Table of Content

20 September 2017, Volume 26 Issue 9

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Simulation of soil moisture dynamics and ryegrass growth in the hilly region of Sichuan Province using the environmental policy integrated climate model

WANG Xue-Chun, WANG Hong-Ni, HUANG Jing, YANG Guo-Tao, HU Yun-Gao

2017, 26(9):  1-13.  DOI: 10.11686/cyxb2016446

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The definition of soil moisture dynamics is very important to improve the management of ryegrass pasture. The use of the environmental policy integrated climate (EPIC) model can improve the accuracy of cropping system simulations, thereby providing better information for decision making. In this study, field experiments and computer simulations were used to analyze the growth process of ryegrass and the dynamics of soil moisture in ryegrass pastures. Then, the accuracy of the EPIC model to simulate ryegrass growth and soil moisture was evaluated. The results showed that available soil water in the deep soil layer (0.4-0.6 m) was relatively lower from March to May, but increased from May to October. Appropriate nitrogen fertilization (75-225 kg/ha) significantly increased the forage yield and leaf area index of ryegrass pastures in the hilly region of Sichuan Province. The correlation index values between observed and simulated available soil water in the 0-1 m soil layer ranged from 0.86 to 0.95 with RRMSE values ranging from 6.0% to 17.2%. The range of correlation index values between observed and simulated soil water in the 0-1 m soil layer was 0.57-0.92, and most values were >0.85. The correlation index values between simulated and observed values of forage yield, leaf area index, and height of ryegrass were >0.90, and there were no significant differences between simulated and observed values. In conclusion, the EPIC model can simulate soil moisture and forage yields of ryegrass pastures. These simulations can be used to evaluate the suitability of grain-forage cropping systems for the hilly regions of Sichuan Province.

Shear strength tests of the root-soil composite system of alpine grassland vegetation at different stages of degradation and the determination of thresholds in the Yellow River source region

LIU Chang-Yi, HU Xia-Song, DOU Zeng-Ning, LI Xi-Lai, XU Zhi-Wen

2017, 26(9):  14-26.  DOI: 10.11686/cyxb2017005

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The aim of this study was to determine the shear strength of the root-soil composite system from sites with vegetation at different stages of degradation. The selected study area was the alpine grassland in Henan County, Qinghai Province, in the source region of the Yellow River. Shear strength tests were conducted to systematically analyze the characteristics of root-soil composite samples from sites with vegetation at different stages of degradation. The results showed that the grassland in the study area had an irregular oval-shaped pattern of degradation, with more severe degradation close to the center of the oval. From the outside to inside of the irregular oval, the grassland could be divided into a non-degraded (ND) area, a slightly degraded (SD) area, a moderately degraded (MD) area, and a heavily degraded (HD) area. As the degree of degradation increased, the diversity and abundance of local plants decreased, and introduced plants gradually replaced local plants and became dominant. The proportion of roots in soil and the shear strength of the root-soil composite system decreased with increasing degradation. The shear-strength thresholds of the root-soil composite system between neighboring degradation areas were also determined. The threshold of the cohesion of the root-soil composite system between ND and SD was 28.07 kPa, that between SD and MD was 20.46 kPa, and that between MD and HD was 9.21 kPa. This research to quantify differences in the strength of the root-soil composite system among grasslands with vegetation at different stages of degradation has theoretical value for further scientific studies, and will be useful for developing strategies to prevent and manage grassland degradation.

Response of soil nitrogen mineralization to different stocking rates on the Stipa breviflora desert steppe

HAN Meng-Qi, PAN Zhan-Lei, JIN Yu-Xi, QIN Jie, LI Jiang-Wen, WANG Zhong-Wu, HAN Guo-Dong

2017, 26(9):  27-35.  DOI: 10.11686/cyxb2017118

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Nitrogen mineralization is a key process affecting nitrogen availability and nitrogen cycling in soils. The desert steppe is a grassland ecosystem with poor resources, a harsh climate, and a relatively simple vegetation structure. Therefore, it is important to study nitrogen availability on the desert steppe to maintain the stable development of these grasslands. In this study, the net nitrogen mineralization rate was monitored over the whole growing season by using the top-buried tube culture method. We monitored the net nitrogen mineralization rate under four grazing treatments [0 (CK), 0.91 (light grazing), 1.82 (moderate grazing), 2.71 (heavy grazing) sheep/(hm²· a)], and analyzed the relationships between environmental factors (soil temperature and humidity) and soil nitrogen content and mineralization. The aim of these analyses was to provide reference data to develop strategies for the sustainable utilization of nitrogen in the desert grassland ecosystem. The soil net nitrogen mineralization rate first increased and then decreased during the growing season, and the effect of stocking rate was higher in July and August in the peak growth period. The net nitrogen mineralization rate was highest in the moderate grazing treatment [1.82 sheep/(hm²·a)] and lowest in the heavy grazing treatment [2.71 sheep/(hm²· a)]. Pearson’s correlation analyses showed that the nitrification rate was positively correlated with net nitrogen mineralization rate, and the net nitrogen mineralization rate was greatly affected by nitrification during the whole growing season. There was a significant negative correlation between soil water content and net nitrogen mineralization rate, but not between soil temperature and net nitrogen mineralization rate. In summary, the moderate grazing treatment [1.82 sheep/(hm²·a)] represents the ideal stocking rate to maintain a stable nitrogen mineralization rate in desert steppe grasslands.

