Table of Content

20 June 2012, Volume 21 Issue 3

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Spatio-temporal pattern and change of Nagqu grassland and the influence of human factors

SONG Chun-qiao, YOU Song-cai, LIU Gao-huan, KE Ling-hong, ZHONG Xin-ke

2012, 21(3):  1-10. 

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Nagqu serves as an important and demonstration center of Tibetan stockbreeding development located in an extremely harsh natural environment with vulnerable ecosystems.In recent years, large areas of alpine grassland ecosystems of Northern Tibet have severely degraded and have been threatened by soil erosion, desertification, and human activities. The annual variation of vegetation is influenced by both natural conditions and human disturbances. To efficiently solve the complex resource-related and environmental issues, it is necessary to clarify how human factors affect the normal growth of rangeland vegetation. Various statistical analyses and time-series NDVI (normalized difference vegetation index) datasets from MODIS sensors between 2000 and 2009, were used to monitor the spatio-temporal variation of grassland. The relationships between grassland degradation and various human factors are discussed based on qualitative and quantitative systematic analysis. 1) Due to snow melting related to global warming, the vegetation in some desertified and snow-covered regions of high altitude mountains showed an actively recovering trend, while the grasslands in purely livestock-breeding counties (such as Nagqu, Amdo and Nyainrong) of central Nagqu had some degenerative phenomenon; 2) The spatial patterns of density maps of residential distribution and road network, vegetation NDVI image, and yearly variation map of vegetation NDVI showed similar spatial clustering characters, indicating that human activities directly influenced growth and reproduction of plants in flourishing vegetation cover; 3) Taking Nagqu town and state highway No. 109 as typical instances of human factors, the vegetation in regions closer to town centers or the road axis with more intense human disturbances showed more severe degradation. Further statistical analyses showed a linear upward trend for population, numbers of livestock and traffic-construction projects in Nagqu, which will bring serious threats to sustainable development of local pastures; 4) Additionally, the grassland in Nagqu was also destroyed by grinding of tourists’ and herders’ vehicles, mining, digging herbal medicine, house-construction projects for low-income residents, and mice disasters. In order to protect the healthy development of Nagqu’s rangelands and local economy, several feasible and constructive measures are proposed.

Influence of enclosure on community characteristics of alpine meadow in
the northeastern edge region of the Qinghai-Tibetan Plateau

MIAO Fu-hong, GUO Ya-jing, MIAO Peng-fei, GUO Zheng-gang, SHEN Yu-ying

2012, 21(3):  11-16. 

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Enclosures are one of the measures to restore degraded grassland by turning grazing grasslands into protected grasslands but the period of fencing is the key to influencing the plant community. A six year field experiment was conducted to determine the responses of community features of alpine meadow to enclosure at Tianzhu Autonomous County on the northeastern edge of the Qinghai-Tibetan Plateau. The cover, height, species diversity and biomass of the alpine meadow first increased, then decreased, and finally decreased again as the enclosure was prolonged, peaking at the fourth year. These results suggest that a 4-year enclosure is suitable for alpine meadows in the study region.

Species diversity distribution pattern of alpine grasslands communities along a
precipitation gradient across Northern Tibetan Plateau

WANG Jing-sheng, ZHOU Yu-ting

2012, 21(3):  17-25. 

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Aboveground biomass and community stricture at 40 sites with grazing exclusion were surveyed on a west-east alpine grassland transect along precipitation gradient in Northern Tibetan Plateau to evaluate effect of growing season rainfall on both aboveground biomass and species diversity and to discuss the relationship between aboveground biomass and species diversity indexes. The precipitation pattern significantly affected species richness, Shannon-Wiener diversity and Pielou evenness indexes of the alpine communities in inner Northern Tibetan Plateau and that community structure related closely with primary productivity. All of aboveground biomass, species richness, Shannon-Wiener diversity index and Pielou evenness index exponentially increased with growing season precipitation addition. In the relationship between species richness and aboveground biomass of alpine grasslands, the discriminant coefficient of the hump-shaped model (R²=0.754) was slightly higher than linear regression (R²=0.743), however, species richness monotonically increased with aboveground biomass of alpine grasslands along Northern Tibetan Plateau Transect without any monotonic decreasing interval in the hump-shaped model. Moreover, hump-shaped model in our results indicated that species richness more likely showed a monotonic decreasing with aboveground biomass when it was more than 121.17 g/m² and to make this humped relationship to be standard. Hump-shaped models described both Shannon-Wiener biodiversity and Pielou evenness index with aboveground biomass that decreasing intervals were relatively narrower than increasing ones and peak values took place at aboveground biomass of 71.90 and 60.90 g/m² respectively.

Research on the change of grassland vegetation coverage using 3S technology in Gannan

WANG Hao, LI Wen-long, DU Guo-zhen, ZHU Xiao-li

2012, 21(3):  26-37. 

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Using the dimidiate pixel model and 3S technique (GIS, RS, GPS), a new vegetation coverage analyze model was built on the basis of the NDVI vegetation index. The vegetation coverage was estimated in Gannan state in 2002, 2004, 2006 and 2008 with MODIS data and the characteristics of the vegetation coverage dynamics was analysed. From 2002 to 2008, the deterioration of rangeland vegetation coverage in Gannan was general, and the degradation level of the first stage vegetation was high. The change in grassland vegetation cover reflected the trend of conversion from high-stage (the 1st and 2nd stage) to low-stage (the 4th and 5th stage) coverages. It further confirmed that the grassland vegetation in Gannan area is progressively degrading more seriously. The result will be useful for further academic research and rangeland management.

The role of soil seed bank in vegetation succession under grazing exclusion in
Stipa bungeana grasslands on the Loess Plateau

ZHAO Ling-ping, CHENG Ji-min, SU Ji-shuai

2012, 21(3):  38-44. 

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Understanding the coupling effect on above- and below-ground species composition was important for exploring the succession process and its mechanism of degraded grasslands under grazing exclusion. The study respectively made the succession gradient analysis on vegetation and soil seed bank using detrended correspondence analysis (DCA) and unweighted pair-group method with arithmetic means (UPGMA) cluster analysis on the relationship between vegetation and soil seed bank in Stipa bungeana grasslands on the Loess Plateau. The results indicated that with grazing exclusion years increasing, S. bungeana grasslands had the following succession stages: the cluster growth of weeds→S. bungeana emerging in large numbers→the stable development of S. bungeana. The vegetation succession showed a clear positive direction, however, no clear trend in soil seed bank. The vegetation succession stages influenced the relationship between vegetation and soil seed bank. The similarity between vegetation and soil seed bank in early succession was higher than late-succession stages, indicating soil seed bank made a relatively larger contribution to vegetation restoration in early-succession stages. Overall, soil seed bank played a minimal role in the process of vegetation succession under the grazing exclusion in S. bungeana grasslands. Therefore, the internal driving forces of vegetation succession under grazing exclusion in typical steppe were propagule dispersal and asexual reproduction, not soil seed bank.

Biomass spatial fractal characteristics and phosphorus nutrient dynamics of Suaeda salsa
under different growth conditions of the intertidal zone in the Yellow River estuary

MOU Xiao-jie, SUN Zhi-gao, LIU Xing-tu

2012, 21(3):  45-53. 

