Table of Content

20 December 2017, Volume 26 Issue 12

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Physicochemical and biological properties of soil in Haloxylon ammodendron plantations with different states of degradation

LIU Jiang, XU Xian-Ying, ZHANG Rong-Juan, CUI Wen-Tian, ZHAO Peng, DING Ai-Qiang, FU Gui-Quan

2017, 26(12):  1-12.  DOI: 10.11686/cyxb2017090

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Haloxylon ammodendron was introduced to the Minqin region from Xinjiang province in the 1960s. It became the primary species for windbreak and sand stabilization planting. The area in H. ammodendron plantation forest in Minqin County is about 3.5×10⁴ ha, 51.5% of the total plantation forest area. Degradation H. ammodendron forest had been observed since the 1970s, seriously threatening the survival and development of the Minqin Oasis. The aim of this study was to investigate the physicochemical and biological properties of soil under H. ammodendron forests with different degradation states in the Minqin oasis-desert ecotone, Gansu. 12 plots were selected in the degradation gradient; soil samples were collected from 0-5 cm, 5-10 cm, 10-20 cm depths from a representative area in each plot. Each plot was assigned (using vegetation indices) to one of four degradation grades (no degradation, light degradation, moderate degradation and severe degradation) using hierarchical cluster analysis. The soil physicochemical properties, microbial number, and enzyme activities were analysed. The effect of degradation of H. ammodendron forest on soil bulk density, total salt content, cation exchange capacity was not obvious, but soil organic gradually decreased and pH changed complexly with increasing degradation and increasing of soil depth. The total number of microbes and microbe species decreased with increasing soil depth; numbers of bacteria were much higher than actinomycetes in 0-5 cm soil depth, but they were similar in deeper soil layers. Fungi were not prevalent in any soil layers.Increased degradation was not associated with changes in the number of fungi observed.Enzyme activity decreased with increasing soil depth with increased degradation. The impact of degradation of H. ammodendron forest on protease activity, catalase activity, urease activity was greater than for invertase activity, the former showed greater sensitivity to changes in resources and environment. There were strong correlations among soil physicochemical properties, number of soil microbes and soil enzyme activities, but the correlation among soil physicochemical indicators, between soil bulk density, number of actinomycetes and other indicators were not significant. Soil fertility and biological properties in degraded H. ammodendron plantations have declined; restoration of the soil is necessary for restoration of these forests.

Impacts of polyacrylamide and grass root systems on micro-aggregates of purple soil in barren hillside badlands

WANG Run-Ze, CHEN Yun, LI Tie, ZHOU Tao, HE Bing-Hui, LIU Xiao-Hong, LIU Zhi-Peng, SHAN Zhi-Jie

2017, 26(12):  13-23.  DOI: 10.11686/cyxb2017060

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In order to explore the improvement effects of polyacrylamide (PAM) and grass roots on soil in badlands, the composition, distribution, structural and fractal characteristics of soil micro-aggregates in purple soil were measured after six months exposure to various treatments, including blank control (CK), polyacrylamide on the soil surface, grass planting alone, “Cynodon dactylon+PAM” and “Trifolium repens+PAM”. The results indicated that the proportion of large particle size micro-aggregates of each experimental treatment increased while the proportion of small particle size micro-aggregates decreased, compared to CK. Hence, the mean weight soil specific area (MWSSA), dispersion coefficient and dispersion rate of experimental treatments significantly decreased (The minimum values were 0.30, 0.15 and 0.60 times those of CK, respectively). The mean weight diameter, aggregation states and degree of aggregation of each experimental treatment significantly increased (The maximum values were 1.17, 1.49 and 1.28 times those of CK, respectively). The fractal dimension of micro-aggregates in experimental treatments also decreased. All the structural parameters of micro-aggregates in soils of treatment GY-PAM₁ (C. dactylon planting and liquid application of 30 g/m³ polyacrylamide) were superior to the other treatments and this treatment showed greater reduction in erodibility. The root system parameters of “grass+PAM” were better than those of grass-planting alone. The total root length and the root length in the diameter (d) class d≤0.2 mm were the major factor and critical diameter class affecting structural stability and erodibility reduction of purple soil in barren hillside badlands.

Effects of mulching time on soil temperature and moisture and potato yield in the hilly area of Southern Ningxia

