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Duan T.,Lanzhou University | Duan T.,Key Laboratory of Grassland Agro Ecosystems | Duan T.,University of Adelaide | Shen Y.,Lanzhou University | And 5 more authors.
Plant and Soil | Year: 2010

Agricultural practices aimed to reduce soil erosion and improve crop yield have been suggested to influence the activity of arbuscular mycorrhizal (AM) and root pathogenic fungi. We conducted a two-year field survey to investigate the effect of recently introduced agricultural practices on crop yield, AM colonisation and percentage isolation of root-invading fungi on the heavily eroded Loess Plateau of China. A rotation of maize (Zea mays L.), winter wheat (Triticum aestivum L.) and soybean (Glycine max L.) replaced monoculture of winter wheat. No-tillage (NT), and return of previous crop residues to the field in tilled (CTR) and non-tilled (NTR) systems replaced conventional tillage (CT). Yield, biomass and phosphorus content of the crops showed similar trends. Residue application increased yields of maize and soybean independent of tillage treatment in 2004, but only under CT in 2005. CT slightly increased maize yield. Neither residue application nor tillage treatment affected yield of wheat. None of the treatments influenced total percent isolation of root-invading fungi from wheat roots. The increase of some individual pathogenic fungi in NT did not translate into reduction of yield by disease. Importantly, the recommended practices did not have a penalty on yield while maintaining high levels of AM colonisation. © 2009 Springer Science+Business Media B.V.


Duan T.,Lanzhou University | Duan T.,Key Laboratory of Grassland Agro Ecosystems | Duan T.,University of Adelaide | Facelli E.,University of Adelaide | And 4 more authors.
Soil Biology and Biochemistry | Year: 2011

The effects of soil disturbance and residue retention on the functionality of the symbiosis between medic (Medicago truncatula L.) and arbuscular mycorrhizal fungi (AMF) were assessed in a two-stage experiment simulating a crop rotation of wheat (Triticum aestivum L.) followed by medic. Plants were inoculated or not with the AMF, Glomus intraradices and Gigaspora margarita, separately or together. The contribution of the arbuscular mycorrhizal (AM) pathway for P uptake was determined using 32P-labeled soil in a small hyphal compartment accessible only to hyphae of AMF. In general AM colonization was not affected by soil disturbance or residue application and disturbance did not affect hyphal length densities (HLDs) in soil. At 4 weeks disturbance had a negative effect on growth and phosphorus (P) uptake of plants inoculated with G. margarita, but not G. intraradices. By 7 weeks disturbance reduced growth of plants inoculated with G. margarita or AMF mix and total P uptake in all inoculated plants. With the exception of plants inoculated with G. margarita in disturbed soil at 4 weeks, the AM pathway made a significant contribution to P uptake in all AM plants at both harvests. Inoculation with both AMF together eliminated the negative effects of disturbance on AM P uptake and growth, showing that a fungus insensitive to disturbance can compensate for loss of contribution of a sensitive one. Application of residue increased growth and total P uptake of plants but decreased 32P in plants inoculated with the AMF mix in disturbed soil, compared with plants receiving no residue. The AMF responded differently to disturbance and G. intraradices, which was insensitive to disturbance, compensated for lack of contribution by the sensitive G. margarita when they were inoculated together. Colonization of roots and HLDs in soil were not good predictors of the outcomes of AM symbioses on plant growth, P uptake or P delivery via the AM pathway. © 2010 Elsevier Ltd.


Li W.,Lanzhou University | Li W.,Key Laboratory of Grassland Agro ecosystems | Xu J.,Lanzhou University | Xu J.,Lanzhou University of Finance and Economics
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2014

In the past 15 years (1995-2010), remotely sensed landscape index analysis, indoor and outdoor experimental analysis and statistical analysis were utilized to study a typical alpine wetland at Maqu County in eastern Qinghai-Tibet Plateau of China for the relation between landscape change and climate change. We investigated: 1) The decision tree module for wetland information extraction was built through analyzing data with spatial character, spectrum character and statistic. 2) changes of alpine wetland landcover and the main climate characteristics (temperature, precipitation) of the alpine wetland; and 3) dynamic changes and causes of alpine wetland landscape. The results indicated the method of decision tree was suitable for information extraction of alpine land, and the local climate change was the primary cause for resulting in reduction of wetland areas and degradation of wetlands in the last many years. © 2014 IEEE.


