Table of Content

20 September 2015, Volume 24 Issue 9

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Orginal Article

The wild Gentianopsis paludosa resources of Tanchang County, Gansu

ZHOU Chuan-Meng, CHEN Yuan, GUO Feng-Xia, YANG Hui-Zhen, ZHANG Xue-Jun

2015, 24(9):  1-9.  DOI: 10.11686/cyxb2014427

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The wild Gentianopsis paludosa resources in Tanchang County were comprehensive surveyed in order to further explore the distribution and abundance of this species. Survey and sampling techniques followed those published in the Nationwide Chinese Medicine Survey technical notes. 1060 small sample plots and 265 permanent sample plots at 53 sample sites representing seven ecological zones were collected. Wild G. paludosa was found in eleven permanent sample plots and twenty six small sample plots representing three ecological zones and three sampling sites. Plants were distributed over an area of 1.27 ka containing 3474.36 kg of medicinal material, 2605.77 kg of economically valuable material and 912.02 kg of permitted annual harvest. The Shannon-Weaver diversity index of quantitative characteristics ranged from 2.11 to 2.86 resulting in 23.08%-61.83% of the variation coefficient for ten agronomic traits; lateral root numbers had the greatest and leaf numbers the least influence. Increasing altitude (2234 to 2699 m) resulted in greater flower numbers, stem diameter, plant height, fresh weight and dry weight per plant. It is concluded that wild G. paludosa has high genetic diversity but is not widely distributed suggesting that measures should be taken to protect this valuable resource.

Investigation of soil nutrient and plant community dynamics after vegetation planting on a rocky slope

DUAN Yu-Ting, WANG Zhi-Tai, XU Xiao-Ming

2015, 24(9):  10-18.  DOI: 10.11686/cyxb2014435

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Using conventional plant community survey methods three rocky slopes were constructed to simulate physicochemical properties of soil and the artificial vegetation restoration of the Guiyang City beltway south loop in an indoor experiment. It was found that: 1) The content of alkali hydrolyzable nitrogen (AN), available potassium (AK), available phosphorus (AP), organic matter (OM) showed an upward trend, by 2013, the average content of AN reached a lower level, the average content of AK maintained high level, the average content of AP reached a higher level, the average content of OM at the middle level. 2) With longer recovery time, slope total species number has increased substantially and the fluctuation of gradual, they have seasonal variation, Species composition and proportion and dominant changed, to change to the local natural vegetation. 3) In 2009 July-2012 year in June, plant herb layer coverage and high risen, by 2013 they have reduced, a certain number of shrub planting in the slope, and the slope restoration effect is good. 4) There are 18 pairs of significant correlation indicator between slope community total species number, plant height and coverage, the soil available nutrients N, P, K and OM, but in the relationship between soil nutrient and plant community characteristics, only AN and AP and total plant species, shrub layer plant height have significantly correlation.

Use of the ‘3414’ fertilization design to determine optimal fertilization rates for Rheum tanguticum

QI Hao, CHEN Yuan, GUO Feng-Xia, CAO Shi, GUO Zhi-Jun, YANG Yu-Feng

2015, 24(9):  19-29.  DOI: 10.11686/cyxb2014409

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To determine the optimal fertilization program for Rheum tanguticum, we evaluated the effects of different amounts of nitrogen, phosphorus, and potassium fertilizers on the yield and economic benefits of the plant, based on the ‘3414’ fertilization design. Based on plant yields and economic benefits, the success of the fertilization treatments was ranked as follows: fertilized>non-fertilized, and NPK>P>N>K. The effects of pairwise interactions on yield and economic benefits, from strongest to weakest, were ranked as follows: NP> PK>NK and PK>NP>NK, respectively. In all treatments except for the excess N treatment, total anthraquinone, total ash, and water content in the R. tanguticum roots met the standard of the Pharmacopoeia of the People’s Republic of China. The data for plant yield and economic benefits under the different fertilizer treatments fitted well with ternary quadratic, binary quadratic, and simple quadratic equations. Therefore, these equations represented the relationships between fertilizer quantity and yield/economic benefits. Taken together, the results of this study show that the fertilization program producing the highest yield (12384.3 kg/ha) under the local experimental conditions was N 74.06 kg/ha, P 55.07 kg/ha, and K 36.56 kg/ha. The fertilization program resulting in the best economic benefits was N 73.33 kg/ha, P 54.58 kg/ha, and K 36.37 kg/ha, resulting in 12012.6 kg/ha of yield and 196126.0 yuan/ha of economic benefit.

