Acta Prataculturae Sinica

Multi-dimensional structure of pratacultural science

REN Ji-zhou, HOU Fu-jiang

2010, 19(3): 1-5.

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Concept of dimension has been generally used both in natural science and humanities among modern scientific system. Dimension owns its reality of theoretic system and is one part of scientific framework. Pratacultural science has four dimensions where Grassland Typology, Grassland Ecological Chemistry, Grassland Agro-ecology and Pratacultural Information System constitutes typological dimension, chemical dimension, systematic dimension and information dimension, respectively. Typological dimension plays a key role in cognition of grassland phenomena, chemical dimension is primary indicator of ecological efficiency and economic efficiency of pratacultural system, systematic dimension maintains the existence and continuation of modern pratacultural industry and Pratacultural science and information dimension forms the ‘neural networks’ of modern Pratacultural science. Every dimensional subject has the distinctive and whole theory system whilst four dimensional subjects infiltrate mutually and develop crosswise, which is expressed in three knowledge sectors and the other subjects of Pratacultural science. In this way, dimensional subjects integrate and condense Pratacultural science and hence produce the multi-dimensional structure with high ecosystem diversity.

Grazing impact on distribution pattern of the plant communities and populations in Stipa krylovii steppe

ZHAO Deng-liang, LIU Zhong-ling, YANG Gui-xia, XIN Xiao-ping, LIANG Cun-zhu, WANG Wei, WANG Li-xin

2010, 19(3): 6-13.

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A continuous period of four years (2006-2009 years) rotational grazing experiment was carried out on Stipa krylovii steppe in the central part of Inner Mongolia in the summer and autumn. With combination of photography and geographic information systems, we had studied ecological effects of grazing on the distribution pattern of plant populations and communities in different grazing intensities experimental plots. The photographic images and experimental data showed that there had formed patches with different sizes and structures in different grazing areas, also the gradient sequence of communities and population and plant production were caused by a different cycle and intensity of grazing. However, the patches in no-grazing enclosed control area(G5) were still original Ass.S. krylovii and Ass. Leymus chinensis. The percentage of the number and area of patches、the plants composition and above-ground biomass were all relatively stable in G5. In different grazing intensity experiments plots(G1、G2、G3),there formed different gradient on the number, area, population structure, plant abundance, circumference and above-ground biomas. Ass.S. krylovii and population patch become fragmentation and individual plant become miniaturization due to different grazing intensity. Moderate grazing makes the patch structure and above-ground biomass emerge in the effects of compensatory growth of plants. This study showed that the changes of plant patch structure in community and population pattern were the basic for population colonization and recession during grassland succession, and also the mechanism for the succession of grassland plant communities.

Evaluation of MODIS MOD13Q1 data in desertification in the north area of Xinjiang

LIU Yan, LI Yang, CUI Cai-xia, RUAN Hui-hua

2010, 19(3): 14-21.

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We use MODIS MOD13Q1(vegetation indices 16-day L3 global 250 m)data to compute cumulative sum of 16 scenes MOD13Q1 data from late May to late September in 2008 and 2007 when the vegetation in growing, convert vegetation coverage, compute the desertification Index and classify. The classification result objectively reflects spatial distribution of desertification in the north area of Xinjiang. Non-desertification area mainly distributes in the mid-high parts of Tianshan Mountain, Altai Mountain and some oasis. The other areas also have varying degree of desertification. Therefore MOD13Q1 data can be efficiently applied to large scale environment change and remote sensing monitoring of desertification process. In the paper, We can access regional temperatures, precipitation by spatial interpolation of DEM,annual mean maximum temperature and annual mean precipitation data gathered in the 37 weather stations. DI and temperature have high positive correlation, while DI and precipitation have negative correlation by correlation analysis of DI, temperature, precipitation.

Analysis of AHP strategic decisions for the ecological risk of grazing system and management decisions in an alpine meadow at Gannan, Gansu

LI Wen-long, SU Min, LI Zi-zhen

2010, 19(3): 22-28.

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This study explored the primary risk factors restricting the development of stockbreeding and the characteristics of its varied temporal-spatial distribution in eco-economic terms. It further reveals the connotation of ecological risk analysis. Based on the multi-hierachy AHP strategic decision model, the ecological risks of a grazing management system in the alpine meadow at Maqu, Southern Gansu were comprehensively analyzed. Among the factors leading to the degeneration of vegetation and the formation of sandy soil, long-term overgrazing was the main factor, with a weighting of 0.480 3. The risk of reduction in rainfall from global climate change, mouse and insect pests, were weighted 0.290 2 and 0.155 8 respectively. Effects of other human improper activities (e.g. digging medicinal herbs and mining) were less important and weighted at only 0.073 7. Among the strategic measures of management, rotational grazing (to reduce the density of grazing), reseeding, fertilization and enclosure for the degraded pasture showed the best effects, and the combination weightings were 0.306 0 and 0.266 1. Deratization and establishing artificial pasture also showed some effects. Based on the above risk evaluation analysis, the main management decision for a precautionary measure of the ecological risk was proposed, being quantitative support for meadow resource protection and sustainable development.