Li W.,Lanzhou University | Xu J.,Key Laboratory of Grassland Agro ecosystems | Xu J.,Lanzhou University | Xu J.,Lanzhou University of Finance and Economics | Wang H.,CAS Research Center for Eco Environmental Sciences
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2014

Based on the dimidiate pixel model and remote sensing technique, a new alpine grassland vegetation coverage analysis model on the basis of NDVI index was built and the fractional vegetation coverage was estimated in Gannan state in year 2000, 2002, 2004, 2006, 2008 and 2010 from MODIS data. Thus, the character of dynamic changes of the grass vegetation coverage was figured out with the varied 5 levels estimation results of vegetation fractional coverage and results of transfer matrixes based on GIS spacial analysis in the past 11 years. The results indicated that from year 2000 to 2010, the deterioration of grassland vegetation coverage in Gannan was general, and the degradation of level 1 the best stage of grass vegetation cover is higher absolutely. What's more, the change of grassland cover indicated the trend of transform from high-stage (level 1, level 2) to low-stage (level 4, level 5) coverage. The research informed the fact further that the grassland vegetation in Gannan area is degrading more and more seriously, and it will be useful to the academic research and rangeland management by government. © 2014 IEEE.


Li W.,Lanzhou University | Li W.,Key Laboratory of Grassland Agro Ecosystems | Xu J.,Lanzhou University | Xu J.,Lanzhou University of Finance and Economics
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2012

In this study, remotely sensed landscape index analysis over 15 years, indoor and outdoor experimental analysis and statistical analysis were utilized to study a typical alpine wetland at Maqu County in eastern Qinghai-Tibet Plateau in China for the relation between landscape change and climate change. We investigated: 1) changes of alpine wetland landcover; 2)changes of the main climate characteristics (temperature, precipitation) of the alpine wetland; and 3) dynamic changes and causes of alpine wetland landscape. The results indicated the local climate change was the primary cause for resulting in reduction of wetland areas and degradation of wetlands over the last 15 years. © 2012 IEEE.


Zhang X.,Key Laboratory of Grassland Agro Ecosystems | Fan X.,Lanzhou University | Li C.,Key Laboratory of Grassland Agro Ecosystems | Nan Z.,Key Laboratory of Grassland Agro Ecosystems
Plant Growth Regulation | Year: 2010

The effects of cadmium (Cd) on germination, and antioxidative enzyme activity (AEA) involving superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase, and on amounts of malondialdehyde and proline present within Achnatherum inebrians, were determined for specimens infected (E+) vs. non-infected (E-) by Neotyphodium gansuense, and cultivated in the presence of various concentrations of CdCl2 (0, 50, 100, 200 and 300 μmol/l). Under high Cd concentrations (100, 200 and 300 μM), E+ (vs. E-) specimens exhibited a higher germination rate and index, and higher values for shoot length, root length and dry biomass, but there was no significant difference (P > 0.05) under low Cd concentrations (0 and 50 μM). AEA and the proline content increased, but malondialdehyde content declined in the E+ (vs. E-) specimens under high Cd concentrations (100, 200 and 300 μM). There was no significant difference (P > 0.05) under low Cd concentrations (0 and 50 μM). Endophyte infection was concluded to be of benefit to the germination and anti-oxidative mechanisms within A. inebrians under plant exposures to high CdCl2 concentrations. © Springer Science+Business Media B.V. 2009.


Song H.,Key Laboratory of Grassland Agro Ecosystems | Song H.,Lanzhou University | Nan Z.,Key Laboratory of Grassland Agro Ecosystems | Nan Z.,Lanzhou University
PLoS ONE | Year: 2015

Asexual Epichloë species are likely derived directly from sexual Epichloë species that then lost their capacity for sexual reproduction or lost sexual reproduction because of interspecific hybridization between distinct lineages of sexual Epichloë and/or asexual Epichloë species. In this study we isolated asexual Epichloë endophytes from Elymus species in western China and sequenced intron-rich regions in the genes encoding β-tubulin (tubB) and translation elongation factor 1-α (tefA). Our results showed that there are no gene copies of tubB and tefA in any of the isolates. Phylogenetic analysis showed that sequences in this study formed a single clade with asexual Epichloë bromicola from Hordeum brevisubulatum, which implies asexual Epichloë endophytes that are symbionts in a western Chinese Elymus species likely share a common ancestor with asexual E. bromicola from European H. brevisubulatum. In addition, our results revealed that asexual E. bromicola isolates that are symbionts in a western Chinese Elymus species and sexual Epichloë species that are symbionts in a North American Elymus species have a different origin. Further analysis found that Epichloë species likely originated in Eurasia. In addition, the results support the hypothesis that migratory birds or humans might have aided the dispersal of these fungal endophytes to other continents. © 2015 Song, Nan.

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