Correlations between soil microbial biomass and soil physical and chemical properties in grassland in Chabuchaer County

Saiyaremu·Halifu, Aikebaier·Yilahong, SONG Rui-Qing, Abudousaimaiti·Naihemaiti

2017, 26(9):  36-44.  DOI: 10.11686/cyxb2016485

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Microorganisms are involved in the transformation and circulation of soil nutrients, and are also sources and sinks of soil nutrients. These processes and the abundance of soil microorganisms are sensitive to environmental changes. Therefore, changes in the abundance of microorganisms are an important index of changes in soil quality. In this study, grassland soil samples collected at altitudes of 1191-2656 m in Chabuchaer County, Ili, Xinjiang, were analyzed by chloroform fumigation extraction to determine differences in the quality and activity of soil microorganisms among different altitudes. The results showed that biomass carbon (21.05-331.58 mg/kg) and biomass nitrogen (8.75-95.61 mg/kg) were higher at the soil surface than in middle and lower layers, and differed significantly with altitude and among soil depths (P<0.05). The microbial biomass increased with increasing altitude from 1191 m to 2216 m (331.58 mg/kg, 95.61 mg/kg) and then significantly decreased as the altitude increased from 2216 m to 2656 m (21.05 mg/kg, 12.41 mg/kg). This may have resulted from changes in environmental and climatic conditions such as precipitation and the types and quantities of vegetation. Correlation analyses showed that soil biomass carbon was positively correlated with soil nitrogen and the carbon∶nitrogen ratio (P<0.05). Soil microbial biomass was positively correlated with moisture content at 0-20 cm depth (P<0.05, r=0.755^*) and with altitude, organic matter, bulk density, and available nitrogen (P<0.05). Soil microbial biomass showed negative correlations (P<0.05) with soil pH, total nitrogen, and the carbon∶nitrogen ratio. At the soil depth of 20-40 cm, soil microbial biomass was significantly positively correlated with available nitrogen (P<0.05, r=0.829^*). Soil microbial biomass showed positive correlations with altitude and total nitrogen (P<0.05), and a negative correlation (P<0.05) with the carbon∶nitrogen ratio. At the soil depth of 40-60 cm, soil microbial biomass showed negative correlations with altitude and the carbon∶nitrogen ratio (P<0.05), and positive correlations (P<0.05) with organic carbon, available nitrogen, total nitrogen. These results showed that soil microbial biomass responds to changes in soil fertility; therefore, it can be used as a biological index of soil fertility.

Effect of root rot on fiber yield and yield-related traits of ramie (Boehmeria nivea)

BAI Yu-Chao, WANG Hui, GUO Ting, LI Lin-Lin, YANG Rui-Fang, SHE Wei, CUI Guo-Xian

2017, 26(9):  45-56.  DOI: 10.11686/cyxb2017099

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Ramie (Boehmeria nivea) and its products are important traditional and export commodities in China. The aim of this study was to investigate the effects of root rot on the main yield-related traits of ramie in a 7-year field experiment. We determined fiber yield and seven agronomic traits (plant height, stem diameter, ramet number, harvest ratio, fresh bark thickness, fresh bark yield, and bast fiber content). The relationships between root rot and these factors were evaluated by correlation analyses, multiple regression analyses, and path analyses. The results showed that the average root rot rate of Zhongzhu-1, Tri-1, and Xiangzhu-3 was up to 14.71% and the fiber yield decreased by 14.94% during the 7-year field experiment. The plant height, harvest ratio, and bast fiber content increased during the field study, with increases of 0.0181 m, 0.2925%, and 0.1792% per year, respectively. However, the stem diameter, ramet number, fresh bark thickness, fresh bark yield, and fiber yield decreased at 0.0089 cm, 0.1057×10⁴ plants/ha, 0.001 mm, 0.6439×10³ kg/ha, and 0.3634×10² kg/ha per year, respectively. The correlation coefficients between fiber yield and yield-related traits were as follows: fresh bark yield (r=0.9108), plant height (r=0.4226), fresh bark thickness (r=0.4176), ramet number (r=0.2777), harvest ratio (r=0.2640), bast fiber content (r=0.1235), and stem diameter (r=0.0395). There were highly significant correlations between fiber yield and plant height, fresh bark thickness, and fresh bark yield (P<0.01) and significant correlations between fiber yield and ramet number and harvest ratio (P<0.05). The path analysis indicated that fresh bark yield played the greatest role in fiber yield (P=1.0446), followed by bast fiber content (P=0.4262). The plant height, stem diameter, ramet number, harvest ratio, and fresh bark thickness indirectly affected fiber yield via their contributions to fresh bark yield.

Effects of cutting time on the yield and nutritive value of alfalfa on the Loess Plateau

HU An, KANG Ying, CHEN Xian-Jiang, HOU Fu-Jiang

2017, 26(9):  57-65.  DOI: 10.11686/cyxb2016487

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Cutting time is one of the key factors affecting the yield and quality of alfalfa. In these experiments, we evaluated the effects of different cutting times in 2009 and 2010 on the yield and quality of alfalfa hay. The hay yield and crude protein yield of alfalfa were highest at the early flowering stage (P<0.001). Cutting before the early flowering stage resulted in significantly decreased hay yield and crude protein yield (P=0.003). As the interval between the first and second cutting times increased, the contents of neutral detergent fiber, acid detergent fiber, and crude fiber increased (P<0.001), and the crude protein content decreased (P<0.001). With the first cutting at early flowering, an interval of 72 days (2009) and 68 days (2010) resulted in the highest yield and crude protein production (2275.2 kg/ha and 180.2 kg/ha, respectively, in 2009; 2063.6 kg/ha and 263.1 kg/ha, respectively, in 2010). These results indicate that the appropriate time for the first cutting of alfalfa on the Loess Plateau is at the early flowering stage in mid-June, and that of the second cutting is approximately 70 days later in late August.

