Zhangye City Research Articles

Modelling and Evaluation of Potato Water Production Functions in a Cold and Arid Environment

This study was conducted at the Yimin Irrigation Experiment Station, Minle County, Zhangye City, Gansu Province, from April to October in 2019 and 2020. The relationship between water consumption and yield of potato at different stages of fertility under deficit-regulated irrigation was analyzed in a field trial study over two growing seasons. The results showed that the average annual water consumption in the tuber bulking stage was the largest, reaching 185.35~239.52 mm, followed by the average annual water consumption in the tuber initiation stage and starch accumulation stage, which were 100.02~132.30 mm and 82.48~112.36 mm, respectively, and the average annual water consumption in the seedling stage was the least, at 49.32~69.81 mm. Simultaneously, the average annual yield of potatoes in the treatment of WD1 was the highest, reaching 47,766.96 kg·hm−2, followed by CK, which was 43,707.6 kg·hm−2, and the yield of WD6 was the smallest in the treatment of moderate water deficit during tuber initiation, which was only 35,721.25 kg·hm−2. Combining the four moisture production function models of Jensen, Minhas, Blank and Stewart, the Jensen and Stewart models were identified as suitable for the potato moisture production function in a cold and arid environment. The water production function model was used to investigate the relationship between water consumption and yield in each growth period of potato, and to provide a theoretical basis for the optimization of the irrigation system under deficit-regulating irrigation conditions for potato in this irrigation area.

A Case Analysis of Dust Weather and Prediction of PM10 Concentration Based on Machine Learning at the Tibetan Plateau

Dust weather is common and disastrous at the Tibetan Plateau. This study selected a typical case of dust weather and analyzed its main development mechanism in the northeast of the Tibetan Plateau, then applied six machine learning methods and a time series regression model to predict PM10 concentration in this area. The results showed that: (1) The 24-h pressure change was positive when the front intruded on the surface; convergence of vector winds with a sudden drop in temperature and humidity led by a trough on 700 hPa; a “two troughs and one ridge” weather situation appeared on 500 hPa while the cold advection behind the trough was strong and a cyclone vorticity was formed in the east of Inner Mongolia. (2) The trajectory of air mass from the Hexi Corridor was the main air mass path influencing Xining City, in this case, since a significant lag in the peak of PM10 concentration appeared in Xining City when compared with Zhangye City. (3) The Multiple Linear Regression was not only timely and effective in predicting the PM10 concentration but had great abilities for anticipating the transition period of particle concentration and the appearance date of maximum values in such dust weather. (4) The MA and MP in the clean period were much lower than that in the dust period; the PM10 of Zhangye City as an eigenvalue played an important role in predicting the PM10 of Xining City even in clean periods. Different from dust periods, the prediction effect of Random Forest Optimized by Bayesian hyperparameter was superior to Multiple Linear Regression in clean periods.

Comparative Study on Farmland Circulation between Plains and Mountainous Areas in an Arid Region: A Case Study of Zhangye City in Northwest China

Farmland circulation is essential for agricultural scale management. Due to rapid urbanization and industrialization, a large number of rural laborers have migrated to cities, resulting in accelerated farmland circulation. Revealing the farmland circulation in different geographical environments is conducive to efficient farmland management but remain largely unknown. To this end, based on the questionnaire survey data and statistical data of Zhangye City, we compared the features of farmland circulation between plains and mountainous areas, and used the binary logistic regression model and other methods to analyze the main factors affecting differentiated farmland circulation at the plot level. The main circulation modes and proportions in the plains were leasing (54.4%), exchange (22.4%), and subcontracting (16.2%), while the single leasing mode in mountainous areas accounted for 89.5%. The scale management units of more than 33.33 ha accounted for 6.48% and 30.72% in plains and mountainous areas, respectively. The proportion of circulation periods exceeding 5 years were 28.13% and 2.23% in plains and mountainous areas, respectively. The factor of “degree of farmland fragmentation” positively affected (p < 0.01) the farmland circulation in plains areas but negatively affected (p < 0.01) that in mountainous areas. The “farmland circulation price” promoted (p < 0.01) farmland circulation in both plains and mountainous areas. Whereas the “actual water diversion” (p < 0.01) and “river source water” (p < 0.05) only had varying degrees of negative impacts on farmland circulation in plains areas. Decision makers should practice management measures such as regulating farmland circulation behavior, formulating reasonable farmland circulation pricing models, and integrating farmland to promote the circulation and efficient use of farmland.

