Table of Content

20 January 2024, Volume 33 Issue 1

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An analysis of grassland spatial distribution and driving forces of patterns of change in grassland distribution in Guizhou Province from 1980 to 2020

Wan-yang YU, Yi-fan CHEN, Fa-yong FANG, Jin-xin ZHANG, Zhou LI, Long-shan ZHAO

2024, 33(1):  1-18.  DOI: 10.11686/cyxb2023185

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Grassland plays an important role in controlling rocky desertification and supporting animal husbandry in karst areas. Information about grassland spatial distribution patterns and driving forces of change in grassland patterns in karst areas is important for planning maintenance of regional grassland ecological functions and achieving sustainable development. Based on land-use datasets， in this study， we analyzed the spatial patterns and changes of grassland distribution in Guizhou Province from 1980 to 2020. Combined the landscape pattern and spatial autocorrelation to deeply identified the evolution law of grassland spatial distribution patterns and effective management areas. And quantified the driving forces of the spatial distribution patterns evolution of grassland by using geographic detector. It was found that： 1）In the past 40 years， the change of grassland area in Guizhou Province can be divided into three stages： a growth period （1980-2000）， a decline period （2000-2015） and a recovery period （2015-2020）， with an overall decrease from 1980 to 2020 of 176.88 km². The areas that have undergone changes mainly occurred in the western and southern regions of Guizhou Province， with the main changes being transfer between grassland， forest， and cultivated land. The overall spatial occurrence of grassland could be summarized as “high in the west and south， low in the east and north”. 2）Over time from 1980 to 2020， the degree of fragmentation of grassland increased， the degree of aggregation decreased， and the shape tended to become complex. Grassland patches at the county level are more fragmented and scattered， but their shapes are more regular， than at provincial level. 3）The Anselin Local Moran’s I tool was used to assess the uniformity of aggregation. Using this analytical approach， the spatial clustering patterns of high-high aggregation and low-high aggregation， concentrated in the western and southern regions， were detected. 4）The spatial distribution pattern of grassland was affected mainly by natural factors， among which elevation was the dominant factor， explaining up to 42.9% of data variation for grassland spatial distribution. The power of elevation to explain grassland spatial distribution pattern was enhanced by considering other factors as statistically interacting with elevation， in particular livestock industry output， mean annual temperature， density of population and GDP. Under the overall distribution pattern of grassland dominated by elevation， the differences and changes in social and economic factors between regions significantly affected the evolution of grassland spatial distribution patterns， and regional policies also played an important guiding role.

Nitrogen fertilizer threshold and uncertainty analysis of typical grassland on the northern slopes of Tianshan Mountains

Qi-fei HAN, Long YIN, Chao-fan LI, Run-gang ZHANG, Wen-biao WANG, Zheng-nan CUI

2024, 33(1):  19-32.  DOI: 10.11686/cyxb2023097

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In the context of climate change and increasing human activities， a series of ecological problems have emerged in arid and semi-arid regions as one of the important and very vulnerable components of the terrestrial ecosystem. Exploring the impact of climate change and human activities on the net primary productivity （NPP） is of great significance for the rational use of natural resources and the sustainable development of agriculture and animal husbandry. Nitrogen fertilization is a way to promote increased NPP and appropriate fertilization can improve the NPP of grassland. To further explore the potential use of N fertilization， this study investigated four grassland types， alpine meadow （AM）， mid-mountain forest meadow （MMFM）， low mountain dry grassland （LMDG） and plain desert grassland （PDG）， distributed along the altitude gradient on the northern slope of Tianshan Mountains， and employed a denitrification-decomposition model to analyze the NPP responses of the typical grassland ecosystem in this region to the application of different nitrogen fertilizers， and reveal the nitrogen fertilizer threshold and the optimal fertilization strategy. It was found that： 1） Appropriate nitrogen addition led to an increase in NPP of all types of grassland ecosystems， but there was a threshold value for the response of grassland NPP to fertilizer application， and different types of grassland NPP had different threshold values. There was no unified optimal fertilization method applicable to the four types of grassland. LMDG grassland ecosystem is the most sensitive to nitrogen application. 2） The maximum NPP in PDG grassland was achieved by applying 100 kg·ha^-1 nitrate twice a year， and the maximum NPP was 68.72 g C·m^-2·yr^-1. The maximum NPP fertilization strategy in LMDG grassland is 260 kg·ha^-1 of urea applied twice a year， and the maximum NPP value is 263.28 g C·m^-2·yr^-1. The maximum NPP of MMFM was achieved by applying 80 kg·ha^-1 of urea once a year， and the maximum NPP is 171.22 g C·m^-2·yr^-1. In AM grassland， anhydrous ammonia reached the maximum value of NPP （114.62 g C·m^-2·yr^-1） with the minimum amount of fertilizer （60 kg·ha^-1） and was the best nitrogen fertilizer in this grassland type. 3） The result of Monte Carlo uncertainty analysis shows that PDG and LMDG is more sensitive to fertilization time， and the effect of fluctuation in fertilizer application rate variation on LMDG and MMFM is more obvious.

