 3） There was a significant negative correlation between the H₂O-P and soil bulk density （BD）； The NaHCO₃-P_i， NaHCO₃-P_o， NaOH-P_i， NaOH-P_o， CHCl-P_o and residual-P showed positive correlations with soil total carbon （TC） and total nitrogen （TN） but negative correlations with soil pH and BD. The CHCl-P_i exhibited no significant correlation with any of the environmental factors. Soil BD， pH， soil moisture content （SMC）， TC and TN together explained 78.79% to the variation of soil phosphorus fractions， with soil pH having the largest contribution （52.29%）. In conclusion， the various soil phosphorus fractions presented various patterns of decrease with increased soil degradation. Loss of soil organic phosphorus in degraded soils was relatively high. Those results are expected to provide scientific clues for future soil nutrient conservation initiatives and for planning of ecological restoration management of degraded alpine meadow in Zoigê.

Effects of mixed litter with different degrees of decomposition on the decomposition characteristics of semi-arid grassland in northern Shanxi

Wen-jie LU, Jin-yun QI, Cong WU, Ya-hong JING

2023, 32(12):  47-57.  DOI: 10.11686/cyxb2023082

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Plant residues that are decomposed to varying degrees are widely distributed in the litter layer of semi-arid grassland. In this study， a field litter bag experiment was conducted to determine the effect of the degree of decomposition of litter at burial on the overall decomposition process. Decomposition trajectories of fresh and aged litter samples and samples made up of a mixture of fresh and aged litter from three native plant species （Stipa bungeana， Artemisia argyi， and Artemisia gmelinii） that grow in semi-arid grassland of northern Shanxi were measured. The treatments were fresh litter （L_Fresh）， aged litter （L_Aged）， and an equal-ratio mixture of fresh and aged litter （L_Mix）. It was found that the mass remaining percentage of mixed litter with different degrees of decomposition decreased with the increase of decomposition time. It exhibited highest interaction when the plant litter decomposed after 335 days. The observed values of the mass remaining percentage in the S. bungeana L_Mix treatment and the A. gmelinii L_Mix treatment were 5.12% and 4.68% lower than the expected values， respectively， showing a synergistic effect， while the A. argyi L_Mix treatment showed an additive effect. In addition， the S. bungeana L_Mix treatment promoted nitrogen release and inhibited cellulose decomposition. The A. gmelinii L_Mix treatment promoted carbon release and lignin decomposition. In conclusion， a mixed litter comprising both fresh and aged material with different degrees of decomposition changed the decomposition rate and promoted nutrient release， thus affecting nutrient cycling in the studied grassland ecosystem.

Effects of different livestock assembly on the productivity of yak and Tibetan sheep in warm-season pastures

Bin FENG, Xiao-xia YANG, Wen-ting LIU, Yu-zhen LIU, Wei-dong LV, Zhen-xiang ZHANG, Cai-cai SUN, Qin-yuan ZHOU, Fang-cao WANG, Ze-hang YU, Quan-min DONG

2023, 32(12):  58-67.  DOI: 10.11686/cyxb2023034

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This research explored the effect of different livestock assembly on livestock productivity under moderate grazing intensity. Five experimental grazing treatments were established： Yak only grazing （YG）， Tibetan sheep only grazing （SG）， yak and Tibetan sheep grazing mixed 1∶6 （MG1∶6）， yak and Tibetan sheep grazing mixed 1∶4 （MG1∶4）， yak and Tibetan sheep grazing mixed 1∶2 （MG1∶2）. We studied the daily weight gain of yaks and Tibetan sheep at different stages in the herbage growing season and the effects of different livestock assembly on the nutrition， feed intake， and weight gain of yaks and Tibetan sheep in the warm season. It was found that： 1）The daily weight gain of yaks and Tibetan sheep in the pasture re-greening and growing periods was significantly greater than that in the browning-off period （P<0.05）. 2）There was no significant difference in daily gain of yak and Tibetan sheep under the different livestock assembly （P>0.05）， but the weight gain of yaks in the warm season was highest in YG， and was also relatively high in the treatments MG1∶2 and MG1∶6. The weight gain of Tibetan sheep in the warm season was the highest in MG1∶2， and relatively high in SG and MG1∶4 treatments. 3）There was no significant difference in nutrition and feed intake per unit area of livestock under the different livestock assembly （P>0.05）. When grazing a single livestock class， the weight gain per unit area of SG was the highest， and under mixed grazing of yaks and Tibetan sheep， the weight gain per unit area of MG1∶2 was the highest. In conclusion， supplementary feeding of yaks and Tibetan sheep during the browning-off period of the season is of great significance for maintaining livestock productivity， and the livestock assembly of MG1∶2 was the optimum ratio for mixed grazing of yaks and Tibetan sheep.