β diversity characteristic of vegetation community on south part of Gurbantunggut Desert and its interpretation

ZHAO Huai-bao, LIU Tong, LEI Jia-qiang, GUI Dong-wei, ZHAO Xin-jun

2010, 19(3): 29-37.

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β diversity is an important index characterizing composition variation of vegetation community. The southern part of Gurbantunggut Desert is taken as the study area in this paper, on the basis of vegetation survey in 67 plots, β diversity variation of vegetation community in the study area is analyzed first in longitudinal and latitudinal directions, and then the method of variance partitioning is used for analyzing contribution ratio of environment variable, soil seed bank variable and spatial variable to β diversity differentiation, discussing the mechanism of β diversity differentiation of desert vegetation. It is shown with the results that β diversity is an increase of species similarity from west to east in longitudinal direction, and the species succession rate declines; a decrease of species similarity from north to south in latitudinal direction, and the species succession rate increases slightly. Regarding interpretation of β diversity differentiation, the environment variables such as 30-year’s average monthly precipitation play a decisive role in distribution of desert vegetation community, while the interpretation ratio of soil variable and spatial variable are relative low. Comparing with soil heterogeneity, the variation of soil seed bank has a bigger impact on β diversity differentiation. The main environmental variables, soil variables effect were scale dependent. Neutral process determined by the spatial structure also plays a role. It is found out that although environment variables (including soil variable), soil seed bank variable and spatial variable are taken into consideration, nearly 50% of β diversity differentiation cannot be interpreted, which indicates that some other environment variables and random process have impact on the variation of vegetation community.

Effect of ecological factors on plant communities of the Cele River Basin on the north slope of the middle Kunlun mountains

GUI Dong-wei, LEI Jia-qiang, ZENG Fan-jiang, JIANG Yuan, MU Gui-jin,YANG Fa-xiang

2010, 19(3): 38-46.

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This research explored the relationships between environmental factors and vegetation patterns in the arid mountain ranges. The Cele River Basin on the north slope of the middle Kunlun mountains was selected as the study area to set up 63 plots at altitudes ranging from 1 960 to 4 100 m. Eighteen variables were used as indicators of spatial position, soil characteristics, and topography. The types of plant community in this region were investigated in relation to environmental factors using TWINSPAN, DCA and DCCA. In order to eliminate redundant environmental variables, the environmental factors which significantly influence plant community composition were chosen by forward selection and Monte Carlo tests. 1) The plant communities in this region could be divided into 4 types by TWINSPAN. 2) The results of DCA ordination indicated that the main factor restricting the distribution of communities was altitude. The number of species increased with increasing altitude. A comparison of the ordination of species with that of quadrats showed that the ordination plot of the dominant species in plant communities was similar to that of the plant community type. To some extent, the distribution of the former determined that of the latter. 3) Six environmental variables (e.g. altitude) were used in the species-environment correlation analysis. The ordination result of DCCA indicated that altitude was more important than other environmental factors because the change of altitude gradient would lead to changes in both temperature and humidity gradients. The first axis indicated the gradient of altitude between communities, while the second axis was the pH gradient between communities. Compared with other areas, the scarcity of plant species and the differentiation of plant communities were obvious in the arid mountain range. The altitude was an important factor that influenced the plant species and vegetation patterns. Using methods of Quantitative Ecology better result of ecological relationships between vegetation and environment can be obtained.

A study on the biomass of Oxytropis coerulea-Carex dispalata meadow and Bothriochloa ischaemum hassock in Wutai mountain

MA Ni, SHANGGUAN Tie-liang, ZHANG Qiu-hua, ZHANG Zuo

2010, 19(3): 47-55.

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A locating quadrat investigation and forage harvest methods were applied to study the phytocoenological characteristics, biomass and height dynamics in meadows dominated by Oxytropis coerulea and Carex dispalata, or by hassocks of Bothriochloa ischaemum in the Wutai mountains of Shanxi province. Both species composition and community structure differed greatly between the two communities. The total biomasses of the two communities were 7 282.98 and 4 184.68 g/m² respectively, of which the aboveground biomass (stem, leaves, and spike) were 1 018.34 and 890.08 g/m² while the underground biomasses were 6 264.64 and 3 294.60 g/m². In addition, the height dynamics of the dominant species in the two communities including O. coerulea, C. dispalata, B. ischaemum and Themeda japonica were simulated using the Logistic model, starting from recovering to blooming stage. The F-test showed there were significant correlations. However, the heights of O. coerulea and C. dispalata decreased rapidly due to the abscission of seed and apex of dried-up and broken stems during the maturation and withering stages, which therefore did not fit the Logistic model.