Vegetation distribution patterns and root mechanical properties of selected plant species on the Xijitan giant landslide in the upper reaches of the Yellow River

Ji-mei ZHAO, Xia-song HU, Jiang-tao FU, Chang-yi LIU, Guang-yan XING, Fu-cheng YANG, Pei-hao ZHANG, Zhe ZHOU

2024, 33(1):  33-49.  DOI: 10.11686/cyxb2023074

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This research investigated the distribution pattern of vegetation and the root mechanical properties （tensile resistance， tensile strength） of selected plant species （Achnatherum inebrians， Stipa aliena and Poa crymophila） on the Xijitan giant landslide in the upper reaches of the Yellow River， and also the influence of soil nutrient status on field distribution of these species. Methodology included quadrat investigation of species distribution， root system extraction， soil sampling of 3-10 cm soil depth， and single root tensile tests. It was found that herbs were the main species sparsely mingled with shrubs. Based on redundancy analysis， soil water content （P<0.01， F=12.7）， pH （P<0.05， F=8.0） and total nitrogen （P<0.05， F=4.5） were the main factors affecting the distribution of the plant communities in this area. Furthermore， tensile strength of roots of the same species was different in different growth positions， and tensile strength of roots of different species in the same position also differed. Average tensile strength and tensile resistance of single root of P. crymophila plants located in the middle of the landslide were significantly higher than those growing in the front and rear edge of the landslide. Average tensile strength and resistance of single root of the three dominant herbs located in the middle of the landslide were S. aliena （9.10 N， 80.29 MPa）， P. crymophila （7.51 N， 49.78 MPa）， and A. inebrians （6.69 N， 34.82 MPa）， respectively. The results provide a theoretical basis and practical guidance for planting to control slope soil and water loss in shallow landslides.

An investigation of foliar spraying of selenium fertilizer for selenium enrichment and cadmium reduction in alfalfa

Xu-qin BAI, Chun-yun JIA, Wen-shuan LI, Ya-min LI, Chang-feng LIU, Xiu-yun HAN, Mei-han CHU, Zong-qiang GONG, Xiao-jun LI

2024, 33(1):  50-60.  DOI: 10.11686/cyxb2023070

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This research investigated foliar spraying of selenium fertilizer as a means to alleviate cadmium stress and enhance selenium content in alfalfa （Medicago sativa） plants exposed to different concentrations of cadmium （0， 1 and 10 mg·kg^-1 Cd； Cd₀， Cd₁ and Cd₁₀， respectively）. Two M. sativa cultivars， Caoyuan No.3 and Zhongmu No.1 were selected for study. In the experiment， effects of foliar selenium fertilizer spray （0， 50 and 100 mg·kg^-1 Se； Se₀， Se₅₀ and Se₁₀₀， respectively） on plant selenium enrichment and cadmium reduction were evaluated by measurement of plant height and biomass， and of the levels of total selenium， selenomethionine （SeMet） and cadmium in the roots， stems and leaves of the alfalfa plants when they were at the first flowering stage. It was found that the application of exogenous selenium promoted the growth and increased selenium levels of alfalfa. This was evidenced by significantly greater plant height， biomass， total selenium and SeMet content of the two alfalfa cultivars， while cadmium levels and the coefficients of cadmium enrichment and cadmium transport were significantly decreased. Both plant height and biomass always ranked Cd₀>Cd₁>Cd₁₀ at any given concentration of foliar Se spray， and usually ranked Se₁₀₀>Se₅₀>Se₀ at any given soil Cd concentration. Plant tissue Cd contents were generally greater than 10 mg·kg^-1 Cd dry weight at Cd₁₀， in the range 0.2-0.6 mg·kg^-1 Cd dry weight at Cd₁， and less than 0.02 mg·kg^-1 Cd dry weight at Cd₀ and always decreased by approximately 20% from Se₀ to Se₁₀₀. The total amount of selenium and SeMet in each organ ranked leaf>stem>root， and cadmium content ranked stem<leaf<root. Under the same conditions， plant height， biomass， total amount of selenium and SeMet of Zhongmu No.1 were higher than those of Caoyuan No.3， while the cadmium content was lower than that of Caoyuan No.3. We consider that the best result of selenium enrichment and cadmium reduction was achieved under growing conditions of 1 mg·kg^-1 Cd in soil and selenium fertilizer 50 mg·kg^-1.