Antioxidant capacity, bioactive compounds, and volatile constituents of flowers of Hypericum perforatum at different harvest stages

GE Li, YAO Yuan-Yuan, KANG Tian-Lan, LI Jing-Yao, HE Heng-Jun, YANG De-Long, LI Meng-Fei

2017, 26(9):  66-74.  DOI: 10.11686/cyxb2016484

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The aim of this study was to investigate the antioxidant capacity and the contents of total flavonoids, phenolics, and hypericin in Hypericum perforatum flowers at different harvest stages (bud stage, blooming stage, fruit stage). Flowers at each stage were extracted in 70% ethanol, and the extracts were subjected to high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The I% (inhibition percentage) and FRAP (ferric reducing/antioxidant power) values were significantly higher at the bud and blooming stages than at the fruit stage, but did not differ significantly between the bud and blooming stages. The contents of total flavonoids, phenolics, and hypericin differed significantly among stages, with the highest contents at the blooming stage, followed by the bud stage, and then the fruit stage. Thirty-seven compounds were separated and identified in the 70% ethanol extracts from flowers at the blooming stage. The main components were 1,1-diethoxy-ethane (19.26%), 1-hexadecanol (17.85%), β-ylangene (10.71%), (Z,Z)-9,12-octadecadienoyl chloride (8.42%), hexadecanoic acid ethyl ester (8.40%), phytol (5.79%), and caryophyllene oxide (4.56%). These results indicated that the optimal harvest stage of H. perforatum flowers is at the bud to blooming stages, when the flowers contain high levels of bioactive compounds, antioxidants, and volatile components. This study provides important reference information for the large-scale cultivation of H. perforatum.

Relationship between Notopterygium forbesii quality and soil factors in Gansu Province

XIE Fang, ZHANG Ya-Jun, CHANG Li-Ming, LIU Shuai, CHEN Chen

2017, 26(9):  75-82.  DOI: 10.11686/cyxb2016444

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Notopterygium medicine is the dried rhizome and root of Notopterygium incisum or Notopterygium forbesii, which are members of the Umbelliferae. The aim of this study was to evaluate the quality of cultivated N. forbesii in Gansu Province and its relationship with soil factors. Samples of N. forbesii were collected from cultivation areas in Gansu Province biennially, and the fresh samples were analyzed to determine notopterol and isoimperatorin contents. Soil samples were also collected and the following 10 factors were analyzed: the contents of organic matter, total nitrogen, total phosphorus, available phosphorus, available potassium; volume weight; pH; the contents of cosmids, silt, and grit. The relationships between chemical compounds and ecological factors were analyzed by Pearson’s correlation analysis and redundancy analysis (RDA). The results showed that, in all samples, the contents of notopterol and isoimperatorin met the requirements of the Chinese Pharmacopoeia. The contents of notopterol and isoimperatorin in N. forbesii differed among different cultivation areas, and N. forbesii samples showed certain regional characteristics. The highest total contents of notopterol and isoimperatorin were in samples from Wudu District, Kangle County, and Zhuoni County. Organic matter, total nitrogen and total phosphorus were significantly and positively correlated with notopterol, available potassium was significantly and negatively correlated with notopterol content. Volume density and vailable phosphorus were the most important soil factor and were extremely positively correlated with isoimperatorin content, total nitrogen and organic matter were positively correlated with isoimperatorin. Isoimperatorin content was significantly negatively correlated with available potassium. Therefore, the soil volume weight, total nitrogen, organic matter, available phosphorus and available potassium were identified as the main factors influencing the accumulation of chemical compounds in N. forbesii, and soil volume weight enhanced the accumulation of chemical composition. Wthin a certain range, the higher the soil organic matter and total nitrogen contents, the higher the notoptetol and isoimperatorin content in N. forbesii. The mount of available potassium in soil should be controlled to ensure high-quality N. forbesii. These results can be used to promote the cultivation and quality of N. forbesii in Gansu Province.

Effect of nitrogen supplementation on growth of white clover under cadmium stress and alleviation of cadmium toxicity

DONG Ji-Fei, ZHANG Fan, HU Yu-Han, LI Jun-Cheng, LI Wei, WANG Xian-Shu

2017, 26(9):  83-91.  DOI: 10.11686/cyxb2016461

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We investigated the effect of exogenous nitrogen on the growth of white clover (Trifolium repens) under cadmium stress and on Cd toxicity. White clover plants grown in pots were treated with N and/or Cd, and their growth, biomass, chlorophyll content, antioxidant enzyme activity, Cd content, glutathione (GSH) content, and phytochelatins content were determined. Treatment with Cd significantly inhibited the growth and decreased the chlorophyll content of white clover. However, applications of both Cd and N to the soil promoted white clover biomass and chlorophyll content, as compared with the control. The addition of N under Cd stress enhanced plant growth and chlorophyll content, and increased the activities of peroxidase, superoxide dismutase, and catalase, as well as increasing the Cd content. Treatment with Cd alone increased the phytochelatins content and significantly reduced the GSH content. Treatment with N increased the GSH and phytochelatins contents under Cd stress. These results indicated that exogenous N can effectively alleviate Cd toxicity to white clover.