Spatial distribution of the Leymus chinensis population under different grazing intensities in a typical steppe area

Jin-rui WU, Meng-zhen LI, Yong YANG, Ai-jun LIU, Pu-chang WANG, Hasibagen, Shi-jie LYU, Xiang-jun YUN

2023, 32(12):  68-76.  DOI: 10.11686/cyxb2023067

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The aim of this study was to explore the spatial distribution characteristics and trends in the growth of Leymus chinensis under different grazing intensities in a typical steppe area. The L. chinensis population at the Typical Steppe Experimental Station of the Chinese Academy of Agricultural Sciences was subjected to grazing at four intensities： No grazing as the control （CK）， light grazing （LG）， moderate grazing （MG） and heavy grazing （HG）. The data were analyzed using box plot and multifractal methods. The results showed that the spatial distribution of the L. chinensis population under different grazing intensities had multifractal characteristics. The spatial distribution of the L. chinensis population was complex and non-homogenous in the MG and HG treatments， but relatively uniform in CK and the LG treatment. As the grazing intensity increased， the spatial distribution of the L. chinensis population changed from uniform to aggregated， the niche breadth remained comparatively consistent， and the competition intensity among individuals decreased. Regardless of the differences in grazing intensity， the spatial distribution characteristics of the L. chinensis population in this typical steppe area were dominated by large probability subsets， and L. chinensis still occupied a dominant position in the community.

Prediction of shear strength of root-containing soil by a back-propagation neural network optimized with the fireworks algorithm

Jun-lin LIU, Yong HAO, Chun-yan LIU, Yan SHAO, Lang DING

2023, 32(12):  77-89.  DOI: 10.11686/cyxb2023064

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There are various problems with using a back propagation （BP） neural network model to predict the shear strength of root-containing soil， such as low prediction accuracy， a slow calculation convergence rate， and a tendency to generate local extreme values. In this study， we analyzed the influence of different factors on the shear strength of root-bearing soil through direct shear tests， agglomeration tests， root fractal analysis， and other tests， and carried out correlation analyses for each factor. Six factors affecting the shear strength of root-bearing soil， namely the proportion of large aggregates （R_0.25）， mean weight diameter （MWD）， geometric mean diameter （GMD）， fractal dimension of soil （D_d）， root surface area， and root average diameter were selected as input layer nodes for the model， while the shear strength of root-bearing soil was selected as the output layer node. The FangfaGorman theory formula， Kolmogorov theory formula， and an empirical formula were applied in the model. The optimal number of hidden layer nodes in the neural network was determined to be 13. A BP neural network model of 6∶13∶1 was established， and the fireworks algorithm （FWA） was introduced to optimize the BP neural network. The maximum relative errors of the predicted value and the expected value determined using the BP neural network， BP neural network optimized by particle swarm optimization （PSO）， and FWA-BP neural network were 11.12%， 9.06%， and 7.44%， respectively， and the average relative errors were 4.60%， 3.24%， and 1.96%， respectively. Compared with the BP neural network and the PSO-BP neural network， the FWA-BP neural network had a smaller prediction error. For the FWA-BP neural network， the root mean square error （RMSE）， mean absolute error （MAE）， and mean absolute percentage error （MAPE） values were 0.779353， 0.625993， and 5.6679%， respectively， all of which were lower than their corresponding values for the other network models. Thus， the FWA-BP neural network shows greater adaptability and will be superior to the other models in practical applications.