Evaluation of the adaptability of imported red clover germplasm in central Gansu

MENG Li-Juan, ZHAO Gui-Qin

2015, 24(9):  30-42.  DOI: 10.11686/cyxb2014406

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To enrich the red clover (Trifolium pratense) germplasm resource in China and provide superior materials for breeding, we conducted a comprehensive study on the performance of imported red clover germplasm in central Gansu. In total, 31 red clover accessions were evaluated, and 14 traits including morphological, agronomy, and productivity traits were measured. There were significant differences among accessions in growth period, plant height, branch number, leaf area, stem:leaf ratio, regrowth speed, and hay yield. The source of the materials also affected morphological characteristics and productivity. A few accessions showed superior performance of a single trait and could be used directly to increase production. A principal component analysis of the 14 traits indicated that five traits with a 78.94% cumulative contribution rate could be used for comprehensive evaluation of the red clover germplasm. In terms of performance, ZXY2008P-4996 from Russia was the best, followed by Scarlett and Star fire II from the United States. The accession ZXY2008P-5419 had the lowest score and showed the poorest adaptability. The 31 red clover accessions were grouped into four clusters based on principal component indexes.

Response of dominant population niche breadths and niche overlaps to various disturbance factors in typical steppe fenced grassland of China’s Loess Plateau region

JING Guang-Hua, CHENG Ji-Min, SU Ji-Shuai, WEI Lin, SHI Xiao-Xiao, JIN Jing-Wei

2015, 24(9):  43-52.  DOI: 10.11686/cyxb2014410

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The Levins niche breadth and Pianka niche overlap indices were used to assess the response of plant population niches to grazing, burning and fertilization in permanently fenced grassland of the Loess Plateau region. Species with highest niche width in fenced (control group), grazed, burned and fertilized grasslands were Carex rigesaens, Ixeridium chinense, Artemisia sacrorum, and Stipa bungeana, respectively. The niche breadth of S. bungeana in different disturbance situations (ranked highest to lowest) was: fertilization (1.362)>burning (1.244)>fencing (1.088)>grazing (1.026). The richness index for the same four treatments ranked: grazing>fertilization>burning>fencing. The average values of niche overlap of all the species and dominant species ranked: fertilization>fencing>burning>grazing. The pairs of species with the highest niche overlap in fertilized, fenced, burned, and grazed grasslands were, respectively, S. bungeana and C. rigesaens, Stipa grandis and C. rigesaens, S. grandis and C. rigesaens, and I. chinense and Poa sphondylodes, respectively. These findings indicate that human disturbance can increase the species richness and improve plant population niche width to facilitate maximum resource use in permanently fenced grassland.

Nutrient components and rumen degradability dynamics of different Bothriochloa ischaemum populations in Shanxi

JI Qi-Wu, HAN Ru-Dan, DONG Kuan-Hu, MA Xue-Hao

2015, 24(9):  53-62.  DOI: 10.11686/cyxb2014407

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In order to investigate nutrient contents, and dry matter (DM) and crude protein (CP) degradation properties of different Bothriochloa ischaemum populations at heading stage in Shanxi, fifteen Dorper×local breed F₁ male mutton hybrid sheep fitted with permanent rumen fistulas were selected to estimate degradability of DM and CP in the rumen. Findings included: the B. ischaemum populations differed greatly in nutrient content at the heading stage. A population from Taigu had the highest CP content and the lowest neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents, followed by populations from Yuanping and Qinyuan. The rumen degradability for DM and CP of different B. ischaemum populations also differed. The DM degradability of Taigu and Yuanping populations was significantly higher than that of the Xiangfen population at 72 hours (P<0.05). The DM effective degradability of the Taigu population was highest, with a value of 46.39%, followed by Yuanping and Qinyuan populations. Similarly, the CP degradability of the Taigu and Yuanping populations was significantly higher than the Ruicheng population which had the lowest CP degradability at 72 hours (P<0.05). The CP effective degradability of the Taigu population was highest, followed by the Fangshan and Yanggao populations, while there was no significant difference among three other populations (P>0.05). In conclusion, the degradability of DM and CP of the Taigu B. ischaemum population, as tested in rumen fistulated sheep, was the highest, among the tested populations.

The nutritional value of reed canary grass at different growth stages, as determined by in vitro gas production and Cornell net carbohydrate and protein system methods

CHEN Guang-Ji, SONG Shan-Dan, GUO Chun-Hua, BAI Xue, ZHANG Zheng-Fan, ZHANG Yan, YOU Ming-Hong, BAI Shi-Qie