Cloning and preliminary functional analysis of the root gene HgAKR6C of Halogeton glomeratus

Shang-qin HU, Jun-cheng WANG, Li-rong YAO, Er-jing SI, Xiao-le MA, Ke YANG, Hong ZHANG, Ya-xiong MENG, Hua-jun WANG, Bao-chun LI

2024, 33(1):  61-74.  DOI: 10.11686/cyxb2023076

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Aldo-keto reductase （AKR） is a conserved core domain that constitutes Shaker family K⁺ channel protein and plays a key role in plant response to abiotic stress. In this research， Halogeton glomeratus， a halophyte found in the northwest of China， was studied. Based on the results of initial transcriptomic investigation， the salt tolerance gene HgAKR6C was selected and cloned. The total length of the coding sequence （CDS） region of HgAKR6C gene was 951 bp， encoding 317 amino acids. Phylogenetic tree analysis showed that HgAKR6C is closely related to AtAKR6C1 gene in Arabidopsis thaliana. An evaluation of subcellular localization suggests that the gene is primarily localized in the cytoplasm and nucleus. A qRT-PCR analysis of the root gene HgAKR6C showed that the peak expression was reached at 24 h of salt treatment. Construction of yeast heterologous expression vectors to transform defective strains revealed that the HgAKR6C gene may be involved in Na⁺ efflux and mediates K⁺ uptake. In summary， HgAKR6C has the function of regulating salt tolerance in H.glomeratus. The regulatory mechanism of the salt tolerance gene HgAKR6C in the roots of H. glomeratus needs to be further investigated and verified.

Leaf structure， physiology and transcriptome analysis of Salsola collina in response to drought stress

Jiong-rui TAN, Tong-gang ZHA, Ze-yu ZHANG, Xiao-xia ZHANG, Hong-mei TENG, Ling-li WANG, Li-li ZHAO, Ao WANG, Xin-yao WANG

2024, 33(1):  75-88.  DOI: 10.11686/cyxb2023085

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This research investigated the phenotypic， physiological and molecular mechanism of Salsola collina response to drought stress. Plants were cultivated in pots under a controlled， declining soil moisture regime， falling from 80% to 50% of field water holding capacity over 28 days with sample collection at 0， 7， 14 and 28 days.It was found that the palisade tissue changed from dense to sparse and the crystal clusters disappeared initially and then increased across the 28 days of increasing drought stress. The thickness of aqueous tissue initially increased and then decreased （P<0.05）. The area of the main vascular bundle and epidermis thickness after 28 days of drought stress ［（3099.72±151.88） μm² and （23.73±0.68） μm， respectively］ were significantly increased compared to control ［（2065.41±80.08） μm² and （13.71±1.26） μm］ （P<0.05）. Again with increasing drought stress in 28-day-old seedlings， the leaf thickness increased but the area decreased （P<0.05）. Chlorophyll content decreased gradually （P<0.05）， superoxide dismutase （SOD） and peroxidase （POD） activities， proline and malondialdehyde （MDA） contents increased significantly （P<0.05）， H₂O₂ increased significantly at 14 days （P<0.05）， soluble protein content increased initially， then decreased under medium stress and increased under high stress （P<0.05）. Compared with day 0， there were 103， 1560 and 270 differentially expressed genes （DEGs） detected at 7， 14 and 28 days of drought stress， respectively. Gene ontology （GO） enrichment analysis showed that DEGs were significantly enriched in protein phosphatase type Ⅰ complex， integral components of membranes， oxidation-reduction process and oxidoreductase activity， among others. The Kyoto Encyclopedia of Genes and Genomes （KEGG） enrichment analysis showed that the genomes were significantly concentrated on oxidative phosphorylation， ribosome and phototransduction pathways. Abiotic stresses pathway DEGs analysis showed that heat shock protein genes， glutathione peroxidase 2 （GPX2）， POD， SOD， calcium-dependent protein kinase 19 （CPK19） and CBL-interacting protein kinase 9 （CIPK9）， MAP kinase genes， transcription factor protein degradation pathway genes， UDP-glucuronate decarboxylase 1（UXS1） and flavanone 3-hydroxylase（F3H）， among others， were involved in the regulation of drought stress responses. The results provide a reference point for further research on the drought resistance mechanism of S. collina.

