Table of Content

20 August 2015, Volume 24 Issue 8

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Orginal Article

A preliminary study of carbon dioxide, methane and nitrous oxide fluxes from the Gahai wetland

MA Wei-Wei, WANG Hui, LI Guang, ZHAO Jin-Mei, WANG Yue-Si

2015, 24(8):  1-10.  DOI: 10.11686/cyxb2014350

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A study has been undertaken to estimate fluxes of the greenhouse gases carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) in wetlands, to understand the effects of temperature factors on these processes and to estimate global warming potential (GWP). Using static chamber techniques, we measured CH₄, CO₂, and N₂O fluxes from four wetland types in Gansu Gahai Wetlands, China, from July 2011 to July 2012. The results showed high variations in CH₄, CO₂ and N₂O fluxes between the four wetlands, with the smallest values in the subalpine meadow (-0.014±0.126 mg/m²·h), marsh wetland (137.17±284.51 mg/m²·h) and mountain wetland (-0.008±0.022 mg/m²·h) respectively. The highest values of CH₄, CO₂ and N₂O fluxes were in marsh wetland (0.498±0.682 mg/m²·h), mountain wetland (497.81±473.09 mg/m²·h) and herbaceous peat (0.094±0.117 mg/m²·h) respectively. CH₄ and CO₂ fluxes varied seasonally. Maximal fluxes occurred between July-October 2011 and May-July 2012, then decreased and remained relatively steady, with some slight fluctuations during the winter and thawing or freezing periods. Further analysis showed that air temperature, soil temperature (at 5 cm), surface temperature and temperature inside the box were highly significantly positively correlated with CO₂ flux from the four wetlands. These variables were significantly positively correlated with CH₄ flux from mountain wetland but not from the other wetland types. They were significantly negatively correlated with N₂O flux from all four wetland types. The GWP estimates were 35.311, 13.520, 34.816 and 30.236 t CO₂/(hm² ·a) from herbaceous peat, marsh wetland, mountain wetland and subalpine meadow respectively. These results show that marsh wetland could significantly decrease the emission of greenhouse gases from the Gahai Wetlands.

Investigation of wild vine resources in Chengbu, Hunan

WANG Ye-She, CHEN Li-Jun, YANG Xian-Jun, DUAN Lin-Dong

2015, 24(8):  11-23.  DOI: 10.11686/cyxb2014514

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This study investigates wild vine resources in Chengbu County (Hunan Province), with a view to improving their exploration and utilization. We have analyzed the species composition and diversity of wild vines using the methods of field investigation, specimen identification and literature survey. There are 40 families, 88 genera, and 277 species of wild vine in Chengbu, of which very few are ferns and gymnosperms. Only 2 families, 2 genera and 2 species of pteridophyte and only 1 family, 1 genera and 1 species of gymnosperm were found, accounting respectively for 0.72% and 0.36% of the total number of vine species in the region. There are 37 families, 85 genera and 274 species of angiosperms, most of which are dicotyledonous plants, which include 33 families, 80 genera and 245 species, accounting for 88.45% of the total. Monocotyledonous plants are in the subordinate position, with only 4 families, 5 genera and 29 species, accounting for 10.47% of the total. As regards family and genus hierarchy, the family structure is relatively concentrated while the genus structure is relatively decentralized. In terms of life-form, phanerophyte vines outnumber others, accounting for 81.59% of the total. Minority forms include underground buds, therophytes, chamaephytes and hemicryptophytes, accounting for 8.66%, 4.69%, 2.89% and 2.17% of the total respectively. In terms of climbing style, the majority are twining vines, accounting for 46.21% of the total, while the minority styles include hooking, curling and adhering vines, accounting for 24.55%, 21.30% and 7.94% respectively. In terms of floristic composition, the vines are mainly tropical plants, with their 52 genera accounting for 59.09% of the total. Temperate-zone plants constitute a reasonably large proportion, making up 29 genera and 32.95% of the total. As pantropic plants dominate, East-Asian elements are secondary. There is a duality and transition between tropical and temperate elements. Chengbu is rich in wild vine resources with great potential for utilization. Efforts should be made to strengthen the protection and exploration of these resources.

Effects of different years of cultivation abandonment on soil physical, chemical and microbial characteristics in the midstream and downstream of Shiyang River area

CHAI Xiao-Hong, WANG Li-De1, YAO Tuo, HAN Fu-Gui, WEI Lin-Yuan, GUO Chun-Xiu, ZHANG Ying-Hua

2015, 24(8):  24-34.  DOI: 10.11686/cyxb2014395

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Soils have been investigated in midstream and downstream areas of the Shiyang River that had been previously cultivated but abandoned for different numbers of years. The research investigated physical and chemical properties (water content, organic carbon, nitrate nitrogen, ammonium nitrogen, total phosphorus, available phosphorus, total potassium, quick-available potassium, slow-available potassium) and microbes (microbial biomass C, N, P and the number of microorganisms). Results showed that soil ammonium nitrogen and total phosphorus content decreased the longer the land had been abandoned, while water content, organic carbon, nitrate nitrogen, available phosphorus, available potassium and slow-available potassium increased. There were however no significant differences in total potassium and quick-available potassium over the years. Microbial biomass C decreased in 30-40 cm soil layers in land abandoned for shorter periods (1-5 yrs), but increased for longer periods (8-31 yrs). The variability of microbial biomass N increased initially (1-4 yrs), then decreased (4-8 yrs) and finally stabilized (8-31 yrs). Except for 0-10 cm soil layers, the variability of soil microbial biomass P decreased at first (1-2 yrs), then increased (2-8 yrs) and finally decreased (8-31 yrs). Bacteria were the most frequent, followed by actinomycetes, and fungi were the least numerically significant during all stages.