Isolation of GsARHP from Glycine soja and its functional analysis in transgenic alfalfa under alkaline stress

CHEN Ran-Ran, ZHU Ping-Hui, JIA Bo-Wei, SONG Xue-Wei, WANG Zi-Jun, LI Ji-Na, LI Qiang, DING Xiao-Dong, ZHU Yan-Ming

2017, 26(9):  92-103.  DOI: 10.11686/cyxb2016464

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GsARHP, which encodes hypothetical protein up-regulated by alkaline stress, was identified from RNA-seq data of wild soybean (Glycine soja) at the early stage of the salt stress response. Real-time PCR analyses showed that GsARHP was induced by alkali stress. A bioinformatics analysis showed that the gene encodes a hydrophilic protein consisting of 130 amino acids, with a signal peptide but no transmembrane domain. A plant overexpression vector was constructed and transformed into alfalfa by Agrobacterium tumefaciens-mediated cotyledonary node infection. Three transgenic lines were identified by PCR, Southern blotting, and RT-PCR analyses. The non-transgenic lines became wilted and yellow or even died under 0, 100, and 150 mmol/L NaHCO₃ treatment for 14 days, while the transgenic lines grew well under the same conditions. Further analyses showed that the transgenic lines had significantly lower relative plasma membrane permeability and malondialdehyde (MDA) content than did non-transgenic lines (P<0.01), and significantly higher chlorophyll content and CAT activity (P<0.01). These results indicated that overexpression of GsARHP could enhance the alkali resistance of alfalfa.

Enhanced tolerance of Arabidopsis over expressing Fa14-3-3C from tall fescue (Festuca arundinacea) to low-nitrogen stress

LI Xiao-Dong, WU Jia-Hai, SUN Fang, CHEN Guang-Ji, WANG Xiao-Li

2017, 26(9):  104-112.  DOI: 10.11686/cyxb2017058

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Nitrogen is essential for the growth and development of plants, especially gramineous crop plants. In this study, the full-length Fa14-3-3C gene was obtained by rapid amplification of cDNA ends from leaves of tall fescue (Festuca arundinacea). Subcellular localization analyses showed that Fa14-3-3C-GFP was mainly located in the cytoplasm and cell membrane when it was transiently expressed in tobacco epidermal cells. Fa14-3-3C was transferred into Arabidopsis, and three single-copy T-DNA insertion strains showing a 3∶1 hygromycin resistance segregation ratio were obtained. When wild-type and Fa14-3-3C overexpression strains were subjected to nitrogen deficiency, the root fresh weight was higher in strains OE-1 and OE-3 (but not OE-2) than in wild type. Quantitative real-time PCR analyses showed that Fa14-3-3C was highly expressed in OE-1 and OE-3, but not in OE-2, reflecting a dosage effect on the response to nitrogen deficiency. Dynamic analyses of the root growth of wild-type and Fa14-3-3C overexpression strains in nitrogen-deficient medium revealed that OE-1 showed a dramatic advantage over wild-type plants at the early stage of nitrogen deficiency. This was mainly due to compensation growth to alleviate the negative effects of low-nitrogen stress in the OE-1 strain. Therefore, we have cloned a candidate gene conferring resistance to low-nitrogen stress, and verified its molecular function in the model plant Arabidopsis. These results are fundamentally important for breeding crop plants resistant to low-nitrogen stress via genetic engineering.

Establishment of a gene transient expression system mediated by polyethylene glycol in switchgrass (Panicum virgatum) mesophyll protoplasts

QI Ze-Wen, SUN Xin-Bo, FAN Bo, ZHANG Xue, YUAN Jian-Bo, HAN Lie-Bao

2017, 26(9):  113-120.  DOI: 10.11686/cyxb2017029

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Leaves of Alamo switchgrass (Panicum virgatum) were used as materials to establish a transient expression system for mesophyll protoplasts cells. To determine the optimal conditions to obtain protoplasts from switchgrass, we designed a gradient experiment, with three replicates per treatment. First, we determined the optimal age of plants as the source of material. The leaves of etiolated seedlings grown for 1, 2, 3, and 4 weeks were subjected to enzymolysis for 8 h in a solution containing D-mannitol at 0.6 mol/L. Next, we determined the optimal osmotic pressure by exposing leaf material from 2-week-old etiolated seedlings to solutions containing D-mannitol at 0.4 mol/L, 0.5 mol/L, 0.6 mol/L, 0.7 mol/L and 0.8 mol/L. The optimal duration of enzymolysis was determined by subjecting leaf material from 2-week-old etiolated seedlings to enzymolysis for 6, 7, 8, 9, and 10 h in a solution containing 0.6 mol/L D-mannitol. This series of assays showed that the optimal conditions to isolate protoplasts were as follows: 2-week-old etiolated seedlings as the source material, and enzymatic hydrolysis in a solution containing 0.6 mol/L D-mannitol in the dark for 8 h at 28 ℃. The protoplasts obtained using this method were transformed with the plasmid LN-OsMYB103 by a polyethylene glycol-mediated method, and strong green fluorescence was detected by laser confocal microscopy. These results indicated that the protoplasts retained normal biological functions. In summary, we established an integrated transient expression system for protoplasts obtained from switchgrass leaves. This method will be very useful for functional genomics research on switchgrass.