Real-time monitoring and analysis algorithm for key biophysical indicators of cultivated alfalfa in a grassland intelligent perception system

Chun-li MIAO, Zhong-xian LI, Zhi-cheng ZHAO, Shuai FU, Jin-long GAO, Jie LIU, Qi-sheng FENG, Tian-gang LIANG

2023, 32(12):  90-103.  DOI: 10.11686/cyxb2023046

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Alfalfa， as an important high-quality forage， plays a vital role in the development of grassland animal husbandry. Traditional ground surveys and satellite remote sensing to evaluate large-scale alfalfa cover and yield are easily affected by weather， manpower， and financial factors， and have certain limitations when used in spatio-temporal dynamic monitoring. In recent years， with the rapid development of sensors and artificial intelligence （AI） and their widespread application in crop monitoring and analysis， new methods have been developed for accurate and real-time estimation of alfalfa cover and yield. In this study， alfalfa cover and yield estimation models were established using deep learning （DL） and multiple linear regression （MLR） and random forest （RF） methods combined with ground-measured data for alfalfa cultivated in four northern provinces of Xinjiang， Inner Mongolia， Gansu， and Ningxia. The accuracy of all the models was evaluated. It was found that： 1） In general， cultivated alfalfa in northern Xinjiang， Hexi in Gansu， and other regions is mainly irrigated， with concentrated and contiguous plots and flat terrain， and is harvested three to four times a year， with an average yield and vegetation cover of 5362.81 kg·ha^-1 and 96.29%， respectively， at the peak growth period. Alfalfa in Eastern Gansu， southern Ningxia， and other regions is mainly cultivated using a dryland production system， is mostly grown on horizontal terraces in mountainous areas， and is harvested two to three times a year， with an average yield and cover of 3987.57 kg·ha^-1 and 91.55%， respectively， at the peak growth period. 2） For the alfalfa cover deep learning model using unmanned aerial vehicle visible light remote sensing data as inputs， the R² was 0.99， the root mean squared error was 1.44%， and the model accuracy was 92%， indicative of good ability to dynamically monitor cultivated alfalfa cover. 3） Compared with the MLR model， the RF model based on longitude， latitude， altitude， and key biophysical indicators of alfalfa height， cover， and their product provided more accurate estimates of alfalfa yield. The R² of the optimal estimation model test set was 0.69， and the RMSE was 1151.24 kg·ha^-1. In summary， we have established an intelligent perception system based on an algorithm for the rapid evaluation of key biophysical indicators of cultivated alfalfa. These findings provide technical support for the application of networked， automated， and intelligent alfalfa growth data acquisition and dynamic analysis systems in multiple locations and with a high frequency.

Identification of cultivated alfalfa diseases based on AlexNet

Yun-hao LI, Zhong-xian LI, Shuai FU, Zhong-xue ZHANG, Shi-qin MAO, Qi-sheng FENG, Tian-gang LIANG, Yan-zhong LI

2023, 32(12):  104-114.  DOI: 10.11686/cyxb2023060

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Accurate and rapid identification of alfalfa diseases is the key to disease prevention and control in alfalfa grassland. The identification of alfalfa diseases requires a high degree of professional knowledge， identification tools， and a suitable detection environment.Traditional methods for identifying alfalfa diseases include microscopic observations and other means to inspect the diseased parts of the leaves to detect pathogen strains. This disadvantages of those methods are their poor timeliness， high cost， and inability to identify diseases rapidly at multiple locations on a large scale. In recent years， computer-aided methods and deep learning in the field of image recognition have developed rapidly， providing new methods for the intelligent identification of alfalfa diseases. In this study， an alfalfa disease identification model was constructed using image datasets of 13 common alfalfa diseases， the improved AlexNet deep learning convolutional neural network， and 300 iterations of training. The recognition accuracy of alfalfa diseases under different image input resolutions was compared and analyzed. The optimal model for identifying 13 types of alfalfa diseases achieved an overall accuracy of 72%， and the optimal size of the image input was 512 pixels×512 pixels. After removing the images of diseased alfalfa samples with low recognition accuracy， the overall recognition accuracy of five alfalfa diseases， namely brown spot disease， downy mildew disease， anthracnose， black stem and leaf spot disease， and little light lenticel spot disease was increased to 92%， and the optimal input image size was 1200 pixels×1200 pixels. These two models are suitable for the rapid identification of major alfalfa diseases. These results provide technical support for the development of intelligent detection systems for alfalfa diseases based on image recognition.