Interspecific relationships and ecological species groups of dominant herbage species in Eucalyptus grandis plantation

ZHONG Yu, ZHANG Jian, YANG Wan-qin, WU Fu-zhong, FENG Mao-song, LIU Quan-bo

2010, 19(3): 56-62.

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Based on the data of 60 plots obtained from investigation, the interspecific relationships among 16 dominant herbage species in Eucalyptus grandis plantation were studied by using χ²-test, Jaccard’s association index test and Spearman’s rank correlation coefficient test, respectively. The results indicated that most species were independently distributed and not closely related with each other. The major of species pairs correlated negatively, which showed the communities were in the phase of succession and the species composition would change. Indicators of interspecific association adding to correlation coefficient was an effective method to study the relationship between species. The 16 dominant species were classified into three ecological species groups. The Species in same ecological species groups had similar resource utilizing ways and ecological requirements, but those in different groups showed apparent differences. The classification of ecological species groups would provide a theoretical basis on managing herb layer in Eucalyptus grandis plantation.

Fractal study of the distribution proportion of the oasis system in China

LI Jian-lin, WANG Yan, GUO Qiao-ling, FENG Qi

2010, 19(3): 63-69.

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Natural oasis are a key factor of the oasis system and understanding them is very important for developing a persistent artificial oasis environment. The distribution proportion between natural and artificial oasis is quantified as the percentage artificial oasis in the total (PAO). Based on data of oasis landscape observed in Xinjiang Autonomous Region, China, the distribution of PAO was analyzed using fractal theory. 1) The distribution of PAO showed fractal characteristics, and the fractal dimension of PAO increased with the development of the oasis system, so the fractal dimension of PAO can be regarded as a dynamic parameter of oasis evolution. 2) A function between fractal dimension and expectation of PAO was established, and the area of expectation of PAO was 0-85.02%, and the area of fractal dimension of PAO was 0-1.708. That is, natural oasis should occupy at least 15% in a oasis system. 3) Fractal dimension and expectation of PAO of an oasis system in Xinjiang Autonomous Region of China were 0.537 and 53.5% respectively, suggesting that artificial oasis in this region should develop to a certain extent. However, this development should harmonize with the development of natural oasis.

A study on the diversity and aboveground biomass in a Leymus chinensis meadow steppe community under different cutting intensities

HAN Long, GUO Yan-jun, HAN Jian-guo, GUO Yun-jiang, TANG Hua

2010, 19(3): 70-75.

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The effects of cutting intensity on the biodiversity and aboveground biomass of Leymus chinensis meadow steppe were studied at the southern margin of the Inner Mongolian Plateau. Five stubble heights (2, 5, 10, 15 cm, and non-cutting) were designed to represent different cutting intensities. The aboveground biomass of the dominant species, L. chinensis, was significantly reduced by an increase of cutting intensity (P<0.05). The height of aboveground parts in the non-cutting treatment was significantly higher than those under the 10 and 15 cm cutting treatments (P<0.05). The diversity indexes (Margalef index, Simpson index, Shannon-Wiener index and Pielou index) increased with an increase of cutting intensity (P<0.05). The relative density of L. chinensis decreased with an increase of cutting intensity, while that of Cleistogenes squarrosa and Potentilla, increased. Correlation analysis indicated that there was a “single peak” curve between diversity index and aboveground biomass in this steppe community. Diversity index was significantly negatively correlated with the aboveground biomass of L. chinensis.

A study on soil erodibility in a combined experimental trampling and simulated rainfall experiment on a Stipa bungeana steppe in Huanxian County, Gansu Province, China

LIN Hui-long,WANG Miao-miao, LI Xue-ling, WANG Zhao-qi

2010, 19(3): 76-87.

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Soil erodibility differed with various combinations of experimental trampling and simulated rainfall. Under the same simulated rainfall condition, the soil erodibility factor, k, increased as the trampling intensity increased, suggesting that trampling enhanced grazing-induced erosion risk. However, the amplitude of the k value was apparently related to the levels of simulated rainfall: the k value changed in the sequence arid>natural>average>high. There was an interaction between the effects of trampling and simulated rainfall on the k value. Simulated rainfall reduced the trend of k value increase while an increase in trampling intensity did the opposite. A positive correlation was found between the k value and trampling intensity (Coefficient=0.741), and a negative correlation between k value and rainfall level (Coefficient=-0.378). Compared with traditional regression models, the artificial neutral network (ANN) model shows many advantages, such as self-studying, self-organizing, self-adapting and fault tolerance. Therefore k was calculated using the ANN model, based on the independent variables of accumulated trampling effects per unit area and simulated rainfall. The ANN model allows the complicated soil erodibility mechanisms to be skipped and to directly establish the relationship between soil erodibility and factors influencing it. e.g. trampling and rainfall. This study is an innovative attempt to evaluate soil erodibility more precisely.