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From May to November 2008, biomass spatial fractal characteristics and phosphorus nutrient dynamics of Suaeda salsa under different growth conditions in the intertidal zone of the Yellow River estuary were studied. The logarithm values of aboveground biomass and plant height of S. salsa in middle (JP1) and low tidal flat (JP2) were linearly correlated, and the ranges of fractal dimensions (D) were 1.692-3.839 and 2.260-3.955, respectively. The dynamic accumulation of aboveground biomass of JP1 and JP2 had self-similarity, being a fractal growth process which fitted the increase rule of power function: D was 2.012 and 2.366, respectively. The changes of total phosphorus (TP) content in roots and stems of JP1 and JP2 were consistent, generally decreasing in the growing season, while TP content in leaves fluctuated greatly. The amount of P accumulation and rate of different organs of JP1 and JP2 showed significant seasonal changes, and the values in aboveground parts were generally higher than those in roots. The P allocation ratios were significantly different among different parts of JP1 and JP2 in different phases and were in the order leaf＞stem＞root, with values of (45.38±20.08)%, (38.88±20.30)%, (15.74±8.94)% for JP1 and (57.08±15.49)%, (35.30±13.12)%, (7.63±5.25)% for JP2 respectively. The N/P of JP1 plants (9.87±3.47) was less than 14, implying that N might be the limiting nutrient. The N/P of JP2 plants (15.73±5.00) was between 14 and 16 indicating that both might be limiting nutrients, but that the effect of P is greater. Further studies indicated that the differences between JP1 and JP2 in biomass, TP content, P accumulation amount and rate, P allocation ratio and nutrient limiting status were correlated to their ecological characteristics and water and salinity conditions of the habitat.

Responses of soil particulate organic carbon and nitrogen along an altitudinal
gradient on the Helan Mountain, Inner Mongolia

YANG Yi, NIU De-cao, WEN Hai-yan, ZHANG Bao-Lin, DONG Qiang, Chen Ju-lan, FU Hua

2012, 21(3):  54-60. 

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The physical fractionation method was used to measure the contents of soil particulate organic carbon (POC) and particulate organic nitrogen (PON) in eight grassland sites along an elevation gradient on the Helan Mountain, Inner Mongolia. The relationships of POC, PON and their proportion with vegetation characteristics and environmental factors were analyzed. Both POC and PON declined significantly with altitude and with soil depth. Meanwhile, POC and PON changed significantly among vegetation types. The proportions of POC and PON reduced considerably with the altitude from 2 940 to 1 820 and 1 700 m. Among the four vegetation types, proportions of both POC and PON were the highest in the alpine meadow and lowest in the desert steppe. The proportions of POC and PON had significant positive correlations with vegetation cover, aboveground plant biomass and mean annual precipitation, but a significant negative correlation with mean annual temperature.

Efficiency of fertilizing biogas slurry on nitrate accumulation and N utilization of Pennisetum

CHEN Zhong-dian, ZHONG Zhen-mei

2012, 21(3):  61-68. 

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The experiment was conducted on the way of cultivated soil column, which was to study efficiency of fertilizing biogas slurry on nitrate accumulation and N utilization of Pennisetum according to fertilizing different levels N of biogas slurry(seven levels of N that was from N0 to N6 designed were 0, 5, 10, 20, 40, 80, 160 kg/ha of equivalent nitrogen fertilized,9 times for every 45 days of cutting period).The result showed that N levels of biogas slurry had an effect on the content of Pennisetum nitrate,and the relations between them were positive correlation. In high levels of N fertilizer,however,the contents of Pennisetum nitrate in different cutting periods were all less than 0.25% of toxic limits for nitrate.In addition,content of Pennisetum crude protein and production of CP were going up with the increased levels of N,the maximums were 21.35% and 44.09 g/pot, respectively. Analyzing the efficiency of N utilization, protein,physiological N,agronomic nitrogen and nitrogen partial factor productivity showed that efficiency of N utilization would be lower,and the loss rate would also be larger with the increasing N levels in biogas slurry. N content of soil column leaching analyzed showed that the quantity of N leaching had the trend of going up with increasing N levels,treatment N5 and N6 in one year were 80.69, 312.3 mg respectively. In addition,soil total nitrogen content of group N5 and N6 below 40 cm soil layer were also significantly higher than other groups(P>0.05). It was concluded that in one cutting period,the quantity of Pennisetum grassland absorbing N in biogas slurry was lower 360 kg/hm² of pure nitrogen,which should be reasonable.

Effect of row space on population component composition, biomass structure
and energy distribution of Elymus sibiricus

LIU Jin-ping, YOU Ming-hong, BAI Shi-qie

2012, 21(3):  69-74. 

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The root, stem, leaf and inflorescence of Elymus sibiricus cv. Chuancao No.2 population were determined at the flowering stage of the third year to elucidate the effect of row space on the quantitative trait of components, biomass structure, accumulation and distribution proportion of energy. There were highly significant differences in total tiller and the ratio of fertile to total tiller between different row spacings, and significant differences in eustipes length and number, and natural height of each tiller, but there was no significant difference in leaf length, width and number of tillers. Significant effects of row space were found on the depth and distribution range of root, length of sear stalk, ear number of fertile tillers, and the biomasses of leaf, stem, root, and inflorescence. The importance showed a descending order of stem> leave> root > inflorescence. No significant differences were found in energy value of single leaf, stem, root and inflorescence between row spaces, but significant differences were found in energy accumulations of leaf, stem, root and inflorescence in the order stem> leaf> inflorescence> root. There was a significant difference in energy distribution among row spaces: leaf > stem > inflorescence > root. The 30 cm row space is optimum for forage production, and 60 cm is the best for seed yield.

Geographic distribution and prediction of potential suitable regions of Iva xanthifolia

XU Zhi-dong, DING Guo-hua, LIU Bao-dong, CHI Chun-yu, XIAO Wei, JIN Xiao-xia, LI Chun-ye

2012, 21(3):  75-83. 

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Foreign invasion plant flase ragweed (Iva xanthifolia)is spreading rapidly in the Northeast of China, which threatens the natural ecosystem and does harm to people’s health. By doing field work distribution of flase ragweed in Northeast China was detected. Maxent ecological niche models help to predict the potential suitable regions of flase ragweed both in China and the other parts of the world. And natural intermittent points classification method of ArcGIS helps to classify the risk regions. The receiver operating characteristic curve was applied to access the prediction accuracy. The main environmental variables were analyzed by Jackknife approach and response curve of environmental variables. The results showed that flase ragweed had a wildly suitable regions which continue to spread its areas. In China, the suitable distribution area mainly locates in the North, the Northeast, the East, the Central, the Southwest and the Northwest of China; most of the suitable regions were in Heilongjiang, Jilin, Liaoning, Shanxi, Shanxi, Henan, Hebei, Shandong, Beijing, Tianjin, Neimenggu and Xinjiang. In the world, risk regions existed worldwide except Antarctica; the risk regions mainly lie in North America (including Canada and America), Africa (Morocoo), Europe (Spain, Croatia, Hungary, Slovakia, Bosnia-herzegovina, Serbia, Macedonia, Bulgaria, Georgia, Armenia and Azerbaijan), and Asia (Turkey, Iran, Kazakhstan, Tajikistan, China, North Korea, South Korea and Japan). The above areas show that middle latitude regions with higher average annual temperature, the lowest in the coldest month or lower average temperature in coldest quarter are the most suitable for flase ragweed to grow.

Distribution and seasonal dynamics of ergot alkaloids in Elymus
dahuricus-endophytic fungus symbiont

XU Rui, NAN Zhi-biao, ZHOU Yan-fei, LI Chun-Jie

2012, 21(3):  84-92. 