Drip irrigation of arbuscular mycorrhizal fungal spores and their growth-promoting effects on alfalfa

JING Peng-Cheng, LV Yan-Ping, WANG Shu-Lin, CHEN Yi-Shi, LU Wei-Hua

2017, 26(9):  121-131.  DOI: 10.11686/cyxb2016453

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We drew an isoline map of soil moisture content, soil salt content, and spores of arbuscular mycorrhizal fungi (AMF) on alfalfa using Sufer software to analyze the AMF migration state before and after regular drip irrigation. Alfalfa was drip-irrigated at different rates with solutions containing AMF spores. The mycorrhizal infection rate, number of nodules, biomass, and sporulation performance were measured after 50 days of irrigation to evaluate the effects of supplying AMF by this method. The results showed that the number of AMF spores in aqueous solution decreased over time, the soil moisture content was low in upper soil layers and high in deeper soil layers before drip irrigation, and the soil conductivity distribution was uniform. The AMF spores were mainly concentrated in the 10-25 cm soil layer after drip irrigation. The drip water was mostly concentrated within 30 cm of the dripper, and the soil water in this region was higher after drip irrigation than before. Salts were also distributed by the dripper, and concentrated in soil at a distance of 30-45 cm from the dripper. The AMF spores were mainly concentrated within 0-25 cm distance of the dripper, and their abundance decreased with increasing distance from the dripper. Alfalfa growth was affected by drip irrigation of AMF fungal spores and the distance from the dripper. The aboveground biomass and height of alfalfa were significantly higher for plants close to the dripper than for plants more distant from the dripper (P<0.05). The aboveground and belowground biomass of alfalfa were higher for plants irrigated with Gi AMF spore solution than for those in the control (P<0.05). The underground biomass was significantly higher for alfalfa plants irrigated with Gm, Gi, and Ge AMF spore solutions than for those in the control (P<0.05). There was no significant difference in underground biomass of alfalfa between plants irrigated with Gv AMF spore solution and those in the control. The number of alfalfa branches was significantly higher for plants irrigated with Gi AMF spores than for plants in the control (P<0.05). The root nodule number, spore number, and infection rate of alfalfa were significantly higher for plants irrigated with Gi and Ge AMF spore solutions (P<0.05) than for those in the control. The distance from the dripper significantly affected underground biomass, plant height. and number of spores (P<0.05). The interaction between distance from the dripper and AMF strain did not have significant effects for most tested indices, except for infection rate, nodule number, and root length. These results showed that drip irrigation of a solution containing Gi AM fungal spores is beneficial for alfalfa.

Effects of interactions between a grass endophyte and an arbuscular mycorrhizal fungus on perennial ryegrass growth

LI Fang, LI Yan-Zhong, DUAN Ting-Yu

2017, 26(9):  132-140.  DOI: 10.11686/cyxb2016445

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The aim of this study was to determine the effects of interactions between an arbuscular mycorrhizal (AM) fungus and an endophyte on the growth of perennial ryegrass (Lolium perenne). Ryegrass plants were grown in pots in a greenhouse and inoculated with the AM fungus Claroideoglomus etunicatum, Rhizophagus intraradices, and a mixture of C. etunicatum and R. intraradices, and then plant height, root length, biomass, phosphorus content, soluble sugars content, soluble protein content, and photosynthetic indexes were monitored. The results showed that the average AM colonization by C. etunicatum, R. intraradices, and the mixture of both species was 44.04%, 34.13%, and 41.13%, respectively. The average AM colonization was 22.28% lower in endophyte-infected ryegrass than in endophyte-free ryegrass. Both the AM fungus and the endophyte increased the morphological, physiological, and biochemical indexes of perennial ryegrass. The total P content, total dry weight, photosynthetic rate, total soluble sugars content, and soluble protein content was 48.21%, 21.12%, 73.53%, 147.12%, and 24.27% higher, respectively, in the plants co-inoculated with C. etunicatum and grass endophyte than in uninoculated plants. Both fungi enhanced shoot growth and root growth, but in general, the AM fungus significantly increased shoot and root growth, while the endophyte mainly increased the shoot growth of perennial ryegrass.

Effect of seed coatings on foxtail millet seedling growth and incidence of downy mildew disease

ZHANG Da-Zhong, LIU Jia-Jia, QU Yang, LIANG Ji-Bao, ZHANG Xia, HAN Ya-Li, FENG Bai-Li

2017, 26(9):  141-147.  DOI: 10.11686/cyxb2016449

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Downy mildew disease is the most serious threat to the quality and yield of foxtail millet. The aim of this study was to determine the effects of seed coatings on the growth of foxtail millet seedlings and the incidence of downy mildew disease. Seeds of the foxtail millet cultivars Jingu 29 (susceptible) and Fenxuan 3 (resistant) were coated with two different formulae (formula 1, F1: Metalaxyl+Mancozeb+Imidacloprid+potassium phosphate monobasic; formula 2, F2: Tebuconazol+Imidacloprid+potassium phosphate monobasic) at three concentrations (0.1%, 0.2%, 0.3% of seed weight, respectively). Then, the seedlings were monitored to determine downy mildew incidence, agronomic characters, functional leaf area, and shoot dry matter accumulation and yield. Both formulas significantly reduced the incidence of downy mildew disease with a dose-dependent effect. The two formulae did not affect node number and ear diameter, but they increased stem diameter and 1000-grain weight with a dose-dependent effect. The plant height and spike length of seedlings were higher in the 0.1% formula treatments than in the control (no seed coating). The functional leaf area decreased as the formula concentration increased. The dry weights of the stem, leaf, sheath, and panicle decreased with increasing formula concentration. The yields of Jingu 29 in the 0.1% formula 1 and formula 2 treatments were 4471.7 kg/ha and 4420.6 kg/ha, respectively, significantly higher than that in the control (4284.8 kg/ha). Both formulae significantly reduced the incidence of downy mildew, and formula 2 at the 0.1% concentration resulted in the best quality and yield of foxtail millet.

