Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
Not a member yet
4476 research outputs found
Sort by
Ethylene response pathway modulates attractiveness of plant roots to soybean cyst nematode Heterodera glycines
No full textPlant parasitic nematodes respond to root exudates to locate their host roots. In our studies second stage juveniles of Heterodera glycines, the soybean cyst nematode (SCN), quickly migrated to soybean roots in Pluronic F-127 gel. Roots of soybean and non-host Arabidopsis treated with the ethylene (ET)synthesis inhibitor aminoethoxyvinylglycine (AVG) were more attractive to SCN than untreated roots, and significantly more nematodes penetrated into roots. Moreover, Arabidopsis ET insensitive mutants (ein2, ein2-1, ein2-5, ein3-1, ein5-1, and ein6) were more attractive than wild-type plants. Conversely, the constitutive triple-response mutant ctr1-1, was less attractive to SCN. While ET receptor gain-of-function mutant ein4-1 attracted more SCN than the wild-type, there were no significant differences in attractiveness between another gain-of-function ET receptor mutant, etr1-3, or the loss-of-function mutants etr1-7 and ers1-3 and the wild type. Expression of the reporter construct EBS: beta-glucuronidase (GUS) was detected in Arabidopsis root tips as early as 6 h post infection, indicating that ET signaling was activated in Arabidopsis early by SCN infection. These results suggest that an active ET signaling pathway reduces root attractiveness to SCN in a way similar to that reported for root-knot nematodes, but opposite to that suggested for the sugar beet cyst nematode Heterodera schachtii
Monitoring the Invasion of Spartina alterniflora Using Multi-source High-resolution Imagery in the Zhangjiang Estuary, China
No full textSpartina alterniflora (S. alterniflora) is one of the most harmful invasive plants in China. Google Earth (GE), as a free software, hosts high-resolution imagery for many areas of the world. To explore the use of GE imagery for monitoring S. alterniflora invasion and developing an understanding of the invasion process of S. alterniflora in the Zhangjiang Estuary, the object-oriented method and visual interpretation were applied to GE, SPOT-5, and Gaofen-1 (GF-1) images. In addition, landscape metrics of S. alterniflora patches adjacent to mangrove forests were calculated and mangrove gaps were recorded by checking whether S. alterniflora exists. The results showed that from 2003-2015, the areal extent of S. alterniflora in the Zhangjiang Estuary increased from 57.94 ha to 116.11 ha, which was mainly converted from mudflats and moved seaward significantly. Analyses of the S. alterniflora expansion patterns in the six subzones indicated that the expansion trends varied with different environmental circumstances and human activities. Land reclamation, mangrove replantation, and mudflat aquaculture caused significant losses of S. alterniflora. The number of invaded gaps increased and S. alterniflora patches adjacent to mangrove forests became much larger and more aggregated during 2003-2015 (the class area increased from 12.13 ha to 49.76 ha and the aggregation index increased from 91.15 to 94.65). We thus concluded that S. alterniflora invasion in the Zhangjiang Estuary had seriously increased and that measures should be taken considering the characteristics shown in different subzones. This study provides an example of applying GE imagery to monitor invasive plants and illustrates that this approach can aid in the development of governmental policies employed to control S. alterniflora invasion
Drought Priming at Vegetative Growth Stage Enhances Nitrogen-Use Efficiency Under Post-Anthesis Drought and Heat Stress in Wheat
No full textTo study the effects of early drought priming at 5th-leaf stage on grain yield and nitrogen-use efficiency in wheat (Triticum aestivum L.) under post-anthesis drought and heat stress, wheat plants were first exposed to moderate drought stress (drought priming; that is, the leaf water potential reached ca. -0.9 MPa) at the 5th-leaf stage for 11days, and leaf water relations and gas exchange rates, grain yield and yield components, and agronomic nitrogen-use efficiency (ANUE) of the primed and non-primed plants under post-anthesis drought and heat stress were investigated. Compared with the non-primed plants, the drought-primed plants possessed higher leaf water potential and chlorophyll content, and consequently a higher photosynthetic rate during post-anthesis drought and heat stress. Drought priming also resulted in higher grain yield and ANUE in wheat under post-anthesis drought and heat stress. Drought priming at vegetative stage improves carbon assimilation and ANUE under post-anthesis drought and heat stress and their combination in wheat, which might be used as a field management tool to enhance stress tolerance of wheat crops to multiple abiotic stresses in a future drier and warmer climate
Growing season methane emissions from a permafrost peatland of northeast China: Observations using open-path eddy covariance method