Short-term responses of flowering phenology and community structure to nitrogen, phosphorus and potassium in an alpine meadow on the Qinghai-Tibetan Plateau

YANG Yue-Juan1, 2**, ZHANG Hao3**, ZHOU Hua-Kun1*, YE Xin2, 4, YAO Bu-Qing1, ZHANG Chun-Hui, MA Zhen, ZHAO Xin-Quan

2015, 24(8):  35-43.  DOI: 10.11686/cyxb2014369

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Fertilizers (N, P & K) were applied to a Kobresia humilis meadow at the Haibei Alpine Meadow Ecosystem Research Station to determine the effects of fertilizer on plant flowering phenology and community structure. Fertilizer application increased the effective accumulated soil temperature at 5 and 10 cm depth: nitrogen>phosphorus>potassium>control treatment. The first floweing day and end flowering day was delayed in a number of plant species including Elymus nutans, Agrostis hugoniana, Poa crymophila, Kobresia humilis, Carex atrofusca, Scirpus distigmaticus and Saussurea superb (P<0.05), whereas in Potentilla anserine and Gentiana straminea flowering was advanced (P<0.05). Flowering duration in Gramineae was lower than in Cyperaceae and Forbs following fertilizer application. The application of nitrogen and phosphorus promoted the formation of a heterogeneous community. Heterogeneity, assessed using nonmetric multidimensional scaling, was lowest in control fertilizer treatments followed by potassium, phosphorus, and finally nitrogen application.It was concluded that E. nutans, K. humilis, G. straminea and S. superb were sensitive to the application of nitrogen and phosphorus in K. humilis meadow.

Influence of barnyardgrass (Echinochloa crusgalli) on the growth of double-cropping paddy rice and its economic threshold

ZHANG Ji-Li, WU Shang, SHI Xu-Gen, LI Bao-Tong, TANG Li-Mei

2015, 24(8):  44-52.  DOI: 10.11686/cyxb2014365

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Barnyardgrass (Echinochloa crusgalli) is an important weed in double-cropped paddy fields in southern China and a significant threat to rice production. To determine the influence of barnyardgrass on the growth of double-cropped paddy rice and its economic infestation threshold, the growth and yield of paddy rice under different barnyardgrass densities were investigated using field experiments and modelling. Results showed that plant height, tiller numbers, effective spikes, grain numbers/panicle, 1000-grain weight and grain yield of double-cropped early and late rice decreased with increasing barnyardgrass density. The exponential regression model “y=be^ax” was able to adequately describe the relationship between barnyardgrass density and tillers, effective spikes and yield of double-cropped early rice, while a quadratic regression model “y=ax²+bx+c” was best for plant height, grains/panicle, 1000-grain weight and yield loss. A quadratic regression model “y=ax²+bx+c” was best able to describe the relationship between barnyardgrass density and plant height, tillers, effective spikes, grains/panicle, 1000-grain weight, grain yield and yield loss of double-cropping late rice. Herbicides (butachlor, quinclorac, or penoxsulam) were applied to control barnyardgrass; the economic infestation levels for barnyardgrass were 1.64%-2.91% and 1.28%-2.28% in double-cropped early and late paddy fields, respectively, and the economic thresholds were 0.63-1.23 plant/m² and 1.30-1.85 plant/m², respectively. Barnyardgrass severely inhibited rice growth and yield. Herbicide application effectively and economically controlled barnyardgrass.

Effects of gibberellic acid on nonstructural carbohydrates content in rice (Oryza sativa) straw harvested at different times

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

2015, 24(8):  53-64.  DOI: 10.11686/cyxb2014378

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Gibberellic acid (GA) could effectively delay plant senescence and improve the feed quality of rice (Oryza sativa) straw, but studies have shown that rice plants with applied GA are slow to ripen. In order to investigate the nonstructural carbohydrates (NSC) content of rice straw at different harvest times after GA application, four different rice varieties have been studied: Liangyoupeijiu (late maturing medium indica), Wuyujing 3 (late maturing medium japonica), Nanjing 44 (early maturing late japonica), and Nanjing 46 (medium maturing late japonica). The study investigated three GA application times: 7 days after anthesis (GA-7), 15 days after anthesis (GA-15) and 21 days after anthesis (GA-21). Two harvest times were also set (1: the control grain had reached 80% maturity; 2: 6 days after harvest time 1). The NSC content [including water soluble carbohydrates (WSC) and starch] in different parts of rice straw have been analyzed. The top 3rd internodes of rice plant were used to make freehand cross-sections to observe the starch granule quantities. The results indicate that the NSC content in rice straw is considerable, with japonica scoring higher than indica varieties. The stem is the main storage organ for NSC. WSC content was higher than starch content. At harvest time 1, the optimal GA application time for Liangyoupeijiu was 15 d after anthesis, for Wuyujing 3 21 d after anthesis, and for Nanjing 44 7 d after anthesis. The optimal GA spraying time for Liangyoupeijiu was 21 d after anthesis, 15 d after anthesis for Wuyujing 3, and 21 d after anthesis for Nanjing 44. For Nanjing 46, the optimal GA application time at both harvest times was 15 d after anthesis. Spraying GA during the late growth period could effectively increase the NSC content in rice straw for the indica rice variety Liangyoupeijiu and the medium japonica rice variety Wuyujing 3, but the effects for late maturing japonica varieties Nanjing 44 and Nanjing 46 were not significant.