2015, 24(9):  63-72.  DOI: 10.11686/cyxb2014399

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The objective of this study was to evaluate the nutritional value of reed canary grass at different growth stages using in vitro gas production and the Cornell net carbohydrate and protein system (CNCPS) methods, and to compare results from these two methods. The in vitro gas production method was used to determine gas production, fermentation parameters (a, b, c), dry matter (DM) digestibility, and the degradation rates of neutral detergent fiber (NDF) and acid detergent fiber (ADF) at heading, flowering, seed filling and milk ripe growth stages of reed canary grass. CNCPS components were also determined for comparison of the two methods. The cumulative total gas production and the a value (122.68 and 4.46 mL) at the flowering stage were significantly higher than those at other stages, and they tended to decrease from the heading to milk ripe stages. Similarly, DM digestibility and degradation rates of NDF and ADF at the heading and flowering stages were significantly higher than those at the seed filling and milk ripe stages. As reed canary grass matured, the crude protein (CP) and soluble protein (SOLP) contents tended to decrease, and were significantly lower at the seed filling and milk ripe stages than at the heading and flowering stages NDF, ADF and acid detergent lignin (ADL) components increased while the NDF insoluble protein (NDFIP) and ADF insoluble protein (ADFIP) generally decreased. The carbohydrate (CHO) content at the filling and milk ripe stages was significantly higher than that at the heading and flowering stages, while sugar content in CHO (CA) and non-structural carbohydrate (CNSC) contents were higher at the heading and flowering stages. The unavailable fiber (CC) content was also higher at the milk ripe stage. The protein component, the non-protein nitrogen (PA), and the bound protein (PC) showed similar trends to those of CA and CC. The levels of CNSC, CA, starch+non-starch polysaccharide fractions (CB₁), CB₂, PA, and low degradability protein (PB₃) levels of reed canary grass were significantly or very significantly correlated with the gas production at different time points. Therefore, the nutritional value of reed canary grass was the highest at the flowering stage, followed by the heading stage, filling stage and milk ripe stage in that order. The results from the two evaluation methods, in vitro gas production and the CNCPS method, were closely correlated, suggesting that it was feasible to estimate CNCPS components of forages using the in vitro gas production method.

Preliminary studies on transgenic chicory using the sulphur-amino acid gene, γ-zein, mediated by Agrobacterium tumefacien

ZHANG Yu, BAI Shi-Qie, LI Cong

2015, 24(9):  73-79.  DOI: 10.11686/cyxb2014307

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Sulfur-containing amino acids have important physiological functions related to animal nutrition and immunity. To improve the sulfur-amino acid content of chicory, leaves of chicory were transformed with the Sulphur-amino acid gene γ-zein, an important prolamin storage protein from Zea mays and a green fluorescent protein (GFP) gene using Agrobacterium mediated transfusion. After co-culture, selective differentiation and regeneration, hygromycin resistant plants were obtained. Resistant plants were detected using PCR, PCR-southern, dot blot hybridization and RT-PCR. The results demonstrated that the γ-zein genes had been integrated into the genome of chicory and expressed on a nucleic acid level in the transgenic plants.

Arbuscular mycorrhizal fungi diversity in saline-alkaline Leymus chinensis grasslands on the Songnen Plain

ZHANG Yi-Fei, BI Qi, YANG Yun-Fei, ZHANG Zhong-Hui, HU Chang-Qun, YANG Yu-Chun, ZHAO Shan-Shan, WANG Xiang-Gang

2015, 24(9):  80-88.  DOI: 10.11686/cyxb2014426

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Arbuscular mycorrhizal fungi (AMF) are beneficial microorganisms, distributed widely in many different soil types. The investigation of species diversity of AMF in extreme environments is a rapidly developing area of research because of the potential benefits for ecosystem restoration. Screening for effective arbuscular mycorrhizal fungi species is regarded as an important approach to successful revegetation. The identification of arbuscular mycorrhizal species and their distribution were investigated in 15 natural saline-alkaline Leymus chinensis grasslands in 12 regions of the western Songnen Plain. The occurrence frequency, species richness and spore density were also investigated. The ability of AMF to infect roots of L. chinensis, including colonization rate and infection intensity, and the effect of soil pH were measured. In total, 11 species from 4 different families were identified; 72.4% of species belonged to Glomus. One species, G. mossea, was found at all sites. High soil pH strongly decreased AMF species richness in natural saline-alkaline communities of L. chinensis, but did not affect spore density. Disturbance of soil through erosion may be an important factor influencing spore density in soil because AMF spores were seldom detected in bare soil where the surface had been significantly disturbed. Root colonization rate was positively correlated with infection intensity. The infection of L. chinensis roots was increased with increasing AMF species richness, depressed by increasing soil pH. Our research indicated that there was an abundance of AMF species in saline-alkaline grassland able to infect roots of L. chinensis, and suggested approaches for screening saline-alkaline tolerant AMF species with the potential to help restore the degraded grassland ecosystem on the Songnen Plain.