Identification and analysis of alfalfa virus disease based on sRNA deep sequencing technology

Jiang DU, Zhen-nan MA, Chen-yan WANG, Li ZHANG, De-fu WANG, Yan-bing NIU

2023, 32(12):  115-125.  DOI: 10.11686/cyxb2023053

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Medicago sativa is an important forage， but the infection with alfalfa virus disease seriously affects the yield and nutritional quality of alfalfa. In this study， the virus pathogens of alfalfa samples， which exhibited mosaic， wrinkled， and curled leaves， collected from Botanical Garden of Shanxi Agricultural University were identified by small RNA deep sequencing technology and RT-PCR/PCR methods. It was found that the diseased leaf samples were co-infected by alfalfa mosaic virus （AMV）， pea streak virus （PeSV）， alfalfa dwarf virus （ADV） and alfalfa leaf curl virus （ALCV）. The whole genome sequence of ALCV isolate SXTG （OP748371） was obtained by PCR amplification. Sequence analysis showed that the complete sequence of ALCV isolate SXTG shared the highest similarity with the ALCV isolate Colonia Dora （MG792026）， namely 97.34%. Sequence alignment analysis of the AMV CP gene （OP748369） nucleoside sequence and its encoded amino acid sequences showed that the AMV isolate SX had the highest similarity with the AMV isolate ACat （MW835977）， with nucleotide and amino acid similarities of 99.24% and 99.54%， respectively. Similarly， the amplified ADV CP gene sequence was uploaded to GenBank， the registration number OP957285 was obtained and the isolate was named ADV Shanxi Taigu alfalfa isolate （SXJZ）. Sequence analysis showed that the isolate SXJZ had the closest genetic relationship with ADV isolate N1 （MZ221810）， with an amino acid sequence similarity of 99.43%. Further sequence alignment analysis of the amino acid （OQ108501） encoded by PeSV CP gene showed that the similarity of the amino acid encoded by the coat protein of the Shanxi alfalfa isolate （SXJZ） and other PeSV isolates was 100%. This is the first time that the compound infection of ALCV， ADV， AMV and PeSV has been detected in alfalfa plants in Shanxi Province. These results will help to understand the molecular evolution of the virus disease infecting alfalfa and provide a theoretical basis for the prevention and control of the virus disease.

The effects of arbuscular mycorrhizal fungi and melatonin on the heat tolerance of perennial ryegrass

Hong-jian WEI, Wen-yuan HE, Yue WANG, Ming TANG, Hui CHEN

2023, 32(12):  126-138.  DOI: 10.11686/cyxb2023129

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High temperature stress is a major factor limiting the growth and development of cool-season grasses. To investigate the effects of individual inoculation with arbuscular mycorrhizal fungi （AMF）， exogenous melatonin， and their combined application on the growth and heat tolerance of perennial ryegrass （Lolium perenne）， a pot experiment was conducted. The current research aimed to test and analyze the effects of AMF and exogenous melatonin treatments under high temperature stress on the growth of perennial ryegrass， endogenous melatonin levels and expression of its synthesis genes， antioxidant capacity， and content of osmotic adjustment substances. The results showed that high temperature stress significantly inhibited the growth of perennial ryegrass， while exogenous melatonin treatment increased the colonization rate of AMF in the roots of perennial ryegrass. Inoculation with AMF and/or melatonin treatments promoted the growth of perennial ryegrass under high temperature stress， increased the endogenous melatonin content in the roots of perennial ryegrass， upregulated the expression of melatonin synthesis genes， reduced relative electrical conductivity （EL）， malondialdehyde （MDA） content， and polyphenol oxidase （PPO） activity， and enhanced the activities of root antioxidant enzymes （SOD， POD， CAT， and APX） and phenylalanine ammonia-lyase （PAL）， as well as the content of flavonoids， proline， total phenols， soluble sugars， and betaine. Notably， the combined application of AMF and melatonin showed a synergistic effect in improving the heat tolerance of perennial ryegrass. In summary， inoculation with AMF and melatonin treatment upregulated the expression of melatonin synthesis genes in the roots of perennial ryegrass， increased the endogenous melatonin content， enhanced antioxidant enzyme activities， reduced oxidative damage， and improved osmotic adjustment capacity， thereby enhancing the heat tolerance of perennial ryegrass.