Effect of intercropping potatoes with oats on the photosynthetic characteristics and yield of potato

WU Na, LIU Xiao-Xia, LIU Ji-Li, LU Wen

2015, 24(8):  65-72.  DOI: 10.11686/cyxb2014349

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Intercropping systems with four different potato-oat row ratios (2∶2, P₂O₂; 2∶4, P₂O₄;4∶2, P₄O₂;4∶4,P₄O₄) were tested to determine effects on the photosynthetic characteristics and yield of potato. During the flowering period, potato leaf area index (LAI) and leaf weight ratio (SLW) decreased significantly. After the first crops of oats are harvested, potatoes receive more light and growth space; thus SLW recovered to a degree. When the crops were mature, the LAI of potato in intercropping systems was higher than that in monoculture. Compared with other intercropping ratios, the LAI and total chlorophyll content under P₄O₄ treatment were significantly higher during the entire growth period. During the flowering period, net photosynthetic rate (P_n), stomatal conductance (G_s) and transpiration rate (T_r) of potato in intercropping systems significantly reduced compared to those in monoculture, while intercellular CO₂ concentration (C_i) significantly increased. However, the photosynthesis indexes decreased at maturation point. Compared to monoculture, intercropped potato returned significant increases in production, possibly due to increased tuber yield and marketable yield per plant, as well as reduced numbers of small potato. The highest yield was obtained under P₄O₄ treatment. Intercropping with oats also returned land equivalent ratios (LER) greater than 1. LER was highest (1.22) under the P₄O₂ treatment, followed by the P₄O₄ treatment. The results suggest that potato/oat row ratios of 4∶2 or 4∶4 perform better than other ratios in this intercropping system.

Effects of GA₃ and CEPA on photosynthetic characteristics and antioxidant enzymes in the flowering phase and the flowering response of Lilium casa blanca

SUN Wei, PAN Yuan-Zhi, QIN Lin-Lan

2015, 24(8):  73-84.  DOI: 10.11686/cyxb2015041

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The process changes of flowering phase(the squaring stage, the early flowering stage, blooming stage, ending flowering) and the changes of photosynthetic characteristics, antioxidant enzymes, the flowering response of Lilium casa blanca were studied using the bulbs of L. casa blanca as pot experimental material under the coordination treatment of gibberellin (GA₃) and ethrel (CEPA).The results showed that, 1) It increased the plant height, thick stems, bud length and flower diameter,advanced the blooming stage and extended the days of blossom of L. casa blanca under the treatment of GA₃ and CEPA during the flowering phase. There were significantly positive correlation between GA₃ and plant height, stem diameter and bud length, while there were a significantly positive correlation between CEPA and stem diameter, bud length and flower diameter. GA₃ made a significant influence in earlier and middle flowering in L. casa blanca. However, CEPA made a significantly negative correlation with ending flowering; 2) The treatment of GA₃ and CEPA both advanced the photosynthetic pigment in leaves of L. casa blanca, and alleviated the downward trend of chlorophyll at the ending flowering time effectively, also it prolonged the photosynthesis time in leaves; 3) The treatment of GA₃ and CEPA both significantly promoted photosynthetic rate (P_n), conductance to H₂O (G_s), transpiration rate (T_r) and stomatal limitation value (L_s), But there were a significantly negative correlation between intercellular CO₂ concentration (C_i), transient energy utilization efficiency (LUE) and others. Analysis showed that, the treatment of GA₃ and CEPA enhanced the activity of leaf cells, increased the intensity of photosynthesis in leaf; 4) MDA content in leaves is lower than CK significantly under the treatment of GA₃ and CEPA during the flowering phase, and the activity of SOD and CAT increased. At the same time, the treatment of GA₃ and CEPA slowed down the downward trend of SOD activity in the middle and ending flowering time, relieved the ageing process of L. casa blanca, and it reached the purpose of extending the time of blossom of L. casa blanca. Comprehensive analysis shows that, the treatment of GA₃ and CEPA advanced the photosynthetic characteristics and antioxidant enzymes of L. casa blanca, It made a significant influence in the blossom quality and flowering phase. Among them, the coordination treatment GA₃ 200 mg/L+CEPA 30 mg/L is the best in regulation on advancing flowering time and extending the days of blossom in L. casa blanca, followed by the single treatment CEPA 60 mg/L and GA₃ 200 mg/L. However, the adjust action decreased in high concentrations coordination treatment GA₃ 200 mg/L+CEPA 60 mg/L and GA₃ 300 mg/L+CEPA 30 mg/L.