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Ergine and ergonovine contents in leaf blades, pseudostems, leaf sheaths, roots and seeds of four populations of Elymus dahuricus infected by grass endophyte (Neotyphodium) from Wulingshan (WLS), Qinyuan (QY), Wutaishan (WTS) and Baiwangshan (BWS), were detected in April, June, August and October of 2009 using high performance liquid chromatography. In April, June, and August the highest contents of ergine were detected in leaf blades (5.037-30.037 mg/kg) and sheaths (6.259-22.255 mg/kg), while in October the highest values were found in the seeds (5.045-8.971 mg/kg) and leaf blades (3.119-6.658 mg/kg). Ergine contents in leaf blades, pseudostems and leaf sheaths in April or June (13.831-30.037 mg/kg) were significantly higher than those in August or October (3.119-6.658 mg/kg). Ergine contents in the roots in August (0.552-0.576 mg/kg) were significantly lower than those in other months. The distributions of ergonovine in different tissues showed a similar pattern to those of ergine. The highest contents of ergonovine were detected in leaf blades (2.206-8.226 mg/kg) and sheaths (0.268-5.490 mg/kg ) in April, June and August, while in October the highest values were also found in the seeds (1.647-5.664 mg/kg) and leaf blades (1.353-2.251 mg/kg). Ergonovine contents in leaf blades, pseudostems and leaf sheaths in April or June (5.102-8.226 mg/kg) were significantly higher than those in August or October (1.353-2.251 mg/kg). The lowest contents of ergonovine were found in August (0.128-0.283 mg/kg). The contents of ergine and ergonovine in the whole plant of these four populations were different in different months. Ergine contents were significantly higher than ergonovine contents in total ergot alkaloids. Ergine contents were significantly linearly correlated with ergonovine contents.

Biological characteristics of a pathogen of turfgrass root rot disease

GU Li-jun, XU Bing-liang, LI Bin, LIANG Qiao-lan

2012, 21(3):  93-98. 

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The chief pathogen was identified as Pythium aphanidermatum and its morphology, cultural characteristics and pathogenicity were investigated. The optimal temperatures for fungal growth were 30-35℃ but it could grow in the range 15-40℃.The temperature range for sporangium production was 15-25℃. The best pH was 7-8 for hyphal growth, 9-10 for sporangium development, six for oospore development. The best cultural condition for mycelial and oospore growth was 24 h in the dark while the optimum treatment for sporangium growth was 24 h under light. Ultraviolet irradiation can accelerate the growth of hyphae and sporangia but it inhibits oospore production. The best source of carbon was amylum and the best source of nitrogen was ammonium nitrate.

Variation of Al tolerance in the germplasm resources of centipedegrass in China

LI Shan, JIANG Qiao-feng, LIU Jian-xiu

2012, 21(3):  99-105. 

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The small-volume solution culture method was used to evaluate the aluminum (Al) tolerance of 51 centipedegrass accessions and two cultivars (‘TifBlair’ and ‘Common’) from the USA as a basis for selecting centipedegrass resources with strong Al tolerance thus providing an experimental basis for futher genetic improvement. Significant growth differences were found among 53 accessions treated with 1 500 μmol/L Al, and the CVs of relative root weight, relative shoot weight, and relative total weight were 20.55%, 15.62% and 15.52%, respectively. Using the membership function value method, 51 centipedegrass accessions were classified into five groups with different levels of Al tolerance. Twenty-one accessions belonged to groups 1-3 (Al-tolerant type), accounting for 39.6% of the total accessions, 13 accessions belonged to group 5 (Al-sensitive type), accounting for 24.5%, and 19 accessions belonged to group 4 (intermediate Al-tolerant type), accounting for 35.9%. ‘TifBlair’ and ‘Common’ were intermediate types, indicating a good potential for developing the genetic resource of Al tolerance in centipedegrass.

Cloning and sequence analysis of terminase gene of glycoalkaloid biosynthesis
metabolismic pathway in potato

LU Yan-mei, ZHANG Jun-lian

2012, 21(3):  106-116. 

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The potato steroidal glycoalkaloids (SGAs) is an important secondary metabolites in solanaceae and liliaceae. It is closely related to the antireversion force of plan itselfe and product quality, simultaneously, it has a wide pharmacological activity in pharmacology. Solanidine: UDP-glucosyltransferase(SGT) was the key enzyme of the terminal of SGAs anabolic pathway in Solanum tuberosum.Studying the gene structure and its encoding enzyme protein characteristic plays an important role in the process of the regulation of SGAs synthesis and production of SGTs by microbial fermentation in plant. Analyzing the structure and properties of three enzyme protein encoded by glycosyltransferase cDNA structure and properties by bioinformatics method. Total RNA was extracted from stem of S. tuberosum and three glycoalkaloid synthase gene (SGT1, SGT2 and SGT3) fragment was obtained by reverse transcription polymerase chin reaction (RT-PCR). It was cloned into pMD^R19-T vector and the positive clones identified by PCR were sequenced. Three SGT enzyme gene fragments were gained from stem of S. tuberosum, each of which contains 1 467-1 518 bp and encodes a peptide of 488-505 amino acids. Similarity comparisons show that they share over 99.12% similarity in nucleotide sequence and over 99% similarity in amino acid sequence with those of other plant SGTase gene (U82367.2, DQ 218276.1 and DQ 266437) in GenBank, UDPG glycosyltransferase conserved domain and many important functional sites. the PI=5.52-5.62. The 3D structure of protein was predicted by homology comparative modeling in Swiss-Model, the results showed that the 3D structure of SGT was highly similar to that of the glycosyltransferase, so it was inferred that SGT3 should be a member of glycosyltransferase superfamily that has function of steroidal glycoalkaloid. sgt1, sgt2 and sgt3 similar gene obtained here was rhamnosyl transferase gene, and its sequence was submitted with GenBank: sgt1, No: JN695005; sgt2, No: JN695006; sgt3, No: HM188447.

The clonal diversity and structure of Hippophae rhamnoides ssp.sinensis
in eastern Qinghai-Tibet Plateau in China

XU Lu, SU Xue, DONG Li-na, ZHANG Hui, CHEN Wen, JIANG Long-long, LIU Jing-xia, SUN Kun

2012, 21(3):  117-124. 

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RAPD (random amplified polymorphic DNA) marker was used to detect clonal structure and diversity of Hippophae rhamnoides ssp. sinensis in eastern Qinghai-Tibet Plateau in China and analyze the possibility relationships between clonal diversity and its influencing effects. Our objectives were to examine the adaptive strategies of alpine plants to varied environments and establish a foundation for understanding reproduction and distribution of clonal plants. We selected 14 random primers for amplification and found average 55.75 repetitive loci with average 15.13 polymorphic loci (total average percentage of polymorphic loci was 27.64%). We differentiated 26 RAPD genotypes or clones among the 184 plants sampled, which formed 89 ramets by clonal growth. Features of size and shape of H. rhamnoides were small with only 3.4 ramets per gemets and 1.75 m between neighbouring ramets on average. Mean Simpson’s index was 0.85, and average E was 0.87, slightly lower than the plants which application of DNA molecular markers. Therefore, the H. rhamnoides populations growing in eastern Qinghai-Tibet Plateau have high capability of clonal growth. The formations of H. rhamnoides are guerill type and expand based on some dominant genets in populations, these distribution pattern increase the adaptation ability to the altiplano environment. The colonisation time, habitats and community composition have to a certain degree affected the clonal diversity of H. rhamnoides populations.

Genetic diversity of Pisum sativum germplasm resources by ISSR

ZENG Liang, LI Min-quan, YANG Xiao-ming

2012, 21(3):  125-131. 

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The genetic diversity of the 73 materials of Pisum sativum from both at home and abroad were analyzed by ISSR marker. 11 primers were selected from 100 primers which have the clearly and polymorphic bands, a total of 91 bands were obtained by 73 materials, including 78 polymorphism bands.On average, each primer amplification site for 8.2 and the polymorphism percentage was 86.4%. Shannon’s index was 0.420 2 in average and the number of effective alleles was 1.451 8, the genetic similarity coefficient ranged from 0.406 5 to 0.934 0 and shows rich genetic diversity. Use groups by UPGMA cluster analysis to the genetic similarity coefficient 0.52 for boundaries, 73 materials are divided into five types, clustering basic accord with geographical origin of close materials for a class together, has a certain regional distribution.