Characteristic of asexual endophytes isolated from Elymus species in northwest China

SONG Hui, NAN Zhi-Biao, TIAN Pei

2015, 24(9):  89-95.  DOI: 10.11686/cyxb2014411

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Forage grasses (Poaceae) often harbour endophytes belonging to the Neotyphodium and Epichloë (Clavicipitaceae, Ascomycota) genera. Neotyphodium endophytes, the asexual state of Epichloë species, helps to protect cool-season grasses against biotic and abiotic stresses including drought, disease, herbivory and parasitism and enhance aboveground and belowground vegetative and reproductive growth. There is little information on colonial diversity of asexual endophytes isolated from Elymus species in northwest Chinese. In the present study, different geographic populations of Elymus species were tested using the aniline blue screening method; 15 endophyte strains were isolated from endophyte positive plants. The average growth rate (on potato dextrose agar) of the isolated strains was 0.41-0.85 mm/day and was correlated with altitude. Endophyte strains isolated from regions below an altitude of 3000 m grew faster than strains isolated from regions above 3000 m. The colonial morphology of endophyte strains isolated from regions above 3000 m was similar whereas the colonial morphology of endophyte strains isolated from lower altitudes differed. In addition, the phylogenetic trees showed that endophytes collected above 3000 m were clustered whereas endophyte strains from lower altitudes demonstrated a star-like topology. The results will provide a theoretical basis for the identification of endophyte from northwest Chinese Elymus species.

Isolation, identification, and biocontrol effects of Bacillus spp. from the rhizosphere of alfalfa

LIU Sha-Sha, CHENG Yuan-Yuan, ZHANG Dan, WANG Xiao-Dan, LIU Jia-Li, GUO Chang-Hong

2015, 24(9):  96-103.  DOI: 10.11686/cyxb2015026

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The aims of this study were to identify two Bacillus spp., CYY-6 and CYY-42, isolated from the rhizosphere of alfalfa, and to evaluate their ability to inhibit Fusarium oxysporum, the causal pathogen of alfalfa root rot. Based on physiological, biochemical, morphological, and 16S rDNA sequencing analyses, strain CYY-6 was identified as Bacillus licheniformis and CYY-42 as Brevibacillus brevis. Both strains were able to synthesize siderophores, although at different levels. In a dual culture assay, both strains inhibited the growth of F. oxysporum. Based on the inhibition zones, the inhibitory rates of CYY-6 and CYY-42 against F. oxysporum were 49.3% and 56.3%, respectively. The fermentation broth of each strain resulted in deformed growth of the mycelia and spores of F. oxysporum. The mycelia were twisted, broken, or fragmented, and the number of spores was significantly decreased. Strains CYY-6 and CYY-42 showed 57.55% and 64.03% inhibition of alfalfa root rot in pot experiments, indicating that both strains have potential applications in controlling alfalfa root rot.

Optimizing the culture conditions and determining the stability of antibiotic secretion by Polygonum viviparum of the endophytic bacteria Bacillus mojavensis

YANG Cheng-De, CHANG Tao, XUE Li, FENG Zhong-Hong, YAO Yu-Ling, LI Ting, CHEN Xiu-Rong

2015, 24(9):  104-112.  DOI: 10.11686/cyxb2014086

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One strain of Bacillus mojavensis (ZA1) is known to have a strong antibacterial effect against the pathogen of potato gangrene (Phoma foveata). In this study, P. foveata was isolated as a fungal pathogen and the method of petri dish confrontation was used to determine culture conditions for optimizing and stabilizing production of the antibiotic secreted by ZA1. The results showed that the optimum culture medium for ZA1 consisted of 200 g potato, 10 g peptone, 20 g sucrose and 1000 mL distilled water. The optimum fermentation temperature of ZA1 was 17.8℃.The optimum pH value of ZA1’s culture medium was 6.9. The optimum 150 mL triangle bottle volume of ZA1 was 20 mL. The optimum culture mode of ZA1 was shaking cultivation in the dark for 96 hours. Results showed that the EC₅₀=0.1228 μL/mL against P. foveata after optimization was 37 times higher than the EC₅₀=4.5888 μL/mL against P. foveata before optimization. Crude extracting of bacteriostatic from ZA1 showed that the characteristics of high temperature resistance and relative activity could reach 76.62% after it was treated at 90℃ for 2 hours. Relative activity was stable and could not be destroyed under UV irradiation for 30 minutes. The bacteriostatic extract of ZA1 had good acid and alkali resistance. When it was treated by pH=3 and pH=11, the relative activity was 92.87% and 85.11% respectively. It was not sensitive to protease and heavy metal ions such as Ag⁺, Cu²⁺, Zn²⁺ and Fe³⁺. Relative activity remained at 86.93% after Ag⁺ treatment.

A study of outbreak occurrence and economic threshold of downy mildew on Astragalus membranaceus