Effect of different levels of N supply on P accumulation characteristics of a ‘mining ecotype’ of Pilea sinofasciata

YU Hong-Mei, LI Ting-Xuan, ZHANG Xi-Zhou, ZHENG Zi-Cheng, YU Hai-Ying

2015, 24(8):  85-92.  DOI: 10.11686/cyxb2015023

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Quantities of P fertilizer and organic fertilizer are supplied in agro-ecosystems to improve the soil available P content and maintain soil fertility, but ultimately resulting in P immobilization and accumulation in the soil. Phytoextraction is a practical method for recovering the excess P after soils have become enriched. In order to provide a theoretical basis for extracting excess P from soil to assist with prevention and control of non-point source pollution, it was necessary to determine the P accumulation characteristics of a ‘mining ecotype’ (ME) of Pilea sinofasciata. This material had previously been screened as showing promise for P extraction from enriched soil. The effects of different levels of nitrogen (N) supply (0, 70, 140, 210, 280, 350 mg N/kg) on plant growth and P accumulation characteristics in the ME of P. sinofasciata were analyzed,with a non-mining ecotype (NME) as contrast. All treatments had the same P supply (400 mg P/kg soil). Pot experiments were carried out in a greenhouse at Sichuan Agricultural University, Sichuan province, China in 2013. Key results were: 1)For both shoot and root biomass, P accumulation of P. sinofasciata significantly increased with increased N supply up to 140 mg/kg, and then decreased with additional N supply. Shoot P accumulation of the ME was maximized at 140 mg/kg N supply, and ME demonstrated greater shoot P accumulation (223.73 mg/plant) than the NME (159.79 mg/plant) under different rates of N supply. The bioaccumulation coefficient of the ME was more than 1, while translation rate was more than 50%, and as high as 71%-88%. 2) The activities of acid phosphatase and phytase in P. sinofasciata peaked at N application rates of 350 mg/kg and 140 mg/kg, respectively, and the activities of these two enzymes in the ME were markedly higher (P<0.05) than those in the NME, being increased by a factor of 1.22-1.67, and 1.02-1.07, respectively. In conclusion, the P. sinofasciata ME showed substantial P accumulation ability under N application rates of 70-210 mg/kg. Thus, P. sinofasciata is a good candidate species for P phytoextraction, with the best results obtained when N was added at 140 mg/kg soil.

Effects of brassinosteroid application on osmotic adjustment and antioxidant enzymes in Leymus chinensis under drought stress

SONG Ji-Xuan, LI Jin-Huan, LIU Mei-Ru, NIU Jian-Hang, WANG Ran, LV Jun, ZONG Xue-Feng, WANG San-Gen

2015, 24(8):  93-102.  DOI: 10.11686/cyxb2015001

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Droughts have become increasingly severe in pastoral areas of China and have greatly constrained the productivity of grassland. The influence of brassinosteroids(BR) on the growth and drought tolerance of Leymus chinensis has been studied under controlled soil and water conditions using a pot experiment design. The results showed that drought stress substantially disrupted plant growth and development but that BR could effectively alleviate this damage. The most effective concentration of BR was 0.1 mg/L. Plant height, leaf area, dry weight, water content, chlorophyll a, chlorophyll b, carotenoids, root activity, proline, soluble protein, soluble sugar and 5 kinds of enzyme activity increased with all BR concentrations except for the highest concentration level. BR decreased malondialdehyde (MDA) content and leaf electrical conductivity. The optimal concentration of BR increased the content of photosynthetic pigment and promoted the accumulation of dry matter and root activity compared to the drought control. These changes might be closely related to the decrease of membrane lipid peroxidation production, MDA content and membrane permeability. Also significant may be the increase of osmotic adjustment substances such as proline, soluble protein, soluble sugar, and the enhancement of antioxidase activities such as superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glutathione reductase.

Effects of acidity and/or aluminum stress on seed germination and seedling growth of alfalfa

YANG Dan-Na, LUO Ye-Feng, XIE Jia-Qi, ZHANG Qin, YANG Lie

2015, 24(8):  103-109.  DOI: 10.11686/cyxb2014362

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Alfalfa seeds (cv.Golden empress) were treated with acidic (pH 3.0, 4.5, 6.0, 7.5) and aluminum (0, 50, 100, 200 mg/L Al³⁺) solutions to study the effects of pH and Al³⁺ stresses on seed germination and seedling growth. The results showed that acidity significantly inhibited germination and seedling growth of alfalfa; lower pH had a greater effect than higher pH. Germination rate, germination potential, germination index, stem length and root length of untreated seeds (control) and seeds treated with 50 mg/L Al³⁺ were significantly higher (P<0.05) than all other treatments. Germination and seedling growth were seriously reduced by higher Al³⁺ treatments (100 mg/L or 200 mg/L) which resulted in a significant decrease in the growth index (P<0.05). The combination of acidity and aluminum stress on germination and seedling growth of alfalfa were greater than those of either stress in isolation. Even the treatment of pH<4.5 and Al³⁺>50 mg/L had a significant negative effect on seed germination and growth.