Seasonal variations of total phosphorus in marsh soils from open and closed wetlands

XIAO Rong, BAI Jun-hong, GAO Hai-feng, DENG Wei, CUI Bao-shan

2010, 19(3): 88-93.

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The Fulaowenpao and Erbaifangzi wetlands were chosen as typical sites in which to study characteristics of the seasona1 dynamics of total phosphorus (TP) in marsh soils from closed and open wetlands and to discuss the relationship between TP and other physical and chemical properties. TP content in the 0-100 cm depth of Fulaowenpao wetland soil ranged from 48.77 to 377.19 mg/kg, and in the Erbaifangzi wetland, from 45.65 to 574.17 mg/kg. On a seasonal basis, soil TP content in the two wetlands decreased first and then increased. From December 2008 to May 2009, soil TP content remained high, then decreased slowly from May to August. It remained very low during September and October, and finally gradually increased between October and December. Soil TP was mainly distributed in the 0-40 cm top soils in both wetlands, with a low content that was little different below. Soil TP content of the two wetlands did not reach a level that caused eco-toxic effects. There was an obvious positive correlation between plant TP and soil TP. However, the vegetation of Fulaowenpao wetland was restricted by nitrogen and phosphorus while there was limitation to Erbaifangzi vegetation only from nitrogen. There were remarkable positive correlations between soil TP and total nitrogen, organic matter and soil clay, and but no significant correlation between soil TP and soil C/N in the two wetlands. pH negatively correlated with soil TP in Erbaifangzi wetland, but not in Fulaowenpao wetland.

Spatial distribution of soil nutrients and soil microbes in five arbore-bushe-grass lands at the south-north hills in Lanzhou, China

ZHONG Fang, ZHAO Jin, SUN Rong-gao, LI Zheng-ping,WANG Wan-peng

2010, 19(3): 94-101.

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The spatial distribution of soil nutrients and soil microbes in five arbores-bushes-grass lands at the south-north hills in Lanzhou was studied. The results showed that: 1) the soil organic matter and total N content in the soil of Caragana korshinskii land were significantly larger than lands of Tamarix austromongolica, Lycium chinense, Reaumuria soongorica and Platycladus orientalis types (P<0.05), the soil chemical property was improved. The ranking of the soil nutrient contents was C. korshinskii type>T. austromongolica type>L. chinense type>R. soongorica type>P. orientalis type. The amount of soil microbes was the most abundant at the C. korshinskii type land. 2) The quantity of microbes and nutrient content clearly decreased with the soil depth in the different land because of soil fertility factor. The quantity of microbes in the 0-10 cm layer was 47.86% of total microbes. 3) The interaction was existed among vegetation, soil nutrient and soil microbial quantity in some extend.

Effects of nitrogen and phosphorus on seedling growth and total alkaloids of Sophora flavescens

LIN Hai-ming, JI Ying, WANG Bin, DU Yan-bin

2010, 19(3): 102-109.

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The effects of nitrogen (N) and phosphorus (P) on seedling growth, chlorophyll, Chl concentration, total alkaloids concentration and total alkaloids yield of Sophora flavescens was studied. Four levels of N were applied at the rates of 0 (Control), 38, 75, and 150 kg/hm² using urea (N 46%) fertilizer, and three levels of P at 0 (Control), 23, and 45 kg/hm² using single superphosphate (P₂O₅ 12%) in a virgin land test. Seedling stem height, bud numbers, plant fresh weight, root fresh weight, and root dry weight of S. flavescens increased significantly when N and P were applied. The interaction of nitrogen and phosphorus was significant. The treatment of 150 kg/hm² N and 23 kg/hm² P led to significantly (P≤0.05) greater stem height, bud numbers, plant fresh weight, root fresh weight and root dry weight than the control (increases of 27.1%,31.7%,123.2%,104.8%, and 120.0% respectively). The results for the treatment of 75 kg/hm² N and 23 kg/hm² P were close to these. Root dry weight/root fresh weight and root dry weight/total plant dry weight increased with P applied. The root diameter and the xylem diameter were greatest with 150 kg/hm² N and 23 kg/hm² P applied, increasing by 26.4% and 39.8% respectively compared with the control (P≤0.05). There was a significant positive effect of nitrogen and phosphorus on root bark thickness which increased with N and P applied to a maximum at 45 kg/hm² P applied. The treatment of 150 kg/hm² N and 23 kg/hm² P led to significantly (P≤0.05) greater leaflet numbers per plant, leaflet area, plant area, leaflet fresh weight, leaflet dry weight than the control (50.9%, 79.8%, 168.0%, 58.5%, and 87.1% respectively). There were positive effects of nitrogen and phosphorus on seedling Chl concentration, total alkaloids concentration and total alkaloids yield of S. flavescens. Chl concentration and total alkaloids concentration were greatest with 75 kg/hm² N and 45 kg/hm² P applied, increasing by 80.3% and 71.0% respectively compared with the control (P≤0.05). It is proposed that the positive effect of nitrogen and phosphorus on root dry weight is due to the positive effect on main root dry weight, and that the root diameter increased with N and P applied due to the increase in xylem diameter and root bark depth, and that total alkaloids concentration increased with N and P applied due to the increase in Chl concentration.