Acute toxicity study of glyphosate and cyhalofop-butyl to Daphnia carinata

LI Jia, YUAN Ling

2017, 26(9):  148-155.  DOI: 10.11686/cyxb2016474

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Daphnia is a key organism in the food chains of plants, microbes, and animals in aquatic ecosystems. Glyphosate is widely applied to crop fields, orchards, green land, and water, and accounts for about 60% of registered herbicides in China. Cyhalofop-butyl is widely used to control Echinochloa crusgalli in paddy fields. The use of these two herbicides has increased markedly in recent years in China. Therefore, it is important to investigate the toxicity of glyphosate and cyhalofop-butyl to zooplankton to understand their effects on aquatic ecosystems. In this study, Daphnia carinata, a standard bio-monitor of water quality, was cultivated in dechlorinated tap water and fed with Scenedesmus obliquus at (20±0.5) ℃ under light at 1200 lx supplied by fluorescent lamps. Four-day-old D. carinata were incubated in solutions containing glyphosate or cyhalofop-butyl at different concentrations. The acute toxicity of these two herbicides to the movement, survival, and phototaxis of D. carinata was evaluated. Both herbicides were toxic to D. carinata. The semi-lethal concentration (LC₅₀) of glyphosate in 24 h, 48 h, and 96 h was 66.58, 29.60, and 12.33 mg/L, respectively, and that of cyhalofop-butyl was 63.15, 51.91, and 34.41 mg/L, respectively. These dosages represented only 0.15%-0.81% (glyphosate) and 17.21%-31.58% (cyhalofop-butyl) of those applied in the field. Both glyphosate and cyhalofop-butyl had significant adverse effects on the swimming ability and phototaxis index of D. carinata. The concentrations causing significant changes in the phototaxis index at 3 h were 4.59 mg/L for glyphosate and 14.20 mg/L for cyhalofop-butyl; these concentrations corresponded to 0.06% and 7.10% of the field dosage, respectively. These results showed that glyphosate and cyhalofop-butyl are very toxic to daphnia. Therefore, their effects on the aquatic food chain should not be ignored. Changes in the phototaxis of D. carinata in response to herbicides at low concentrations may serve as an index of herbicide bio-toxicity in fresh water.

Fermentation quality and microbial quantity during aerobic storage of corn silage

WANG Xu-Zhe, JIA Shu-An, ZHANG Fan-Fan, LU Wei-Hua, ZHANG Qian-Bing, MA Chun-Hui

2017, 26(9):  156-166.  DOI: 10.11686/cyxb2016450

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The objective of this study was to analyze the effect of density on the fermentation quality and microbial content of whole plant corn (Zea mays) silage, to provide a reference for selecting the appropriate density for silage in practice. The silage material was Xinsiyu 10, which was compacted to varying densities (350, 400, 500, 600, and 700 kg/m³) and then fermented for 50 days. The fermentation quality, microbial content, and aerobic stability of silage samples after 12, 24, 36, 60 and 108 h exposure to air were evaluated using an online multi-channel data logger temperature recorder. The results indicated that the pH value, lactic acid content, acetic acid content, NH₃-N content, and amounts of lactic acid bacteria, molds, yeasts, and aerobic bacteria significantly decreased during ensilage (P<0.05). Oxygen exposure time had a significant effect on the above indicators (P<0.01) during aerobic exposure. At 108 h after opening silos, the 600 kg/m³ treatment had the highest lactic acid bacteria content (up to 8.17 lg cfu/g FW) and the lowest pH value, NH₃-N content, fungi content (5.38 lg cfu/g FW) and yeasts content (7.72 lg cfu/g FW). The 600 kg/m³ treatment also showed the highest stability among the treatments (100 h in air; P<0.05). In summary, these results indicate that 600 kg/m³ is the best density for producing corn silage with high fermentation quality and aerobic stability.

Effects of homo- and hetero-fermentative lactic acid bacteria on the fermentation characteristics, nutritional quality, and aerobic stability of whole corn silage