“山地-绿洲-荒漠”复合系统土地利用变化的生态系统服务权衡与协同效应——以张掖市为例

PDF HTML阅读 XML下载 导出引用 引用提醒 “山地-绿洲-荒漠”复合系统土地利用变化的生态系统服务权衡与协同效应——以张掖市为例 DOI: 10.5846/stxb202109122560 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（42101276）；甘肃省科技计划项目（20JR5RA529）；国家自然科学基金项目（41661035）；国家自然基金地区基金（41961027） Ecosystem service tradeoffs and synergies effects of land use change in Mountain-Oasis-Desert complex system: A case study of Zhangye City Author: Affiliation: Fund Project: National Natural Science Foundation of China, No.42101276; Science and Technology Project of Gansu Province, No.20JR5RA529; National Natural Science Foundation of China, No.41661035; Regional Fund of National Natural Science Foundation of China, No.41961027 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:开展复合生态系统土地利用变化的生态服务效应研究可为优化国土空间格局和强化生态系统管理提供重要的基础依据。以干旱区"山地-绿洲-荒漠"复合系统的典型区域张掖市为例，基于1987年、2000年和2018年3期土地利用数据，以乡级行政区为基本单元，引入相对优势度指数划分山地、绿洲、荒漠子系统，研究复合系统的土地利用变化特征及生态系统服务权衡/协同效应。结果表明：（1）张掖市复合系统呈现地域分异特征，由南部山地系统，中部绿洲系统和北部荒漠系统构成；山地系统以林地和草地为主，绿洲系统以耕地和建设用地为主，荒漠系统以未利用地为主。（2）从时间上看，2000-2018年各系统的土地利用变化更强烈，其中，绿洲系统的耕地面积增加量最大，为363.08km2，荒漠系统的建设用地面积增加幅度最大，为78.23%。各系统土地利用转移模式为：山地系统以草地转耕地为主，绿洲系统和荒漠系统以未利用地转耕地为主。（3）张掖市复合系统的生态服务价值呈增加趋势，其中，荒漠系统生态服务价值量的增幅最大，各子系统的价值量之间的关系表现为山地系统 > 绿洲系统 > 荒漠系统，耕地对各系统生态服务价值贡献量最大。（4）张掖市土地利用变化的协同效应大于权衡效应，其中荒漠系统的生态服务之间均为协同关系，山地系统中供给服务与其他服务呈现权衡关系，占比32.73%，绿洲系统中调节服务与其他服务呈现权衡关系，占比18.18%。 Abstract:Research on the ecosystem service effects of land use change in complex ecosystem can provide an important basis for optimizing land spatial pattern and strengthening ecosystem management. Taking Zhangye City, a typical area of Mountain-Oasis-Desert complex system in arid area as an example, based on three phases of land use data in 1987, 2000 and 2018, taking the township administrative region as the basic unit, the comparative advantage index is introduced to divide the mountain, oasis and desert sub-system, and the land use change characteristics of the complex system and the trade-off/synergy effects of ecosystem services are studied. The results show that:(1) The complex system of Zhangye City presents the characteristics of regional differentiation, which is composed of southern mountain system, central oasis system and northern desert system. The mountain system is mainly consisted of forest land and grassland, the oasis system is mainly consisted of cultivated land and construction land, and the desert system is mainly consisted of unused land. (2) In terms of time change, the land use change of each system was more intense from 2000 to 2018. Among them, the increase of the cultivated land area of oasis system was the largest with 363.08 km2, and the increase rang of the construction land area of desert system was the largest with 78.23%. The land use transfer mode of each system is as follows:the mountain system is mainly from grassland turn into cultivated land, and the oasis system and desert system are mainly from unused land turn into cultivated land. (3) The ecosystem service value of the complex system in Zhangye City shows an increasing trend. Among them, the increase rang of the ecosystem service value of the desert system is the largest. The relationship between the value of each sub-system is mountain system > oasis system > desert system, and compared with other land use types, the contribution of the cultivated land to the ecological service value of each system is the largest. (4) The synergy effect of land use change in Zhangye is greater than the trade-off effect. Among them, the ecosystem services of the desert ecosystem are all synergistic relationships. The supply service of the mountain system has a trade-off relationship with other services, accounting for 32.73% of the trade-off relationship, and the regulation service of the oasis system has a trade-off relationship with other services, accounting for 18.18% of the trade-off relationship. 参考文献 相似文献 引证文献

干旱区绿洲城镇景观生态风险时空变化分析——以张掖绿洲乡镇为例

PDF HTML阅读 XML下载 导出引用 引用提醒 干旱区绿洲城镇景观生态风险时空变化分析——以张掖绿洲乡镇为例 DOI: 10.5846/stxb202105111234 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家社科基金重大项目（18ZDA053）；国家自然科学基金项目（41661035） Spatio-temporal evolution of landscape ecological risk in oasis cities and towns of arid area: A case study of Zhangye Oasis Township Author: Affiliation: Fund Project: National Social Science Foundation of China（No.18ZDA053）; National Natural Science Foundation of China,（No.41661035） 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:科学评估与分析干旱区绿洲乡镇景观生态风险，对优化绿洲土地资源管控和维护干旱区绿洲生态系统稳定性具有重要现实意义。以张掖市绿洲乡镇为对象，基于土地利用数据和景观格局指数，结合ArcGIS空间分析功能，研究其景观生态风险时空特征及影响因素。结果表明：1987-2018年，耕地和建设用地变化明显，分别增加429.03 km2和236.26 km2；整体景观生态风险呈下降趋势，并呈"南北高、中间低"格局特征；各乡镇风险水平在空间上正向聚集，位于绿洲边缘地区的乡镇风险变化明显；人为活动干扰是近年风险水平变化的主要因素。研究成果可为西北干旱区绿洲生态保护与治理提供决策参考。 Abstract:The scientific assessment and analysis of landscape ecological risks in oasis towns is of great practical significance for optimizing management and control of oasis land resources and maintaining the stability of oasis ecosystem in arid areas. Based on land use data and landscape pattern index, combined with ArcGIS spatial analysis function, this paper studied the temporal and spatial characteristics and influencing factors of landscape ecological risk in oasis towns in Zhangye City. The results showed that the cultivated land and construction land have changed significantly from 1987 to 2018, with an increase of 429.03 km2 and 236.26 km2, respectively. The overall landscape ecological risk level showed a downward trend and the pattern of high in the north and south while low in the middle. The risk level of each township is positively aggregated in space, and the dramatic change of the estimated risk was also found on the edge of the oasis. Human disturbance is the main factor of risk level change in recent years. The research results can provide decision-making reference for ecological protection and management of oases in arid areas of northwestern China. 参考文献 相似文献 引证文献