SUN Jiao, GUO Xin-Nian, LIANG Jin-Xiu, CHEN Gang, ZHANG Guo-Hui, ZHOU Tao

2017, 26(12):  24-34.  DOI: 10.11686/cyxb2017017

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This study determined the effects of mulching time on soil temperature in 0-20 cm soil layers and soil moisture storage in 0-120 cm soil layers, and on potato yield (Solanum tuberosum) in a rain-fed agricultural area of Southern Ningxia. The experiment was conducted at Touying County, Guyuan City (106°44' E, 36°10' N) from 2013 to 2015. The following 4 treatments were evaluated: no mulching, plastic film mulch applied before sowing, plastic film mulch applied in spring, and plastic film mulch applied in autumn. Results showed that, compared with no mulching, all the treatments increased soil temperature, especially the autumn treatment, which was 1.0 ℃ higher than no mulching. They can also increase soil temperature during early spring and decrease temperature differences at the initial stage of potato growth. All the mulching treatments increased soil moisture storage at the initial stage and promoted water consumption during the tuber expanding stage, especially the autumn treatment. This promoting effect was evident mainly in the 20-60 cm soil layers, especially in dry years and years with average rainfall. Mulching with plastic film in autumn significantly increased potato tuber yields to 34543 kg/ha, 40.8% higher than the no mulching treatment, and there was a 23.5% increment in potato water use efficiency to 77.5 kg/(ha·mm). There were highly positive correlations between tuber yield, soil temperature and soil moisture storage during early spring, but significantly negative correlations with soil temperature before the sowing stage. In conclusion, the autumn plastic film mulching treatment can increase soil temperature and moisture during the early spring period and accumulate soil water depleted after the potato tuber expansion period. Results showed that this is an appropriate treatment which has a significant impact on potato yield.

Effects of hybrid, plant density and plastic film mulching on yield and water use efficiency of dryland maize

LI Shang-Zhong, FAN Ting-Lu, ZHAO Gang, WANG Lei, DANG Yi, ZHANG Jian-Jun, TANG Xiao-Ming, WANG Shu-Ying

2017, 26(12):  35-47.  DOI: 10.11686/cyxb2017250

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The objective of this experiment was to study the effects of hybrids, plant density and plastic film mulching on plant traits, water consumption, grain yield and water use efficiency of dryland maize to help identify opportunities to more effectively utilize limited water resources. A split-split plot designed field experiment was established; the main plot treatments were full plastic film mulching on double ridges and planting in catchment furrows (FFDRF) and flat planting with narrow plastic film mulching (NF). The split-plot treatment was hybrid; Xianyu335, Jixiang1hao and Jiudan4hao and the split-split-plot treatment was plant density; 4.5×10⁴ (Low), 6.75×10⁴ (Middle) and 9.0×10⁴ (High) plants/ha. Plant height, leaf area index (LAI), dry matter, soil moisture at 0-2 m depth, grain yield and water use efficiency were assessed. The results showed that FFDRF increased height, LAI, grain yield and water use efficiency because it more allowed more effective utilization of limited precipitation compared with NF. Increased plant density reduced 100-grain weight and grain number per spike however, increased density resulted in increased dry matter, grain yield and water use efficiency. The 9.0×10⁴ plants/ha density increased dry matter, grain yield and water use efficiency by 8.3%, 5.2%, 3.4% and 27.7%, 32.9%, 28.1% compared with the 6.75×10⁴ and 4.5×10⁴ treatments, respectively. Xianyu335 and Jixiang1hao performed better than Jiudan4hao at high plant densities; grain yield and water use efficiency were highest in Xianyu335; 3.7%,1.7% and 43.8%,37.1% higher than Jixiang1hao and Jiudan4hao, respectively. Water consumption increased with increasing plant density and differed among hybrids; Xianyu335>Jixiang1hao>Jiudan4hao. Hybrids, plant density and plastic film mulching influenced the optimum plant population, water consumption, grain yield and water use efficiency of dryland maize, varieties had the greatest effect followed by plant density and mulch. Selection of appropriate hybrids and plant densities when using and plastic film mulch modes should be undertaken to maximize potential yields.

Interactive effects of soil moisture and nitrogen application rate on seedling growth of alfalfa

WANG Qian, JI Shu-Ren, SHEN Yi-Xin

2017, 26(12):  48-55.  DOI: 10.11686/cyxb2017079

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Soil moisture significantly affects crop response to fertilizer application. This study investigated the effect of nitrogen application on the growth of alfalfa (Medicago sativa) in the middle and lower reaches of the Yangtze River and evaluated the interaction between soil moisture and nitrogen application rate effects with a semi-controlled pot experiment conducted in Nanjing. The experiment included three soil moisture levels (50%, 70% and 90% of maximum water holding capacity) and four nitrogen application rates (0, 90, 180, 270 kg/ha). Dry matter accumulation and nitrogen use efficiency increased with increasing soil moisture level. Under the same soil moisture level, dry matter accumulation and nitrogen use efficiency increased with appropriate N application rates, but decreased with excess nitrogen application. The interaction effect between soil moisture and nitrogen application rate was statistically significant. The effect of fertilizer nitrogen was significantly enhanced at higher soil moisture levels. With increased soil moisture, the effect of nitrogen application at moderate rates was also enhanced. Therefore, when soil moisture level is lower, nitrogen application should be carried out with irrigation. In the middle and lower reaches of the Yangtze River where there is high soil moisture, more nitrogen application could increase forage yield and nitrogen use efficiency of alfalfa.