MIAO Fang, ZHANG Fan-Fan, TANG Kai-Ting, JIA Shu-An, WANG Xu-Zhe, MA Chun-Hui

2017, 26(9):  167-175.  DOI: 10.11686/cyxb2016478

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The overall aim of our research was to improve the fermentation characteristics, nutritional quality, and aerobic stability of whole-corn silage. We investigated the effects of homo- and hetero-lactic acid bacteria on the fermentation characteristics, nutritional value, and microorganism content of whole-corn silage. Lactic acid bacteria were added to whole corn plants and sealed in a vacuum bag. The control (CK) had no added inoculant. The T group contained Lactobacillus plantarum+Pediococcus acidilactici at 1∶1, 1×10⁵ cfu/g; the Y group contained Lactobacillus buchneri at 4×10⁵ cfu/g; and the T+Y group contained all of these homo- and heterofermentative lactic acid bacteria. The following indexes were analyzed to evaluate fermentation: nutritional quality, microbial content on the 60th day of fermentation, microbial content, and CO₂ gas production on the 5th day after opening the bag. The treatments were ranked as follows: pH, T+Y>T>CK>Y (P=0.001); lactic acid content, T+Y>Y>T>CK (P=0.095); ammonium nitrogen content, T+Y>Y>T>CK (P=0.011); number of yeasts, T+Y>T>Y>CK (P=0.023); number of molds, T+Y>T>Y>CK (P=0.028); dry matter content, T+Y>T>Y>CK (P=0.020); water soluble carbohydrates content, CK>T+Y>Y>T (P=0.190); neutral detergent fiber content, Y>CK>T+Y>T (P=0.001); acid detergent fiber content, CK>T>Y>T+Y (P=0.730); crude ash content, T+Y>T>Y>CK (P=0.030). There was no significant difference among treatments in crude protein content, acid detergent lignin content, starch content, crude fat content, and the number of aerobic bacteria and lactic acid bacteria (P>0.05). On the 5th day after opening the bag, the treatments were ranked as follows: pH, T+Y>T>CK>Y (P=0.001); CO₂ production, CK>T>Y>T+Y (P=0.007); mold count, T+Y>Y>T>CK (P=0.001); aerobic stability, Y>T+Y>CK>T (P=0.021). On the 5th day after opening the bag, there was no significant difference among the treatments in the number of aerobic bacteria, lactic acid bacteria, and yeasts (P>0.05). The comprehensive values of the four treatments, as calculated from the 16 indexes by a membership function analysis, were as follows: Y (0.652)>T+Y (0.528)>CK (0.492)>T (0.441).

Records of alfalfa in local chronicles between the Ming and Qing dynasties

SUN Qi-Zhong, LIU Qian, LI Feng, TAO Ya

2017, 26(9):  176-188.  DOI: 10.11686/cyxb2017097

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Local chronicles provide valuable historical data. Some chronicles list alfalfa as an important product resource between the Ming and Qing dynasties. These records have great significance for tracking the development of alfalfa during this time. This research focused on local chronicles in east, northeast, and north China between the Ming and Qing dynasties. We used various text analyses to investigate and card alfalfa records in 101 local chronicles. The results showed that alfalfa was cultivated in east, north, and northwest China during the Ming and Qing dynasties, and was particularly common in north and northwest China, especially in Anhui, Shandong, Henan, Hebei, Shanxi, Shanxi, and Gansu Provinces. Some local chronicles recorded details of not only alfalfa cultivation, but also its ecology, biological characteristics, and utilization. First, alfalfa with its perennial roots was used to fertilize soil by cultivation for 3 or 4 years, then the alfalfa was turned over and another crop was planted. This increased the yield and success rate of crops grown on saline land. The local chronicles of Hebei Province noted that two alfalfa species (Medicago sativa and Medicago falcata) were cultivated there during the Qing Dynasty. The chronicles described the importance of alfalfa as both a forage crop for cattle and horses, and as a food for humans, especially during times of famine.

Advances in typical patterns to include grass species in orchards and mechanisms to regulate resources within the orchard-grass system in China

YANG Mei, WANG Ya-Ya, LU Jiao-Yun, LIU Min-Guo, DUAN Bing-Hong, YANG Hui-Min

2017, 26(9):  189-199.  DOI: 10.11686/cyxb2017140

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Including grass species in orchards is an advanced technology to manage soil, thereby promoting sustainable fruit production. It has been 40 years since this technology was introduced into China, and researchers have paid much attention to the changes in microclimate, soil features, and fruit production in orchard-grass systems. However, little attention has been paid to the patterns of orchard-grass systems and how they affect the distribution of resources. This paper summarizes some typical patterns of including grass species in Chinese orchards, and describes how they work under different conditions. The effects of including grasses in the orchard on soil water and fertility, light radiation, and pests and weeds are discussed. There are multiple patterns of orchard-grass systems, with different types and proportions of grass species that affect the moisture content and fertility within the system. Suitable patterns of orchard-grass systems may increase water infiltration into the soil, reduce water evaporation, and reduce soil erosion. They can also help to increase soil fertility and enhance the activity of beneficial soil microorganisms. These patterns can enhance the interception of light radiation and improve the light environment beneath the trees. Additionally, including grass species may help to enhance the resistance of the orchard-grass system to pests and weeds. These advantages have great potential to diversify the outcomes of orchards and to improve their quality. However, unsuitable combinations of orchard and grass species, and/or inappropriate sowing methods can lead to competition for water and nutrients in soils and worsen the deficit of those resources, leading to negative effects on production. The information summarized in this review will help to improve research on orchard-grass systems and the use of appropriate planting patterns in Chinese orchards.

Effects of altitude on plant productivity and species diversity in alpine meadows of northern Tibet

LI Wen-Han, Ganjurjav H, CAO Xu-Juan, YAN Yu-Long, LI Yu, LUO Wen-Rong, HU Guo-Zheng, DANJIU Luobu, HE Shi-Cheng, GAO Qing-Zhu