Ways to Improve the Productivity of Oasis Agriculture: Increasing the Scale of Household Production and Human Capital? A Case Study on Seed Maize Production in Northwest China

Oasis agriculture in arid areas faces the constraints of scarce resources and a fragile ecological environment. Improving agricultural production efficiency is the key solution. However, there are few studies analyzing the relationship between farmers’ production efficiency and planting scale from a micro-empirical perspective. Herein, we study the seed-producing corn growers in Zhangye city, and supplement special survey data with national input–output survey data. We use data envelopment analysis to measure agricultural production efficiency, and tobit regression to calculate the marginal effects of factors affecting production efficiency on farms of different scales. The results show that production efficiency is greater for large-scale farmers than for small-scale farmers. Duration of technical training, education time of laborers, planting income, and productive expenditure are significantly positively correlated with production efficiency. Average age of farmers and the amount of pesticide and fertilizer use are significantly negatively correlated with production efficiency. Off-farm activities improve the production efficiency of small-scale farmers but inhibit it for medium- and large-scale farmers. Differences exist in marginal impacts for different scales of farmland. We conclude that expanding the scale of family farms and optimizing human capital are effective for improving agricultural production efficiency in arid oasis areas.

First report of Leptosphaeria biglobosa 'canadensis' causing blackleg on oilseed rape (Brassica napus) in China.

Oilseed rape (Brassica napus L.) is one of the most important oilseed crops in China. It is widely cultivated in China, with winter oilseed rape in Yangtze River basin and in southern China, and spring oilseed rape in northern China. In August 2017, a survey for Leptosphaeria spp. on spring oilseed rape was conducted in Minle county, Zhangye city, Gansu Province, China. The symptoms typical of blackleg on basal stems of oilseed rape were observed in the field. A large number of black fruiting bodies (pycnidia) were present on the lesions (Fig. 1A). The disease incidence of basal stem infection in the surveyed field was 19%. A total of 19 diseased stems were collected to isolate the pathogen. After surface sterilizing (75% ethanol for 30 s, 5% NaOCl for 60 s, followed by rinsing in sterilized water three times), diseased tissues were cultured on acidified potato dextrose agar (PDA) plates at 20°C for 7 days. Twelve fungal isolates were obtained. All fungal isolates produced typical tan pigment on PDA medium, and produced pycnidia after two weeks (Fig. 1B). Colony morphological characteristics indicated that these isolates might belong to Leptosphaeria biglobosa. To confirm identification, multiple PCR was conducted using the species-specific primers LmacF, LbigF, LmacR (Liu et al. 2006). Genomic DNA of each isolate was extracted using the cetyltrimethylammonium bromide (CTAB) method. DNA samples of L. maculans isolate UK-1 and L. biglobosa isolate W10 (Cai et al. 2015) were used as references. Only a 444-bp DNA band was detected in all 12 isolates and W10, whereas a 333-bp DNA band was detected only in the UK-1 isolate (Fig. 1C). PCR results suggested that these 12 isolates all belong to L. biglobosa. In addition, the internal transcribed spacer (ITS) region of these 12 isolates was analyzed for subspecies identification (Vincenot et al. 2008). Phylogenetic analysis based on ITS sequence showed that five isolates (Lb1134, Lb1136, Lb1138, Lb1139 and Lb1143) belonged to L. biglobosa 'brassicae' (Lbb) with 78% bootstrap support, and the other seven isolates (Lb1135, Lb1137, Lb1140, Lb1141, Lb1142, Lb1144 and Lb1145) belonged to L. biglobosa 'canadensis' (Lbc) with 95% bootstrap support (Fig. 1D). Two Lbb isolates (Lb1134 and Lb1136) and two Lbc isolates (Lb1142 and Lb1144) were randomly selected for pathogenicity testing on B. napus cultivar Zhongshuang No. 9 (Wang et al. 2002). Conidial suspensions (10 μL, 1 × 107 conidia mL-1) of these four isolates were inoculated on needle-wounded cotyledons (14-day-old seedling), with 10 cotyledons (20 wounded sites) per isolate. A further 10 wounded cotyledons were inoculated with water and served as controls. Seedlings were maintained in a growth chamber at 20°C with 100% relative humidity and a 12-h photoperiod. After 7 days, cotyledons inoculated with the four isolates showed necrotic lesions in the inoculated wounds. Control cotyledons had no symptoms (Fig. 2). Fungi re-isolated from the infected cotyledons showed similar colony morphology as the original isolates. Therefore, L. biglobosa 'brassicae' and L. biglobosa 'canadensis' appear to be the pathogens causing the observed blackleg symptoms on spring oilseed rape in Gansu, China. In previous studies, L. biglobosa 'brassicae' has been found in many crops in China, including oilseed rape (Liu et al. 2014; Cai et al. 2015), Chinese radish (Raphanus sativus) (Cai et al. 2014a), B. campestris ssp. chinensis var. purpurea (Cai et al. 2014b), broccoli (B. oleracea var. italica) (Luo et al. 2018), ornamental kale (B. oleracea var. acephala) (Zhou et al. 2019a), B. juncea var. multiceps (Zhou et al. 2019b), B. juncea var. tumida (Deng et al. 2020) and Chinese cabbage (B. rapa subsp. pekinensis) (Yu et al. 2021 accepted). To the best of our knowledge, this is the first report of L. biglobosa 'canadensis' causing blackleg on B. napus in China.