Forage crop rotation and it’s benefit in the purple farming area of Sichuan province

PANG Liang-yu, ZHANG Hong, LUO Chun-yan, HUANG Jing-jing, FU Deng-wei, FENG Wen-qiang, LIN Chao-wen, ZHANG Xin-quan

2010, 19(3): 110-116.

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The aim of this study was to introduce forage crops as a main rotation crop, and to establish an efficient crop rotation suitable for the slope arable land of the purple soil area in Sichuan. A completely randomized block design was used with three replicates during three years of study. Compared with that from the CK, the yields of fresh forage, feedstuff dry matter and crude protein were promoted by 800%-900%, 50%, and 100%, respectively under a crop rotation with wheat and ryegrass, or with oats in winter and with grass sorghum and chicory in summer. The benefit of wheat was more than 30% and the yield was maintained. The new crop rotations can maintain foodstuff yield in the purple soil area, and at the same time, can improve the yields of feedstuffs, thereby providing security of high quality feedstuff for stockbreeding. These are sustainable crop rotations in the slope purple farming area of Sichuan province.

Effect of cold stratification on dormancy and germination of four Carex species seeds

LUO Xian, PAN Yuan-zhi, YANG Xue-jun, WU Ju-ying, TENG Weng-jun, FAN Jun-gang

2010, 19(3): 117-123.

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The effect of cold stratification on dormancy and germination of four Carex species seeds were studied. The germination percentage (GP), germination index (GI), endogenous hormone content, and soluble sugar and starch were measured to explore the causes of dormancy. Stratification treatment elevated GP and GI of the seeds. The GP of C. humilis var. nana and of C. lanceolata seeds increased from 34% to 84% and from 40% to 81%, respectively and the GI of C. breviculmi and C. giraldiana seeds increased from 7.88 to 18.15 and from 2.86 to 5.20, respectively. High levels of endogenous ABA content may be an important factor for Carex seed dormancy. Soluble sugar content positively correlated with GI.

Distribution characteristics of endophytic bacteria isolated from forage grasses

CHE Jian-mei, LIU Bo, ZHANG Yan, HU Gui-ping, HUANG Qin-lou, CHEN Zhong-dian, WENG Bo-qi

2010, 19(3): 124-131.

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The endophytic bacteria were isolated from different forage grasses according to culture method and identified by using fatty-acid identification technology. The results showed that the contents of endophytic bacteria of hybrid pennisetum “Minmu six”, which was 26.800×10⁴ CFU/g, was higher than other forage grasses. The endophytic bacteria isolated from different forage grasses were from 19 species belonging to 12 genera. The cluster analysis results showed that the 19 strains could be separated into 4 groups. It was concluded that the distribution characterics of endophytic baceria were related to different forage grasses and different isolated parts, especially to the different forage grasses.

Effect of exogenous metallothionein on blood GSH-Px and CAT gene expression in dairy cattle

ZHANG Bin, TAN Qiong, LI Li-li, LIU Hai-lin, DE Xinghou, XIAO Ding-fu,CHEN Yu-guang, LUO Jia-jie, BI Xiao-yan

2010, 19(3): 132-138.