Exogenous nitric oxide elevated alkali tolerance of Avena nuda seedlings

LIU Jian-Xin, WANG Jin-Cheng, WANG Rui-Juan, JIA Hai-Yan

2015, 24(8):  110-117.  DOI: 10.11686/cyxb2014352

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The effects of sodium nitroprusside (SNP) as a nitric oxide (NO) donor on growth, leaf reactive oxygen metabolism and osmotic accumulation in naked oat (Avena nuda) seedlings under NaHCO₃ stress were investigated by a sand nutrient cultivation method. SNP exposure at concentration ranges of 1-200 μmol/L, especially at 25 μmol/L, significantly alleviated NaHCO₃-related growth inhibition of seedlings by decreasing the levels of O2·-, H₂O₂, malondialdehyde and organic acid, and increased the activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and plasma membrane H⁺-ATPase in leaves under 75 mmol/L NaHCO₃ stress. Similarly, the concentrations of reduced glutathione, soluble sugar, soluble protein, free amino acid and proline as well as K⁺/Na⁺ ratio were also increased significantly in seedling leaves under the same stress, but ascorbic acid concentration was not affected significantly. The results indicate that NO may alleviate the damage and growth inhibition caused by alkali stress in naked oat seedlings via activation of antioxidant system activity, acceleration of osmotic accumulation and maintenance of Na⁺ and K⁺ balance, thus improving alkali resistance of the naked oat plants.

QTL mapping and genetic analysis for grain weight in wheat (Triticum aestivum) under different water environments

HU Liang-Liang, YE Ya-Qiong, LV Ting-Ting, LI Meng-Fei, LIU Yuan, CHANG Lei, CHAI Shou-Xi, YANG De-Long

2015, 24(8):  118-129.  DOI: 10.11686/cyxb2015071

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To better understand the molecular quantitative genetic and QTL patterns affecting thousand-grain weight (TGW) in wheat (Triticum aestivum) in different water environments, QTL mapping and genetic analysis were performed for TGW using a mixed linear model approach. TGW was evaluated for recombinant inbred lines (RIL) with 120 progenies from a cross between Longjian 19 (drought tolerant) and Q9086 (drought sensitive) under different water regimes in three environments. Phenotypic expression of TGW in the RILs was highly sensitive to water status and showed wide variation and transgressive segregation. TGW was found to be subject to complex quantitative genetic regulation by minor-effect polygenes, which were easily affected by water environments. A total of 19 additive QTL (A-QTL) and 38 pairs of epistatic QTL (AA-QTLs) were detected for TGW in wheat, distributed on all chromosomes including 1A, 3B, 4D and 6A. Expression of these QTLs influenced the phenotypic variation of TGW resulting in both up- and down-regulation. The magnitude of these effects on TGW ranged from 1.24%-10.94% and 0.38%-2.89%, respectively. Three A-QTLs, Qtgw.acs-1B.1, Qtgw.acs-2A.1 and Qtgw.acs-4A.1, were detected in multiple environments. In addition, four A-QTL hot-spot regions for TGW were also found at some specific locations, e.g., Xmag2064-Xbarc181 on chromosome 1B, Xwmc522-Xgwn122 on chromosome 2A, Xwmc446-Xgwm610 on chromosome 4A and Xwmc603-Xbarc195 on chromosome 7A. Most of the interaction effects of A-QTLs and AA-QTLs associated with drought-stressed environments were linked to down-regulation of the TGW variations. The additive and the additive×environment interaction effects may be the main genetic factors in TGW inheritance, and if so their expression would decrease TGW. The findings of this study should be useful for the genetic improvement of drought tolerance using molecular marker-assisted selection in wheat.

Genome-wide screening and characterization of the U-box gene family in Medicago truncatula

ZHENG Xing-Wei, SHAO Lin-Hui, LI Cong

2015, 24(8):  130-141.  DOI: 10.11686/cyxb2015102

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The U-box domain genes typically exist in multiple variants within plant genomes, and most of them belong to the ubiquitin/proteasome system as E₃ ubiquitin ligase. They play key roles in the regulation of growth, in development, in reproduction as well as in response to environmental stress. In this study, bioinformatics methods were applied to identify U-box family genes of M. truncatula through whole genome screening. A phylogenetic tree was created using the MEGA6 program. Gene structure and chromosome location were defined by GSDS and Mapinspect. A total of 41 U-box genes distributed unevenly on 8 chromosomes were identified from M. truncatula. The U-box proteins were classified into six major classes based on their motif compositions and phylogeny relationships. The expression profiles of M. truncatula U-box genes showed characteristics of tissue specificity and response to salt, drought and nitrogen stress. These results will be useful for future functional analyses of the U-box family genes in M. truncatula.