Scenario-Based Analysis of Land Use Competition and Sustainable Land Development in Zhangye of the Heihe River Basin, China

Rapid economic growth has a significant impact on land use change, which would threaten the natural ecology. Zhangye city of the Heihe River Basin, China is an ecologically vulnerable region where land use changes significantly due to socioeconomic development and population increases. The study employed a computable general equilibrium of land use change (CGELUC) model to simulate land use change and then used a dynamic land system (DLS) model to spatialize land use change during 2015–2030 under three development scenarios in Zhangye city. The three development scenarios are the baseline scenario (BAU), the resource consumption scenario (RCS) and the green development scenario (GDS). We found that economic growth would lead to land demand increases in high value-added industries and decreases in low value-added industries. The cultivated land would decrease while the built-up area would increase. By 2030, the cultivated land will decrease by 8.16%, 10.89% and 4.16%, respectively, under BAU, RCS and GDS, while the built-up area will increase by 8.61%, 10.39% and 4.75%, respectively. The expansion of built-up area under RCS presents spatial characteristics of centralized distribution, while spatial characteristics of uniform discrete distributions are presented under GDS. The expansion of ecological land under GDS would be considerable, especially in the north of Sunan County and Gaotai County, and around the natural reserve of Ganzhou County. This paper provides a scientific reference for coordinating economic development and ecological protection in the rapidly developing urbanized areas in western China.

Spatial Pattern Analysis of a Water-Related Ecosystem Service and Evaluation of the Grassland-Carrying Capacity of the Heihe River Basin under Land Use Change

A key challenge to the sustainability and security of grassland capacity is the protection of water-related ecosystem services (WESs). With the change of land use, the supply of aquatic ecosystem services has changed, and the grassland-carrying capacity has been affected. However, the correlation mechanism between WESs and the grassland-carrying capacity is not clear. In this study, we used the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model to evaluate the impact of land-use change on WESs, and made a tradeoff analysis between WESs and grassland-carrying capacity. Considering that the Heihe River Basin (HRB) was an important grassland vegetation zone, which was a milestone for the development of animal husbandry in China, HRB was taken as a case. The main findings are as follows: (1) the spatial distribution of WESs shows the dissimilation rule, the upper reaches are the main water yield area, the soil retention is weakening in the middle and lower reaches, and the pollution has further increased in the middle and upper reaches. (2) The carrying capacity of animal husbandry decreased in the upper reaches, increased in Shandan County and Zhangye City in the middle reaches, and decreased sharply in other regions. (3) There was a positive correlation between the livestock-carrying capacity and nitrogen export in 2018, which was increasing. As the change of land use has changed the evapotranspiration structure, WESs have undergone irreversible changes. Meanwhile, the development of large-scale irrigated farmland and human activities would be the source of a further intensification of regional soil erosion and water pollution. Therefore, it is necessary to trade off the WESs and animal husbandry under land-use change. This paper revealed how WESs changed from 2000 to 2018, the characteristics of the changes in the spatial and temporal distribution, and the carrying capacity. It aims to provide a scientific basis for coordinating the contradiction between grassland and livestock resources, improving the regional ecological security situation, and carrying out ecosystem management.

The driving force of water resource stress change based on the STIRPAT model: take Zhangye City as a case study

The driving force of water resource stress change based on the STIRPAT model: take Zhangye City as a case study

First Report of Fusarium equiseti Causing Fusarium Wilt on Potato (Solanum tuberosum) in China.

