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    20 December 2012, Volume 21 Issue 6
    Prospect of ecological restoration through tapping energy crops in Northern interlaced zone of arable lands and grasslands
    CHENG Xu, ZHU Wan-bin
    2012, 21(6):  1-7. 
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    To idle arable land and converts it to forest/grassland in western China has been proved as an effective way to ecological restoration and to stop desertification. However the relevant policy of subsidy is unsustainable, and subsequent agro-industries is difficult to establish based on the fallow fields. Although climate conditions do not favor to cropping of grain in the interlaced zone of agriculture area and pasture, it does relatively favor to the planting of vegetation (biomass)-oriented crops, thus gaining relatively higher ‘system productivity’. China owns very limited arable land, but ample resource of grassland and forest land. Newly emerged energy cropping system in the developed countries could be adopted in China on vast marginal land of Loess Plateau. The so-called dedicated energy crops, such as Miscanthus and switchgrass etc., have been primarily tested within Loess Plateau, and proved to be the promising crops for ‘win-win solution of ecological benefits and economic benefits. It is estimated that there are about 20 million hectares of marginal land that are suitable to energy grasses and will be produced more than 400 million tons of biomass feedstuff annually, thus making this area one of the most important feedstuff base candidate for bioenergy industry in China.
    Response of soil respiration to grazing intensity, water contents, and temperature of soil in different grasslands of Inner Mongolia
    YANG Yang, HAN Guo-dong, LI Yuan-heng, CHEN Zhi-fang, WANG Cheng-jie
    2012, 21(6):  8-14. 
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    Determination of soil respiration plays a key role in the assessment of carbon budgets in different ecosystems. Soil respiration rates under four different grazing intensities (no grazing, light grazing, moderate grazing and heavy grazing) were measured in desert steppe, typical steppe and meadow steppe in Inner Mongolia using a Li-8100 open circuit soil C Flux measuring system. Regression analyses were done between soil respiration and soil temperature (at 10 cm depth of soil), as well as soil respiration and air relative humidity. The grassland type, grazing intensity and their interaction had significant effects on soil respiration. The effect of grazing intensity on soil respiration was significant in desert steppe and typical steppe, but not significant in meadow steppe. In different grasslands, as grazing intensity increased, the soil respiration initially increased but then decreased. Variance analysis showed that there were significant differences in soil temperature at 10 cm depth of soil and in air relative humidity among different grassland types, but no differences were found between different grazing intensities.
    Effects of different exclosure management on soil and plant characteristics of sandy grassland
    WANG Hui, WANG Hui, HUANG Rong, MA Wei-wei
    2012, 21(6):  15-22. 
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    To discuss the restoration of soil and plant of degraded sandy grassland, 19-year-old exclosure (19-year-old artificial restoration), 19-year-old exclosure (5-year-old artificial restoration), 10-year-old exclosure (natural restoration) sandy grassland were chosen to be the study subjects. Combining field survey with laboratory experiments, the influence of different exclosure management on soil physicochemical properties and plant characteristics of sandy grassland were researched taking, the mobile sand as the control. 1) Compared with the mobile sand, the plant height, density, crown diameter, coverage, biomass and soil nutrient of 19-year-old exclosure (19-year-old artificial restoration) sandy grassland increased, while soil bulk density, sand (0.05~2 mm) content of the surface layer (0~20 cm) decreased. The plants and soil gradually formed an interaction system with restoration of degraded sandy grassland. 2) The effects of slope on soil physicochemical properties and plant characteristics of exclosure were more significant than mobile sand (P<0.05). In the enclosed lands, SOC, TN, TP, and TK, available N, available P and available K increased from upper slope to foot slope. 3) The exclosure sandy grassland (artificial restoration) had better improvement on soil physicochemical properties and plant characteristics compared to sandy grassland restored by only natural force. It is an appropriate method for recovery of degraded sandy grassland in northern China.
    Effects of drought stress simulated by PEG on seed germination of four desert plant species
    YANG Jing-ning, WANG Yan-rong
    2012, 21(6):  23-29. 
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    The seeds of four important desert plants: Haloxylon ammodendron, Reaumuria soongorica, Ceratoides latens and Suaeda glauca were collected from the Alashan arid desert, Inner Mongolia. The effects of drought stress on seed germination under PEG treatment and of germination recovery under optimal conditions after presoaking with PEG solution were studied in a series of laboratory tests. The germination and radical growth of the four desert plant species were subjected to different degrees of inhibition with reduced osmotic potential of a series of PEG solutions. The lower the osmotic potential, the more apparent the inhibitory effect. However, slight drought stress promoted the germination of R. soongorica, C. latens and S. glauca, improved the germination index of R. soongorica and S. glauca, and stimulated the radical growth of the four desert plants. The lowest thresholds of osmotic potential for germination were -3.0 (H. ammodendron), -2.1 (R. soongorica and C. latens) and -1.5 MPa (S. glauca). H. ammodendron had the strongest drought resistance, and S. glauca, the weakest. Under optimal conditions, the seeds presoaked with PEG solution recovered their germination after drought stress was relieved. The seeds presoaked for longer suffered greater damage from drought stress, and at the longest times germination was suppressed completely. Shorter duration presoaking improved germination percentage and index of R. soongorica significantly, stimulated the radical growth of H. ammodendron, R. soongorica and C. latens, but suppressed the radical growth of S. glauca.
    Effects of nitrogen and phosphorus on seed germination and seedling growth of Suaeda salsa under different growth conditions of the Yellow River Estuary
    SONG Hong-li, SUN Zhi-gao, SUN Jing-kuan, MOU Xiao-jie, JIANG Huan-huan, SUN Wen-guang, SUN Wan-long
    2012, 21(6):  30-41. 