Effects of low temperature stratification on emergence of Lycium ruthenicum under drought at different sowing depths

ZHAO Jing-Zhong, KONG Dong-Sheng, WANG Li, GUO You-Yan

2017, 26(12):  56-66.  DOI: 10.11686/cyxb2017088

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The emergence of fruits and seeds of Lycium ruthenicum after low temperature stratification and storage at room temperature in dry conditions was investigated. Emergence rate, emergence potential, seedling index and recovery rate of germination under different intensities of drought stress and different planting depth in sand were simulated using PEG-6000 solution. The germination rate of seeds and fruits treated with PEG solution was increased by 60.00% and 16.66% respectively compared with the control. The time to emerge was reduced by 7 and 9 days respectively, indicating that low temperature stratification could effectively eliminate the dormancy of seeds and fruits of L. ruthenicum. High osmotic potentials (-0.03 to -0.10 MPa) did not influence emergence indicating that under mild drought stress, fruit germination was not affected by low temperature stratification. Both the seed and fruit were able to germinate after drought stress was relieved. It was concluded that the optimum sowing depth of seeds and fruits of L. ruthenicum is 1 and 3 cm respectively. It is also possible to successfully plant the fruit of L. ruthenicum rather than plant seedlings, saving time and labour.

Effects of neutral and alkaline salt stresses on the growth and physiological metabolism of Kentucky bluegrass

ZHANG Qiang, LIU Ning-Fang, XIANG Zuo-Xiang, YANG Zhi-Jian, JIANG Yuan-Li, HU Long-Xing

2017, 26(12):  67-76.  DOI: 10.11686/cyxb2017086

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In order to investigate the effects of neutral and alkaline salt stresses on growth, leaf electrolyte leakage, chlorophyll content, photosynthetic characteristics, proline content and organic acid metabolism, two Kentucky bluegrass (Poa pratensis) cultivars, ‘Midnight' (tolerant of saline-alkaline conditions) and ‘Voyager Ⅱ' (sensitive to saline-alkaline conditions) were subjected to neutral and alkaline salt treatments in hydroponic culture in growth chambers. The growth rate, chlorophyll content and photosynthesis decreased and leaf electrolyte leakage increased significantly under both types of salt stress, particularly under alkali stress. The tolerant cultivar showed less variation in response to the two salt stresses than the sensitive one. Leaf proline content only increased under neutral salt stress in both cultivars and no increase was observed under alkali stress. Oxalic acid was the only organic acid secreted by roots of either cultivar and increased significantly under alkali stress. The contents of leaf and root malic acid, citric acid and succinic acid in both cultivars hardly changed under neutral salt stress, but increased under alkali stress, with greater increase in ‘Midnight' than in ‘Voyager Ⅱ'. Alkaline salt stress caused more damage to Kentucky bluegrass than neutral salt stress. Under neutral salt stress, proline accumulation was the key metabolite associated with change in the osmotic potential. Under alkaline salt stress, organic acids were linked to regulation of pH values in the plant and the rhizosphere. Midnight, the cultivar tolerant of both types of salt stress, can maintain a higher photosynthesis rate and organic acid metabolism, and stronger ability to regulate pH in the plant and in the rhizosphere under neutral and alkaline salt stresses. In summary, Midnight possesses stronger tolerance to neutral and alkaline salt stresses in Kentucky bluegrass.

Physiological responses of different quinoa varieties to salt stress and evaluation of salt tolerance

YANG Fa-Rong, LIU Wen-Yu, HUANG Jie, WEI Yu-Ming, JIN Qian

2017, 26(12):  77-88.  DOI: 10.11686/cyxb2016412

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The aims of this study were to evaluate the physiological responses of quinoa plants to salt stress and to compare salt tolerance among different quinoa varieties. Seeds and seedlings of different quinoa varieties were pretreated with 100, 200, 300, 400, and 500 mmol/L NaCl solutions. The seed germination index, seedling biomass, and other physiological and biochemical characteristics were determined to analyze the mechanisms of salt tolerance in quinoa. The salt tolerance of the different quinoa varieties was evaluated by a membership function method. As the NaCl concentration increased, the seed germination percentage increased and then decreased, the germination potential and germination index decreased significantly, and the contents of chlorophyll and soluble proteins and activities of antioxidant enzymes (superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase) increased and then decreased. The peak in the activities of the antioxidant enzymes was at 300 mmol/L NaCl. The contents of soluble sugars, proline, and malondialdehyde increased significantly as the NaCl concentration increased. These results suggested that increased contents of soluble sugars and proline, increased activities of antioxidant enzymes, and decreased malondialdehyde contents in seedlings may contribute to adaptation to salt stress and promote seedling growth in the presence of NaCl. In conclusion, the threshold of salt tolerance in quinoa seedlings was 300 mmol/L NaCl. Longli No.1 was the most salt-tolerant quinoa variety, and Longli No.4 was the least salt-tolerant variety.