Identification of CibHLH1 and its effect on photosynthetic characteristics in Chrysanthemum indicum var. aromaticum

Jin-xiu HAN, Bin CHEN, Yan-ting LIU, Ru MENG, Li-yan JIN, Miao HE

2024, 33(1):  89-101.  DOI: 10.11686/cyxb2023087

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The basic helix-loop-helix （bHLH） transcription factors are the second largest transcription factor family in plants and play an important role in plant growth and development， secondary metabolism and response to environmental stress. In this study， we cloned CibHLH1 using the leaf cDNA of Chrysanthemum indicum var. aromaticum as the template. The cloned gene has a 738 bp full-length sequence， and a 630 bp open reading frame. Multiple sequence comparison and phylogenetic investigation showed that CibHLH1 had the highest homology with CmbHLH1 of Chrysanthemum morifolium. The expression level of CibHLH1 was the highest in the flowers and lowest in roots. Subcellular localization revealed that the gene was located in the nucleus. CibHLH1 was transformed into tobacco （Nicotiana tabacum） by the leaf disk method to further study its functions. We found that the leaves of overexpressed tobacco became yellow and the contents of chlorophyll a， chlorophyll b and total chlorophyll were significantly reduced. The light response curve and photosynthetic physiological indexes of transgenic tobacco were evaluated， the results showed that overexpression of CibHLH1 decreased the maximum net photosynthetic rate， apparent quantum yield， light saturation point and water use efficiency， but increased the transpiration rate， stomatal conductance and light compensation point. In summary， CibHLH1 negatively affected the photosynthetic capacity of plants by reducing the content of photosynthetic pigments.

Genome-wide identification and expression analysis of the SOD gene family in Alternanthera philoxeroides

Shuo HAN, Xiao-wen HAN, Yi-feng HU, Zhong-yi CHEN, Yong-xing ZHU, Jun-liang YIN

2024, 33(1):  102-116.  DOI: 10.11686/cyxb2023100

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Superoxide dismutase （SOD） is a conserved antioxidant enzyme， which plays an important role in plant growth and development and stress response. Currently， there is a lack of systematic understanding of the SOD gene family members of Alternanthera philoxeroides （Ap）. This study systematically identified and analyzed the SOD gene family in A. philoxeroides using bioinformatics methods. The physicochemical properties， conserved motifs， gene structure， phylogenetic relationship， miRNA targeting relationship and expression pattern were analyzed. The results showed that a total of 43 ApSOD proteins were identified， of which 22 belonged to the Cu/ZnSOD subfamily and 21 belonged to the Fe/MnSOD subfamily. Protein characteristic analysis showed that 36 ApSOD proteins were hydrophilic proteins， and 37 ApSOD proteins were stable proteins； subcellular localization prediction showed that most Cu/ZnSOD proteins were localized in chloroplasts or the cytoplasm， and most Fe/MnSOD proteins were localized in mitochondria. Conserved domain analysis showed that members of the same subfamily had similar conserved motifs and gene structures. Prediction of miRNA targeting relationships showed that 17 miRNAs target to 14 ApSODs through cleavage or translation inhibition. Expression pattern analysis showed that the expression level of ApSODs were relatively stable in different environmental conditions and tissues. The expression patterns of 6 ApSODs were analyzed by RT-qPCR under herbicide treatment. Six ApSODs were significantly up-regulated within 7 d under oxadiazon and fluroxypyr stresses； under fluoroglycofen stress， the expression of four ApSODs initially increased and then decreased， and then increased again with extended duration of herbicide exposure. Under glyphosate stress， the expression of six ApSODs were significantly up-regulated at 7 d； the expression of four ApSODs were significantly down-regulated at 1 d under isoproturon stress. These results indicate that ApSODs showed different expression patterns under the stress of different herbicides. This study systematically identified and characterized the ApSOD family members and provided a preliminary description of the expression characteristics of six genes under herbicide stress， laying a foundation for further research on the biological role of ApSODs in response to herbicide stress.

Screening and identification of whole rice surface dominant lactic acid bacteria

Li-juan HUANG, Rong-ji SUN, Wen-jing GAO, Zhi-fei ZHANG, Gui-hua CHEN

2024, 33(1):  117-125.  DOI: 10.11686/cyxb2023075

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In this study， dominant lactic acid bacteria that colonize the leaf and stem surfaces of rice Oryza sativa plants were isolated， screened and identified， in order to develop a collection of potentially bacterial strains potentially useful in silage making as a biological resource. The epiphytic lactic acid bacteria of whole rice plants were isolated by the plate coating method. The growth rate and acid-producing capacity were screened initially， and the antioxidant capacity included H₂O₂ tolerance， 1， 1-diphenyl-2-picrylhydrazyl （DPPH） free radical， hydroxyl free radical and superoxide anion free radical scavenging rate were used as selection criteria for rescreening. The physiological and biochemical characteristics and molecular biological identification of the selected dominant lactic acid bacteria were analyzed. In total 154 strains of lactic acid bacteria were isolated from the rice plants. After 48 h culture， 16 strains were found with optical density at 600 nm （OD_600nm） value greater than 2 and pH value less than 4， among which 9 strains had antioxidant capacity. A strain designated YMA3 had the best overall performance， with scavenging rates of DPPH free radical， hydroxyl free radical and superoxide anion free radical of 72.23%， 72.46% and 86.33%， respectively. YMA3 was identified as Enterococcus faecalis， and showed strong adaptability to high temperature or acidic environments.