Potato (Solanum tuberosum) is one of the most economically important crops in China, containing carbohydrates, protein, fiber, numerous vitamins and minerals, and is a heart healthy food (Raidl, 2020). Potato infected by Fusarium spp. exhibits quality and yield decline, and even death. In infected plants, the upper leaves exhibit chlorosis, the lower leaves wither and the vascular bundles of stems and tubers turn yellow, and then tan to brown. In August 2018, symptomatic potato stems and roots were collected from Zhangye city, Gansu province, China. Diseased stem tissues were surface sterilized with 75% alcohol for 30 s, and then rinsed in sterile water. The tissue pieces were placed on potato dextrose agar (PDA) and incubated at 25°C in darkness. Fusarium-like colonies were consistently isolated and three monoconidial isolates were obtained. Isolate 3SMJ-2 was selected as a representative for morphological characterization, molecular analysis, and pathogenicity tests. 3SMJ-2 was inoculated in PDA liquid medium, grown on a shaker for 7 days at 25℃ to obtain a mix suspension of hypha fragments and spores (107 spores/mL). Healthy potato plants, named "Xin Daping" and were planted in pots (17 cm diameter by 12 cm) filled with 2L of sterile soil per pot. After 8 weeks, the plants were inoculated with the inoculum or distilled water. Then they were incubated in growth chambers at 25°C under a 12-h/12-h day/night potato period with 90% relative humidity for 24 h. For each treatment, 3 pots were inoculated. After 50 days, 100% of the inoculated potato plants exhibited wilt symptoms similar to those in the field but the control plants were symptomless. A Fusarium identical to strain 3SMJ-2 was re-isolated from symptomatic potato plants to fulfilling Koch's postulates. Morphological characteristics of the re-isolated strain were identical to the original isolate, which confirmed pathogenicity of strain 3SMJ-2 originally isolated from the potatoes. Colonies of 3SMJ-2 were white with short conidiophores, a few microconidia and sickle-shaped macroconidia (25.2 to 42.9× 3.1 to 4.6 µm) (n = 60) with 4~7 septa, and mostly 5 septa, after cultivated on PDA in an incubator at 25℃ for 14 days. Spherical terminal or intercalary chlamydospores were observed on the mycelium. Strain 3SMJ-2 was identified preliminarily as Fusarium sp. based on morphological characteristics (Leslie et al., 2006). Genomic DNA was extracted from 3SMJ-2 using the OMEGA Fungal DNA kit according to the manufacturer's protocol. The internal transcribed spacer (ITS), translation elongation factor 1-alpha (TEF) and RNA polymerase II second largest subunit (RPB2) were amplified using ITS1/ITS4 (White et al., 1990), Ef728M/Tef1R (Stępień et al., 2012) and 5F2 /7cR (O'Donnell et al., 2007), respectively. After sequencing by Beijing TSINGKE Biological Technology Co., Ltd., 3 fragments of approximately 519 bp, 587 bp and 1059 bp from the strain 3SMJ-2 were deposited in GenBank as MN420681, MW561963 and MW561964. The ITS, TEF and RPB2 sequences were 100%, 100% and 99.8% identical to those of F.equiseti (KY365589, KF499577, and MH582110). Based on the pathogenicity tests, morphological characteristics and molecular analyses, we identified the strain 3SMJ-2 as F. equiseti, the pathogen causing Fusarium wilt on potato in Zhangye City. Although, F. equiseti has been reported to cause root rot of cowpea (Li et al., 2017) and sugar beet (Cao et al., 2018) in China. To our knowledge, this is the first report confirming F. equiseti causing potato wilt in China. Potato is an economically important crop in Gansu and the occurrence of the new disease caused by F. equiseti on potato needs to be properly managed to reduce yield loss.

A Study of E. coli Contamination in Household Drinking Water: A Case Study in Rural Areas of Zhangye City, Northwest China

The objective of this study was to investigate Escherichia coli ( E. coli ) contamination in drinking water samples collected from a number of rural habitations of Zhangye City, Northwest China. A total of 37 villages along the Heihe River in Zhangye City were selected. The presence of E. coli was tested for using the MicroSnapTM E. coli Test Kit, which is a rapid bioluminogenic method for detection and enumeration of E. coli bacteria. Test results demonstrated that drinking water in 81.1% of the villages was contaminated with E. coli according to the Chinese Sanitary Standards for Domestic and Drinking Water. Majority of the higher E. coli CFU values were tested from villages located in the urban areas in Zhangye City. The data suggested that contamination of the drinking water in the rural habitations of Zhangye City was related to animal husbandry practices. In addition, the interactions of surface and groundwaters is not direct causes of the E. coli contamination found in Zhangye City. The occurrence of E. coli in drinking water may increase the risk of water-related diseases and health problems in local residents. It is therefore strongly recommended that solar energy technology be taken to protect water resources from contamination.

First Report of Seedling Blight of Oat (Avena sativa) Caused by Microdochium nivale in China.