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The effect of exogenous metallothionein on gene expression of antioxidant enzymes in dairy cattle was conducted with 24 lactating Chinese Holstein cows, which were randomly divided into four groups (A, B, C, and D), and supplemented with 0, 4.0, 8.0, and 12.0 mg Zn-MT respectively by intravenous injection. Blood samples were collected every 15 days and the levels of GSH-Px and CAT gene expression in the cows were determined. The levels of GSH-Px gene expression of the cows in groups C and D, and the level of CAT gene expression in group C were greater (P<0.05) than those in group A. The level of CAT gene expression in group D was greater than those in groups A (P<0.01), B (P<0.05), and C (P>0.05), while there were no significant differences (P>0.05) in either GSH-Px and CAT gene expression levels between groups A and B. The levels of GSH-Px and CAT gene expression peaked at the 30th day and descended at the 45th day after the supply of exogenous metallothionein. The levels of GSH-Px gene expression at the 30th day and CAT gene expression at the 15th day and the 30th day after the supply of exogenous metallothionein were greater (P<0.05) than those before the supply. It is suggested that exogenous Zn-MT can promote the levels of GSH-Px and CAT gene expression of dairy cattle, showing a time-dependent and dose-dependent manner.

Effect of the amount of C₃ or C₄ plants in diets on the quality and main chemical components of beef

YAN Gui-long, CAO Chun-mei, DIAO Qi-yu, TU Yan, YUN Qiang

2010, 19(3): 139-147.

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In a fattening trial and a slaughter test of 36 Simmental crossbred bulls, C₃ plant components (soybean meal, wheat bran, Triticum aestivum, cotton seed meal and alfalfa hay) and C₄ plant components (corn stalk silage, maize alcohol lees and Zea mays) were compared to evaluate their effects on the quality and main chemical components of beef. There were no significant effects of dietary C₄ plants on the growth rate of beef cattle, the contents of fatty acids, amino acids, moisture, the shear force value, cooking loss, drip loss, marbling score and eye muscle area of beef. Similar results were obtained with dietary C₃ plants.

Effect of supplemental acrylate to diet on digestion and metabolism of sheep

WANG Lei, LIU Zhi-qiang, YANG Ju-qing, DOU Lai-yi, YANG Kai-lun

2010, 19(3): 148-154.

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The effect of acrylate supplementation on the digestion, metabolism and body weight gain of sheep was investigated. Twenty-five healthy male China Merino sheep (Xinjiang type) with an average body weight of 32 kg were fed on a diet consisting of 25% concentrate and 75% forage. The sheep were divided into five groups: a control group, propionic groups (feed supplemented with 8 or 12 mmol propionic/d·sheep) and acrylate groups (feed supplemented with 8 or 12 mmol acrylate/d·sheep). There was no obvious effect of acrylate supplementation on (DMI) compared with the control and propionic groups. The addition of acrylate led to an increase (P>0.05) in hemicellulose digestibility by 5.15%-9.70% and cellulose digestibility by 3.64%-5.73% (P>0.05). The digestibility of calcium and phosphorus in the group fed 8 mmol acrylate was greater by 2.86% and 8.39% respectively (P>0.05) than that in the group fed 8 mmol propionic. Addition of acrylate at 8 and 12 mmol/d·sheep reduced urea nitrogen excretion by 12% and 18% (P>0.05) respectively, but elevated nitrogen retention rates by 5.35% and 3.91% (P>0.05). There was no obvious effect of addition of acrylate on body weight gain and feed efficiency compared with the control and propionic groups. It is suggested that acrylate supplementation did not significantly affect sheep DMI and digestibility of DM, CP, OM, hemicellulose, cellulose, and the metabolism of nitrogen compared with the controls.

Genetic diversity of wild Cynodon dactylon germplasm detected by AFLP markers

QI Xiao-fang, ZHANG Xin-quan, LING Yao, CHEN Shi-yong, LIU Wei

2010, 19(3): 155-161.

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Amplified fragment length polymorphism(AFLP)molecular markers were applied to detect the genetic variation of 44 agrestal accessions of Cynodon dactylon collected from Africa, Sichuan, Chongqing, Yunnan, Guizhou, and Tibet in China. A total of 462 bands were amplified by ten AFLP primer pairs from C. dactylon genetic DNA, of which 452 (97.64%) bands were found to be polymorphic. The AFLP-based genetic similarity values among 44 C. dactylon accessions ranged from 0.64 to 0.95, and the average Nei’s coefficient was 0.76. Analysis of cluster and principal component analysis showed that all the accessions could be distinguished by AFLP markers and divided into 5 groups. Accessions from the same area were almost all classified into the same group associated with their geographical distributions. Therefore, complex geographical ecological environments are important factors for genetic diversity and geographical distribution of C. dactylon.

Cloning and sequence analysis of the chalcone synthase gene (CHS) from Fagopyrum dibotrys

MENG Hua, LI Cheng-lei, WU Qi, SHAO Ji-rong, CHEN Hui

2010, 19(3): 162-169.