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    From October to November in 2010, the effects of nitrogen and phosphorus on seed germination and seedling growth of different phenotypes of Suaeda salsa under different growth conditions of the Yellow River Estuary were studied. Seed germination rates of S. salsa in the middle (JP1) and low (JP2) tidal flats reduced with increasing salinity. Under the same conditions of salinity, the JP1 germination rate was higher than that of JP2, due to growth rhythm and tidal action. Under high salinity conditions, germination rate, root/weight and root/shoot reached the maximum at a high nitrogen concentration. Thus high concentrations of nitrogen alleviated the saline toxicity. The effect of phosphorus on S. salsa was complex. Without salinity, there was no effect of phosphorus on root/weight, root/shoot, stem/weight and leaf/weight. At a salt concentration of 300 mmol/L, a moderate level of phosphorus retarded the growth of roots and stems, but favored leaf growth, and the root/shoot reached a maximum at the highest phosphorus concentration. Under high salinity conditions, S. salsa seedling growth depended on location: for JP1, root/weight and root/shoot increased as phosphorus concentration increased, and leaf/weight decreased but for JP2, the opposite changes were observed.
    Variation of seed mass and SLA of 63 plant species in different habitats at various altitudes on the eastern Qinghai-Tibet Plateau
    QI Wei, GUO Shu-qing, CUI Xian-liang, YANG Min, ZHANG Yong-dong, DU Guo-zhen, BU Hai-yan
    2012, 21(6):  42-50. 
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    Seed mass and specific leaf area (SLA) are two representative parameters of plant reproductive traits and vegetative traits, both of which are important parts of plant life-histories. We measured the seed mass and SLA of 63 plant species from four families (Saxifragaceae, Gentianaceae, Ranunculaceae and, Caryophyllaceae) on the eastern Qinghai-Tibet Plateau and studied how altitude and habitat influenced them. 1) The relationship between seed mass and SLA was marginally significantly negative (P=0.066). 2) Seed mass was not correlated with altitude (P>0.05) in the four families as a whole and in Ranunculaceae and Gentianaceae, but was significantly negatively correlated with altitude in the other two families. The habitats had no effect on seed mass when considered alone, but had significant effects when combined with altitude. 3) SLA significantly decreased with altitude in all four families and in Ranunculaceae and Gentianaceae but not in other two families. 4) Moreover, SLA was biggest in the meadow and least in the forest. SLA significantly decreased with altitude in the meadow, but not in other habitats. The variation of the two traits showed an active response or adaptation of the plant to the harsh environment on the eastern Qinghai-Tibet Plateau.
    Effect of super absorbent polymer on the growth and root morphology of Haloxylon ammodendron seedlings
    LI Xing, JIANG Jin, SONG Chun-wu, MIN Shou-jun, ZHANG Heng, JIANG You-wei
    2012, 21(6):  51-56. 
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    The effect of different concentrations of super absorbent polymer (SAP) on soil moisture, growth and root morphology of 1-year Haloxylon ammodendron was studied. 0.2% SAP significantly increased soil moisture at a depth of 30-40 cm when soil moisture was relatively low. 0.05% SAP promoted the growth of assimilating shoots of H. ammodendron, notably from April to June when soil moisture was relatively high, but 0.2% SAP had the most obvious effect from July to September when soil moisture was relatively low. The height, crown width, new branch length, and basal diameter of H. ammodendron were significantly improved when the SAP concentration was 0.2%. Both 0.05% and 0.2% SAP concentrations significantly improved root surface area by 64.65% and 125.62% respectively and total root length by 81.68% and 130.92%. It was concluded that the optimal SAP concentration for H. ammodendron growth was 0.05% from April to June, and 0.2% from July to September.
    Influence of lead gradient stress on the physiological and biochemical characteristics of perennial ryegrass (Lolium perenne) seedlings
    LIU Hui-qin, HAN Ju-cai, LIU Hui-ping, KANG Xin-ran
    2012, 21(6):  57-63. 
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    The effects of lead concentrations (500, 1 000, 1 500 mg/L) on the antioxidant enzymes (SOD, POD), cell membrane (MDA, the relative conductivity) and osmoregulation substances (soluble sugar and proline) in the leaves of perennial ryegrass (Lolium perenne) were studied after different stress durations (7, 14, 21, and 28 d) in a pot experiment. SOD activity increased initially and then decreased with the increase in lead concentration. At lower concentrations (500, 1 000 mg/L) and shorter durations (7, 14 d), SOD activity significantly increased but then declined rapidly. POD activity decreased significantly with increases in stress duration and lead concentrations. POD activity was minimum (45.9 U/g) at the 28th day and 1 500 mg/L of lead. With increases in stress duration and lead concentrations, MDA content and the relative conductivity generally increased. MDA content was positively linearly correlated with lead concentration (R2>0.96). Soluble sugar content showed complex change trends, and tended to reduce at the higher concentrations and longer durations. Proline content significantly increased at the lower lead concentrations. If lead concentration exceeded the limit of perennial ryegrass tolerance, proline content would decline. It indicated that perennial ryegrass can be tolerant to lead stress but there is progressive damage under the stress.
    Response of plant growth and photosynthetic characteristics in Suaeda glauca and Atriplex triangularis seedlings to different concentrations of salt treatments
    PENG Yi-quan, XIE Tong, ZHOU Feng, WAN Hong-jian, ZHANG Chun-yin, ZHAI Rui-ting, ZHENG Qing-song, ZHENG Chun-fang, LIU Zhao-pu
    2012, 21(6):  64-74. 