Comparative studies on strontium tolerance of four Avena sativa varieties

QI Lin, YANG Ying-Bo, WANG Xiao-Ling, ZHAO Wei

2017, 26(12):  89-97.  DOI: 10.11686/cyxb2017268

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Strontium (Sr) is a common fission product of U-235 and Pu-239. Radioactive isotopes are toxic because they are heavy metals and also because of their radioactivity. The fate of radio nuclides in the environment is similar to that of stable elements therefore the behavior of stable Sr-88 in the environment should be regarded as a useful analogue for predicting the long-term fate of Sr-90. Phytoremediation is an emerging alternative technology which utilizes plants to remove metals from the environment. To investigate the ability of oats to accumulate strontium four oat varieties (Bende, Baiyan No.2, Baiyan No.7 and Dingyou No.6) were exposed to five strontium levels (0, 25, 100, 500 and 1000 mg/kg). Plants were cultivated for 30 days. Strontium accumulation and distribution in plants, growth, MDA content, as well as POD, SOD and CAT activity were measured. The results showed that the root and shoot biomass of oat seedlings were increased early and decreased later with increased strontium concentration. Strontium accumulation increased with increased strontium levels; ranked leaf> root>stem. Translocation decreased with increasing strontium concentration. The high strontium treatments increased the MDA content and inhibited POD activity whereas SOD activity increased. The root, stem and leaf of oats could accumulate strontium but most was accumulated in the leaf. All four varieties were able to be classified as hyper accumulators of strontium. Low strontium concentration increased the activities of antioxidant enzymes.Under high strontium concentrations SOD and CAT played an important role in scavenging active oxygen. Oats were able to accumulate and tolerate high concentrations of strontium and could be used for phytoremediation of strontium polluted soils.

Effect of freezing stress on ROS metabolism and cold-induced genes in Poa pratensis var. anceps cv. Qinghai

SHI Yi, NIU Kui-Ju, YU Qian-Qian, LIU Wen-Hui, MA Hui-Ling

2017, 26(12):  98-107.  DOI: 10.11686/cyxb2017054

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To explore the mechanism of cold tolerance of Poa pratensis var. anceps cv. Qinghai (BJ) plants were exposed to cold acclimation (10/5 ℃) for 3 d followed by freezing stress (-10 ℃) for 24 h, with P. pratensis var. ‘Midnight II' (WY-2) as control, and ROS accumulation, antioxidant enzyme activity and stress related gene expression were monitored. Rate of the production of O^-·₂, levels of H₂O₂ and MDA, activity of SOD, CAT, APX, GR and the relative expression of the antioxidant enzyme genes were measured, as well as several cold induced genes. The results demonstrated that freezing stress increased the O^-·₂ production rate, and H₂O₂ and MDA levels in both BJ and WY-2. ROS accumulation and MDA content of BJ were lower than those in WY-2. SOD, APX and GR activity was depressed by freezing stress in BJ, while CAT activity initially increased and then decreased. Only APX in BJ showed higher activity than that in WY-2. At the same time, the expression levels of Cu/ZnSOD, CAT, APX and GR related genes were increased in the two varieties. The relative expression of the enzyme related genes in BJ was higher than WY-2. The cold induced gene DREB2 was down-regulated in BJ, while the ERF, DREB1, CSP, and HSP genes were up-regulated. Among these genes, ERF, CSP and HSP showed higher expression levels in BJ than in WY-2. In conclusion, the accumulation of ROS in BJ was lower than that in WY-2 under cold and freezing stress. Meanwhile antioxidant enzyme related genes and cold related transcription factors showed higher relative expression levels in BJ than in WY-2 under cold and freezing stress. Those differences may contribute to the higher cold tolerance of BJ.

Cloning and expression analysis of MsLEA4-4 from Medicago sativa

JIA Hui-Li, WANG Xue-Min, GUO Ji-Cheng, GAO Hong-Wen, WU Xin-Ming, LIU Jian-Ning, SHI Yong-Hong, DONG Kuan-Hu, WANG Yun-Qi

2017, 26(12):  108-116.  DOI: 10.11686/cyxb2017202

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Late embryogenesis abundant (LEA) proteins are widely involved in many adverse situations for plants. In this study, we isolated a LEA4 gene from alfalfa by homology cloning strategy, termed MsLEA4-4. The MsLEA4-4 encoding revealed 512 amino acids and structure analysis showed that the gene contains eleven repeating TAQAAKEKTQQ amino acids sequences. Quantitative real-time PCR was used to detect MsLEA4-4 expression quantities in adverse situations. Results revealed that the expression of MsLEA4-4 was up-regulated by drought (PEG), salinity (NaCl), Cu²⁺, Zn²⁺ and ABA stress. Gene expression was highest at 2 h and 8 h under the stress of NaCl, Cu²⁺ and Zn²⁺. Under chilling and drought stress, the gene showed a rising trend. These results indicate that the MsLEA4-4 protein may be involved in the regulation of environment stress responses in alfalfa. The plant expression vector pCAMBIA3301-MsLEA4-4 was constructed and transgenic plants were obtained through infecting inflorescences of Arabidopsis by Agrobacterium tumefaciens-mediated transformation. The vector sequence was tested by antibiotic (PPT) and PCR in the genome of transgenic plants and indicated that the target gene had been transferred. This study provides basic information for further study of the MsLEA4-4 function in stress-tolerance regulation in alfalfa.