Natural hybridization between Miscanthus sinensis and M. floridulus revealed
by phylogenic analysis using morphological traits and Adh1 sequences

ZHU Ming-dong, JIANG Jian-xiong, XIAO Liang, AI Xin, QIN Jing-ping, CHEN Zhi-yong, YI Zi-li

2012, 21(3):  132-137. 

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Phylogenic analyses based on the morphological characters and Adh1 gene sequences were carried out to identify natural hybridization between Miscanthus sinensis and M. floridulus. One putative hybrid (AD431) clustered together with M. floridulus samples and other putative hybrids (AD623, AD512, AD620, AD619 and AD627) grouped with M. sinensis samples. However, two divergent types of Adh1 gene sequences were observed in all samples of putative hybrids, one of which clustered with M. sinensis while the other clustered with M. floridulus on the Adh1 phylogeny, suggesting that they are true hybrids between M. sinensis and M. floridulus. This study provides a basis for further research on genetic relationship between the two Miscanthus species.

A study on leaf anatomic traits and drought resistance of Medicago rutenica in Inner Mongolia

LI Hong-yan, LI Zhi-yong, SHI Wen-gui, CAI Li-yan, LIU Lei

2012, 21(3):  138-146. 

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The aged leaves of wild Medicago rutenica in 32 populations were observed in Inner Mongolia using paraffin wax embedded sections to analyse and evaluate drought resistance. Optical microscopy was used to measure the anatomical structure of drought-related parameters including the thicknesses of the upper and lower cuticles, leaf, palisade and spongy tissues, the diameter of the vascular bundles, the ratio of palisade to spongy tissue, the tightness of leaf palisade tissue structure and the looseness of leaf sponge tissue structure. Nine indexes differed significantly. There were significant correlations between the thicknesses of the upper and lower cuticles, leaf, palisade and spongy tissues and drought resistance. The eigen value of the third principle component was 1.621 and accumulative rate was 86.67%. The first three principle factors generalized the main information of 9 characters. The 32 populations were divided into 5 groups by the UPGMA method. The membership function to evaluate drought resistance showed that No.16 and 27 had strong drought-resistant while No.22 was weak.

Effects of Ni and Cu on antioxidative enzymes in Peganum harmala

LU Yan, LI Xin-rong, HE Ming-zhu, FENG Li, HUANG Lei, ZENG Fan-jiang

2012, 21(3):  147-155. 

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Peganum harmala seeds were sown in plastic pots in a greenhouse and seedlings were treated with Ni or Cu solutions at different concentrations (50, 100, 200, and 400 mg/kg) and without Ni or Cu solution (control). Ni or Cu accumulation, lipid peroxidation and the activities of antioxidative enzymes in the leaves and roots of P. harmala were examined and measured after Ni or Cu treatment. The Ni or Cu content in the leaves and roots of P. harmala increased in a dose-dependent manner. For Ni, the leaf was the preferential organ for metal storage, while for Cu, it was the root. Malondialdehyde content increased in the leaves and roots with the increase in Ni or Cu concentration, indicating lipid peroxidation increasingly aggravates with the stress. In the leaves of P. harmala, the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) and glutathione reductase (GR) increased with the increase in Ni concentration, suggesting that together they play an important role in the ROS scavenging process, while in the roots, the activities of SOD, CAT and APX decreased, but POD and GR increased, suggesting both might play an important role in weakening Ni-induced oxidative damage. The five antioxidative enzymes increased as a whole in the leaves of Cu treated P. harmala, indicating they might be exerting a certain antioxidant function, protecting seedlings from Cu-induced oxidative damage. In the roots, APX activity was reduced, but the activities of SOD, CAT, POD and GR were enhanced, suggesting they could be effective in lessening Cu-induced oxidative damage.

Effect of drought stress using PEG-6000 on the growth and osmotica of Sedum lineare

ZHANG Yan-qing, RUAN Liang

2012, 21(3):  156-162. 

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Plants of Sedum lineare were treated with PEG-6000 at concentrations of 5%, 10%, 20%, or 30% to simulate drought stress, or without PEG-6000 treatment (control). The fresh and dry weights, water content, root dehydrogenase activity, and contents of inorganic matter, organic matter, inorganic osmotica, and organic osmotica of S. lineare were determined. Seven organic acids were determinated by high-performance liquid chromatography. Compared with the control, under PEG-6000 treatment, fresh and dry weights, water content, root dehydrogenase activity, contents of inorganic matter, Na⁺, K⁺, and NO₃^- decreased, but those of organic matter, free amino acid, proline, and soluble sugar increased, while soluble protein content initially increased and then decreased. HPLC showed that the change rates of seven organic acids differed from each other. Comprehensive analysis indicated that the simulated drought stress inhibited the growth of S. lineare, and the inhibitory effect became stronger with the increase in PEG-6000 concentration. Under the simulated drought stress, S. lineare did not accumulate inorganic osmotica (Na⁺, K⁺, NO₃^-), but used organic osmotica (such as free amino acids, proline, soluble sugar, soluble protein, oxalic acid and propane diacid) for osmotic adjustment.

Analysis on dominant factors influencing water potential of Phragmites australis in extremely arid areas

FU Ai-hong, CHEN Ya-ning, LI Wei-hong

2012, 21(3):  163-170. 

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Phragmites australis grown in the transitional belt between the desert and oasis of dry areas in the lower reaches of the Tarim River in Xinjiang was studied. Meteorological factors, soil moisture, soil salt and leaf water potential of P. australis were measured to analyze daily changes of leaf water potential of P. australis grown with various depths of groundwater. Environmental factors dominating water potential were examined, and they indicated thresholds that reflected water potential changes. 1) When the groundwater became deeper, the daily peak of leaf water potential was reduced; 2) When the groundwater became deeper, the 0-110 cm soil layers became dryer, and P. australis horizontal roots distributed into deeper soil layers; 3) In arid areas, the survival strategy of P. australis appeared to be “higher soil moisture benefits population expansion, while lower soil moisture promotes the height of individual plants”; 4) Soil moisture and air temperature were the dominant factors influencing the change of leaf water potential. P. australis prefers soil containing 10%-20% of water. The threshold of soil moisture at which leaf water potential changed was 18.07%, and the threshold of air temperature was 33.48℃. Leaf water potential did not change if soil water was>18.07% or air temperature was below 33.48℃. This study provides a theoretical basis for mitigating drought stress of P. australis and maintaining its normal growth.

Exogenous salicylic acid on alleviating salt stress in alfalfa seedlings

ZHOU Wan-hai, SHI Shang-li, KOU Jiang-tao

2012, 21(3):  171-176. 

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In order to make clear the physiological and biochemical mechanisms of exogenous salicylic acid (SA) on salt resistant capability of alfalfa, Medicago sativa cv. Gannong No.3 was used as material to study the effect of exogenous SA on alfalfa seedling growth, organic osmotic regulation substance contents and anti-oxidization system on condition of 150 mmol/L NaCl stress using foliar application. The result indicated that 150 mmol/L NaCl salt stress had conspicuous inhibitory effect on alfalfa seedling growth, while significant increase in shoot heigth, root length, fresh weight and plant chlorophyll content were found when 0.25 mmol/L exogenous SA had been applicated, together with significant decrease in free proline and malondialdehyde (MDA) contents in leaves and rootsand increase in soluble protein; superoxide dismutase (SOD), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) activities in leaves were found significantly increased, and no change was found in catalase (CAT), ascorbic acid (AsA) and reduced glutathione (GSH); for the root, GPX activity, AsA and GSH contents were found increased, and no change was found in SOD, CAT and APX activities, indicating that exogenous SA could regulate organic osmotic regulation substances and protect the anti-oxidization system in alfalfa seedling, and alleviate the injure of salt stress on alfalfa plants.