CHEN Tai-Xiang, YANG Xiao-Li, CHEN Xiu-Rong, Li Chun-Jie, WANG Han-Qi, WANG Yan

2015, 24(9):  113-120.  DOI: 10.11686/cyxb2015066

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To determine outbreak occurrence, economic infection level and economic threshold of downy mildew (Peronospora astragalina) on Astragalus membranaceus in Gansu Province, the disease dynamics and the correlation between disease and weather conditions were analysed based on data from fixed on-site field investigation and systematic field surveys. A curve fitting technique was used to define the relationship between disease index and yield loss for A. membranaceus. Fungicides to control the disease were tested. It was found that the peak period for downy mildew occurrence was from early August to mid-September, the disease risk index was low after mid-September. Statistical analysis revealed that the disease risk index increased gradually with the increasing mean night relative humidity and disease cardinality. The logarithmic regression model (y=33.81 ln x-97.15) adequately described the relationship between disease index (x) and yield loss (y) of A. membranaceus. The economic injury levels for downy mildew on A. membranaceus treated with 5% Pyraclostrobin·55% Metiram diluted 800 times were 5.65%, and the economic threshold was about 17.73. Sensitivity testing for fungicides showed that 22.5% Famoxadone·30% Cymoxanil diluted 1500 times, 5% Pyraclostrobin·55% Metiram diluted 1000 times, 8% Cymoxanil·64% Mancozeb diluted 400 times, 75% Chlorothalonil diluted 350 times and 65% Zineb diluted 500 times could be used in rotation to control powdery mildew on A. membranaceus.

Responses of soil microorganisms to Artemisia annua leaf litter or artemisinin

LI Qian, YUAN Ling, YANG Shui-Ping, HUANG Jian-Guo

2015, 24(9):  121-129.  DOI: 10.11686/cyxb2014425

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Artemisia annua releases many kinds of allelochemicals into soils via dead plant residues, either by rain leaching or root exudation. Dead leaves of A. annua contribute more than 80% of the total artemisinin that enters soils during the growth period of A. annua. Allelochemicals released by the dead leaves reduce the growth and yields of succeeding and adjacent crops. Soil microbes play roles in nutrient transformation, organic matter recycling, toxicant decomposition, and hormone efflux, and thus, are important for plant growth and development. However, little is known about the effects of these allelochemicals on soil microorganisms. In these experiments, artemisinin and A. annua leaf litter were each added to soil and changes in microbial biomass and community structure were evaluated. The growth and reproduction of culturable microorganisms in soils showed wide variations in response to A. annua leaf litter or artemisinin. For example, the number of fungi increased but the numbers of actinomycetes, azotobacteria, nitrobacteria, and nitrite bacteria significantly decreased in soils containing A. annua leaf litter or artemisinin. The results suggested that both leaf litter or artemisinin inhibited organic matter mineralization, nitrogen bio-fixation, mobilization of phosphorus and potassium, and nitrification. The soil microbial quotient decreased, while the metabolic quotient increased, after A. annua and artemisinin were added to soils. This result indicated that artemisinin and other allelochemicals in the leaf litter interfered with the metabolism of soil microorganisms. The types and total contents of signature phospholipid fatty acids of microbes such as actinomycetes and protozoa decreased in soils containing leaf litter or artemisinin. The diversity and evenness indices of the microbial community also decreased, suggesting that the soil microbial ecosystem deteriorated as the densities of various microbial groups decreased. Therefore, artemisinin and allelopathic chemicals released from A. annua leaf litter affect the microbial community structure in soils, and may pose a risk to soil ecosystems in the areas where A. annua is widely cultivated. Further research is required to clarify the mechanisms by which allelopathic chemicals from A. annua change the structure of microbial communities in soil.

Nitrogen fertilizer effects on a 15 year old mixed species alpine pasture after two years

CAO Wen-Xia, LIU Hao-Dong, LI Wen, XU Chang-Lin, LI Xiao-Long, SHI Shang-Li

2015, 24(9):  130-137.  DOI: 10.11686/cyxb2015007

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Five different gramineous mixed pastures planted in 1999 were studied, and pasture productivity and plant community characteristics were recorded during two consecutive years of N fertilization at 75 kg N/ha (N₁), 150 kg N/ha (N₂), 225 kg N/ha (N₃), or 0 kg N/ha (CK). N fertilization enhanced the pasture productivity and height of these alpine pastures, but reduced plant species richness and diversity to some extent. The optimal fertilization rate for these 15 year old pastures was 150 kg N/ha per year, as this application rate improved pasture productivity and maintained the dominance of gramineous species in the plant communities. The nitrogen response differed between years and pasture with a large proportion of Elymus nutans was more responsive to N fertilizer than other pasture types. This experiment also demonstrated that single N fertilizer applications may enhance community stability or productivity of these alpine, perennial, mixed cropping cultivated grasslands.

Performance of Hangmu No.1 alfalfa in the Lanzhou region

YANG Hong-Shan, CHANG Gen-Zhu, ZHOU Xue-Hui

2015, 24(9):  138-145.  DOI: 10.11686/cyxb2015012

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Outer space mutation breeding has become an important characteristic of mutation breeding in china. The first variety of alfalfa bred by space mutation in China is ‘Hangmu No.1’.The characteristic of Hangmu No.1 alfalfa are high multifoliate rate, hay yield and nutrient content. To test the productive performance of Hangmu No.1, comparative testing was conducted in Lanzhou. The results indicates that Hangmu No.1 had significantly increased leaf mass, 5.72% higher than controls; Hay yield was 14237.5 kg/ha, 13.26% higher than the control varieties; crude protein content from the first and second harvest (anthesis stage) were 20.08% and 18.42% respectively, 2.97% and 5.79% higher than control varieties. Essential amino acids and trace element contents were also significantly higher than control varieties. Correlation analysis between multifoliate rate and others agronomic traits revealed that multifoliate rate was significantly positively correlated with hay yield, crude protein content, and amino acid content. This study indicates that the multifoliate trait can improve yield and nutritional value of alfalfa hay.