Enhancing drought and heat tolerance in Lolium spp. through overexpression of the FaSAMDC gene

ZENG Qing-Fei, WEI Xin, CAI Yi-Ming, SHU Jian-Hong, WU Jia-Hai, WANG Xiao-Li

2017, 26(12):  117-127.  DOI: 10.11686/cyxb2017208

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To obtain new ryegrass germplasm with enhanced drought and heat tolerance a genetic transformation experiment using plants from the genus Lolium was conducted. By using mature seeds of ryegrass as explants and adoption of the overexpression vector,tissue culture and regeneration system of ryegrass, and genetic transformation mediated by Agrobacterium tumefaciens, the S-adenosylmethionine decarboxylase gene cloned from Festuca arundinacea (FaSAMDC) was introduced into the genome of ‘Tetragold' annual ryegrass and ‘Four Seasons' perennial ryegrass. Eighty-nine transgenic plants (45 Tetragold and 44 Four Seasons) were regenerated from independent resistant calli, which were confirmed by antibiotic resistance screening, PCR assay and southern hybridization analysis; the transgenic frequency was 2.93% and 2.28%, respectively. Drought and heat resistant tests under high temperature (30 ℃) and moderate drought stress showed that in Tetragold, the root to shoot ratio was 7.1% higher, leaf relative water content (RWC) 13.1% higher and the RWC descent scope 5.5% lower than the controls; for transgenic Four Seasons plants the root to shoot ratio was 6.5% higher, RWC 12.5% higher and the RWC descent scope 6.5% lower than the control; differences between transgenic plants and controls were all statistically significant (P<0.05), indicating that drought and heat resistance in transgenic plants was significantly improved. Observations of morphological and growth characteristics showed that, compared with non-transgenic plants, leaf length, plant height and main stalk pitch number of transgenic plants were lower but leaf width and tiller number per plant were higher. Leaves of transgenic plants were darker in colour and plants tended to become compact with tufted leaves suggesting that the inserted FaSAMDC gene was involved in the regulation of physiological function, such as gene expression and cell division. The transgenic material developed in the study could be used as foundation for the cultivation of new ryegrass varieties with enhanced drought and heat resistance.

Differential gene analysis of Poa pratensis in response to drought stress

LENG Nuan, LIU Xiao-Wei, ZHANG Na, XU Li-Xin

2017, 26(12):  128-137.  DOI: 10.11686/cyxb2017130

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Drought is one of the main factors affecting the productivity of Poa pratensis. This study was undertaken to reveal the change of gene expression profile of P. pratensis in the absence of a reference genome. The high-throughput Illumina Hiseq sequencing platform was used to investigate the transcriptome of a control group (CK) and a drought treated group (D) of P. pratensis. The sequencing data were subsequently analyzed to help reveal the molecular mechanisms of drought response in P. pratensis. The results showed that 24465 differentially expressed genes were detected under drought treatment. After screening 4143 up-regulated genes and 4415 down-regulated genes were obtained, accounting for 34.98% of the total number of differentially expressed genes. The genes related to protein kinase, protein phosphatase, carbon metabolism and ABA can be used as the main research object to study the drought response mechanism of P. pratensis. qRT-PCR analysis showed that the expression of 8 randomly differentially expressed genes was consistent with the high-throughput sequencing results. In addition, a series of genes for indole-3-glycerophosphate synthase, protein phosphatase, carbohydrate kinase, calcium binding protein and chlorophyll a/b binding protein were selected as candidate genes for drought stress related to P. pratensis. This laid the foundation for potentially revealing the molecular mechanism of drought response in P. pratensis.

Fitness of resistant backcross generation (BC3F2-3) between glufosinate-resistant transgenic oilseed rape and wild Brassica juncea

WANG Xiao-Lei, WANG Jian, ZHANG Qing-Ling, YAN Jing, QIANG Sheng, SONG Xiao-Ling

2017, 26(12):  138-151.  DOI: 10.11686/cyxb2017129

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One of the concerns about releasing transgenic herbicide-resistant oilseed rape (Brassica napus, AACC=38) is that herbicide-resistant (HR) transgenes from transgenic oilseed rape may escape to wild Brassica juncea. If this happens, wild B. juncea with the HR trait might pose new problems for weed control. Therefore, it is necessary to evaluate gene flow from HR transgenic oilseed rape to wild B. juncea before it is released. The fitness components and composite fitness of BC3mF2, BC3pF2, BC3mF3 and BC3pF3 (m=backcross progeny obtained with wild B. juncea as maternal plants; p=backcross progeny obtained with wild B. juncea as paternal plants.) between glufosinate-resistant transgenic oilseed rape and wild B. juncea under different densities and different planting proportions were measured in the field. In pure plots, the composite fitness of BC3F2 and BC3F3 were not different to wild B. juncea either at low density (15 plants/plot), or high density (30 plants/plot). In mixed plots, at low density under 4:1, 3:2 proportions, the composite fitness of the backcross generations was lower than that of wild B. juncea except for BC3mF3, which was similar to wild B. juncea. Under 1:1 proportion, the composite fitness of the backcross generations was lower than that of wild B. juncea except for BC3mF2 and BC3mF3, which were similar to wild B. juncea. At high density, the composite fitness of all backcross generations was lower than that of wild B. juncea irrespective of proportions. There was no correlation between fitness components of BC3mF3 and planting density. BC3F2 and BC3F3 between glufosinate-resistant transgenic oilseed rape and wild B. juncea have the ability to establish in field, particularly BC3mF3. Therefore, hybridization between transgenic oilseed rape and wild B. juncea, including backcrosses between wild B. juncea and F₁ or subsequent generations, should be prevented.