Oat (Avena sativa) is extensively planted as a fodder crop on the vast ranges of northern and northwestern China, and it has become an important supplementary feed for grazing livestock (Yang et al. 2010). Microdochium nivale has been reported associated with seedling blight in many temperate regions (Imathiu et al. 2010) and the damage can result in serious loss of oat production. In August 2018, a serious seedling blight of oat (cv. Baiyan 7; about 30-day-old) was observed in the field in Shandan County, Zhangye City, Gansu Province (38.22° N, 101.22° E). More than 20% of oat plants were severely affected. Symptoms included leaf chlorosis and wilt. The root systems of infected plants were black and severely rotted, often with only a small amount of fine root remaining after removal from the soil. Twenty isolations were made from blackened roots on potato dextrose agar (PDA) and five isolations (TM-1, TM-2, TM-3, TM-4 and TM-5) were further purified by a single-spore method (Choi et al. 1999). Each isolate was identical based on preliminary molecular analyses of their DNA sequences of ITS by blast in the NCBI GenBank. The representative isolate TM-2 was selected for sequencing of the RNA polymerase II subunit (RPB2) gene. The isolated colonies were grown on PDA and formed colonies of approximately 62 mm (diameter) in 5 days at 25 ± 1 °C. Colonies exhibited entire margins, the color varied from white to pale yellow, and the sparse aerial mycelium were villous-floccose and cottony. The conidia were falcate, straight to curved, apex pointed or obtuse to subacute, lacking basal differentiation, 0-3-septate, most one-septate, 2.2 to 3.1 × 12.3 to 22.6μm (av.= 2.8 ×17.6; n=50). These morphological characteristics were consistent with previous descriptions of Microdochium (Zhang et al. 2010). Molecular identity was confirmed by sequencing partial sequences of ITS gene (ITS1 and ITS4 primers) (White et al. 1990) and RPB2 regions (RPB2-5f2 and RPB2-7cr) (O'Donnell et al. 2010). Sequences were deposited in GenBank under accessions MN428647 (RPB2) and MN428646 (ITS). Blast search revealed that both of the ITS and RPB2 sequences to be 99% similar to the corresponding sequences of M. nivale(CBS 116205) accession numbers KP859008.1 and KP859117.1. For pathogenicity tests, millet seed-based inoculum of M. nivale was prepared using a modified procedure of Fang et al. (2011). Three-week-old healthy oat seedlings of cv. Baiyan 7 were transplanted into potting mix containing millet seed-based inoculum of M. nivale at a rate of 3%. Control seedlings for comparison were transplanted into pots containing uninoculated potting mix. After 10 days, all the inoculated plants had developed seedling blight symptoms and that were similar to those observed in the field; while control plants remained healthy. The pathogen was reisolated from inoculated plants and identified as M. nivale based on morphological characteristics and the molecular methods described above. To our knowledge, this is the first report of seedling blight of oat caused by M. nivale in China.

First report of cyst nematode (Heterodera elachista) on Zea mays in Gansu Province, China.

The cyst nematodes are important plant-parasitic nematodes and make detrimental economic impacts worldwide. Heterodera elachista attacks rice in Japan (Ohshima 1974), Iran (Tanha et al. 2004) and China (Ding et al. 2012) and also attacks corn in Italy (De Luca et al. 2013) and northeast China (Xiao et al. 2019). Considering this nematode can infect these two most important crops with high reproduction rates, special attention should be paid to avoid its spread to new areas by soil, water, and agricultural practices. A survey for cyst nematodes was performed in fields of corn seed for propagation in September 2018 in Zhangye City, Gansu Province, which is the biggest corn seed production base in China. One hundred seventy four samples were collected by the zig-zag method in about 25 ha corn fields. Each soil sample containing approximately 1 kg soil in total was from the mixture of 20 cores (20 cm in depth and 0.2 cm in diameter). Cysts were detected in 6 out of 174 samples using the sieving-decanting method (Byrd et al. 1983). The six samples from ~ 1.2 ha corn fields in which plants displayed symptoms of dwarf, yellow leaves and earlier wilting had an average of 14 ± 2.8 cysts per 100 g soil. The cysts (n = 30) were dark brown, spherical to lemon shape, protruding, tapered vulva with ambifenestrae separated by a vulva slit, obvious and medium-sized underbridge, few dark-brown vesicles and clear swollen protrusion around underbridge and cyst cuticle with a zigzag pattern. Morphological measurements of the cysts included body length (excluding neck) (range =359.4 to 498.6 μm, mean = 429.5 ± SD 39.3 μm), vulva slit length (34.3 to 42.8, 37.9 ± 2.5), fenestral length (31.2 to 43.8, 38.0 ± 4.4) and width (26.1 to 31.4, 29.3 ± 1.6), underbridge length (74.7 to 82.9, 78.3 ± 2.8). J2 (n = 20) had the following measurements: body length (386.6 to 454.9, 425.3 ± 21.8), stylet length (17.1 to 22.2, 19.2 ± 1.6), stylet knob width (3.4 to 4.3, 3.9 ± 0.3), tail length (50.5 to 60.5, 55.5 ± 3.3) and hyaline tail length (25.0 to 34.6, 29.1 ± 3.1). The morphological characteristics are consistent with the Italian population of H. elachista through the comparison of the measurements. DNA was extracted from a single cyst randomly chosen (n = 5) using the protocol described by Subbotin et al. (2001). The ITS-rDNA and D2/D3 fragments of the 28S rRNA were respectively amplified with universal primers pairs TW81 and AB28 (Subbotin et al. 2001) and D2A and D3B (Castillo et al. 2003), and sequenced (Tsingke Biological Technology, Beijing, China). The consensus ITS sequence (GenBank Accession No. MN699476, 1037 bp) had 98.37 to 99.60% similarity with the H. elachista from corn in Italy (KC618469) and in China (MH712504), and from rice in China (HM560778) and in Iran (AF498391). The D2/D3 sequence (GenBank Accession No. MN699477, 746 bp) exhibited 99.60 to 99.73% similarity with that of H. elachista from rice in China (JN202922, HM560842), and from corn in Italy (KC618462). This nematode population was identified as H. elachista according to the morphological and molecular features. Twenty-day-old corn seedling (cv. Tiannuo) was inoculated with 3000 J2 and eggs in a pot filled with sterile soil. Eight plants were inoculated and two uninoculated plants were used as controls. J2 were found in the stained roots at 10 d after inoculation and J4 were detected at 30 d. These inoculated plants exhibited yellowing and dwarfing similar to the symptoms observed initially in the field, and the control grew normally. After 60 d, the average of 28 cysts were detected from each inoculated plant. This is the first report of H. elachista in Gansu Province, northwest China.