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    In order to get the response mechanism of Suaeda glauca and Atriplex triangularis to different salinity level, we investigated the alteration of different concentrations of NaCl with Hoagland solution on plant biomass, height, water content (WC), chlorophyll (Chl) content, carotenoid (Car) content, Chl/Car, Chl a/Chl b, Pn, Gs, Ci, Tr, water use efficiency (WUE) and stomatal limitation (Ls) in S. glauca and A. triangularis seedlings in this study. 1) Compared with control, treatment with 100 mmol/L NaCl significantly increased the dry weight, height and shoot WC of S. glauca plant, however, 100 mmol/L NaCl did not affect the plant height of A. triangularis, decreasing its shoot dry weight and WC markedly. Treatment with 400 mmol/L NaCl had no effect on the shoot dry weight (DW) and WC of S. glauca, but it heavily reduced shoot DW and WC of A. triangularis. With salinity of 800 mmol/L NaCl, DW and WC of two plants were decreased significantly, and the decrease of A. triangularis was much more than that of S. glauca. 2) Treatment of 100 mmol/L NaCl did not affect the Chl content, and treatments of 200 and 400 mmol/L NaCl significantly decreased the Chl content in both two plants. However, the decrease was much more significantly in S. glauca than that in A. triangularis under 200 and 400 mmol/L NaCl. Treatment of 100 mmol/L NaCl significantly increased the Car content of S. glauca, but did not affect the Car content of A. triangularis. Treatments of 200 and 400 mmol/L NaCl significantly decreased the Chl content in both two plants. Similarly, the decrease was much more significantly in S. glauca than that in A. triangularis. All NaCl treatments did not affect Chl a/Chl b in both plants and Chl/Car in A. triangularis, but Chl/Car in S. glauca was descended in first and ascended at last as NaCl concentrations rising. 3) We found that values of Pn, Gs and Tr in S. glauca were all ascended under treatment with 100 mmol/L NaCl, while 100 mmol/L NaCl significantly decreased the Pn, Gs and Tr in A. triangularis. Under stresses of 200 and 400 mmol/L NaCl, Pn, Gs and Tr were significantly decreased in both two plants. However, Pn and Tr were decreased more significantly in A. triangularis than in S. glauca. With the increase of salinity, the Ci value in S. glauca was gradually decreased. Meanwhile, in A. triangularis, the Ci value was descended in first and then ascended, and Ci in the treatment of 800 mmol/L NaCl was obviously higher than that in the control. 4) Biomass of S. glauca showed highly significant positive-correlation with its Tr, Pn, shoot WC, Car content, root WC, Gs, root shoot ratio, plant height, Chl content and Ci, and showed highly significant negative-correlation with its Chl/Car and Ls. For A. triangularis, its biomass was highly significant positive-correlation with shoot WC, Chl content, Pn, Car content, Tr, Gs, root WC and plant height, but highly significant negative-correlation with Chl a/Chl b. To sum up, S. glauca and A. triangularis both have high salt resistance. Compared with A. triangularis, S. glauca having better adaptation to salt was owing to maintaining higher photosynthetic and water use efficiency. Under severe salt stress, the reduction in photosynthesis of S. glauca was mainly due to stomatal limitations, while for A. triangularis, the reduction in its photosynthesis was mainly due to non-stomatal limitations.
    Dynamics of leaf water potential of spring wheat and responses to environmental factors under different tillage practices on dry land
    LI Jie, CAI Li-qun, ZHANG Ming, ZHANG Ren-zhi
    2012, 21(6):  75-81. 
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    Based on a long-term experiment conducted in the Loess Plateau, the dynamics of leaf water potential of rain watered spring wheat, and the relationships between leaf water potential and environmental factors under different tillage patterns were studied. During the whole growing season, leaf water potential was highest in the early morning and lowest at 12:00 to 14:00, after which it gradually rose again. The daily average value of leaf water potential under no-till cultivation with straw mulching was higher than those under other treatments. The order of leaf relative water content at different growth stages was: heading>jointing>flowering>filling stage, and leaf relative water content under no-till with straw mulching was significantly higher than that under conventional tillage. The dynamics of water saturation deficient showed the opposite trends to that of relative water content. Leaf water potential under different conservation tillage patterns had significant correlations with soil water content, air temperature, solar radiation, relative air humidity and air water potential. Air water potential had the greatest effect on the dynamics of leaf water potential in these areas, followed by relative air humidity, air temperature and solar radiation.
    Effects of salicylic acid on growth and photosynthetic characteristics of Melilotoides ruthenica in branching stage under different water stress
    CUI Xiu-mei, LIU Xin-bao, LI Zhi-hua, SUN Kai-yan, LI Hui, ZHANG Ting-ting
    2012, 21(6):  82-93. 