Construction and analysis of a suppression subtractive hybridization library for the potato virus induced response gene

LI Zhong-Wang, CHEN Yu-Liang, OU Qiao-Ming, YE Chun-Lei, PEI Huai-Di, LIU Xin-Xing, WANG Hong-Mei, LUO Jun-Jie

2017, 26(12):  152-159.  DOI: 10.11686/cyxb2017063

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Potato virus accumulation is one of the important reasons for the decline of yield and quality in potato production. In order to screen and clone the potato virus induced response gene, we constructed a suppression subtractive hybridization (SSH) library using cDNAs from potato virus disease carrying plant leaf as the tester, and those cDNAs from a virus-free seedling leaf as the driver. To verify the effect of library, 98 randomly selected positive clones were identified by PCR from the library and sequenced, and 45 high quality non repeat sequences were obtained. By blast analysis in GenBank, we found that 14 of them were sequences belonging to the potato virus gene, 22 of them had high homology with known genes, and 9 of them had no homologous reference gene. Two frequently found ESTs in the library were analyzed using quantitative real time PCR, and their expression was induced by potato virus. The results therefore showed that the SSH library was constructed successfully. This work has thus laid a foundation for further screening for potato virus related pathogenicity, and induction of corresponding defense response genes. This may lead to analysis of the molecular mechanisms of interaction between the potato plant and the virus, and use of biotechnology to cultivate virus resistant potato varieties.

Effects of Glomus mosseae and grass endophytes on the growth of Lolium perenne under phosphorus addition

GUO Yan-E, WANG Xiao-Yu, GAO Ping, DUAN Ting-Yu

2017, 26(12):  160-169.  DOI: 10.11686/cyxb2017071

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This study aimed to determine the effects of arbuscular mycorrhizae fungi Glomus mosseae and grass endophytes on the growth, nutrient absorption and phosphatase activities of Lolium perenne without phosphorus addition (P₀) and with 50 mg/kg phosphorus addition (P₅₀). Seeds of perennial ryegrass infected with grass endophyte (E⁺) and without grass endophyte (E^-) were used to establish plants with and without the endophytes. The results showed that: 1) AM fungi and grass endophytes had significant effects on the host biomass (P<0.05); plants infected by both AM fungi and grass endophytes (AME⁺) had the lowest biomass. Plants infected by only Glomus mosseae had the highest biomass under P₀, while plants free of the two symbiosis fungi reached their highest biomass under P₅₀. 2) Phosphorus addition increased mycorrhizal colonization of perennial ryegrass by 11.40%, while infection with grass endophytes inhibited plant mycorrhizal colonization by 18.65% and 11.77% under P₀ and P₅₀ respectively. 3) G. mosseae had no significant effect on the absorption of P (P<0.05). Grass endophytes increased the content of total N, while AM colonization decreased the total N of plants with grass endophytes. 4) Phosphorus addition significantly increased phosphatase activities (P<0.05). Plants infected by AM fungi and grass endophytes had the highest phosphatase activities across the treatments. Each of the two symbiosis fungi improved plant growth when taken alone; however, they showed competition on photosynthate and did not enhance plant growth and nutrition absorption when applied together.

The correlation between cell microstructure induced by 2,3-butanediol and fungal resistance of creeping bentgrass