Physiological Responses of Indigofera spicata to different flooding stress

XIN Jun-liang, HUANG Bai-fei, YANG Zhong-yi, YUAN Jian-gang, XU Ya-xing

2012, 21(3):  177-183. 

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Plants grown on the both banks of tidal rivers or river channels with the water level fluctuating seasonally must possess the characteristic of tolerance against flooding. In this study, a flooding experiment was conducted to investigate the variations of survival rate, chlorophyll content, root vitality and root to shoot ratio in order to explore the responses to flooding stress and explain the physiological mechanisms for the flooding tolerance in Indigofera spicata. Six flooding treatments were carried out, including water levels at 5, 10 and 20 cm above soil surface and at 0, 15 and 40 cm above plant top. This work could provide the theory basis for the feasibility of I. spicata using for both banks of tidal rivers or river channels with the water level fluctuating seasonally. The results showed that: 1) I. spicata had a survival rate of 100% after 21 d flooding. Before I. spicata was flooded, the chlorophyll content was 1.94 mg/g. After 3 days of flooding, the chlorophyll contents decreased to 63.2% and 83.9% of the initial value. But the chlorophyll contents were 1.21-1.69 mg/g after 21 days of flooding. This implied that chlorophyll content significantly decreased under flooding stress (P<0.05) but it could maintain a certain level for a long time. 2) Root vitality of underground root significantly decreased with the increasing of flooding time. The initial value was 256.26 μg TTC/(g·h), but the values had decreased to 23.43-71.96 μg TTC/(g·h) after 21 days of flooding. However, adventitious root with stronger root vitality rapidly produced in the flooded stems under semi-submerging conditions. The root vitalities of adventitious root were 123.74-234.31 μg TTC/(g·h) on days 21 of semi-submerging. 3) Shoot biomass significantly decreased and root to shoot ratio gradually increased 6.9%-142.5% with the increasing of flooding duration. This indicates that I. spicata has a strong flooding tolerance, which may make it be able to be applied in river channels of water level changes.

Photosynthetic physiological response of Lolium perenne to NaHCO₃ stress

LIU Jian-xin, WANG Xin, WANG Rui-juan, JIA Hai-yan

2012, 21(3):  184-190. 

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To explore the photosynthetic physiological response of forage to alkaline stress, ryegrass (Lolium perenne) seedlings grown in sands in a greenhouse were exposed to NaHCO₃ at concentrations of 0, 50, 100, 150, or 200 mmol/L in Hoagland’s nutrient solution. The effect of NaHCO₃ stress on the photosynthetic pigment content, gas exchange and chlorophyll fluorescence parameters, and the xanthophyll cycle in the leaf was assessed.1) With an increase in NaHCO₃ concentration, the chlorophyll and carotenoid contents decreased gradually, but the chlorophyll a/b increased continuously. Net photosynthetic rate (P_n), stomatal conductance, transpiration rate, and stomatal limitation to P_n of ryegrass leaves decreased, but the intercellular CO₂ concentration increased, suggesting that non-stomatal limitation was the main cause of the P_n decrease under alkaline stress. 2) The initial fluorescence and non-photochemical quenching (NPQ) increased with increasing concentration of NaHCO₃, while the maximum fluorescence value (F_m), maximal photochemical efficiency (F_v/F_m), actual yield (Φ_PSⅡ), and photochemical quenching of PSⅡ decreased significantly. 3) With an increase in NaHCO₃ concentration, the antenna efficiency at open centers in the presence of NPQ decreased, the deviation from full balance between PSI and PSⅡ improved, the absorbed light energy allocated to the photochemical reaction of PSⅡ reduced, while the proportion of energy lost during antenna heat dissipation increased significantly. The de-epoxidation extent of the xanthophyll cycle (A+Z)/(V+A+Z) initially increased but then decreased, suggesting that antenna heat dissipation dependant on the xanthophyll cycle was the main mechanism for excessive energy dissipation.

Response of photosynthetic physiology of perennial ryegrass (Lolium perenne) to Cd²⁺ stress

LIU Jun-xiang, SUN Zhen-yuan, GOU Ping, QIAN Yong-qiang, JU Guan-sheng, HAN Lei

2012, 21(3):  191-197. 

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Effects of Cd²⁺ on biomass of Lolium perenne were studied, and Cd accumulative characteristics were also elaborated. L. perenne were treated with Cd²⁺(0, 5, 10, 20 mg/L) for 6 days. The biomass of aboveground and underground decreased significantly . With the Cd²⁺ concentration increasing, the Cd content in L. perenne increased significantly, and the distribution proportion of Cd in underground decreased significantly, contrary in the aboveground. L. perenne had the excessive ability in absorbing and transporting Cd. In order to explore the photosynthetic physiology response of L. perenne to Cd²⁺ stress, explaining the biomass change affected by Cd²⁺, L. perenne were treated with Cd²⁺(5 mg/L) for 0, 0.25, 1, 3, 6 days respectively. The photosynthetic pigments contents did not change significantly, whereas the gas exchange parameters and the chlorophyll fluorescence parameters were affected significantly. Within 1 d, the change of Pn, Gs and Ci were consistent, the reduce of net photosynthesis rate was caused by stomatal limitation factors. When the plants were treated 3 and 6 d, Pn significantly decased by 24.4% and 23.4% compared with untreated, the recuce was caused by non-stomatal limitation factors. Tr significantly increased by 74.1% when treated 1 d, this promoted Cd transporting to aboveground. Within 3 d, F_v/F₀ significantly increased by 14.4%, 21.0%, 14.4% compared with untreated, and F_v/F_m significantly increased by 3.1%, 3.2%, 3.1% respectively. ΦPSⅡ, rETR and qP significantly decreasd by 25.3%,25.3%,21.1% when treated 6 d, the PSⅡ light reaction ability reduced. The qN significantly decreasd by 15.6% and 41.5% when treated 0.25 and 1 d, then significantly increasd, the photoprotective capacity was increased. Compared with untreated, Y(NO) significantly increased by 30.8% and 37.8% when treated 0.25 and 1 d, and decreased significantly when 3 and 6 d. Y(NPQ) significantly decreased by 36.9% when treated 1 d, whereas significantly incerased by 17.0% when treated 6 d, the extent of photosynthetic apparatus damage was reduced.

Response of PSⅡ photochemistry efficiency and photosynthetic pigments during exposure of
alpine plants Saussurea superba to natural UV-B radiation

DING Wei, SHANG Yan-xia, SHI Rui, SHI Sheng-bo

2012, 21(3):  198-205. 

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A UV-B-exclusion study was performed in alpine Kobresia humilis meadow during plants growing season. The PSⅡ photochemistry efficiency, photosynthetic pigments and UV-B-absorbing compounds were measured on native alpine plant Saussurea superba. 1) The 3 min dark adapted quantum efficiency of PSⅡ photochemistry, F_v/F_m, showed an increasing trend after a short-term removal UV-B radiation from natural sunlight in all measurements. These means there were photo-inactivation and/or photo-damage of photosynthesis occurred in PSⅡ reaction center. 2)There were same tendency in PSⅡ photochemistry efficiency Φ_PSⅡ and photochemical quenching qP for all measurements during plants growing season; The Φ_PSⅡ and qP were increased and NPQ decreased after removal UV-B treatment, which means that there was an increasing in PSⅡ photochemistry efficiency and a decreasing in non-photochemical quenching and current solar UV-B intensity can impair photosynthetic function. 3)The reduction of photosynthetic pigments contents were mainly caused by the reducing of leaf thickness and relative increase of photosynthetic pigments contents in amb UV-B treatment a specious phenomenon. In summary, strong solar UV-B radiation in Qinghai-Tibet region has a potential negative influence on photosynthetic physiology process in S. superba. UV-B-absorbing compounds were not influenced during the short-term removal of UV-B radiation, mainly due to strong stabilization of these compounds existed in the epidermal layer of the alpine plant S. superba and can provide effective defense against the natural solar UV-B intensity.