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    The pot experiment was conducted to determine the effects of the different concentrations [0(The control), 0.02, 0.10, 0.50, 2.50 mmol/L] of salicylic acid on the growth, the physiology characteristics and photosynthetic characteristics of Melilotoides ruthenica in branching stage under normal irrigation (80% field capacity), mild water stress (60% field capacity), moderate water stress (40% field capacity)and severe water stress (20% field capacity) in order to understand the effects of salicylic acid on drought tolerance of M. ruthenica in branching stage. The results showed that under mild and moderate water stress, treatment with 0.1 mmol/L salicylic acid significantly increased leaf relative water content, chlorophyll content, soluble protein content, the activities of superoxide dismutase (SOD), peroxidase (POD) and catlase (CAT), photosynthetic rate (Pn) and stomatal conductance (Gs) compared with the control, but stomatal limitation value (Ls) were significantly decreased; Under severe water stress, treatment with 0.5 mmol/L salicylic acid significantly increased plant height, primary shoot number, leaf area, leaf relative water content, chlorophyll content, free proline content, soluble protein content, the activities of SOD, POD and CAT, Pn, Gs and water use efficiency (WUE) compared with the control, but electrolyte leakage, malondialdehyde (MDA) content and Ls were significantly decreased. The results suggested that salicylic acid with the appropriate concentrations could increase the drought resistance of M. ruthenica and improve its growth in branching stage under water stress.
    Temporal and spatial disparities of soil enzyme activities during the spring wheat growing season under different tillage systems
    LUO Zhu-zhu, HUANG Gao-bao, CAI Li-qun, ZHANG Ren-zhi, LI Ling-ling, XIE Jun-hong
    2012, 21(6):  94-101. 
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    Based on field experiments conducted in Dingxi on the western Loess Plateau, the effects of four treatments: conventional tillage (T), conventional tillage with stubble retention (TS), no tillage with no stubble retention (NT), no tillage with stubble retention (NTS) on temporal and spatial disparities of soil enzyme activities during the spring wheat growing season were studied. Soil catalase, urease, alkaline phosphatase and invertase activities under NTS were significantly higher than those under T, being 24.02%, 8.74%, 20.51% and 31.45% respectively at 0-30 cm depth during spring wheat growing seasons, while the effects of NT and TS on soil enzyme activities were seasonal. There was a decreasing trend of soil enzyme activities with increasing soil depth under NT and NTS treatments. Soil catalase, urease, alkaline phosphatase and invertase activities under T treatment and soil urease and alkaline phosphatase activities under TS treatment increased then decreased with increasing soil depth, while soil catalase and invertase activities under TS treatment decreased. Analysis of variance indicated that the greatest effects of the growing seasons were on soil urease activity, and of tillage and cover on soil invertase activity, while soil catalase activity had the most effect on the interactions of various factors.
    Effect of drought stress on polyamine metabolism in the leaves and roots of alfalfa
    LIU Yi, ZHANG Chun-mei, XIE Xiao-rong,YAN Fang, HU Dan
    2012, 21(6):  102-107. 
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    Changes in the contents of endogenous polyamines (PAs) and the activities of metabolic enzyme in the leaves and roots of alfalfa under drought stress were studied to clarify the theoretical role of polyamine metabolism in alfalfa drought-resistance. The contents of PAs (Putrescine, Spermidine, Spermine) and the activities of ADC, ODC and PAO in the leaves and roots of alfalfa initially increased but then decreased with time. With drought stress intensification, the rising amplitude of PAs content and the activities of ADC and ODC increased. There was a significant positive correlation between Put content and the activities of ADC and ODC in the leaves and roots, suggesting that both ADC and ODC were the major pathways of Put biosynthesis in alfalfa under drought stress. Moreover, it indicated that there was a significant positive correlation not only between PA (Spd and Spm) contents and PAO activity in the leaves and roots of alfalfa but with polyamine metabolism in the leaves and roots as well. There was a close relationship between polyamine metabolism and alfalfa drought-resistance.
    Reparations of Ca2+ and P on N-fixation of alfalfa-rhizobia after acid aluminum stress
    WANG Xiao-feng, LUO Zhen, LIU Xiao-yan, ZHU Dan, XIA Zhi-qiang, ZHOU Jian-hua, ZHANG Lei
    2012, 21(6):  108-116. 
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    In this paper, we used alfalfa and acid tolerate alfalfa rhizobium stain, Sinorhizobium meliloti 91522, as materials in water culture to study the effect of calcium and phosphorus on quorum sensing (QS) and N-fixation of alfalfa-rhizobia after acid aluminum stress. The research showed that calcium and phosphorus could repair the symbiosis nodular process of alfalfa-rhizobia after suffering from acid and Al toxicity; comparing with the control treatment, which is no Ca2+ and P treatment, under the conditions of 10 mmol/L Ca2+ and 4 μmol/L P, the nodulation time was 14 days earlier, nodular number had increased by 247.09%, the nodular ratio achieved to 90%, hair deformation rate of Medicago sativa increased from 3.33% to 28.89%. When 10 mmol/L Ca2+ and 4 μmol/L P were added, the nitrogenase activity improved significantly, and Ca2+could enhance the QS of S. meliloti significantly as well, hence promoting alfalfa to perceive the nodular signal. Preliminary tests proved that Ca2+ and P could recover the symbiosis nodular process and nitrogenase activity after alfalfa suffered from acidity and Al toxicity.
    Effects of fertilizer combinations on the cation-anion balance of alfalfa
    LI Yun-qi, GAO Xiang-pei, LI Qiu-feng, LI Jian-guo, CAO Yu-feng, GAO Yan-xia, TANG Shu-xia, YU He-xing, LI Yue-e, JIA Hai-jun, YANG Wu
    2012, 21(6):  117-122. 