Physiological and biochemical responses of Medicago sativa seed to cobalt stress

ZHANG Hu, KOU Jiang-Tao, SHI Shang-Li

2015, 24(9):  146-153.  DOI: 10.11686/cyxb2015148

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The aim of this study was to investigate the mechanism of cobalt (Co) stress damage on Medicago sativa as experiment materials, The effects of different concentrations (0, 0.25, 0.50, 1.00, 2.50, 5.00 mmol/L CoCl₂) of Co on M. sativa (cv. Gannong No.3) seed germination and seedling physiological and biochemical characteristics were assessed. The results indicate that Co stress significantly inhibited seed germination and seedling growth. Seed germination potential, germination rate, germination index, vigor index, seedling sprout length, radicle length, root activity and dry weight were significantly reduced with increasing cobalt concentration. The inhibitory effects of Co stress on germination potential was higher than that of cobalt stress on germination rate, and the inhibitory effects of Co stress on radical growth was higher than that on the plumule. Co significantly reduced the soluble protein content, soluble sugar content, proteolytic enzyme activity, superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and catalase (CAT) in seedling leaves. However free proline content increased dramatically at lower Co concentrations but declined at higher concentrations. At higher Co concentrations, O2·- (superoxide anion radical), OH^· (hydroxyl radical), H₂O₂ and malondialdehyde increased significantly. This illustrates that under high Co stress, the seedling antioxidant system activity and active oxygen scavenging ability of M. sativa decreased, inhibiting M. sativa seed germination and seedling growth.

Change in starch grains and flower bud differentiation of Lilium pumilum bulbs during breaking of dormancy under refrigerated conditions

LIU Fang, TIAN Zhong-Ping, CAI Ying-Jie, ZHANG Yu, ZHOU Yun-Wei

2015, 24(9):  154-162.  DOI: 10.11686/cyxb2014428

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Changes in starch grains and flower bud differentiation of lily (Lilium pumilum) were studied during the breaking of dormancy at 5℃. Observations of paraffin sections under a microscope revealed that the height of the growth cone and the width of apical buds increased gradually during cold storage. The flower bud differentiation process in lily could be divided into four stages: the floral primordium differentiation stage from 0 to 48 days, the outer perianth primordium differentiation stage at 60 days, the inner perianth primordium differentiation stage at 72 days, and the stamen and pistil primordium differentiation stage at 84 days. The number of starch grains in apical bud cells gradually decreased as the duration of the cold temperature treatment extended. There were almost no mitotic cells in the plant tissues from 0 to 24 days of cold storage. The number of mitotic cells increased gradually after 36 days in cold storage, reaching 2.6 at 84 days of cold storage.

Effects of lead stress on growth, physiology, and lead ion accumulation and transportation in gramineous forages

LI Hui-Fang, WANG Yu, YUAN Qing-Hua, ZHAO Gui-Qin

2015, 24(9):  163-172.  DOI: 10.11686/cyxb2014303

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Fourteen gramineous forages were stressed by different lead treatments (0, 10, 50, 100, 200, 300 mg/kg) at the seedling stage in pots. By measurement of plant height, tiller number, shoot and root biomass, antioxidant enzyme activities and shoot and root lead ion content, the effects of lead stress on growth, physiology, accumulation and transportation were analyzed. At low levels of lead exposure, plant height, tiller number and shoot biomass were generally increased, then reduced gradually with increasing lead exposure. Agropyron elongatum G₅ from Turkey was found to have a high lead tolerance. With increasing lead exposure, lead ion content in roots and shoots increased gradually, while the bio-concentration factor and transfer factor decreased gradually except for Elymus dahuricus G₇ and G₈. The content of lead ions in roots was significantly higher than that in shoots, from which we concluded that the root was the main organ by which Poaceous forages accumulate lead ions. The content of lead ions in shoots of E. dahuricus G₇ and G₈ were higher than in other germplasm, indicating a high capacity for lead accumulation and transportation. From physiological analysis of seven evaluated varieties, it was found that with increased lead exposure, proline content increased gradually, and catalase (CAT) activity decreased gradually, while peroxidase (POD) and superoxide dismutase (SOD) were elevated at low levels of exposure, but decreased at higher levels of exposure.