Screening and identification of two potassium solubilizer strains and their effects on the yield and quality of alfalfa

Yan-jia WANG, Bo-ang HU, Jia-xin CHEN, Li-ting XU, Lin YAO, Li-rong FENG, Chang-hong GUO

2023, 32(12):  139-149.  DOI: 10.11686/cyxb2023036

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The study aimed to isolate and screen high-efficiency potassium solubilizing bacteria （KSB）， and to quantify the effects of KSB application on plant yield and quality. The KSB strains were screened by silicate bacteria media from the rhizosphere soil of alfalfa （Medicago sativa）， and subsequently the strains were identified by morphological， 16S rDNA sequence， and physiological and biochemical analysis. Pot experiments were conducted to evaluate the effect of inoculation with KSB strains on the yield and quality of alfalfa. Two high-efficiency KSB strains XLT-4 and XLT-7 were obtained with potassium solubilization rates of 10.53% and 9.75%>CK， and identified as Priestia megaterium and Peribacillus frigoritolerans， respectively. These two KSB strains had the metabolic capacity for phosphorus solubilization， siderophore-production and indole acetic acid secretion. Inoculation with XLT-4 and XLT-7 significantly increased plant height， root length， dry and fresh weight above ground and below ground， root activity， the contents of P， K and crude protein in leaves， while the contents of neutral detergent fiber and acid detergent fiber were significantly lower than in CK plants. In addition， the inoculation of the two KSB also improved the enzyme activity and available potassium content in alfalfa rhizosphere soil. In this study， the two KSB strains made a major contribution to improving the yield and quality of alfalfa， and these two organisms are high quality strain resources for the development of microbial preparations.

Processing and nutritional values of silage made from Ceratoides arborescens

Yuan-zhi XU, Xin-ping LIU, Li-long WANG, Hong-jiao HU, Yu-hui HE, Tong-hui ZHANG, Jia-qi JING

2023, 32(12):  150-159.  DOI: 10.11686/cyxb2023066

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Ceratoides arborescens is a semi-shrub forage with excellent quality， its nutritional value can be improved by ensiling. The aim of this study was to determine the optimum method to produce C. arborescens silage. A 3×4 two-factor experimental design was used to study the effects of the water content of the raw material （45%， 55%， 65% w/w） and probiotic concentration （0， 0.02， 0.04， 0.06 g·kg^-1） on the quality of C. arborescens silage. It was found that the water content and probiotic concentration had significant effects on the nutrient composition of C. arborescens silage （P<0.05）， the water content had significant effects on the contents of crude protein， crude fiber， and ash （P<0.01）， and the probiotic concentration had significant effects on the ash content （P<0.05）. At water contents lower than 65% （w/w）， the nutritional value of the silage increased with increasing water content. With increasing probiotic concentration， the nutritional value of the silage initially increased and then decreased. The optimal conditions for making C. arborescens silage were 65% （w/w） water content of the raw material and 0.02 g·kg^-1 added probiotic. The results of this study provide scientific support and a theoretical basis for the efficient production of C. arborescens silage. Successful ensilage of C. arborescens will promote the development of grass husbandry and help to solve the shortage of feed resources for livestock.

Effects of the lead halide perovskite on the seedling growth of Elymus nutans

Ting-lun LI, Yi-heng LI, Hui YU, Zai-li JIANG, Li-tao TANG, Chang-ting WANG, Lei HU