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    The effects of fertilizer combinations on the cation-anion balance of alfalfa were analysed using a quadratic regression orthogonal rotating combination design. The most common cation in alfalfa was K+, which ranged from 2.40% to 4.01%, followed by Cl- (0.84%-1.09%) and S2- (0.35%-0.58%), while the lowest was Na+, 0.09%-0.22%. The cation-anion balance ranged from 155 to 501 mEq/kg DM. The factors that had a significant negative impact on the cation-anion balance in alfalfa were potassium sulfate and magnesium oxide. Even though the effects of ammonium chloride and superphosphate on the cation-anion balance were not significant, the interactions between ammonium chloride, superphosphate, and magnesium oxide significantly affected the balance. All of the fertilizers lowered the balance to 216.55 mEq/kg DM, which was not significant. However, the combination of fertilizers lowered the balance to 80.55 mEq/kg DM. The fertilizer combination which retained the lowest balance was 50 kg/ha potassium sulfate, 275 kg/ha ammonium chloride, 1 000 kg/ha superphosphate, and 55 kg/ha magnesium oxide.
    Effect of nitrogen application on the absorption of calcium, magnesium and sulfur in Wancao 2 and Zea mexicana
    ZHANG Xiao-yan, WANG Li-li, ZHU Jian-hua, DONG Shu-ting, LIU Feng
    2012, 21(6):  123-129. 
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    To study the effect of nitrogen application on the absorption of mineral elements in Wancao 2 and Zea mexicana, the content, accumulation rate and output of calcium, magnesium and sulfur in different organs were analyzed. The contents of Ca, Mg and S in Wancao 2 and Z. mexicana were the highest under N1 treatment (300 kg/ha, as base fertilizer). The contents of Ca and S in leaves were higher than those in stalk, while the content of Mg in stalk was higher than that in leaves. The contents of mineral elements in the first harvest of Wancao 2 were higher than those in Z. mexicana. The accumulation rate and amount of Ca, Mg and S in single plants of Z. mexicana were significantly higher than those of Wancao 2, while their accumulation rate declined gradually in aftergrass (growth after the first cut). The output of the three mineral elements in Wancao 2 was significantly higher than that in Z. mexicana. Seperate applications of nitrogen fertilizer increased the output of mineral elements in Wancao 2 compared with total application as base fertilizer. The regression analysis showed that the order of the three mineral elements influencing biomass of Wancao 2 was Ca>S>Mg, while for Z. mexicana it was S>Mg>Ca. The biomass of single plants increased with an increase in the mineral element contents in both herbages. Briefly, a total application of 300 kg/ha nitrogen as base fertilizer should lead to higher mineral nutrition in forages.
    Effect of acarbose addition on acute and subacute rumen acidosis in an in vitro fermentation study
    MAO Sheng-yong, HE Wen-bo, ZHU Wei-yun
    2012, 21(6):  130-136. 
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    The effect of acarbose addition on ruminant fermentation was investigated in three experiments. In the first and second experiments, the effects of acarbose addition on subacute rumen acidosis was studied. The final concentration of acarbose in the media was 0, 0.1, 0.2 or 0.4 mg/mL. In the first study, the substrate consisted of 0.8 g cracked corn and 0.2 g Chinese dry grass. As compared with the control, the acarbose addition increased the pH value and the ratio of acetate to propionate, and decreased acetate, propionate, butyrate, isobutyrate, total volatile fatty acid and lactic acid concentrations. In the second experiment, the substrates consisted of cracked sorghum, corn, barley and wheat. The acarbose supplement increased pH, NH3-N, lactate concentration and the ratio of the acetate to propionate, and decreased acetate, propionate, butyrate and TVFA concentration. In the third experiment, the effect of acarbose addition on acute rumen acidosis was investigated, the pH, acetate, propionate, acetate, propionate, valerate, isovalerate and TVFA concentrations were reduced by acarbose addition, while the pH value was improved. There were no significant changes in the isobutyrate, butyrate, and isovalerate concentrations. In general, these results indicated that acarbose addition increased the pH value and reduced lactic acid concentration, and it has the potential to prevent rumen acidosis.
    Effect of isoflavone in red clover on the growth and immune functions, and in the antioxidant indices in ovariectomized rats
    YU Lian-ping, HAO Zheng-li, LI Fa-di, MENG Xiang-jun, CHEN Xing-rong, LI Xin-yuan
    2012, 21(6):  137-144. 
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    This study explored the influence of isoflavone in red clover (Trifolium pratense cv. Minshan) on animal growth, organism immunity and antioxidant functions. Eighty female Sprague-Dawley rats (Rattus norvegicus) at the 50-60 day old were randomly and evenly assigned to eight groups. The rats in groups 1 to 7 with the ovary excised were given red clover isoflavone daily at the rates of 320, 160, 80, 40, 20, 10 or 0 mg/(kg·d) by gavage. The rats in group 8 were given the normal saline as the sham operation group. 1) Red clover isoflavone inhibited the growth of the ovariectomized rats to some extent, but there was no dose-dependent effect. 2) The transformation rate of T lymphocytes increased in response to the isoflavone at the lower doses, indicating that red clover isoflavone at the lower doses could be used as the immunopotentiator to improve the immunity of animals. The appropriate amount to add was 10 mg/(kg·d). 3) Red clover isoflavone had an obvious antioxidative effect. The correct addition (>80 mg/kg·d) may reduce the concentrations of CHO, HDL and LDL, but increase SOD activity in the serum. In addition, the isoflavone had a weak estrogen-like effect. The appropriate level for addition of the isoflavone was 80 mg/(kg·d) for the ovariectomized rats.
    Research on the trace element contents of a soil-grass-Przewalski’s gazelle ecosystem in Hudong, Qinghai, China
    ZHOU Li-ye, PU Xiu-ying
    2012, 21(6):  145-150. 