Effect of exogenous abscisic acid on the cold resistance of Brassica rapa cv. Longyou (winter rape) 8 cultivated at different foliar in northern China

LIU Hai-Qing, WU Jun-Yan, SUN Wan-Cang, LIU Zi-Gang, QIAN Wu, YANG Jian-Sheng, MA Li, FANG Yan, LI Xue-Cai

2015, 24(9):  173-180.  DOI: 10.11686/cyxb2014403

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The aim of this study was to determine the effects of exogenous abscisic acid (ABA) on the cold resistance of Brassica rapa (winter rape, cultivar Longyou 8) under low temperature stress. Leaves of Longyou 8 were sprayed with 10 mg/L ABA when the plants were at the three-, five-, six-, and seven-leaf stages before winter. Plants at the same stages were sprayed with distilled water as the control. The overwintering rate, yield and physiological and biochemical indexes of Longyou 8 were determined after a cold treatment (-5℃). The plants sprayed with ABA showed significantly increased overwintering rates and yields, higher activities of antioxidant enzymes, and increased contents of physiological and biochemical substances that function as osmotic regulators. The effect was extremely significant after low temperature stress, when the overwintering rate and yield of ABA-treated plants were 14.3% and 8.0% higher than their respective values in the control plants. The activities of superoxide dismutase, peroxidase, and catalase were 39.8%, 20.8%, 31.0% higher, respectively, in ABA-treated plants than in control plants after the low temperature treatment. The contents of soluble protein, soluble saccharides, and free proline were 104.5%, 120.1%, and 77.7% higher, respectively, in the ABA-treated plants than in control plants after the low temperature treatment. The best stage for ABA application was the six-leaf stage. Application of ABA also increased root activity and decreased the contents of malondialdehyde, a marker of lipid peroxidation. Together, these results show that spraying with ABA can improve the cold resistance of winter rape in northern China.

Effects of exogenous glycine betaine on the physiological characteristics of Zoysia japonica under low-temperature stress

LIANG Xiao-Hong, AN Meng-Ying, SONG Zheng, XU Guang-Chen, PUYANG Xue-Hua

2015, 24(9):  181-188.  DOI: 10.11686/cyxb2014431

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Glycine betaine (GB) is an important compatible solute that is associated with stress tolerance in plants under low-temperature stress. To investigate the effect of exogenous GB on the physiological indexes of Zoysia japonica under low-temperature stress, GB at 0, 50, 100, and 150 mmol/L was applied as a foliar spray to ‘Qingdao’, a Z. japonica cultivar, before transferring the plants to growth chambers. The plants were grown under average temperatures of 8℃/2℃ (day/night) for 28 days in the low-temperature treatment, and under average temperatures of 28℃/24℃ (day/night) in the control. Exogenous GB alleviated the loss of turf quality and chlorophyll content, and reduced the increase in electrolyte leakage and malondialdehyde content in Z. japonica under low-temperature stress. Exogenous GB increased the activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase, leading to lower H₂O₂ and O2·- contents. Also, exogenous GB enhanced the osmotic adjustment capacity of the plants by increasing the concentrations of proline and soluble protein. These results indicated that exogenous GB enhanced the resistance of Z. japonica to low-temperature stress, and 100 mmol/L exogenous GB was the most effective concentration.

A review of herbage storage in pastoral areas of China

JIA Yu-Shan, DU Shuai, WANG Zhi-Jun, YOU Si-Han, Ge-Gen-Tu

2015, 24(9):  189-196.  DOI: 10.11686/cyxb2015177

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With the steadily increasing demand for animal products and the associated development of pastoral animal husbandry, the options for herbage storage in pastoral areas of China have been receiving greater attention. There are logistical problems of matching herbage supply to animal demand in Chinese pastoral farming, arising from both inter-annual and seasonal variation in herbage production. Winter snow, summer drought and extreme weather events or other natural disasters are among the factors responsible. The variability in feed supply seriously restricts the development of animal husbandry enterprises and herbage storage is one available solution. In the longer term, the establishment of suitable mechanisms for herbage storage is a fundamental necessity for ongoing development of China’s pastoral agriculture, and is also a fundamental requirement for success of the “shopping basket program”. This paper reviews the current situation with respect to herbage storage in animal production systems in China. Strategies to resolve animal husbandry issues caused by temporal imbalances between pastoral forage production and animal demand, are discussed.

Plant traits and soil properties in pasture mini-patches in an alpine meadow

SHI Ming-Ming, ZHANG Yong-Chao, ZHANG Dian-Ye, REN Yun-Tao, ZONG Wen-Jie, FU Hua, NIU De-Cao