Profiling multiple heavy metal contamination and bacterial communities surrounding an iron tailing pond in Northwest China

Northwest China is abundant in iron ore reserves and has become one of the important iron ore mining bases in China. However, the contamination and microbial community structure of iron tailing ponds in Northwest China have not been extensively investigated. In the present study, we characterized the main physicochemical properties, the multiple heavy metal contamination, and the bacterial community structure of the soils surrounding an iron tailing pond in Linze County, Zhangye city, Gansu Province. The tailing-associated soils were barren, exhibiting alkaline pH and low organic matter (OM), total nitrogen (TN) and total potassium (TK) compared with the control areas. There was considerable multiple heavy metal pollution in the iron tailing pond, mainly including lead (Pb), manganese (Mn), arsenic (As), cadmium (Cd), zinc (Zn), iron (Fe) and copper (Cu). Among the 303 identified core operational taxonomic units (OTUs), Actinobacteria, Proteobacteria and Deinococcus-Thermus were predominant at the phylum level, and Blastococcus, Arthrobacter, Marmoricola, Kocuria, Truepera, and Sphingomonadaceae were prevalent at a finer taxonomic level. The bacterial richness and diversity of the tailing samples were significantly lower than those of the reference samples. RDA, VPA and Spearman correlation analyses showed that the soil pH, CEC, OM, TP, TK, Cd, Pb, Ni, Zn, As and Mn had significant effects on the bacterial community composition and distribution. This work profiles the basic features of the soil physicochemical properties, the multiple heavy metal contamination and the bacterial community structure in an iron tailing pond in Northwest China, thereby providing a foundation for the future ecological remediation of the iron tailing environment in the area.

Evaluation of satellite-retrieved evapotranspiration based on a nonparametric approach over an arid region

ABSTRACT Daily evapotranspiration (ET) controlled by latent energy (LE) is an important variable used in the study of hydrology, meteorology, and ecology. A constant solar radiation ratio approach was introduced to the LE retrieval algorithm based on a nonparametric ET approach to upscale instantaneous LE temporally. On the basis of the proposed algorithm, this study retrieved the daily and eight-day LE using Moderate-resolution Imaging Spectroradiometer (MODIS) and China Meteorological Administration Land Data Assimilation System products and evaluated the daily and eight-day LE retrieval by using the ground observations and MOD16 product in Zhangye City during 25 June to 15 September 2012. Results show that the temporal-spatial distribution of retrieved result was reliable. The retrieved daily/eight-day LE could capture the dynamic change of ground observations, whereas the MOD16 LE was invalid. The retrieved daily (eight-day) LE was underestimated at all four (two) sites, with bias, root mean square error, and R2 of −7.9 to −2.2 W m−2 (approximately −5 W m−2), 19.8 to 39.0 W m−2 (approximately 10 W m−2), and 0.72 to 0.84 (approximately 0.9), respectively. The proposed approach showed more satisfactory performance than the triangle approach under clear sky condition. The eight-day LE retrieval was considerably better than MOD16 LE and had (no/slight) influence on MOD16 LE (eight-day retrieval). In addition, the accurate estimation of net radiation, soil heat flux, land surface temperature, and air temperature could aid in improving LE retrieval. Future studies would focus on the improvement of the retrieval algorithm, input accuracy, and residuals.