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    The distribution of trace elements in a soil-grass-Przewalski’s gazelle ecosystem were studied together with their influence on the growth and reproduction of Przewalski’s gazelle. Soil and herbages in the habitat of Przewalski’s gazelle together with the blood and the wool of Przewalski’s gazelle were sampled. The contents of Se, Cu, Mn, Fe, Zn and Mo were assayed and their relevance was analyzed. The soil in the habitat had a serious lack of Se and Mo in summer, but of Cu, Mo and Zn in autumn and winter, whereas Fe and Mn were very rich in all three seasons. Cu, Mo and Se were severely lacking in the forage, but Fe, Mn and Zn contents were normal. There were positive correlations for the contents of Cu, Mn Zn and Se in the forage and the soil in summer, for Cu or Zn in antumn and for Mo in winter. In winter, the contents of Fe, Mn, Zn in the blood of Przewalski’s gazelle were higher than in the wool. Cu, Mo, Se content was slightly lower than serum; In addition, one female Cu, Zn in the Przewalski’s gazelle serum were low, the content was 4.96 and 4.63 μmol/L, respectively, the rest of four Przewalski’s gazelle serum Cu, Zn content were about 9.50 and 7.81 μmol/L.
    Observations and study on the pollen morphology of some taxa of Miscanthus (Poaceae)
    LU Yu-fei, JIANG Jian-xiong, AI Xin, XIAO Liang, YI Zi-li
    2012, 21(6):  151-158. 
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    Miscanthus (Gramineae, Poaceae) has recently received comprehensive attention because of its great potential to be developed and utilized as a new renewable energy plant. To accumulate information about pollen morphology of Miscanthus in China for relevant study, the pollen morphology of 39 accessions from Miscanthus sinensis, M. floridulus, M. sacchariflorus, M. lutarioriparius, M. nepalensis, and M. nudipes were observed using light and scanning electron microscopy. The exine sculpture of pollen grains of Miscanthus was of two types: granulate and verrucate. The latter could be divided into three types: obscurely verrucate, verrucate, and obviously verrucate based on differences of the raised extent of verrucation. There were distinct differences in the exine ornamentation and pollen size between the group containing M. nepalensis and M. nudipes and the group consisting of M. sinensis, M. floridulus, M. sacchariflorus, and M. lutarioriparius, supporting the separation of M. nepalensis and M. nudipes from Miscanthus as a standalone genus, Diandranthus. M. sinensis, M. floridulus, M. sacchariflorus, and M. lutarioriparius shared a high similarity in pollen morphology, showing the close affinity between them. Meanwhile, M. floridulus was more advanced than M. sinensis in evolutionary history. Nevertheless, it may be essential to further investigate the exine structure of pollen grains of Miscanthus in order to clarify the phylogenetic relationship and evolutionary level between the taxa of Miscanthus based on pollen morphology.
    ISSR molecular markers analysis of 9 Bermudagrass cultivation varieties
    LIU Jun, ZHAO Qin, YANG Zhi-min
    2012, 21(6):  159-165. 
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    Bermudagrass are one of the most important and abundant warm-season turfgrass in the world. They are same on morphology between different species or varieties, and could not be identified accurately by traditional morphological method or field district test method. Inter-simple sequence repeat (ISSR) is considered to be the most accurate and efficient molecular marker technology currently on variety identification. In this study, we used ISSR on 27 Bermudagrass individuals to identify genetic diversity and construct Bermudagrass fingerprints of 9 accessions. Thirteen primers produced 54 polymorphic bands, of which 34 bands were found to be polymorphic, 4.1 bands per primer on average. The percentage of polymorphic locus was 64.15% on average. The Nei’s genetic similarity coefficient changed from 0.547 to 0.962, the range was up to 0.415. These demonstrated that test material had ample genetic diversity. Cluster analysis showed that all the accessions could be divided into five groups at GS 0.806: Blackjat and Nan jing Bermudagrass clustered into the first group, Riviera and Common Bermudagrass clustered into the second group, Yang jiang Bermudagrass clustered into the third group, Regent clustered into the forth group and Tifway (T-419), Tifeagle, Tifdwarf clusterd into the fifth group. Research showed that 9 Bermudagrass varieties could be identified by fingerprints based on primer UBC810 and UBC857. The study offered theoretical and technical foundation for research genetic diversity and variety identification using ISSR technology, and could be widely used on variety identification, germplasm resources protection, hybrid parents selection, development and utilization.
    Bioinformatics and expression analyses of ethylene response factor genes in Medicago
    CHEN Ting-ting,YANG Qing-chuan, ZHANG Xin-quan, KANG Jun-mei, DING Wang, ZHANG Tie-jun
    2012, 21(6):  166-174. 
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    Ethylene response factors are plant-special transcription factors involved in plant growth and development. The Arabidopsis AP2 domain was used as a probe to search the NCBI Medicago protein database and to analyze the phyletic evolution, secondary structure, hydrophobicity, signal peptide, subcellular localization of Medicago ethylene response factors using bioinformatics software. Primers were designed based on the sequences obtained to analyze the expression patterns of MsERF genes (MsERF1, MsERF2, MsERF6, MsERF7, MsERF9). The MsERF genes had high expression levels in leaves and showed significant differences of expression in different tissues. The expression of MsERF2 was not induced by NaCl and PEG-6000, but was promoted by Al2(SO4)3. The expression of other genes was induced by these three treatments, but the expression patterns were different. ABA reduced the expression of these genes except for MsERF2. IAA had no effect on the expression of these genes except MsERF6. GA3, MeJA, and Eth reduced the expression of all five genes. This research established a solid foundation to further study the function of these genes and provided evidence to study the cross-talk in different signal pathways.