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The conservative sequence of the chalcone synthase gene from Fagopyrum dibotrys 544 bp was isolated by homology cloning, and then the full-length DNA and cDNA ORF (open reading frame) sequences were cloned by genome-walking and RT-PCR, respectively. Sequence analysis showed that the CHS DNA of F. dibotrys was 1 650 bp, including one 462 bp intron. The coding region of cDNA was 1 188 bp, encoding 395 amino acids, designated as FdCHS and included the conserved sites of CHS such as active sites and substrate-binding pocket sites. The homology analysis of FdCHS with that of other plants showed that it was closely related to Rheum palmatum and Polygonum cuspidatum with 94% and 93% homology, respectively. The sequence accession number is GU169470 in GenBank.

Constructing expression vector of genes phaB and phaC drived by specific promoter LTP12 for cotton fiber

MENG Ya-xiong, ZHANG Jin-wen, MA Xiao-le, ZHANG Jin-lin, ZHONG Jun, WANG Hua-jun

2010, 19(3): 170-176.

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The poly-3-hydroxybutyrate(PHB) possesses anti-wrinkle and stay-warm characteristics. It has been hypothesized that the anti-wrinkle and stay-warm ability of cotton fiber would be improved if fiber contains PHB. The genetic engineered cotton plant containing the PHB synthesis would theoretically increase the incorporation of PHB into cotton fiber. As a result, the waterproof ability, anti-wrinkle and stay-warm characteristics of cotton fiber should be improved. In this study, the cotton fiber specific promoter LTP12 and two PHB synthesis genes (phaB and phaC) were integrated into a pBI121. Therefore, a new plant expression vector pBLTPPBPC was constructed.

Seasonal changes of potassium, calcium, and magnesium and their accumulation in different phenotype Suaeda salsa communities in a tidal flat of the Yellow River estuary

MOU Xiao-jie, SUN Zhi-gao, WANG Ling-ling, SUN Wan-long

2010, 19(3): 177-190.

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The seasonal changes of potassium (K), calcium (Ca), and magnesium (Mg) and their accumulation in different phenotypes of Suaeda salsa in the intertidal zone of the Yellow River estuary were studied from May to November 2008. The biomass of different organs of S. salsa in the middle (JP1) and low (JP2) tidal flats showed significant seasonal dynamics, and the values of JP1 were generally greater than those of JP2, according to a parabola model. The amounts of JP1 and JP2 bulk litter increased during the growing season, and could be described by an exponential growth model. The changing patterns of K, Ca, and Mg content in different parts of JP1 and JP2 were different: Changes of K content almost accorded with parabola or linear models, while changes of Ca and Mg contents generally accorded with Gauss curves. The K, Ca, and Mg contents in different parts of JP1 and JP2 at different time periods were significantly different, and the values in the root, leaf and litter of JP1 were much greater than those of JP2, while the Ca, Mg contents in the stem of JP2 were much greater than those of JP1. In addition, the correlations, storage, and accumulation rates of K, Ca, and Mg in different plant parts were also significantly different. In general, the stem and leaf were the main K storage sites, providing 43.02%±20.80% of total storage in JP1 and 48.03%±4.31% in JP2. The leaf was the main storage site for Ca and Mg, providing 40.38%±18.34% and 50.58%±20.73% of the total storage in JP1 and 62.96%±10.56% and 58.02%±10.62% in JP2. Further studies indicated that the differences of biomass, nutrient (K, Ca, Mg) content, storage and accumulation rate in different plant parts between JP1 and JP2 were mainly due to their ecological characteristics, nutrient function of the different organs, and the water or salinity status in the S. salsa habitat.

Research on Cu uptake and tolerance of four pteridophyta plants

LI Ying, WANG You-bao

2010, 19(3): 191-197.

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The tolerance to heavy metal Cu, the absorption and accumulation of Cu by four pteridophyta plants in the vicinity of Cu mine tailings were studied based on analysis of field samples and greenhouse solution-culture pot culture. The results showed that the tolerance capacity of Equisetum ramosissimum and Pteris vittata were stronger than that of Parathelypteris glanduligera and Pteris multifida, and that the ability of absorption and accumulation was presented in the order P. vittata＞E. ramosissimum＞P. multifida＞P. glanduligera. The index of root tolerance of E. ramosissimum and P. vittata was higher with the average content of 1.24 and 0.69, while that of P. multifida was the lowest with the average content less than 0.5. Most of Cu was deposited in the underground parts of the four plants, which were positively correlated with the stress concentration of Cu, while the content of Cu distributed in the above-parts were insignificantly related to Cu concentration. The total heavy metal translocation of P. vittata was higher because of big biomass, with the Cu content of 55.87 mg than that of E. ramosissimum of 5.74 mg in the above-part of both plants when polluted by 20 mg/L Cu. It may be concluded that E. ramosissimum and P. vittata can be chosen for phytoremeditation of Cu polluted areas due to their higher tolerance and accumulation ability and that P. vittata is more suitable for phytopurification and phytomediation of Cu polluted soils, whereas E. ramosissimum is a better species for the purpose of revegetation of the soils polluted by Cu.