Using composite fingerprints to quantify the potential dust source contributions in northwest China

Dust storms have a profound impact on the atmospheric environment, global climate change, and human health, so it is of great importance to strengthen related research. The main areas of occurrence and frequency of dust storms in northwestern China were distinguished by measuring the concentration of geochemical elements in the topsoil and atmospheric dust samples, combined with the HYSPLIT backward trajectory model, MODIS true-color satellite images, and PM10 real-time monitoring data. On this basis, the composite fingerprints method was used to establish an end-member model between the concentration of dust storm samples and topsoil samples, and then to trace the sand and dust sources in northwest China and quantify their source contributions. The results showed that the main potential source areas causing sandstorms were located in the Kumtag Desert, Hexi area, and the Gobi Desert in the central and western parts of Inner Mongolia. Overall, the contributions from natural sources were greater than those from anthropogenic sources, especially at Alxa League. In addition to natural sources, anthropogenic dust sources contributed highly to dust storms, with a contribution rate of approximately 40% in cities. The main dust source in Zhangye City was from agriculture areas. The contribution of the potential dust sources in the west of the study area showed a decreasing trend from west to east because of the distance effect. Because of the influence of the prevailing westerly winds in the east, the sources of dust were relatively extensive. The Badain Jaran Desert and Tengger Desert were not the main dust sources in the study area because of artificial sand control measures and the low amounts of fine-grained components in sandy deserts. These methods and results are of great importance for sustainable development in northwest China.

Biological control of sheep gastrointestinal nematode in three feeding systems in Northern China by using powder drug with nematophagous fungi

ABSTRACT This study aimed to evaluate the efficiency of the powdered formulation with the nematophagous fungi Duddingtonia flagrans against gastrointestinal nematodes of sheep under three feeding systems in Northern China. Each animal in the treatment group received approximately 5×105 spores/kg live weight at twice a week for 6 months. The control group received an equal amount of feeds without fungus. In the grazing system, two herds were selected in the Tongyu County in Northeast China. Among them, 70 sheep as the treatment group and 100 sheep as the control group. These results revealed that fungal group showed a greater reduction in eggs per gram of feces (EPG), infective larvae (L3) per kilogram in pasture and larvae per gram of feces (LPG) after administration and lower parasitic load burden in the tracer lambs compared with the control group (p<0.05). In the semi-confinement system, 20, 15, and 15 sheep from three individual farmers were selected from Zhangye City of Northwestern China; 20 sheep as the control group and the remaining sheep as the treatment group. The fungal group showed a greater reduction in EPG after 150 and 180 days and LGP from 60~180 days after administration (p<0.05). In the confinement feeding system, 40 lambs were randomly divided into the treatment and control groups. The results showed that no differences in EPG and LGP were observed in the two groups (p>0.05). In conclusion, the powder was efficient in controlling sheep gastrointestinal helminths under three feeding systems in Northern China.

Eco-efficiency of oasis seed maize production in an arid region, Northwest China

Improving eco-efficiency in arid areas is the crucial to resolve the dual constraints of scarce water resources and the fragile carrying capacity of the ecological environment on agricultural production. This study investigated the eco-efficiency of seed maize production in Zhangye City, the largest seed maize producer in the arid northwestern region of China. The environmental impacts were assessed through a life cycle assessment and incorporated into a data envelopment analysis model, together with economic factors to evaluate ecological efficiency. A Tobit regression model was applied to identify the key elements affecting eco-efficiency and determine suggestions for further improvements. The results showed that the environmental acidification index of Zhangye was 1.2079–1.3978 times larger than the world per capita level, with the primary cause being the application of nitrogen fertilizer. Water consumption was lower than the world average level. The comprehensive environmental index was lower than the 2000 world per capita level but higher than that of other Chinese regions. A production eco-efficiency evaluation showed that 14.68% of households achieved relatively efficient production. Water was the most influential element. Each additional 100 units of water reduce eco-efficiency by 0.34%. A comparative study of small, medium and large farms was carried out to examine the effect of farm size. Small farms were the most eco-efficient, followed by medium-sized farms, with large farms having the lowest eco-efficiency. The results highlighted that certain targeted policy interventions may be inefficient, including interventions focusing on expansion of the production scale, and that restrictions on fertilizer use and improving water-saving facilities can improve eco-efficiency performance.

Study on the Spatial-temporal Differentiation and Driving Mechanism of Ecological Vulnerability in Zhangye City

Based on the “Sensitivity-Pressure-Resilience” evaluation model, combined with the spatial principal component (SPA) analysis method of GIS, we evaluated the ecological vulnerability of Zhangye City in 2000, 2005 and 2010, then we used geographical detector model to analyse the main driving factors of the ecological vulnerability. The results showed that: 1. The ecological vulnerability of Zhangye City was higher in the West and lower in the East. The average value of ecological vulnerability index was 0.45, which was mild fragile, ecological vulnerability index was the highest in Linze county, and the lowest in Minle county. 2. The overall ecological vulnerability showed a trend of improvement from 2000 to 2010, due to the increase of precipitation in 2005, the ecological vulnerability index was higher than that of 2000 and 2010. 3. Geographical detector results showed that six factors could explain the ecological vulnerability, which ranked as: rainfall in flood season (0.1138) > temperature in high temperature season (0.1116) > elevation (0.0581) > vegetation coverage (0.0532) > topographic relief (0.0411) > biological abundance index (0.0384), and the interaction of the 6 factors had a stronger explanatory power to the ecological vulnerability.