Molecular characterization of the flanking gene of T-DNA insertional, pathogenicity-defective Colletotrichum gloeosporioides mutant strain 1869

XU Pei-Dong, ZHENG Xiao-Lan, ZHAO Yan, LI Qiu-Jie, WU Wei-Huai, HE Chun-Ping, XI Jin-Gen, LIANG Yan-Qiong, ZHENG Jin-Long, QI Shan-Jiang, ZHANG Xiao-Bo, YI Ke-Xian

2015, 24(8):  142-149.  DOI: 10.11686/cyxb2015094

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Colletotrichum gloeosporioides is a fungal pathogen of Stylosanthes guianensis causing anthracnose disease. Pathogenicity defective mutant strains of C. gloeosporioides were screened in the laboratory and strain 1869 selected for study. The mutant strain was compared with wild type strain CH008 for phenotypic characteristics, including colony diameter, colony morphology, sporulation ability and spore germination rate. Colony diameter of CH008 and strain 1869 differed, but the other traits did not. DNA of the mutant strain was extracted, and using thermal asymmetric interlaced PCR (TAIL-PCR) a T-DNA insertion mutation site believed responsible for loss of pathogenicity was identified. The RB and LB flanking sequences at the insertion site were cloned, also using TAIL-PCR. The RB flanking sequence was 467 bp in length, while the LB flanking sequence was 388 bp. The BLAST result showed that the sequence had 92%-96% homology to gene Pac1. By predicting the function of a protein coded by the flanking sequence,we inferred that the gene in question regulated the sensitivity to pH, and in this way affected the pathogenic potential of C. gloeosporioides.

Gene expression of a detoxification enzyme in Tetranychus urticae resistant to fenpropathrin

YANG Shun-Yi, YUE Xiu-Li, WANG Jin-Jun, LIU Chang-Zhong, SHEN Hui-Min, SHEN Yi-Fan, GUO Jin-Mei

2015, 24(8):  150-158.  DOI: 10.11686/cyxb2014321

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The variation of mRNA gene expression is an important pyrethroid insecticide resistance mechanism in Tetranychus urticae. To identify the molecular mechanism for producing detoxification enzymes in T. urticaein response to fenpropathrin, the mRNA expression levels of glutathione s-transferases (GSTs), cytochrome (P450s) and carboxyl/cholinesterases (CCEs) genes in laboratory fenpropathrin susceptible (SS), fenpropathrin resistant (Sp-R) and field strains (LZ-R, GN-R, WW-R, TS-R and LX-R) of T. urticae were measured using quantitative real time PCR (qRT-PCR). The results showed that relative expression levels of different detoxification enzyme genes varied with different strains of T. urticae. Compared with the SS strain, the expression levels of TuGSTd05 in the WW-R and TS-R strains, TuGSTd01 and TuGSTd06 in the LX-R strain were significantly up-regulated,1.42-2.34 times greater than the SS strain, while TuGSTd04 in the GN-Rstrain, TuGSTd05 and TuGSTd09 in the LX-R strain were significantly down-regulated, 0.41-0.70 that of the SS strain. The expression levels of P450s genes CYP406A1 and CYP4CL1 in the LZ-R, GN-R and WW-R strains were significantly up-regulated, 1.80-4.88 times that of the SS strain. The expression level of P450s genes CYP387A1 in the LZ-R strain was also significantly higher (2.19 times) than the SS strain whereas that in the LX-R strain was significantly lower (0.42 times) than the SS strain. Similarly, the expression levels of CCEs gene TuCCE-35 in the WW-R and TS-R strains was significantly higher than the SS strain. However, the gene expression levels of TuCCE-36 did not change in all strains. The significant up-regulation or down-regulation of detoxification enzyme genes (GSTs, p450s and CCEs) among different strains of T. urticae may be associated with the formation of resistance to fenpropathrin.

Genetic diversity of Elymus nutans under different grazing intensities

CHEN Zhao, LIANG Xin-Ping, HOU Fu-Jiang, TIAN Miao-Miao, ZHANG Hong-Rui, YU Ying, GUAN Yong-Zhuo, WANG Cheng-Zhang, YAN Xue-Bing

2015, 24(8):  159-165.  DOI: 10.11686/cyxb2014355

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Grazing can influence the population genetics and evolution of grassland plant species. To study the relationship between grazing and the potential for evolutionary differentiation and gene flow, we used SSR markers to study the genetic diversity of Elymus nutans. The experiment station investigated is based at Azi, in Maqu County in the Gannan region of Gansu Province. The grazing lands were divided into four levels according to different grazing intensities. Eight pairs of SSR primers were used to detect genetic diversity among 800 individual plants from the four populations under different grazing pressures. The effective number of alleles per locus ranged from 1.2267 to 1.9976. We found that materials under moderate grazing intensity had the highest genetic diversity index, followed by the heavy and then light grazing levels. The genetic differentiation coefficient under different grazing levels is 0.5168. This suggests that genetic variation of the four populations exists mainly among populations. In conclusion, no grazing or enclosure is effective for the conservation of E. nutans genetic resources. For grassland utilization, however, moderate grazing is relatively optimal.