Effect of Na⁺ on photosynthetic characteristics of Zygophyllum xanthonylom seedlings under osmotic stress

MA Qing, LOU Jie-qiong, WANG Suo-min

2010, 19(3): 198-203.

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The effect of Na⁺ on the photosynthetic characteristics of seedlings of the succulent xerophyte Zygophyllum xanthoxylum were investigated under -0.5 MPa osmotic stress. Under this stress, the leaf area, chlorophyll (a+b) content, net photosynthetic rate (Pn), stomatal conductance (Gs) and phosphoenolpyruvate carboxylase (PEPCase) activity were significantly elevated by 105%, 33%, 115%, 90%, and 180% respectively at 50 mmol/L NaCl, but the intercellular CO₂ concentration (Ci) was significantly reduced by 17%. In addition, the potential photosynthetic activity (F_v/F₀), primary light energy conversion efficiency (F_v/F_m), and photosynthetic electron transport rate (ETR) of PSⅡ were enhanced by 15%, 5%, and 11% respectively. These results indicate that, under -0.5 MPa osmotic stress, Na⁺ can improve the photosynthesis of Z. xanthoxylum seedlings and enhance the osmotic stress resistance of plants.

Seedling morphology and growth responses of nine Medicago sativa varieties to shade conditions

QIN Feng-fei, SHEN Yi-xin, ZHOU Jian-guo, WANG Qing-shi, SUN Zhi-cheng, WANG Bo

2010, 19(3): 204-211.

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The seedling morphological characteristics and growth dynamics of nine Medicago sativa varieties under shade were studied. The height of Eureka showed significantly less plasticity than other varieties under different levels of shading. All varieties showed a larger morphological plasticity at lower light intensities than at higher intensities: They developed distinctly fewer crown ramus, root nodes, leaves and secondary lateral roots, thinner leaves and taproots at lower intensities. Light intensity had little effect on the taproot length of all varieties. The leaf area of Xinjiangdaye, Alfaking, and Derby showed no obvious difference when other varieties significantly decreased. With decreasing light intensity, both the gross and root biomass allocation significantly decreased while stem and leaf biomass allocation increased. The leaf area ratio significantly increased but the relative growth ratio was significantly reduced with an increase in shading. The different sensitivity to shading of the same organ of different varieties indicated that there were different mechanisms for shade-tolerance among M. sativa varieties.

The photosynthetic characteristics of four forage grasses in Karst rock desertification areas

WEI Lan-ying, ZENG Dan-juan, ZHANG Jian-liang, YOU Ye-ming, JIAO Ji-fei, HUANG Yu-qing

2010, 19(3): 212-219.

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The photosynthetic and leaf traits of four grasses (Zea diploperennis, Medicago sativa, Cichorium intybus, and Pennisetum americanum×Purpureum) were studied in field conditions, together with soil water content and soil bulk density to clarify their physiological adaptability to the Karst rocky desertification environment. There were significant differences of leaf area (LA), dry matter(DW), Chl, specific leaf area (SLA) among these four forage grasses. Zea diploperennis had the greatest LA and DW, while M. sativa had the lowest. SLA was in the sequence C. intybus>M. sativa>Z. diploperennis>P. americanum×Purpureum. M. sativa had the most Chl but there were no obvious differences of Chl between the other three forage grasses, indicating the great differences of the leaf structural traits among these four forage grasses. Z. diploperennis and P. americanum×Purpureum had high P_n, but low T_r and g_s and therefore large WUE and WUEi, but C. intybus and M. sativa were the opposite. This indicated that the intrafamily species Z. diploperennis and P. americanum×Purpureum had similar photosynthetic capacities, while the interfamily species C. intybus and M. sativa had significantly different photosynthetic capacities, even though they shared similar WUE and WUEi. There was no significant difference in water contents in the 0-10 and 10-20 cm soil layers below these four forage grasses, showing that they had little effect on soil water content. However, these different grasses did affect soil bulk density. Correlation analysis showed a significant positive correlation between T_r and water content in the 0-10 cm soil layer for all grasses, and the water content of the 10-20 cm soil layer greatly affected their V_pdl. Comparatively, Z. diploperennis and P. americanum×Purpureum had greater P_n, WUE and WUEi, indicating better adaptability to the Karst environment.

Reasons for an outbreak of grassland grasshoppers and sustainable management strategies for them

SUN Tao, ZHAO Jing-xue, TIAN Li-hua, LIU Zhi-yun, LONG Rui-jun

2010, 19(3): 220-227.

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