No full textThe mid-high latitude permafrost peatlands in the Northern Hemisphere is a major natural source of methane (CH4) to the atmosphere. Ecosystem scale CH4 emissions from a typical permafrost peatland in the Great Hing'an Mountains were observed during the growing season of 2014 and 2015 using the open-path eddy covariance method. Relevant environmental factors such as temperature and precipitation were also collected. There was a clear diurnal variation in methane emissions in the second half of each growing season, with significantly higher emission rates in the wet sector of study area. The daily CH4 exchange ranged from 1.8 mg CH4 m(-2) d(-1) to 40.2 mg CH4 m(-2) d-1 in 2014 and ranged from 3.9 to 15.0 mg CH4 m(-2) d(-1) in 2015. There were no peaks of CH4 fluxes during the spring thawing period. However; large peaks of CH4 emission were found in the second half of both growing seasons. The CH4 emission after Jul 25(th) accounted for 77.9% of total growing season emission in 2014 and 85.9% in 2015. The total CH4 emission during the growing season of 2014 and 2015 was approximately 1.52 g CH4 m(-2) and 0.71 g CH4 m-2, respectively. CH4 fluxes during the growing seasons were significantly correlated with thawing depth (R-2 = 0.71, P < 0.01,) and soil temperatures (R-2 = 0.75, P < 0.01) at 40 cm depth. An empirical equation using these two major variables was modified to estimate growing season CH4 emissions in permafrost peatlands. Our multiyear observations indicate that the time-lagged volume of precipitation during the growing season is a key factor in interpreting locally inter-annual variations in CH4 emissions. Our results suggested that the low temperature in the deep soil layers effectively restricts methane production and emission rates; these conditions may create significant positive feedback under global climate change. (C) 2017 Elsevier Ltd. All rights reserved
A novel unsupervised Levy flight particle swarm optimization (ULPSO) method for multispectral remote-sensing image classification
No full textThe rapid development of earth observation technology has produced large quantities of remote-sensing data. Unsupervised classification (i.e. clustering) of remote-sensing images, an important means to acquire land-use/cover information, has become increasingly in demand due to its simplicity and ease of application. Traditional methods, such as k-means, struggle to solve this NP-hard (Non-deterministic Polynomial hard) image classification problem. Particle swarm optimization (PSO), always achieving better result than k-means, has recently been applied to unsupervised image classification. However, PSO was also found to be easily trapped on local optima. This article proposes a novel unsupervised Levy flight particle swarm optimization (ULPSO) method for image classification with balanced exploitation and exploration capabilities. It benefits from a new searching strategy: the worst particle in the swarm is targeted and its position is updated with Levy flight at each iteration. The effectiveness of the proposed method was tested with three types of remote-sensing imagery (Landsat Thematic Mapper (TM), Flightline C1 (FLC), and QuickBird) that are distinct in terms of spatial and spectral resolution and landscape. Our results showed that ULPSO is able to achieve significantly better and more stable classification results than k-means and the other two intelligent methods based on genetic algorithm (GA) and particle swarm optimization (PSO) over all of the experiments. ULPSO is, therefore, recommended as an effective alternative for unsupervised remote-sensing image classification
Constructed wetlands for saline wastewater treatment: A review
No full textSaline wastewater originating from sources such as agriculture, aquaculture, and many industrial sectors usually contains high salts and other contaminants, which adversely affect both aquatic and terrestrial ecosystems. Therefore, the treatment of saline wastewater, for both salts and specific contaminant removal, has become a necessary task in many countries. Conventional methods (e.g., using physicochemical equipment, biological reactors, or a combination thereof) are feasible for treating most saline wastewaters (sometimes only for the removal of contaminants rather than the salts, e.g., biological reactors). However, the high cost of these techniques limits their application in many areas, especially in developing countries. For this reason, constructed wetlands (CWs) have been successfully used for treating a wide variety of wastewaters, and are eco-friendly and cost effective, and provide a potential alternative technology for saline wastewater treatment. The current review illustrates the latest knowledge on the use of CWs for treating saline wastewater. Though the function of plants and microorganisms in CWs is sometimes inhibited by salts, acceptable treatment effectiveness can still be achieved by screening halophyte, optimizing wetland structure and operation parameters, and by exploring the application of halophilic microorganisms. Factors influencing the effectiveness of CWs for saline wastewater treatment include; wetland structures, operation parameters, water pH, and temperature. Future studies are recommended on the removal of different types of target contaminants, strategies for strengthening the purification process, and on conducting large-scale field experiments under real-world conditions. (C) 2016 Elsevier B.V. All rights reserved