Detection of AMV pathogen of alfalfa virus diseases with different symptom types and its host ranges

Jian-ling ZHOU, Qiao-lan LIANG, Lie-xin WEI, Qi-yu ZHOU, Long TIAN, Ying-e CHEN, Cun-ying WANG, Guo-yin ZHANG

2024, 33(1):  126-137.  DOI: 10.11686/cyxb2023092

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In this study， the level of alfalfa mosaic virus （AMV） and leaf chlorophyll contents in field-grown alfalfa （Medicago sativa） plants with different categories of AMV symptoms were assessed， and a test of the plant species host range of AMV was conducted. Chlorophyll content was determined by an acetone-ethanol extraction method， and AMV was quantified by a double antibody sandwich enzyme-linked immunosorbent assay （DAS-ELISA） method. The pathogenicity of AMV to 32 plant species in nine botanical families was determined for purified virus extract from plants with different symptom types. Four symptom categories of AMV disease were investigated： light mosaic， heavy mosaic， leaf edge chlorosis and yellowing and leaf deformity with leaf-wrinkling and dwarfing. There was a positive correlation between chlorophyll content and AMV content and symptom expression. For the most severe AMV symptom manifestation involving leaf deformation， wrinkling and dwarfing， the chlorophyll a， b， and total chlorophyll content was more than 58% lower than the control， and the carotenoid content was 134.06% higher than the control. The highest AMV content was 252.96 pg·mL^-1. The host range determination showed that purified AMV could infect 27 plant species in 7 families， with the strongest pathogenicity to Cucurbita pepo. In this species， the symptoms were local withered spots， and the concentration of AMV in plant extract at 30 days after inoculation was 316.19 pg·mL^-1.

Evaluation of production performance of six Festuca arundinacea varieties in the Chengdu Plain

Rui ZHANG, Chong-yang HAN, Jia-bang CAI, Yang WANG, Lin-kai HUANG, Xin-quan ZHANG, Gang NIE

2024, 33(1):  138-148.  DOI: 10.11686/cyxb2023072

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In order to identify superior tall fescue varieties for planting in the Chengdu Plain， four varieties of Festuca arundinacea （Kora， Duramax， Tower and Kentucky 31） and two Festulolium varieties （Mahulena and Fojtan） were assessed for phenology， fresh and dry forage yield， nutritional composition and other agronomic traits， and a multivariate evaluation was carried out by grey correlation analysis. It was found that Tower and Kora had the longest seasonal growth period， which was up to 275 days. The average regrowth rate of the six tested varieties ranked Mahulena>Kora>Duramax>Tower>Kentucky 31>Fojtan. The average dry forage yield of Mahulena was the highest at 12790.99 kg·ha^-1. The yield of first-ranked Mahulena was 14.62% and 4.28% higher （P<0.05） than yields of fourth- and third-ranked Tower and Duramax， respectively， while yield of second-ranked Kora was 6.59% （P<0.05） higher than Tower. The plant height of Kora was greatest （100.15 cm）， followed by Tower and Duramax （P<0.05）. Duramax had the highest tiller number （47.33 tillers·plant^-1）， followed by Kora and Mahulena （37.50 and 37.00 tillers·plant^-1， respectively）. These values were all significantly higher than those of Tower. The stem∶leaf of Kentucky 31 was 0.96， higher than that of other tested varieties. The variety with highest crude protein content was Tower （18.60%） and the variety with highest ether extract content was Kora （5.41%）. According to the multivariate comparative analysis using the grey correlation method， Kora， Tower and Mahulena were the best performers among the tested varieties. They displayed excellent field performance and are therefore suitable for utilization in Chengdu Plain area.

Seasonal nitrogen and phosphorus co-application enhances productivity of Festuca kryloviana cv. Huanhu

Zheng-hai SHI, Wen-hui LIU, Yong-chao ZHANG, Yan QIN, Wen-bo MI, Feng LUO, Man LIU, Hui-fang QI