Photosynthesis and water use characteristics among different habitats and plant
functional types in Horqin sandy land

LUO Ya-yong, ZHAO Xue-yong, ZHANG Jing-hui, JIA Wei

2012, 21(3):  206-212. 

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To clarify the plant photosynthesis and water use characteristics among different habitats and different plant functional types, five habitats in Horqin sandy land with decreasing soil fertility were selected to represent inter-dune grassland (IDG), fixed sand dunes (FD), semi-fixed sand dunes (SFD), semi-mobile sand dunes (SMD), and mobile sand dunes (MD). The gas exchange characteristics of 35 species of shrubs and herbages (some species existed in several habitats) were measured across the five habitats. The 35 species were divided into different plant functional types according to their life forms, photosynthetic types and nitrogen-fixation characteristics. The net photosynthetic rate (P_n), water use efficiency (WUE), and intrinsic water use efficiency (WUE_i) decreased with decreasing soil N status. In addition, there were no or few differences in P_n among ILD, FD and SFD sites, and between SMD and MD sites. There was no, or few differences in WUE and WUE_i between ILD and FD sites, and among SFD, SMD and MD sites. Leaf P_n, WUE and WUE_i differed significantly among different plant functional types. Leaf P_n, WUE and WUE were higher in grasses than in herbs and shrubs grasses and shrubs. Leaf P_n, WUE and WUE_i were higher in C₄ plants than in C₃ plants, while there were no significant differences between non-legumes and legumes. Herbaceous plants, especially grasses, should be taken into account more in vegetation recovery in Horqin sandy land.

Response of grassland vegetation to climate warming in the Minqin area

CHANG Zhao-feng, HAN Fu-gui, ZHONG Sheng-nian

2012, 21(3):  213-222. 

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The phenological data from 1974-2009 were analysed and data relating to vegetation samples and meteorology during 2002-2010 were gathered to elucidate the response of desertified rangeland to air temperature and precipitation variations. 1) The rising rate of annual average temperature in the desert area since 1961 was greater than that at the global level or the national (China) level over the past century. 2) The responses of desert plants to temperature variation were mainly displayed as: the advance of spring phenology, the delay of autumn phenology and the extension of growing duration, all of which were greater than those reported in the available literature. 3) Both vegetation cover and pure cover were mainly positively correlated with the annual precipitation and the precipitations during June-July and April-May. Plant density was mainly positively related to the precipitations in August and September. 4) The impact of rising temperatures in spring on plant phenology was greater than that in autumn. The advance of phenophases, from higher to lower in order was: bud-expansion>bud-opening>the beginning of flowering>the beginning of leaf extension and leaf maturity>flower-bud appearance>peak flowering>the end of flowering>fruit maturity. The delay of phenophase, from higher to lower in order, was sequenced as: full leaf-discoloration>the beginning of leaf-fall>the beginning of leaf-discoloration>end of leaf-fall.

Characterizing the evapotranspiration of a degraded grassland in the
Sanjiangyuan Region of Qinghai province

CHEN Dong-dong, XU Shi-xiao, ZHAO Xin-quan, ZHAO Liang

2012, 21(3):  223-233. 

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The evapotranspiration (ET) of degraded grassland in the Sanjiangyuan region was investigated to further elucidate the water cycle in this region. The eddy covariance technique was used to measure evapotranspiration and sensible heat flux continuously for 3 years in this degraded grassland in Qinghai province, China. The annual precipitations (PPT) were 460.7, 496.1, and 480.1 mm for the three consecutive years. The annual ETs were 452.24, 474.24, and 459.57 mm, varying in accord with the annual PPT. About 75% of the annual ET occurred during the growing season from DOY121 to 300. The ratio of ET to PPT was greater than 95% during the study period, indicating that there is some balance between ET and PPT and the average in the growing season for each of the three years were 1.86, 1.92, 1.81 mm/d, respectively. However, the averaged ET was lower than 0.6 mm/d during the non-growing season. The annual and daily dynamics were single peak type curves. The maximum monthly ET rate was 2.0-2.2 mm/d, which occurred mainly in June or July. The daily peak appeared at noon and was 0.21 and 0.10 mm/h during the growing and non-growing seasons respectively. ET was most sensitive to net radiation during the growing season while the effect of air temperature and vapour pressure deficit were secondary. Compared with the non-degraded area of Kobresia humilis meadow, the ET of the degraded grassland was lower in the growing season but higher in the non-growing season. The lower vegetation cover was attributed to this result.

Effects of fertilizing on the manilagrass growth and physiological characteristics

QIAN Yong-sheng, ZHU Jiang-min, WU Jian-bing, ZHANG Xiao-qin, CHAI Ming-liang

2012, 21(3):  234-241. 

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The present study demonstrated the optimal fertilizing strategy for normal growth of manilagrass in the long growth stage through the experiments of fertilization, analyzing the interaction of changing in mass growth, colour, density, uniformaity of lawn and the content of chlorophyll, malondialdehyde, catalase and other physiological factors of manilagrass. The results of manilagrass growth factors indicated, the colour score of urea was better than the compound fertilizer and liquid fertilizer with significant effect on turning green in the lawn. The liquid fertilizer could promoted lawn grow uniformly; and the density of accumulation of compound fertilizer was best among the three types of fertilizers, provided the necessary fertilizer for lawn normal grwth at later stage. The treatments of urea with concentration of 15 kg/667 m² was the best for the highest chlorophyll content, bright green colour and flourishing; the treatment of liquid fertilizer (1 000×) improved the MDA (malondialdehyde) to 0.189×10^-2μmol/g FW, recovering normal growth and alleviating the growth stress for short period; the treatment of compound fertilizer (25 kg/667 m²) effectively enhanced the activity of CAT (catalase) for long time.

Effect of phosphorus deficiency on physiological properties of Medicago falcata

REN Li-fei, ZHANG Wen-hao, LI Yan-su

2012, 21(3):  242-249. 

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The deficiency of available phosphorous (P) in most of the soils in China restricts increases of crop production. There have been many studies on the responses and adaptation to phosphorus deficiency of different plant species in the literature, but there is little information on the effect of phosphorus deficiency on physiological properties of pasture plants, especially native legumes of temperate grassland. In this study, the effect of phosphorus deficiency was studied on two ecotypes (Ximeng and Humeng) of Medicago falcata, which is an important legume in temperate grasslands of northern China and which has good tolerance to cold, drought and infertile soils. The two ecotypes differed in their responses to phosphorus deficiency. There were no significant differences in biomass, area, length and volume of root system, phosphorus content in shoots, or net photosynthetic rate between the two ecotypes under phosphorus-sufficient (500 μmol/L H₂PO₄^-) conditions. However, there were greater reductions in biomass, area, length and volume of root system, shoot phosphorus content and net photosynthesis rate in Humeng than Ximeng ecotypes after low phosphorus treatment (5 μmol/L H₂PO₄^-). Further, there was more exudation of citrate from Ximeng than Humeng ecotypes under phosphorus-deficient conditions. Taken together, the tolerance to phosphorus deficiency of Ximeng is greater than that of Humeng.

Evaluation of the fermentation characteristics of mixed oat green hay and native
pastures in the Qinghai plateau using an in vitro gas production technique

CUI Zhan-hong, HAO Li-zhuang, LIU Shu-jie, CHAI Sha-tuo, ZHAO Yue-ping, ZHANG Xiao-wei

2012, 21(3):  250-257. 