LIU Xing-Ju, MA Yuan, MA Hui-Ling, ZHANG Yong-Mei, YU Qian-Qian

2017, 26(12):  170-178.  DOI: 10.11686/cyxb2017065

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The brown spot caused by Rhizoctonia solani is one of the most common diseases of creeping bentgrass (Agrostis stolonifera) lawns. Application of 2,3-butanediol (2,3-BD ) can induce plant disease response and improve disease resistance. In the present study, creeping bentgrass was inoculated with R. solani after treatment with 2,3-BD (250 μmol/L) and then the cell microstructure of leaves was observed using a paraffin sectioning method. It was found that the disease index of creeping bentgrass without 2,3-BD reached 70.45% after 15 days from inoculation. However, the disease index of creeping bentgrass treated with 2,3-BD was significantly lower, at 21.63% (P<0.05). Compared to leaves of pathogen-infected plants untreated with 2,3-BD, creeping bentgrass leaves with both pathogen inoculation and 2,3-BD treatment had a closely arranged cell structure, smaller cavities, more papillae, and increased upper and lower epidermal cell size. The size increase of upper and lower epidermal cells of 2,3-BD induced plants, compared to uninduced plants, was a factor of 1.19 and 1.26 times, respectively, and was most significant on day 7 after inoculation. The mesophyll cell size increase was the most significant on the 15th day (×1.30). The chloroplast density 1, 7, and 15 days after inoculation was, respectively, 1.25, 1.20, and 1.24 times that of uninduced plants (P<0.05). The size of vascular bundles and ducts did not change significantly at any time, however, the degree of lignification was higher and the cortical tissue became thicker in induced plants. In conclusion, 2, 3-BD can induce resistance of creeping bentgrass to brown spot disease through change in the cell structure. There was a positive correlation between the upper and lower epidermal cell size, the mesophyll cell size, and the number of chloroplasts per cell in creeping bentgrass leaves, and the disease resistance.

Effects of tannic acid on digestion and utilization of nutrients and the metabolic parameters of nitrogen in sheep

PAN Fa-Ming, WANG Cai-Lian, DIAO Qi-Yu, SONG Shu-Zhen, LANG Xia, GONG Xu-Yin, ZHANG Jun-Cheng

2017, 26(12):  179-185.  DOI: 10.11686/cyxb2017135

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An experiment was conducted to determine the effects of tannic acid on nutrient digestion and nitrogen metabolic parameters in sheep, in order to determine the appropriate amount of tannic acid in feed. Four fine-wool wethers (two years old and average live weight of 35±2.15 kg) fitted with permanent rumen fistula were selected and a 4×4 Latin square design with 10 d preliminary and 6 d sampling experiment was used to study the effects of 4 different tannic acid contents on nutrient digestion and nitrogen metabolic profiles. The contents of tannic acid in diets were 0 (A), 10 (B), 15 (C), and 20 (D) g/kg DM. The results indicated that both feed intake and the intake of DM, OM, NDF and ADF were affected by the tannic acid in treatment D (20 g/kg DM) (P>0.01), while the digestibility of DM, OM, NDF, ADF, Ca and P was unaffected by the acid contents (P>0.05). The intake and digestion of N were higher in the A, B and C treatments than in treatment D (P>0.01). N retention increased as the level of tannic acid increased (N retention in treatment C was higher than in treatment A). No differences were observed in N digestibility, pH and total nitrogen in rumen fluids (P>0.05), whereas the levels of NH₃-N and BUN decreased linearly. The level of NH₃-N for diet A was higher than for D (P<0.05) and BUN was higher in the C and D treatments (P>0.01). In conclusion, tannic acid increased rumen bypass proteins. N retention was improved when the ratio of tannic acid was less than 15 g/kg DM, suggesting that the optimal tannic acid content in diets is less than this ratio.

Effects of sterilant and rodenticide on the population of brandt's voles (Lasiopodomys brandtii)

ZHENG Pu-Yang, PENG Zhen, WANG Yong, XU Yun-Hu, HE Bing, WANG Yu-Mei, ZHAO Jing-Rui

2017, 26(12):  186-193.  DOI: 10.11686/cyxb2017083

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In order to study the control effect on population increases of Brandt's voles (Lasiopodomys brandtii), “Beiao” anti-procreate and poisoned baits (Bromadiolone) were used in East Ujimqin Banner Grasslands, Inner Mongolia, with a one-time sufficient dose in spring from May to September in 2013. The tests were conducted in sterile experimental, lethal experimental and control areas. The Brandt's voles were captured by trapping monthly. Results showed that the voles' family group sizes were significantly different in the sterile and lethal experimental areas in May (P<0.05), but not in June (P>0.05). The Brandt's voles' population recovery rate was faster and the birth rate higher in the lethal area compared with the sterile area. The male ratio tendency varied in the sterile area where the “Beiao” male anti-procreate was used. In summary, “Beiao” male anti-procreate demonstrates a better control effect on Brandt's voles.

The suitable addition amount of sweet sorghum wilted silage in the total mixed ration of rabbits

XU Neng-Xiang, DONG Chen-Fei, ZHANG Wen-Jie, CHENG Yun-Hui, GU Hong-Ru, DING Cheng-Long

2017, 26(12):  194-202.  DOI: 10.11686/cyxb2017075

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The objective of this experiment was to investigate the suitable addition amount of sweet sorghum (Sorghum bicolo) wilted silage in total mixed ration for rabbits. The dynamics of feeding and fermentation quality of sweet sorghum with different wilting times were firstly analyzed, so as to select a suitable wilting time for sweet sorghum harvested at wax ripeness stage. The results indicated that wilting for 5 hours was the optimum time, when water content dropped to 59.7% and the nonstructural carbohydrates content was 8.6%. Four different addition amounts (control, 25%, 30% and 35%) of the 5-hour wilted silage were used to make a total mixed ration (TMR) for rabbits, so as to investigate the effects and identify the optimum addition for rabbit growth and health. Weekly increased weight and biochemical indicators after the test were determined. The results showed that when the addition amount increased from 25% to 35% in TMR, the total weight gain after 5 weeks increased from 871.56 g to 950.25 g. When the addition amount was increased from 30% to 35%, the activities of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase enzyme were lower than in the control group. The results indicate that 30%-35% is the suitable addition amount of sweet sorghum wilted silage in rabbit TMR.