2024, 33(1):  149-158.  DOI: 10.11686/cyxb2023069

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In order to clarify the effects of post-harvest fertilization on the herbage yield of Festuca kryloviana cv.Huanhu in the following year， this research investigated the forage and seed yields and fertilizer utilization efficiency of 5-year-old F. kryloviana cv. Huanhu under autumn and spring fertilization in 2018-2019. The experiment included eight treatment combinations with two nitrogen levels （0 and 60 kg·ha^-1， designated N₀ and N₆₀） and four phosphorus levels （0， 60， 75， 90 kg·ha^-1， designated P₀， P₆₀， P₇₅， and P₉₀， respectively）. Agronomic traits， including plant height， stem diameter， the number of reproductive shoot， aboveground biomass and seed yield were measured. It was found that： 1） Nitrogen fertilizer application in both autumn and spring increased the aboveground biomass and seed yield， with increases of over 62.79% and 12.58%， respectively. However， autumn fertilization tended to stimulate the reproductive shoot and maintain seed production， while spring fertilization tended to promote herbage accumulation. Nitrogen application in autumn increased the seed yield by 37.38%-73.99%， compared to spring application. Nitrogen application in spring compared to autumn increased the aboveground biomass by 6.47%-51.19%. 2） Nitrogen fertilizer promoted production of 5-year-old F. kryloviana cv. Huanhu more than P fertilizer. The increase in plant height， number of reproductive shoots， aboveground biomass， and seed yield due to nitrogen application was 20.24%， 19.10%， 133.94%， and 89.66%， respectively. Single phosphorus fertilizer application decreased plant height and number of reproductive shoots by 3.12% and 3.79%， respectively. Due to the synergistic effect of nitrogen and phosphorus fertilizers on seed production， the highest seed yield （233.19 kg·ha^-1） occurred at the N₆₀P₇₅ treatment， under autumn fertilization. 3） Analysis of fertilizer utilization efficiency for aboveground biomass and seed yield showed that there was no seasonal difference in partial factor productivity and agronomic efficiency of phosphorus fertilizer （P>0.05）. The impact of nitrogen fertilizer partial factor productivity and agronomic efficiency on seed yield was 1.37 and 2.74 times greater for autumn than spring fertilization. Regardless of whether nitrogen was applied in spring or autumn， the largest fertilizer partial factor productivity and agronomic efficiency values were observed in the treatment with nitrogen only. With increasing phosphorus application， the fertilizer utilization efficiency showed a decreasing trend at the same nitrogen level. 4） The correlation coefficient between the number of reproductive shoots and seed yield remained above 0.809 （P<0.01）， and the linear equations fitted the relationships between the number of reproductive shoots and seed yield， seed yield and aboveground biomass， and plant height and aboveground biomass well. In summary， to maximize the aboveground biomass， fertilizer use efficiency and seed yield of the long-lived F. kryloviana cv. Huanhu， the use of nitrogen fertilizer was more important than the use of P fertilizer.

A performance evaluation of two crops of forage oats per year in the northern Ordos Plateau

Wen-long LI, Feng LI, Zhong-juan ZHANG, Dian-qing WANG, Huan WANG, Hui-qing JIN, Mu-re TE, Zhi-ling HU, Ya TAO

2024, 33(1):  159-168.  DOI: 10.11686/cyxb2023071

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This study compared oat （Avena sativa） varieties and planting patterns for optimal performance when planting two crops of forage oats per year in northern part of the Ordos Plateau， in order to improve land use efficiency and increase economic returns. Various production characteristics and the nutritional quality of six domestic and foreign oat varieties （Qingyan No.1， Qingyin No.1， Souris， Baler， Helios， and Sweet oat）. Multivariate evaluation of the crop data was performed using the grey correlation method. Ranges recorded for plant height， hay yield， crude protein （CP）， neutral detergent fiber （NDF）， acid detergent fiber （ADF）， potassium （K） and relative feeding quality （RFQ） of different oat varieties in the first crop were 96.77-121.77 cm， 8426.38-14287.07 kg·ha^-1， 8.19%-9.29% DM， 51.47%-59.90% DM， 30.00%-35.83% DM， 1.23%-1.87% and 117.88-161.41， respectively. In the second crop， corresponding values were 68.73-97.20 cm， 4927.07-7082.58 kg·ha^-1， 12.12%-16.34% DM， 39.60%-46.61% DM， 19.49%-24.26% DM， 1.67%-1.94% and 206.09-262.64 respectively. There were significant differences （P<0.05） in the multivariate evaluation indexes among different varieties， except in the crude protein content of crop 1. In the first crop， the plant height， NDF and ADF content of Helios were higher but RFQ was lower than values of other varieties， while Souris had the highest hay yield and lowest K content. In the second oat crop， the plant height and hay yield of Qingyin No.1 ranked first， and its NDF and ADF contents were also the highest. The CP content of Baler was higher， and the K content of Qingyan No.1 was lower than that of other varieties. Plant height， hay and fresh yield were significantly or extremely significantly negatively correlated with CP， K and RFQ （P<0.05， P<0.01， or P<0.001）， while positively correlated with NDF and ADF extremely significantly （P<0.001）. In the grey correlation analysis the weighting coefficients for NDF and RFQ were the highest indicating that these two parameters are important indexes for oat productivity evaluation in this region. The most suitable oat varieties for spring sowing in the first crop and multiple planting in the second crop in north part of the Ordos Plateau are Souris and Qingyan No.1， respectively. So the planting combination of spring sowing Souris and replanting with Qingyan No.1 in the autumn can be recommended in this area， or in edaphically similar areas.