Screening, identification and assessment of endophytic bacteria antagonistic totomato bacterial spot

FENG Zhong-Hong, WANG Yu-Qin, YANG Cheng-De*, XUE Li, CHEN Xiu-Rong

2015, 24(8):  166-173.  DOI: 10.11686/cyxb2014450

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After screening by assessing inhibition zones on nutrient media an antagonistic endophytic bacteria, strain 264ZY7, was identified as having strong antagonistic ability against Pseudomonas syringe pv. tomato which causes bacterial spot on tomatoes. This strain was selected from 120 endophytic bacteria strains isolated from alpine meadow pasture. Strain 264ZY7 produced a 1.22 cm diameter inhibition zone. The bacteria is rod-shaped with a spore size of 1.534 μm×0.571 μm-3.210 μm×0.781 μm, gram-positive and was identified as Bacillus amyloliquefaciens based on morphology and homology analysis of the 16S rDNA and gyrB gene sequence. The control efficacy of strain 264ZY7 on bacterial spot on tomatoes grown in pots ranged up to 69%. It was also able to control fungal pathogens, in particular Fusarium sp. (52.84% efficacy). These results suggest that further development and utilization of this endophytic bacteria strain (264ZY7) should be undertaken.

Identification of cyst nematode in alpine meadow steppe, Gansu

LI Hui-Xia, PENG Huan, PENG De-Liang, ZHU Rui-Dong, XU Peng-Gang, LI Jian-Rong

2015, 24(8):  174-180.  DOI: 10.11686/cyxb2014372

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A survey of grass cyst nematodes in Tianzhu alpine meadow steppe, Gansu Province was conducted in August, 2013. Cyst nematodes were isolated from the roots and root rhizosphere of Kobresia sp. and Kobresia humilis. The nematodes were initially identified as Heterodera avenae based on cyst characteristics, particularly the cyst vulva cones. The cysts were light brown, large lenmon-shaped and contained vulva cones with bifenestrate and obvious bullae and without a vulva under-bridge. The 1045 bp sequence fragment of ITS region was amplified using PCR with general primers AB28 and TW81. The similarities between these groups and H. avena were 99%-100%. Molecular analysis confirmed that the cyst nematodes isolated from Kobresia sp. and Kobresia humilis growing in Tianzhu alpine meadow steppe were H. avenae. This is the first report identifying Kobresia sp. and Kobresia humilis as hosts of H. avenae.

Effects of alfalfa pellet feed on slaughter performance, organ weights and blood biochemical indices of geese

ZHAN Jin-Shun, ZHAN Kang, LIU Ming-Mei, HUO Yong-Jiu, LIN Miao, ZHAO Guo-Qi, YANG Fu-Yu

2015, 24(8):  181-187.  DOI: 10.11686/cyxb2014387

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To investigate effects of alfalfa pellet feed on slaughter performance, organs and blood biochemical indices of geese, 300 healthy Yangzhou geese at 21 d were chosen and randomly divided into 5 groups (control group and trial groups Ⅰ to Ⅳ) with 3 replicates in each group and 20 geese per replicate. The trial period lasted for 7 weeks. The diets of different groups were supplemented with 0 (control group), 8% (group Ⅰ), 12% (group Ⅱ), 16% (group Ⅲ) and 20% (group Ⅳ) alfalfa meal in the first 3 weeks, and 0 (control group), 12% (groupⅠ), 16% (groupⅡ), 20% (group Ⅲ) and 24% (group Ⅳ) in the last 4 weeks, respectively. Key results were: 1) the live weight, semi-eviscerated weight, eviscerated weight, muscle weight, breast muscle weight and tibia weight of geese in group Ⅲ were significantly higher than those in the control group at 42 and 70 days; 2) the thymus weight of geese in group Ⅱ and the liver weight of geese in group Ⅲ were significantly higher than those in the control group (P<0.05) at 42 and 70 days; 3) at 42 days, the levels of TG, TC and LDL of serum in all trial groups except group Ⅱ were significantly lower than those in the control group (P<0.05). In contrast, the control group had significantly higher serum HDL levels than the trial groups. At the 70 days, the levels of TC and HDL of serum in all experimental groups except group Ⅱ were significantly higher than those in control group (P<0.05) but TG levels did not differ between groups. In conclusion, this study indicates that alfalfa pellet diet supplementation can improve slaughter performance, organ development and blood biochemical indices of Yanzhou geese. The optimum levels of alfalfa meal in diet for geese were 16% and 20% at 21 to 42 days and 43 to 70 days, respectively.

Temporal and spatial characteristics of Beijing Golf Courses over the past 30 years

WANG Yong, YU Xin-Fang, ZHUANG Da-Fang

2015, 24(8):  188-198.  DOI: 10.11686/cyxb2014383

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Using Landsat TM/ETM+ images of Beijing from 1986 to 2010, 75 golf courses above 6 ha in area were digitized and analysed. Simultaneously land use/land cover data, geographic data (including roads, administrative division and water bodies) were also used to analyze the spatial and temporal changes of golf courses in Beijing over the past 30 years. The results show that: 1) During 1986 to 2010, the development of golf courses consisted of four categories- “preliminary establishment, stagnation, slow development and rapid development”. Very little development occurred between 1990 and 1999, while slow development occurred in the 2000-2005 period. After 2005 development was rapid. 2) It wasn’t a certain trend that the area of golf courses increased continuously in Beijing, but with spatial differences of golf courses. 3) There was a strong correlation between golf course area changes and land use/land cover. 4) Golf courses were mainly located along the “one ring and two belts”, adjacent to the inner city, the shore of Lake Kanawha and near the rapid traffic line in Beijing.