2017, 26(9):  200-207.  DOI: 10.11686/cyxb2016476

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Changes in the species diversity and productivity of grass communities along altitudinal gradients and the relationship between diversity and productivity are important issues in ecology, and can explain variations among functional groups. The aim of this study was to determine the variations in the species diversity and productivity, and the factors affecting them, in the alpine meadow ecosystem. Field surveys of alpine meadows were conducted at four different altitudes (around 4485, 4535, 4585, 4635 m) in northern Tibet. Plant biomass and species composition were determined, and diversity indexes were calculated from the data. The productivity increased then decreased with rising altitude, and the highest productivity was around 4535-4585 m. In terms of functional groups, sedges moved from a comparative advantage to an absolute advantage as the altitude increased, while forbs and grasses became less important at different rates. Legumes became more important and then less important as the altitude increased. The species richness, Simpson index, Shannon-Wiener index, and Pielou evenness index were significantly higher at middle altitudes than at higher and lower altitudes (P>0.05), leading to a hump-shaped curve in plots of species richness vs. altitude and diversity vs. altitude. There were positive correlations between biomass and the Shannon-Wiener index and between biomass and the Simpson index (P<0.05), but not between biomass and the Pielou evenness index or biomass and the importance of functional groups (P>0.05). These findings indicate that the productivity and diversity of alpine meadows in northern Tibet are strongly influenced by altitude, which is related to variations in many environmental factors. This information will be useful for developing strategies to manage and preserve this important ecosystem.

Effect of lanthanum on root growth of Paspalum notatum seedlings under aluminum stress

LUO Han-Fu, SONG Hua-Wei, LIU Tian-Zeng, ZHANG Ju-Ming

2017, 26(9):  208-213.  DOI: 10.11686/cyxb2016475

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Lanthanum (La) is one of the most vital and active rare earth elements. It can promote seed germination, increase crop output, and enhance plant resistance to environmental stresses. Paspalum notatum, a warm season turfgrass commonly used for conserving soil and water in Guangzhou, was selected to study the effect of La on root growth. Seven-day-old seedlings of P. notatum were grown in hydroponic conditions in an acid solution containing 0.9 μmol/L Al³⁺ with and without 0.3 μmol/L La³⁺. Root morphology, the root dry weight/fresh weight ratio, and root activity were evaluated after 2, 4, and 6 d of treatment. The addition of La³⁺ to the acidic Al³⁺ solution resulted in increased axial root length, root surface area, number of root tips, root volume, and root activity of P. notatum seedlings. These findings indicated that La can promote the root growth of P. notatum seedlings under Al³⁺ stress.

Effects of addition of lactic acid bacteria, glucose, and formic acid on the quality of Amaranthus hypochondriacus silage

LIU Yan-Fang, QIU Hao-Ri, YU Xiong, SUN Guo-Qing, MA Jian, ZHANG De-Long, SENBATI Heilimubuick

2017, 26(9):  214-220.  DOI: 10.11686/cyxb2017164

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The aim of this research was to optimize the method for making Amaranthus hypochondriacus silage. We tested the effects of adding lactic acid bacteria, glucose, and formic acid on the fermentation quality and nutritional composition of A. hypochondriacus silage. The five treatments were as follows: control (no additives), lactic acid bacteria group (lactic acid bacteria added at 0.25-0.33 g/kg), glucose group (glucose added at 30 g/kg), lactic acid bacteria+glucose group (added at the same levels as in individual treatments) and formic acid group (formic acid added at 5 g/kg). Silos containing each treatment were opened on days 1, 3, 9, 30, and 57, and the pH and the contents of lactic acid, ammonia nitrogen, total nitrogen, lactic acid, acetic acid, dry matter, crude protein, and neutral detergent fiber in the ensiling samples were determined. The results showed that the additions accelerated the fermentation process. The addition of glucose and lactic acid bacteria to A. hypochondriacus silage resulted in greater fermentation, more lactic acid, and lower pH values. These additions also significantly reduced the contents of acetic acid and neutral detergent fiber and the ammonia nitrogen∶total nitrogen ratio (P<0.05), and significantly increased the contents of dry matter and crude protein (P<0.05). Adding formic acid markedly decreased the acetic acid content (P<0.05), but did not affect the dry matter content (P>0.05). We concluded that the nutritional composition of A. hypochondriacus can be preserved by making silage. Our results showed that addition of lactic acid bacteria, glucose, and formic acid can improve the quality of A. hypochondriacus silage, and that the best results were obtained by adding lactic acid bacteria and glucose.

Physiological and biochemical indexes of Hu sheep in the alpine region of Northwest China

XIE Yun-Long, LIANG Xin-Liang, YANG Yong-Gui, LI Fa-Di, YUE Xiang-Peng

2017, 26(9):  221-227.  DOI: 10.11686/cyxb2016452

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The aim of this study was to explore the adaptability of Hu sheep in the alpine region of northwest China. Samples from 12 Hu sheep (six males and six females) in the Tianzhu area were collected at 3, 6, 12, and 24 months of age to analyze the effects of sex, age, and their interactions on several physiological and biochemical indexes. The results showed that sex had a significant or extremely significant effect on the mean corpuscular hemoglobin concentration (P<0.05) and glutamic-oxalacetic transaminase activity (P<0.01). Age significantly affected respiration, the number of white and red blood cells, platelet count, mean platelet volume, alkaline phosphatase activity, and total cholesterol (P<0.05). Age had highly significant effects on body temperature, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin concentration, and the activities of glutamic-pyruvic transaminase, glutamic-oxalacetic transaminase, and lactic dehydrogenase (P<0.01). There was a significant interaction between sex and age for mean corpuscular hemoglobin concentration and blood glucose concentration (P<0.05), and a highly significant interaction between sex and age for lactic dehydrogenase activity (P<0.01). The physiological, blood, and biochemical indexes of the test Hu sheep differed from those of Hu sheep in their original domestic region and in low-altitude regions. These findings indicate that Hu sheep are highly adaptable to alpine regions and provide a scientific basis for producing Hu sheep in the Northwest alpine region.