Effects of oat∶feed pea sowing ratio and lactic acid bacteria addition on crop silage fermentation and ruminal degradation characteristics of the resulting total mixed ration

Jia-min ZHANG, Hao GUAN, Hai-ping LI, Zhi-feng JIA, Xiang MA, Wen-hui LIU, You-jun CHEN, Shi-yong CHEN, Yong-mei JIANG, Li GAN, Qing-ping ZHOU, Li-xue YANG

2024, 33(1):  169-181.  DOI: 10.11686/cyxb2023144

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This research investigated the effects of oat∶feed pea sowing ratio and lactic acid bacteria addition on crop fermentation， total mixed ration （TMR） nutritive value and rumen degradation characteristics of the resulting silage. Qinghai sweet oat and Qingjian No.1 feed pea were mixed-planted at oat∶feed pea sowing ratios of 0∶10， 5∶5， 6∶4， 7∶3， 8∶2， 10∶0. In the oat milk-ripening stage and pea-podding stage， crops of the six abovementioned mixtures were harvested and samples of each placed in fermentation bags after inoculation with a lactic acid bacterial preparation （I₁， I₂， I₃， I₄， I₅ and I₆， respectively）_{or uninoculated （C1， C2， C3， C4， C5， C6， respectively）， making a total of 12 treatments. The lactic acid bacterial preparation contained Lactobacillus plantarum 160， Lactobacillus brevis 248 and Lactobacillus pentosus 260 mixed at a ratio of 1∶1∶1 （bacterial activity： about 10⁶ cfu·mL^-1）. The oat∶feed pea mixtures were combined with feed supplement （highland barley straw， rape straw， and rape meal， mixed 1∶1∶1） in a forage∶supplement of 7∶3. After fermentation at （20±5） ℃ for 60 days， the nutrient composition， fermentation quality and rumen degradation characteristics were determined. The results showed that with increase in the proportion of oats， the neutral detergent fiber and acid detergent fiber content increased， the crude protein content decreased， and the gas production decreased. The addition of the mixed lactic acid bacterial preparation significantly reduced dry matter loss， pH and NH3-N/TN （P<0.05）. The dry matter loss in C3 and I3 was 0.38% and 0.15% and both of these values were significantly lower （P<0.05） than those of other treatments in the respective control and inoculated groups. The rumen crude protein and acid detergent fiber degradation rates of the oat-feed pea ensiled TMR were significantly higher than those of the TMR of the two monocrops （P<0.05）， and the rumen degradation rate of I2 was the best. The rumen NH3-N content of C3 was 29.65% and I3 was 31.68%， and both of these values were significantly higher （P<0.05） than those of other treatments in the respective inoculated or control groups. The quality of oat-feed pea silage TMR was evaluated by the membership function and principal component analysis methods， and in these multivariate assessments the highest score was I2 （0.868）， followed by I3 （0.610） and C3 （0.469）. Therefore， when using mixed oat∶feed pea crops to produce ensiled TMR， oat∶feed pea planting ratios of 6∶4 or 5∶5 are optimal for ensuring high quality ensiled TMR feed， based on these results.}

The role of MAPK in plant response to abiotic stress

Xin-miao ZHANG, Guo-qiang WU, Ming WEI

2024, 33(1):  182-197.  DOI: 10.11686/cyxb2023090

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Mitogen-activated protein kinase （MAPK） is a highly conserved serine/threonine （Ser/Thr） protein kinase， occurring widely in eukaryotic intermediate reaction pathways. Plant MAPK has 11 relatively conserved sub-domains， which are all essential elements for Ser/Thr protein kinase to play its catalytic role， and its expression is regulated by reactive oxygen species， nitric oxide and hormones. MAPK phosphorylates a variety of substrates including transcription factors， protein kinases and cytoskeleton related proteins， and plays an important role in regulating plant response to abiotic stresses （salt， drought， extreme temperature， and heavy metals）. In this review， we summarize the results of research on the discovery of plant MAPK family members， their structure and classification， regulatory mechanisms， and their roles in response to various abiotic stresses. We also propose directions for future research. The information in this review provides a theoretical basis and identifies genetic resources for the genetic improvement of crops to produce new， stress-resistant varieties.