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In vitro gas production was used to evaluate for ruminants the fermentation characteristics of mixed oat green hay supplemented with native Kobresia tibetica, Dasiphora fruticosa+Macrophyllous knotweed, and linear leaf Kobresia at ratios of 0∶100, 25∶75, 50∶50, 75∶25 and 100∶0 in the Qinghai plateau. The 48 h gas production and theoretical maximum gas production were positively related to neutral detergent soluble (NDS) content but negatively related to neutral detergent fibre (NDF) and hemicellulose (HC) contents. Gas producing velocity was negatively related to HC content. The lag times were positively related to acid detergent fibre (ADF) and NDF contents, and negatively related to crude protein (CP) and NDS contents. The positive associate effects of different pasture combinations were greater during 12-24 h fermentation, and there was a declining trend of the associate effects as fermentation time increased. When using oat green hay as a nutritional supplement to the ruminants grazing on native grassland, the mixture of oat green hay with the native pastures of K. tibetica, D. fruticosa+M. knotweed, linear leaf Kobresia at a ratio of 50∶50 was appropriate. Therefore, choosing the optimal combination is an effective way to improve the utilization of cold-season pastures of native grasslands in the Qinghai plateau.

Effect of different crude feed on flow of amino acid metabolism and milk protein
content in mid-lactation goats

ZHUANG Su, ZHANG Yuan-shu

2012, 21(3):  258-265. 

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By examining the change of free amino acids of plasma and milk in mid-lactation goats,We explord the effect of different crude feed on flow of amino acid (AA) metabolism and milk protein content. Seven mid-lactation goats were divided into two groups randomly and were fed crude ratio diet of 4∶6 (low concentrate group) and 6∶4 (high-concentrate group). Their plasma were obtained from the jugular vein fistula, and milk samples were collected by hand milking. The content of free amino acids of plasma and milk from all goats were detected by RP-HPLC. Total protein concentration in milk was determined by Bradford method. 14 kinds of amino acids were isolated from plasma and 8 kinds of amino acids were detected from milk in two different diet groups. Amino acid composition of the blood or milk between two groups fed different crude feed ratio was no obvious difference Ketogenic amino acid (Leu, Lys), acultative amino acids (Phe, Ile) and branchedchain amino acids (Leu, Ile, and Val) of the blood were significantly or very significantly higher than that in milk. Ala was only amino acid which very significantly lower in blood than in milk. In high-concentrate group, except for Gly and Ala, the contents of the rest amino acids from blood were lower than that of low concentrate group. Total protein concentration in High-concentrate group was slightly higher than that in low concentrate group. but there was no significant difference. It was suggested that free amino acids in blood can provide the raw material and adequate energy for the synthesis of milk protein. When Mid-lactation Goats were fed high concentrate diet, it may not be conducive to increase the content of milk protein and milk production because of low levels of free amino acids in the blood.

Effect of different Chinese herbal compound on production performance
and immune function of Yunling black goat

LIU Zhi-ying, YANG Guo-rong, WANG Chun-yuan, SUN Juan, HAO Zhi-hui

2012, 21(3):  266-274. 

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Effect of different Chinese herbal compound on production performance and immune function of Yunling black goat was evaluated in this study. 120 adult ewes with close birth date and weight were randomly divided into 4 groups by 30 per group, in which one was chosed as the control group and the other 3 groups as treatments (adding 1.2% of concentrate with Echinacea extract compound, four gentlemen powder and strong powder in the feed, respectively). The experiment included preliminary trial period (7 d, 1/4 of trial amount was added in the first 2 d, 1/3 of it was added in the second 2 d, 2/3 of it was added in the third 2 d, all trial amount was added in the 7th day) and trial period (60 d). All adult ewes were weighed fastingly on the morning of the 0, 30th and 60th day, recorded the total gain, average daily gain, and calculated the feed conversion ratio and the economic effectiveness. 1) In groupⅠ, the total weight gain and average daily weight gain were both the highest, with the value of 6.17 and 0.103 kg, which were 17.97% and 6.18% higher than that of control group respectively, but those of other 2 treatments were both lower compared to the control group; 2) In groupⅠ, the feed conversion ratio was 1.96: 1, and it was lower than that of the control group and groupⅡ by 7.09%, 17.76% and significantly (P＜0.05) lower than that of group Ⅲ by 45.01%; 3) In groupⅠ, the net profit of sheep was the largest with the price of 4.25 Yuan/(d·ewe) which was 15.76% higher compared to the profit 3.58Yuan/(d·ewe) gained from the control group; 4)The number of red blood cell (RBC) and hematocrit (HCT) apparently increased in groupⅠ(P＜0.05), the number of white blood cell (WBC) was higher by 3.98% than that of the control group, and the number of RBC also increased greatly in groupⅡ(P＜0.05); 5) The serum total protein (TP) and globulin (GLB) of groupⅠand Ⅲ were significantly higher than those of the control group (P＜0.05), also the Serum TP was 11.65% and 12.33% higher than that of the control group respectively, and the GLB of the two groups increased by 27.25% and 22.16%; 6) The serum cholesterol (CHO) of the 3 treatments was less than that of the control group (P>0.05), and compared to the control group, the CHO content of groupⅠ,Ⅱand Ⅲ decreased by 15.25%, 2.12% and 6.78%, respectively; 7) In groupⅠand Ⅲ, the immunoglobulin G (IgG) content was higher than that of other groups, especially higher than that of the control group by 3.5 and 1.3 times respectively. In conclusion, the Echinacea extract compound can promote production performance and the immune function of Yunling black goat, and it also increases the economic benefit.

Effect of nitrogen fertilizer source on mineral element content of forage and in
the blood of grazing Guizhou semi-fine sheep

SHEN Xiao-yun, JIANG Hui-mei, YUAN rong, JIA Zhi-hai

2012, 21(3):  275-280. 

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To assess the impact of fertilization on mineral element content in the forage and in blood of grazing Guizhou semi-fine sheep, fertilization and grazing experiments were conducted in the Liangshuiguo pasture area of Weining county. The average concentrations of N in the forages from the fertilized pastures were significantly higher than in those from the control but there were no significant differences between the fertilized pastures. The average concentrations of S, Mn and Zn in forages from the pastures fertilized with ammonium sulfate were significantly higher than those treated with other fertilizers. The application of ammonium sulfate led to a significant reduction in selenium content of the forages. At the end of the study period, the Cu, Fe and Se contents in the blood of Guizhou semi-fine sheep from pastures fertilized with ammonium sulfate were significantly lower than in those fertilized with ammonium nitrate and from the control while the Mn, Zn and S contents were significantly higher. The blood hemoglobin (Hb), packed cell volume (PCV) and serum ceruloplasmin (Cp) contents and the activities of serum SOD, glutathione peroxidase (GSH-PX) and CAT of Guizhou semi-fine sheep from the pastures fertilized with ammonium sulfate were significantly lower than in those fertilized with ammonium nitrate and from the control. Thus, Liangshuiguo pasture area should not be fertilized with ammonium sulfate.

Effect of dietary composition on the digestive and energy metabolisms of yak calves

YANG Shi-hai, LI Shi-xiong, MA Yu-shou, WANG Liu-ying

2012, 21(3):  281-286. 