    Construction and analyses of two suppression subtractive hybridization libraries of Medicago falcata and Medicago truncatula under drought stress
    WANG Tian-zuo, ZHAO Min-gui, ZHANG Wen-hao
    2012, 21(6):  175-181. 
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    Drought is one of the commonest abiotic stresses for plant growth and development. Understanding the mechanisms underlying the tolerance of plants to drought stress is of critical importance for the improvement of plant drought tolerance. Suppression subtractive hybridization (SSH) is a useful tool to identify genes that are differentially expressed. In this study, two cDNA libraries from the leguminous plants Medicago falcata and M. truncatula were constructed and sequenced. The sequences of the two cDNA libraries were classified by GO and KEGG, and the differential expression was analyzed. The number of genes associated with drought resistance was greater in M. falcata than in M. truncatula. The expression levels of the two genes were positively correlated with the tolerance of the two species to drought stress and were higher in M. falcata than in M. truncatula. These results may provide a molecular explanation for some of the greater tolerance to drought stress of M. falcata than M. truncatula.
    Construction and transformation of an over-expression plasmid of the MsZIP gene from Medicago sativa
    LI Yan, SUN Yan, YANG Qing-chuan, KANG Jun-mei, ZHANG Tie-jun, FANG Feng
    2012, 21(6):  182-189. 
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    Based on the MsZIP gene sequence (GenBank No. HQ911778), a cDNA fragment was cloned and connected to the PMD18-T vector to construct PMD-MsZIP. The target fragment and linear plasmid were obtained from the cloning vector PMD-MsZIP and from the plant expression vector PBI121 using dual digestion with XbaI and BamHI. The plant over-expression vector PBI-MsZIP was built through directional connections using T4 DNA ligase. The plasmid was transferred to Agrobacterium LBA4404 by the CaCl2 freeze-thaw method and was then transferred into alfalfa by an Agrobacterium-mediated transformation system. Eleven kanamycin-resistant plants were obtained. Four of them were sampled to detect target fragments and PCR identification showed that the recombinant plasmid had been transferred into alfalfa. The MsZIP gene was successfully over-expressed in transgenic Medicago sativa CV. Zhongmu No.1. To test the function of this gene, the transgenic alfalfa was treated with 200 mmol/L NaCl and 25 μmol/L PEG-6000 for three days, and some physiological parameters were measured. The contents of soluble sugar, soluble protein and proline significantly increased, while the MDA content declined. Over-expressed MsZIP gene enhanced the salt and drought tolerance of alfalfa.
    Phylogeny and function characterization of DREB transcription factors in Leymus chinensis
    MA Xing-yong, PENG Xian-jun, SU Man, ZHANG Le-xin, ZHOU Qing-yuan, CHEN Shuang-yan, CHENG Li-qin, LIU Gong-she
    2012, 21(6):  190-197. 
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    Leymus chinensis is an economically and ecologically important grass that is tolerant to salt, drought and cold stresses. DREB are important transcription factors in plant stress responses. However, there were only two genes of L. chinensis in the GenBank nucleotide and EST databases and only one of them had further study. The identification of 26 L. chinensis DREB ESTs were reported from analysis of transcriptome sequencing data. A phylogenetic tree was inferred from protein sequences of the 26 L. chinensis DREB transcription factors compared with all DREB transcription factors in the Arabidopsis thaliana genome. LcDREB21 belonged to group IV, and was a member of DREB2s. RACE was used to amplify the full-length CDS of LcDREB21 (GenBank accession number: JN860437). qRT-PCR results confirmed that LcDREB21 was induced by drought and high salinity stresses. Transcriptional activation of LcDREB21 was shown by yeast one-hybrid system, and nuclear localization of LcDREB21 was confirmed by expression of GFP fusion. In summary, LcDREB21 showed nuclear specific localization and transactivation activity, and may play roles in response to drought and high salinity stresses of L. chinensis. New members have been added to the family of stress-related genes in L. chinensis, and LcDREB21 could be used to improve stress tolerance in plants through genetic engineering.
    Cloning the gene of γ-tocopherol methyltransferase (γ-TMT) from alfalfa and expression analysis in adverse situations
    JIA Hui-li, WANG Xue-min, GAO Hong-wen, DONG Jie, WANG Yun-qi, LIU Jian-ning, SHI Yong-hong
    2012, 21(6):  198-206. 
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    Alfalfa plays an important role in livestock production and is the most widely cultivated forage plant in China. γ-tocopherol methyltransferase (γ-TMT) is an important enzyme in the vitamin E synthetic pathway. γ-TMT catalyzes the conversion from γ-tocopherol to α-tocopherol which changes the vitamin E composition so that it can be easily absorbed by humans and animals. The full-length cDNA of alfalfa γ-TMT was cloned by RACE-PCR and termed MsTMT. Bioinformatic analysis showed that the full-length cDNA of this gene was 1 306 bp, including a 939 bp open reading frame (ORF), which encoded a polypeptid of 312 amino acids. MsTMT belongs to the AdoMet-MTases, which possess an adenosine deaminase signal (SLSTDDP) and two conserved SAM-domains (XXDXGCGIG, VXXPGGXXIX). Real-time PCR results revealed that the MsTMT gene is expressed in all organs of alfalfa, but especially in the leaves. The expression level of MsTMT in leaves increased with NaCl, PEG and dark stress, but decreased with cooling stress. Exogenous ABA did not affect the gene expression.
    Comparison and analysis of the characteristics of mutant SP2008-3 and adalayd in seashore Paspalum
    CHANG Pan-pan, ZHONG Xiao-xian, LIU Zhi-wei
    2012, 21(6):  207-212. 