Regulation of telomere DNA binding protein and telomerase activity in plants

Shou-jiang SUN, Wen MA, Pei-sheng MAO, Li-ru DOU, Zhi-cheng JIA, Ming SUN, Juan WANG

2024, 33(1):  198-206.  DOI: 10.11686/cyxb2023089

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The investigation of plant senescence and seed deterioration mechanisms has emerged as a prominent and highly significant subject in the field of agricultural science. Plant senescence can exert a profound negative impact on agriculture， while premature senescence of forage grasses can engender diminished grassland productivity and impede the progress of the grass industry. Additionally， seed deterioration leads to an annual loss of viability in approximately 25% of global seeds， resulting in substantial economic losses and significantly hampering the healthy advancement of agriculture. Gaining a comprehensive and profound understanding of plant senescence characteristics and regulatory mechanisms offers immense value not only in unraveling plant ecological adaptations and population stability but also in offering vital practical implications for the selection of senescence retardation techniques and regulatory measures. In the model plant Arabidopsis thaliana， extensive evidence indicates a close and intricate interrelation among chromosomal telomeres， plant senescence， and seed viability. Telomeres， repetitive DNA sequences situated at the chromosomal termini， encompass telomeric DNA and associated binding proteins. Telomere-binding proteins form a pivotal protein ensemble that primarily assumes the role of stabilizing telomere structure and safeguarding telomeres against disturbances originating from the DNA repair system. Moreover， these proteins actively partake in numerous fundamental biological processes， including gene expression， DNA replication， and the modulation of chromosomal architecture. Telomerase， comprising two subunits-telomerase reverse transcriptase （TERT） and telomerase RNA （TER）-exerts its influence on mitochondrial function and the regulation of pertinent gene expression. By exploring the nascent functionalities of telomerase， we can facilitate advances in plant stress resistance， subsequently postponing the onset of plant senescence and creating novel pathways towards enhanced crop yield. Recent investigations conducted on plants have unveiled a compelling correlation between telomere dynamics and plant senescence， yet numerous question remain surrounding the precise mechanisms governing telomere homeostasis in plants. In the light of these findings， this study undertakes a comprehensive review of the roles fulfilled by telomeres and telomere-binding proteins in plant biology， with particular emphasis on the regulatory mechanisms governing telomere length and telomerase activity orchestrated by these pivotal elements. This work serves as a theoretical cornerstone， furnishing a vital reference for subsequent exploration of the intricacies of plant senescence and seed deterioration mechanisms.

A study of pollination ecology of three Meconopsis species with sympatric distribution on Jiajin Mountain

Ren-xiang DING, Hao LIU, Ke-ran ZHU, Yu ZHANG, Xin WANG, Meng YANG, Hao-cheng ZHU, Guang-li LIU

2024, 33(1):  207-216.  DOI: 10.11686/cyxb2023084

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This study investigated the pollination ecology and differences in breeding systems of three Meconopsis species with sympatric distribution on Jiajin Mountain. This study observed and statistically analyzed the flowering phenology and insect pollinators of Meconopsis integrifolia， Meconopsis henrici and Meconopsis punicea and used benzidine hydrogen peroxide and triphenyltetrazolium chloride （TTC） staining methods to detect stigma receptivity and pollen viability， respectively. The results indicated that： 1） The flowering period of M. integrifolia began about one month earlier than that of the M. henrici and the M. punicea， and the flowering periods of the latter two were similar， and the three had overlapping flowering periods. 2） The duration of stigma receptivity of the three Meconopsis species was more than 5 days， and the plant stigma receptivity was the strongest at the 3rd to 4th day of flowering. 3） Within 8 hours after dispersal， the pollen viability of M. integrifolia and M. henrici decreased with time， and the pollen viability of M. punicea initially increased and then decreased. 4） The pollen∶ovule of M. integrifolia pollen was 990±28， and that of M. henrici was 2050±596 （P<0.05）. The pollen∶ovule of M. punicea was intermediate （1380±202）， and not significantly different from the other two species. The three species of Meconopsis display facultative outcrossing. 5） Three species of Meconopsis had the same pollinator， Helicophagella melanura. M. integrifolia was the species visited by the largest number of insect species， while M. punicea attracted the highest total number of insect visits and M. henrici had the lowest total number of insect visits. The main pollinator of M. punicea was a small parasitic fly which only visits this species and lays its eggs on the stigma. In summary， there were differences among the three species in the breeding system： the flowering period and stigma receptivity period of M. integrifolia were the longest， with the strongest stigma receptivity and the highest number of pollinating insects， which compensated for the rapid decline in pollen viability； the pollen of M. henrici could maintain high viability for a long time， but the number of pollinating insects was the least； M. punicea has a unique pollination mode involving a small parasitic fly. They oviposit within the stigma and assist the host in intraspecific pollination， ensuring pollen reaches flowers of the same species.