2015, 24(9):  197-205.  DOI: 10.11686/cyxb2015083

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The patchiness and persistence of plant communities represent grassland responses to outside disturbance, and are the basis of sustainable development of plant communities and biodiversity. The aim of this study was to understand the factors contributing to the maintenance and development of plant communities and the effects of patchiness on soil properties after a disturbance. The changes in the types, number, and areas of mini-patches in meadows were evaluated in meadows with a light, moderate, and heavy density of plateau pika (Ochotona curzoniae) burrows. The plant community structure and soil properties were evaluated for five types of patches in meadows with a moderate number of burrows. Some mini-patches were characterized by a high abundance of a single species, with mini-patch areas ranging from 0.5 m² to 100 m² in an alpine meadow (not including background patches). These types of patches were named according to the main plant species. We chose three approximately 1-hectare sample sites with different burrow densities; light, moderate, and heavy. Three quadrats (20 m×20 m) were placed randomly to determine the types, number, and area of patches within each site. We chose five types of patches from the three sample sites, and selected three typical patches for each type to determine the plant community structure and soil properties. Quadrat sampling (1 m×1 m) was used to determine basic plant traits (composition, height, cover degree, above-ground biomass of vegetation) and soil properties (organic carbon, pH, total nitrogen, available nitrogen, total phosphorus, available phosphorus) in the patches. The meadows with moderate burrow density had the most types of patches and the greatest abundance of patches. The total area of patches tended to increase with greater deterioration caused by plateau pika. The number and areas of Potentilla anserine, Ligularia virgaurea, and Anemone rivularis patches tended to increase, and their areas increased dramatically from the moderate to heavy burrow density. The number and areas of Anaphalis lacteal and Leontopodium japonicum patches tended to decrease, and these patches tend to disappear from as the burrow density increased from moderate to heavy. There were few main types of pasture mini-patches, and the pattern of patches was relatively simple under heavy burrow density. An abnormal increase in the biomass of a single species was the main characteristic of the patches. The expanding propagation of single species affected the structures of plant functional groups and species abundance, and thus, cushioned the effects of other types of disturbance. The results of the principal component analysis showed that the amounts of total nitrogen, available nitrogen, and available phosphorus in soil were lower in four types of patches than in A. lacteal patches and background patches. The coefficients of variation were higher for soil total nitrogen, available nitrogen, and available phosphorus than for other soil properties in patches in the meadows with moderate burrow density. The contents and spatial heterogeneity of soil total nitrogen, available nitrogen, and available phosphorus were more sensitive than the responses of vegetation succession to plateau pika activity. Therefore, it is very important that the supply of total nitrogen and available nutrients are maintained to retain the stability of the alpine meadow ecosystem.

A comparative study of plant biomass in a native grassland exclosure

WANG Hui, WANG Hui, LUO Yong-Zhong, MA Wei-Wei

2015, 24(9):  206-215.  DOI: 10.11686/cyxb2015048

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Plant biomass mainly reflects the energy accumulated by plants. Plant species have evolved specialized strategies to regulate biomass allocation among various organs or between above and below ground biomass. We investigated total biomass and biomass allocation characteristics of 27 shrub and herbaceous species in an exclosure on grassland in a marginal oasis area on sandy soil at Jingtai, Gansu Province. The flower, leaf and stem biomass comprised less than 1.0 g in 89%, 70% and 56% of the 27 species respectively and the root:shoot ratio (R:S) of all species was less than 1. The R:S of Artemisia desertorum, Oxytropis aciphylla, Caragana roborovskyi and Nitraria sibirica differed significantly between natural exclosure and artificially restored sites. The ratio of aboveground biomass:total biomass of annual herbaceous species was significantly higher than those of perennial herbaceous and shrub species. These characteristics are deemed advantageous for biodiversity in this environment.

Effects of saline alkali stress and nitrogen supply on germination and seedling growth of Suaeda salsa

WANG Qian, XIAO Liang, TANG Xiang-Yu, XU Qing, YI Hua-Peng, TIAN Hai-Feng

2015, 24(9):  216-222.  DOI: 10.11686/cyxb2014506

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The effects of different substrates; distilled water, pearlite and saline-alkali soil and saline-alkali stress on seed germination and seedling growth of Suaeda salsa was investigated. Increasing levels of saline alkali stress significantly decreased seed germination of S. salsa. Salt content ranging from 0.00%-3.60% resulted in germination % falling from 89% to 0% linearly. The seed germination rate in the soil was lower than those in water and perlite by 8.00% when salt content was below 1.20%. Above 1.20% salt germination in different substrates were not different. The effect of substrate on seed germination is more important than salinity at salt contents below 1.20%, but salinity controls seed germination at salt contents above 1.20%. Seedling emergence increased to a peak value (70%) with the increase of salt content up to 1.00% and then declined gradually to 0% at salt concentrations above 1.00%. It appears that an optimal level of salinity is necessary for S. salsa seedlings to achieve a high survival rate. Salinity plays a dominant role for S. salsa during the growth period from bud to seedling stage and determines the formation of S. salsa community. Higher or lower salinity than optimum may result in the replacement of S. salsa by other plant species and consequently changes to zonal vegetation communities. When soil salinity is at an optimal level, nitrogen can effectively promote the growth of S. salsa. Elevated salt supply may hamper nitrogen uptake by S. salsa. The nitrogen required to maintain optimum growth of S. salsa may vary with salinity. Therefore, both salinity and nitrogen should be considered when utilising S. salsa as the pioneer species to restore the severely degraded saline soil in the Yellow River Delta.