2023, 32(12):  160-170.  DOI: 10.11686/cyxb2023104

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In this study， the effects of the lead （Pb） halide perovskite on the growth of Elymus nutans， a high-quality forage， were determined. Seedlings of E. nutans were treated with perovskite at six concentrations （0， 36， 72， 130， 170， and 260 mg·kg^-1 Pb²⁺）， and their ability to accumulate and tolerate Pb was determined. The main results were as follows： 1）Pb did not significantly affect the emergence ratio of E. nutans seedlings， but increasing concentrations of Pb resulted in significantly decreased emergence rate and a shorter duration of seedling emergence. 2）Seedling height was significantly inhibited by Pb stress， while single seedling biomass showed a concentration effect， in that it was not affected by Pb²⁺ at concentrations below 72 mg·kg^-1， but was inhibited by Pb at concentrations above 72 mg·kg^-1. Seed germination was completely inhibited by Pb at 260 mg·kg^-1. 3）The Pb accumulation ability of E. nutans seedlings decreased significantly compared with the control group， and the Pb tolerance range of seedlings was 68.42-205.94 mg·kg^-1.^{4）The structure equation model indicated that decreased soil pH and increased soil nitrate nitrogen contents resulting from perovskite directly affected the seedling growth of E. nutans， thus affecting its ability to accumulate and tolerate Pb. In conclusion， the soil pH and nitrate nitrogen content are the key factors affecting the seedling growth of E. nutans， and increasing the soil pH is a feasible strategy to enhance the Pb tolerance of E. nutans in the face of potential leaks of the lead halide perovskite.}

Effects of different salt stresses on triticale seed germination

Chen MENG, Xue-li LU, Ju-ying WANG, Yun-chong WEI, Cheng-sheng ZHANG, Yi-qiang LI, Zong-chang XU

2023, 32(12):  171-180.  DOI: 10.11686/cyxb2023068

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Soil salinization is an important factor that restricts agricultural production. Triticale has high yields and shows strong stress resistance， so it has the potential to improve saline-alkali land. In this study， triticale seeds were treated with five kinds of salts （NaCl， KCl， Na₂SO₄， MgSO₄， NaHCO₃） at different concentrations （10， 25， 50， 100 and 200 mmol·L^-1） and compound salt solutions （NaHCO₃∶NaCl∶Na₂SO₄=1∶15∶84） at concentrations of 0.05%， 0.15%， 0.30%， 0.60% and 1.20% （w/v）. The germination rate， germination potential， germination index， vigor index， seedling length， and root length of triticale germinating seeds and seedlings under different salt stresses were analyzed. The salt tolerance of triticale under different salt stresses was comprehensively evaluated by a principal component analysis and membership function analysis. The results show that the germination rate， germination potential， germination index， and vigor index of triticale seeds decreased gradually as the concentration of each salt increased， and treatment with high concentrations of salts significantly inhibited the germination of the triticale seeds. The seedling length and root length of triticale seedlings also showed a decreasing trend with increasing salt concentrations. Among the salts， NaHCO₃ had the strongest inhibitory effect. The results of the principal component analysis showed that the main indicators for evaluating the salt tolerance of triticale were germination rate， germination index， and root length. The ranking of membership function values showed that triticale had relatively high tolerance to mixed salt treatments and the lowest tolerance to NaHCO₃.

The relationship between the transformation and transport of non-structural carbohydrates and cold resistance in Medicago sativa during cold hardening

Jin-mei ZHAO, Guo-mei YIN, Juan-juan SUN, Yuan WEI, Wei LI, Mao-wei GUO, Si-qi LIU, Jia-qi ZHANG