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A supplementary strategy and feedlotting method for yak calves was sought as a new approach to alleviate the pressure on natural grasslands and allow recovery of natural vegetation. A 3×3 Latin square test of digestive and metabolic trials was designed in Dawu township of Guoluo Prefecture. Three yak calves per treatment were fed with 3 different diets: (A) 100% Elymus nantus silage, (B) 40% concentrate+60% E. nantus silage, and (C) 60% concentrate +40% E. nantus silage.1) There were significant differences in digestibility of dry matter, organic matter, crude protein and energy with the different diets, but there was no significant difference for crude ash. With an increase in percentage of concentrate in the diet, the digestibility of every nutrient ingredient in the different diets gradually decreased; 2) The metabolizability of energy for diet C was significantly lower than that for diets A and B, but the efficiencies of digestive energy conversion into metabolic energy (ME/DE) were not significantly different between the 3 diets. The average conversion efficiency was 0.78; 3) Calcium (Ca) extracted from faeces and urine was significantly different between the diets, while phosphorus (P) differed significantly from urine from the three diets but not from faeces. Ca sediment decreased with the increase in percentage of concentrate, but P sediment was maximum in diet A and minimum in diet B. These results showed that the digestive and energy metabolisms of diets for yak calves were closely bound up with dietary composition. Apparent digestibility decreased with an increase of dietary level. These result provide a scientific basis for supplementary feeding and celerity fattening, which would be an effective approach to speed up turnover of drove and to increase the merchandise ratio of yaks.

Influence of alfalfa saponins on cholesterol metabolism and the expressions of ACAT-2
and HMG-CoAr in the liver of hyperlipidemia rats

WANG Xian-ke, SHI Ying-hua, WANG Cheng-zhang, CHEN Ming-liang, YUAN De-di

2012, 21(3):  287-293. 

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The effect of alfalfa saponins on cholesterol metabolism and the expressions of ACAT-2 and HMG-CoAr in the liver of hyperlipidemia rats was investigated. Forty healthy male Sprague Dawley (SD) rats were randomly divided into four groups: normal (control, A), hyperlipidemia model (B), alfalfa saponins prevention group (C), alfalfa saponins treatment group (D). Except for the controls, rats were fed a high-fat diet for eight weeks. Alfalfa saponins were added by gavage to group C from the first week, and to group D from the fifth week. Body weight, liver index and serum lipid level of the rats were measured. Protein and mRNA expressions of ACAT-2 and HMG-CoAr were measured by enzyme linked immunosorbent assay (ELISA) and real-time PCR methods respectively. 1) The body weight, liver index and serum lipid level of hyperlipidemia rats were significantly reduced, and the fatty degeneration and steatosis in the liver were ameliorated by alfalfa saponins. 2) The protein and mRNA expressions of ACAT-2 in groups C and D were significantly lower than those in group B(P<0.01), but there was no significant difference for HMG-CoAr. In conculsion, alfalfa saponins prevented hyperlipidemia by reducing the expression of hepatic ACAT-2, and by inhibiting the absorption of exogenous cholesterol.

Effect of carbon cycling in grassland ecosystems on climate warming

FAN Yue-jun, HOU Xiang-yang, SHI Hong-xiao, SHI Shang-li

2012, 21(3):  294-302. 

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Human activity-induced greenhouse effects and the impact of consequent global warming on grassland ecosystems have drawn increasing attention. Carbon cycling of grassland ecosystems is an important component in terrestrial ecosystem, and is an essential contribution to carbon sources in the terrestrial biosphere in future. It is necessary to understand the effect of carbon cycling on climate change for the prediction of terrestrial ecosystems and for relevant policy making. This paper reviews current research on the impact of global warming on net primary productivity, soil respiration, litter fall input and decomposition, and on the carbon pool of grassland ecosystems. The mechanisms and processes of grassland ecosystems in responding to global warming are discussed, existing problems in research on carbon cycling of grassland ecosystems are analyzed and possible further research is proposed.

A study on the relationship between the pod, seed development and the occurrence of
seed hardiness of Melissttus ruthenicus

WANG Ying, HOU Yu, LI Xiao-yu, LIN Ji-xiang, YANG Guang, MU Chun-sheng

2012, 21(3):  303-307. 

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Melissttus ruthenicus is a perennial legume and one of the most common fodder plants in northern China. It is a wild, high-quality forage grown mostly for hay, green forage, silage or seed production. However, seed hardiness is a major problem in the seeding of M. ruthenicus. This study evaluated the simple empirical relationship of time and seed hardiness by simultaneously analyzing pod and seed morphological and physiological properties. Pods were harvested at three-day intervals from the 9th day after peak anthesis (DAPA) until pod shattering. The pod and seed both lost green color and turned brown from the 33rd to 36th DAPA. The length, width and thickness of pod and seed differed significantly between sampling dates. Pod length and thickness declined significantly at the 33rd DAPA. Seed length, width and thickness significantly decreased from the 33rd to 36th DAPA. The fresh weight of pod and seed increased at an early developmental stage but decreased markedly thereafter. However, the dry weight of pod and seed increased significantly with sampling dates and reached a maximum at the 27th DAPA, then stabilized from the 27th to 36th DAPA (pod dry weight) and the 30th to 36th DAPA (seed dry weight). The water content of pods and seeds decreased significantly over the sampling dates and reached about 20% at the 33rd and 36th DAPA respectively. Seed hardiness occurred at the 33rd and 36th DAPA when seed water content was about 20%. There was a significant negative correlation between the percentage of hard seed and seed water content. In conclusion, growth stage and seed water content affected the occurrence of seed hardiness. Pod and seed morphological and physiological properties could be reliable and rapid indicators of seed hardiness, providing a simple way to judge the occurrence of seed hardiness. However, the dry weights of pods and seeds could not be used as indicators.

Diurnal dynamics of photosynthetic characteristics of Leymus chinensis under different
grazing intensities taking the Hulunber meadow steppe as an example

YANG Gui-Xia, REN Zheng-Chao

2012, 21(3):  308-313. 

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To explore the response of photosynthetic characteristics of Leymus chinensis to different grazing intensities under continuous grazing, the diurnal dynamics of photosynthetic characteristics in five grazing plots and one enclosing plot were measured using Li-6400 Portable Photosynthesis System. The correlations between the traits of parameters and grazing intensities (R) were analyzed. Daily variation of net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) appeared as a single peak curve and a double-peak curve in all plots on 16th August and 2nd September respectively, but intercellular CO₂ concentration (Ci) showed a U shape trend. In the enclosed plot, Pn, Tr, and Gs were higher than those in the grazed plots. In addition, Pn, Tr, and Gs decreased with an increase in grazing intensity, but Ci increased. It is suggested that the variation range is greater under higher grazing intensities. There were significant negative correlations between Pn, Tr, Gs and R but Ci was significantly positively correlated with R. There were significant differences in Pn, Tr, Gs and Ci among 6 grazing intensities on the two dates. Hence, herding intensity and hydrothermal conditions can inhibit photosynthesis by L. chinensis.

Phosphorus purification of duck wastewater in Baiyangdian Lake basing
on a simulated reed wetland system

LIU Chao, LV Lin-lin, XIE Jian-zhi, TIAN Zai-feng, HU Xiao-bo

2012, 21(3):  314-318. 

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An indoor experiment using undisturbed soil columns from Baiyangdian Lake was carried out to elucidate the purification dynamics of total phosphorus (TP) in a reed growing system and to estimate the environmental capacity of TP. Compared with the control, the reed biomass in duck wasterwater increased by 36.1%, 24.4%, and 24.3%, in the low, medium, and high concentrations respectively of TP. By using the reed wetland system, the TP removal from the duck wastewater was very obvious at different time periods and the removal efficiency reached up to 98%. The purification process of TP tended to decline when the hydraulic retention time was over 3 days. The TP purification of this ecosystem in different periods fitted a power function equation and the best purification efficiency was achieved when the temperature was 23℃. It showed that the best removal effect associated with the shortest hydraulic retention time and the smallest area may be achieved when this system is used to purify high P wastewater and thus ane environmental capacity of 171.71 t/a for TP was calculated.