Effects of crop pattern, tillage practice and water and fertilizer management on weeds and their control mechanisms

ZHAO Yu-Xin, YANG Hui-Min

2015, 24(8):  199-210.  DOI: 10.11686/cyxb2014396

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Field weeds pose significant threats to agricultural production. Weed occurrence is affected by many factors, both natural and artificial. Crop pattern, tillage practices and the management of water and fertiliser are three fundamental factors. In this review paper, we summarize the effects of crop species and the temporal and spatial patterns of cropping. We describe the weed control outcomes of different planting modes, and compare changes in weed communities under different tillage practices and fertiliser applications. Possible control mechanisms are identified by considering the competition for resources between crops and weeds, crop allelopathy and changes in soil seed banks. Reasonable crop rotation, intercropping and mixed intercropping significantly restrain weed occurrence. No-tillage can increase weed community diversity. Straw mulch can reduce weed density and biomass. The effects of fertiliser application on weeds vary due to differences in crop species, fertiliser amount and type. Long-term balanced fertilisation can reduce weed density but increase weed community diversity. Irrigation and improved efficiency of natural precipitation use can inhibit upland weeds, and deep water management at appropriate times can effectively control some weeds in paddy fields. We conclude with some suggestions and prospects for future research on weed control.

Estimating individual above-ground biomass of Leymus chinensis plants

HU Jing, HOU Xiang-Yang, SA Ru-La, GUO Feng-Hui, DING Yong

2015, 24(8):  211-217.  DOI: 10.11686/cyxb2015053

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Biomass is an important component of grassland ecosystem productivity. Models able to describe the productivity of the main plant species in grassland offer the potential to estimate aboveground biomass without physical cutting. In this research the relationships among plant characteristics (leaf number, leaf length×leaf width, stem diameter, stem height and plant height) and individual above-ground biomass was analyzed, subsequently those characteristics able to best predict changes of individual above-ground biomass were selected for modelling. Ninety Leymus chinensis plants were sampled in June (early growing season), July (middle growing season) and August (late growing season), respectively, and total of 270 observations were used to build models able to estimate individual plant above-ground biomass. Equations were obtained using regression analysis using Minitab 16.0, and T-Test analysis was used to compare observed and predicted values. The results showed that leaf length×leaf width and plant height could describe individual above-ground biomass of L. chinensis plants; model Y=-0.193+0.009X₂+0.011X₅ (X₂ indicated leaf length×leaf width,X₅ indicated plant height, P<0.01, R²=0.854).

P fertilization effects on the accumulation, transformation and availability of soil phosphorus

LI Xin-Le, HOU Xiang-Yang, MU Huai-Bin, LI Xi-Liang, GUO Feng-Hui

2015, 24(8):  218-224.  DOI: 10.11686/cyxb2014388

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The effects of phosphorus (P) fertilization on the accumulation, transformation and availability of P in soil chemistry have drawn much attention in recent years. This paper reports on a six-year fertilization experiment (beginning in 2008) with alfalfa grown in the south region of Beijing. The soil type in the study area is fluvo-aquic. Before the experiment was performed, soil organic matter was 11.2 g/kg, total P was 0.77 g/kg, available P was 5.66 mg/kg and soil pH was 8.3 in the topsoil (0-20 cm). The results showed that the contents of total P, available P and inorganic P in various forms decreased markedly without P fertilization and increased significantly when P fertilizer was applied. Total P and available P in soils without fertilization decreased by 6.94% and 16.3% respectively, while in soil treated with six years fertilization they increased by 1.3%-13.0% and 164.7%-335.9% respectively. The effects of different P fertilizer treatments on Ca₂-P content were significant. Ca₂-P content was almost depleted in the non-fertilization treatment, while levels in the fertilization treatment increased 19-36 times. P fertilization also increased the soil content of Ca₈-P, Ca₁₀-P, Al-P, Fe-P, O-P. When fertilization was stopped in 2013 it was found that no significant differences existed in soil P level, alfalfa yield and nutrient content between the treatments of continued fertilization (F₂) and ceased fertilization (F₂'). The results indicate that long term P fertilization has significant and continuous effects. The accumulation of P in soil contents should also enhance future biological performance.

Karyotype analysis and mitotic observation of Elymus sibiricus

ZHENG Hui-Min, MAO Pei-Sheng, HUANG Ying

2015, 24(8):  225-229.  DOI: 10.11686/cyxb2014371

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A study has been undertaken to determine the karyotype of Elymus sibiricus. The results showed that the chromosome number of E. sibiricus was 28, with a pair of satellites on the short arms of the 13^th chromosomes. Its karyotype formula is 2n=4x=24m+4sm (2SAT). The percentage of chromosomes with arm ratios over 2 was 7.14%, and the ratio of the longest to the shortest was 2.04. Its karyotype asymmetry is 2B. There were five phases (Interphase, Prophase, Prometaphase, Metaphase and Anaphase) in the process of mitosis. At interphase the nuclei were dyed homogeneously. During prophase the shape of the slender chromosomes was visible. The individual chromosome could be identified clearly in the prometaphase. At metaphase the chromosomes highly concentrated and the chromatids and centromeres were distinctly visible. During anaphase the chromatids separated and moved to the opposite poles.