2023, 32(12):  181-188.  DOI: 10.11686/cyxb2023047

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This research studied the transformation and transportation of non-structural carbohydrates in the roots and leaves of Medicago sativa and their relationship with cold resistance during cold hardening in two alfalfa varieties： Zhaodong， a strongly cold resistant variety， and was Sardi 10， a weakly cold resistant variety. Experimental plants were subjected to a cooling treatment to simulate early cold-hardening （CH₁）， a low-temperature treatment to simulate advanced cold-hardening （CH₂）， or normal growth conditions （CK） over seven days following cutting. Changes in soluble sugar and starch contents in roots and leaves and the difference between the two varieties were analyzed in regrowth after the seven days to assess cold resistance. It was found that： After cold hardening， the semi-lethal low temperature （LT₅₀） of alfalfa roots and leaves decreased with increase in their soluble sugar and starch contents， and there were significant negative correlations between the LT₅₀ and the soluble sugar and starch contents of roots and leaves. After 14 days of regeneration under normal growth conditions， the soluble sugar and starch contents in the roots and leaves decreased. However， soluble sugar content in roots and leaves of alfalfa increased， starch content in leaves decreased， and starch content in roots changed little after CH₁ treatment. The soluble sugar content in the roots and leaves of Sardi 10 was significantly higher than that in Zhaodong， while the content of starch in the leaves of Sardi 10 was significantly lower than Zhaodong. After CH₂ treatment， the soluble sugar content in Zhaodong roots increased and starch content decreased. The changes in soluble sugar and starch contents in Sardi 10 roots were opposite to those in Zhaodong， and soluble sugar content in Sardi 10 roots was lower than Zhaodong. Cold hardening changed the aboveground-belowground direction transfer of soluble sugar. Starch in the roots of normally growing plants was converted into soluble sugar， which was transported to the leaves and used together with the soluble sugar transformed from the starch of leaves to regenerate aboveground organs. In CH₁， the starch in the leaves of the two varieties was degraded into soluble sugar， which was transported to the roots， resulting in an increased soluble sugar content in the roots and leaves. At this stage， more leaf starch was consumed in Sardi 10 than Zhaodong. In CH₂， Sardi 10 and Zhaodong had reverse starch-sugar transformation directions in the roots， with the transformation from starch to soluble sugar in Zhaodong roots and from soluble sugar to starch in Sardi 10 roots. These results indicate that alfalfa consumes less non-structural carbohydrates during early cold hardening， but transforms starch into soluble sugar in the root in the later stages， resulting in increased root cold resistance. This data provides important insight into the reasons for differences in cold resistance among alfalfa varieties.

Effect of different concentrate to forage ratios on the structure of microflora in yak manure

Hong-xin NIE, Yu-min LI, Kai-yue PANG, Sha-tuo CHAI, Di SHEN, Zi-ming ZENG, Yang LIAO, Xun WANG, Bin XUE, Shu-jie LIU, Shu-xiang WANG, Ying-kui YANG

2023, 32(12):  189-197.  DOI: 10.11686/cyxb2023091

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The aim of this experiment was to study the effects of different ratios of concentrate to forage on the structure of the microflora in yak feces. Twenty-four healthy 3-year-old male yaks with similar body weight were randomly divided into two groups： One group was fed with a diet with a low concentrate to forage ratio （35∶65， C₃₅ group）， and the other group was fed with a diet with a high concentrate to forage ratio （65∶35， C₆₅ group）. The pretest lasted for 15 days and the experiment lasted for 90 days. Then， 16S rDNA high throughput sequencing technology was used to analyze the structural changes in fecal microflora. The main results were as follows： 1） A total of 1702 operational taxonomic units （OTUs） were detected in the feces of the two groups， among which 1273 OTUs （74.79%） were common to the two groups. The number of species， Chao1 index， and Shannon’s index were significantly higher in the C₃₅ group than in the C₆₅ group （P<0.05）. 2） In terms of species composition of the microflora in yak feces， at the phylum level， Patescibacteria and Cyanobacteria were significantly more abundant in the C₃₅ group than in the C₆₅ group （P<0.01）， and Actinobacteriota were significantly more abundant in the C₃₅ group than in the C₆₅ group （P<0.05）. Bacteroidota and Spirochaetota were more abundant in the C₆₅ group than in the C₃₅ group （P<0.05）. 3） Ruminococcus were significantly more abundant in the C₃₅ group than in the C₆₅ group （P<0.01）， and Lachnospiraceae_NK3A20_group were significantly more abundant in the C₃₅ group than in the C₆₅ group （P<0.05）. The number of uncultured was significantly higher in the C₆₅ group than in the C₃₅ group （P<0.01）. The numbers of uncultured_bacterium， Alloprevotella， and Treponema were significantly higher in the C₆₅ group than in the C₃₅ group （P<0.05）. 4）Prediction of the metabolic pathways and functions of fecal microorganisms at the KEGG2 level using PICRUSt revealed a much higher relative abundance of gene families involved in replication and repair， translation， nucleotide metabolism， biosynthesis of other secondary metabolites， and cell growth and death in the C₆₅ group than in the C₃₅ group （P<0.01）. In conclusion， the dietary concentrate to forage ratio significantly affected the diversity and richness of yak fecal microflora. A diet with a high concentrate to forage ratio （65∶35） promoted the proliferation of non-fiber-degrading bacteria and increased the abundance of Alloprevotella， but inhibited the growth of Lachnospiraceae. These results enrich our understanding of the composition and functions of bacterial communities in yak feces.