Simulation of regional temperature change effect of land cover change in agroforestry ecotone of Nenjiang River Basin in China
No full textThe Northeast China is one of typical regions experiencing intensive human activities within short time worldwide. Particularly, as the significant changes of agriculture land and forest, typical characteristics of pattern and process of agroforestry ecotone change formed in recent decades. The intensive land use change of agroforestry ecotone has made significant change for regional land cover, which had significant impact on the regional climate system elements and the interactions among them. This paper took agroforestry ecotone of Nenjiang River Basin in China as study region and simulated temperature change based on land cover change from 1950s to 1978 and from 1978 to 2010. The analysis of temperature difference sensitivity to land cover change based on Weather Research and Forecasting (WRF) model showed that the land cover change from 1950s to 1978 induced warming effect over all the study area, including the change of grassland to agriculture land, grassland to deciduous broad-leaved forest, and deciduous broad-leaved forest to shrub land. The land cover change from 1978 to 2010 induced cooling effect over all the study area, including the change of deciduous broad-leaved forest to agriculture land, grassland to agriculture land, shrub land to agriculture land, and deciduous broad-leaved forest to grassland. In addition, the warming and cooling effect of land cover change was more significant in the region scale than specific land cover change area
Amounts of Stubbles Left in Paddy Fields: Evaluation from the Viewpoints of C Sequestration and Soil Fertility
No full textPlant residues are the main source of organic materials maintaining soil fertility in paddy fields, among which rice stubble has been disregarded of its importance so far. This study highlighted the great amount of rice stubbles retained in paddy fields in comparison with that of corn stubbles. Height of rice stubbles was measured in paddy fields under harvesting methods by hand and harvesters around Harbin and Shaoxing City, China. The height of stubbles above the ground was 5.0 +/- 1.7 cm, 10.1 +/- 2.3 cm and 28.7 +/- 8.4 cm for rice fields harvested by hand and harvesters that left rice straw in the fields without and with cutting it into segments, corresponding to 18-25%, 25-32% and 47-60% of total top part biomass (excluding ears), respectively. These results suggested that the biomass of stubbles left in paddy fields by the second-type harvesters was larger than that of rice straw. Mechanization in harvesting rice plants was 73% in 2014, and the estimated amount of stubbles left in paddy fields was at least 1514 to 1973 kg ha(-1). Comparable measurements of corn plants and stubbles in corn fields showed that the average height of corn stubbles harvested by hand was 9.1 +/- 2.5 cm and the corresponding stubble biomass was only about 7-9% of the total top-part biomass (excluding ears) amounting to 413-639 kg ha(-1). This was the first study that quantitatively elucidated the importance of rice stubbles in C sequestration and soil fertility in paddy fields in recent China
A new species of Uralaphorura Martynova, 1978 from northeast China, with a key to world species of the genus (Collembola, Onychiuridae)
No full textA new species, Uralaphorura liangshuiensis sp. n., has been reported from Xiao Hinggan Mountains (northeast China). The new species is unique in having the pso formulae as 32/133/33332 dorsally and 0/000/0001(0) ventrally, and the ventral psx formula as 3/000/221000. A key to all known species of the genus is given
China's Wetland Databases Based on Remote Sensing Technology
No full textWetland databases can provide the basic data that necessary for the protection and management of wetlands. A large number of wetland databases have been established in the world as well as in China. In this paper, we review China's wetland databases based on remote sensing (RS) technology after introducing the background theory to the application of RS technology in wetland surveys. A key conclusion is that China's wetland databases are far from sufficient in fulfilling protection and management needs. Our recommendations focus on the use of the hyper-spectral imagery, microwave data, multi-temporal images, and automatic classifications in order to improve the accuracy and efficiency of wetland inventory. Further, attention should also be paid to detect major biophysical features of wetlands and build wetland databases in years after the 1980s in China. Considering that great gap exists between RS experts and wetland experts, further cooperation between wetland scientists and RS scientists are needed to promote the application of RS in the foundation of wetland databases