Progress in research on diseases of Avena sativa

LI Chun-Jie, CHEN Tai-Xiang, ZHAO Gui-Qin, NAN Zhi-Biao

2017, 26(12):  203-222.  DOI: 10.11686/cyxb2017089

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Disease is one of the limiting factors for the production of oats (Avena sativa), affecting crop yield and quality directly, and the productivity of grassland agro-ecosystems indirectly as well. Based on a review of published domestic and international literatures, the etiology, seed-borne fungi, rule of occurrence, disease resistance and control measurements of oat diseases are reported. Domestic research progress is compared with international efforts and future development goals for oat disease research are also presented.

A bibliometric appraisal of research on Artemisia from 1986-2016

CHEN Lin, SONG Nai-Ping, WANG Lei, YANG Xin-Guo, LI Xue-Bin, SU Ying, LI Yue-Fei

2017, 26(12):  223-235.  DOI: 10.11686/cyxb2017082

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In order to identify the location of centres of excellence and better understand the global status of research on Artemisia and to objectively assess scientific capability and influence of countries, institutions and individuals undertaking research on Artemisia, a bibliometric analysis was conducted. Our study surveyed literature published from 1986 to 2016 and included in the core collection of the Web of Science^TM database. The number of publications on Artemisia shows a rising trend. In terms of article number, China ranks first, followed by the United States, but from the viewpoint of international cooperation the United States has made the greatest contribution, and Britain also cooperates closely with China. Among research institutions worldwide, the Chinese Academy of Sciences heads the list for article number, first-author papers, and citations of first-author papers. The University of Hong Kong is the institution with the highest total citation count and number of citations of first-author papers. Articles on Artemisia are mostly published in the journals Planta Medica, Phytochemistry, and Journal of Natural Products, but the highest average number of citations per paper appears in the journal Nature. Plant science, chemistry and pharmacology & pharmacy are the top 3 disciplines within which the research has been conducted. Approximately 50% of identified articles were categorized as scientific studies, with fundamental science and technological science accounting for a larger amount, and engineering science a smaller share. Among individuals, Prof. L. K. Sy of Hong Kong University is a leading author of studies on the extraction of Artemisia annua; J. A. Marco Valencia University in Spain, and J. Wen of Peking University have the highest citation frequency. The chemical composition and medicinal application are two commonly studied topics in research on Artemisia.

Effects of different restoration measures on storage of soil organic carbon and nitrogen in typical steppe of the Loess Hilly Area in Ningxia

ZHOU Yao, MA Hong-Bin, JIA Xi-Yang, ZHANG Rui, SU Ting-Ting, ZHOU Jing-Jing, WU Xing-Wang

2017, 26(12):  236-242.  DOI: 10.11686/cyxb2017070

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Land-use strongly influences soil properties such as soil organic carbon (SOC) and total nitrogen (TN). This study has been done to investigate changes in grassland organic carbon and nitrogen storage characteristics under different restoration measures in typical steppe of the Loess Hilly area in Ningxia, which is located in the Yunwu hills (longitude 106°21'-106°27' E, latitude 36°10'-36°17' N, altitude 1800-2100 m) and has a very steep slope (approx. 30-50°). The annual mean temperature is 5 ℃, with a range from approx. 22-25 ℃ in summer (July) to -14 ℃ in winter (January). The annual precipitation is 445 mm, of which 60% occurs in autumn and is associated with storm events in the July-September period that sometimes cause runoff. The storage of organic carbon and nitrogen was measured in 0-10, 10-20, 20-30 and 30-40 cm soil layers for three different restoration measures, including grazed (control), exclosure, contour trenches and fish-scale pits. Our results revealed that the content of SOC and TN were the highest in exclosure grassland (30.35 and 2.92 g/kg respectively), followed by grazed, fish-scale pits and contour trenches (P<0.05). C/N was highest in exclosure grassland, in the middle in contour trenches and fish-scale pits, and the lowest in grazed grassland. The content of SOC and TN under the different restoration measures decreased with increasing soil depth except for the content of TN of 10-20 cm soil layer in contour trenches and fish-scale pits. However, soil depth did not have an effect on soil bulk density under the different measures. The density of SOC and TN was highest in exclosure and grazed grassland, in the middle in fish-scale pits and the lowest in contour trenches. Soil depth had an effect on the density of SOC under different restoration measures whereas it had no effect on the density of TN. The storage of both soil carbon and nitrogen decreased in the following order: exclosure>grazed>fish-scale pits>contour trenches. Organic carbon storage was highly significantly positively correlated with soil organic carbon and total nitrogen content; and nitrogen storage was significantly positively correlated with total nitrogen content.