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    A comparison of botanical properties, of stomatal characteristics of the upper and lower leaf epidermis, and of chromosome identification and RAPD analysis between mutant SP2008-3 and Adalayd in seashore Paspalum was carried out. Stolon internode length and stem diameter were reduced by 34.77% and 11.76% in SP2008-3 compared with Adalayd and leaf length and width were increased by 22.55% and 11.11% respectively. There were no significant differences in erect stem internode length and diameter between SP2008-3 and Adalayd. In the upper leaf epidermis of SP2008-3, stomatal density was 20.58% greater, and stomatal length and width were 9.64% and 6.31% less respectivley than in Adalayd. Stomatal density in the lower leaf epidermis of SP2008-3, was 40.62% greater, and stomatal length and width were 6.73% and 5.33% less than in Adalayd. The somatic chromosome number was 2n=20 in both SP2008-3 and Adalayd. RAPD analysis showed a difference in the DNA: a 1 100 bp band was missing in SP2008-3 when the DNA was amplified by primer S369.
    Genetic diversity of natural Prunus mira populations detected by SRAP
    TAN Jiang-ping, ZENG Xiu-li, LIAO Ming-an
    2012, 21(6):  213-220. 
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    Sequence-related amplified polymorphism (SRAP) markers were used to assess the genetic diversity and population structure of four natural Prunus mira populations from Tibet. A total of 376 bands were amplified from four natural populations by 20 primers, and 338 SRAP loci were found to be polymorphic. A relatively high level of intraspecific genetic diversity was revealed: PPB (percentage of polymorphic loci)=89.89%, H (Nei’s gene diversity)=0.194 3, I (Shannon’s information index)=0.295 5 at the population level, and PPB=89.89%, H=0.246 0, I=0.383 9 at the species level. A low degree of genetic differentiation occurred among P. mira populations as indicated by a Gst (Nei’s Gst analysis) of 0.170 9 but the gene flow between populations was high (1.213 0). UPGMA (unweighted pair group method with arithmetic mean) cluster analysis showed that the 70 individuals were not clustered into four clusters corresponding to the four populations. There was relatively high genetic diversity, low genetic differentiation and a high degree of gene flow between P. mira populations.
    Analysis on the composition structure of plant species in Caragana aurantiaca community in the Yili River Valley Marshes of Xinjiang
    Jianaer·Ahan, ZHAO Yu, ZHANG Wei, YANG Yun-fei, LI Jian-dong
    2012, 21(6):  221-227. 
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    The Caragana aurantiaca community of the Yili River Valley situated on the riverbank marshes near the Jiefang Bridge of Tianshan town of Zhaosu county in Xinjiang. Investigated sample sites in this area, all the 64 species of plants belonged to 29 families, 6 growth forms of plant, 3 growth forms of root, 6 life forms, 5 ecological types of water. Among them, the species of Compositae and Gramineae respectively took the most of 14.0%, and which of Leguminosae are 12.5%. The species of upstanding type were 39.0% of the growth form of plant, as well as those of divaricate type and tufty type were 25.0% and 22.0%, respectively. Among the growth form of root, the most of 50.0% belong to taproot type, as well as brushy root type and rhizome type both reached 25.0%. The life forms of the most belonged to geophyte which was 42.0%, hemicryptophyte and therophyte were 33.0% and 12.5%. The species of mesophyte were the most of ecological type of water which reached 57.8%,and those of mesoxerophyte and mesophydrophyte respectively were 14.0% and 12.5%.In the marshes of Yili River Valley, the plants and roots took on the characters of middle temperate plant community and roots characteristics, the climate was typical middle temperate geophyte, and had a mesophytic habitat.
    Relationship between vegetative potential populations and actual populations of Agropyron michnoi
    JIN Xiao-ming, LIU Ji-dong, LU Xin-shi, SUN Zhao-jun
    2012, 21(6):  228-234. 
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    To understand the adaptive mechanisms in sandy land, the relationship between potential populations and actual populations of vegetative reproduction of Agropyron michnoi modules was studied in different growth areas on sandy land. For vegetative potential populations, the percentage of the juvenile seedlings was 3-4 times higher than that of the dormancy buds and 99% of the vegetative actual population was formed from juvenile seedlings of the previous year. The conversion ratio to juvenile seedlings was greater from the tillering nod seedlings than from the rhizome seedlings. The conversion ratio of winter rhizome seedlings and winter tillering nod seedlings on fixed sandy land was 1.6-1.8 times greater than that on shifting sandy land. These results suggest that as desertified grassland recovers, the effect of vegetative potential populations of A. michnoi on real populations gradually increases thus revealing the mechanisms of reproductive extention and adaptability, and enriching and extending the theories of population reproductive ecology.
    Relationship between productivity and plant functional traits along successive recovery stages in an alpine meadow
    ZHANG Ling-fei, WEI Bin, GE Qing-zheng, HAO Ming, FU Hua, ZHANG Wei-guo, JIANG Xiao-lei
    2012, 21(6):  235-241. 
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    Using a spatial sequence approach instead of a temporal one, plant functional traits and aboveground primary productivity were investigated along successive recovery stages in an alpine meadow on the Qinghai-Tibetan plateau. The functional traits, including plant height, relative growth rate, special leaf area, leaf dry mass content, and total biomass of dominant plant species at the individual and community levels were measured at recovery succession stages of 1, 3, 7, 10, and 15 years. The recovery succession significantly reduced the value of plant functional traits such as plant height, relative growth rate and special leaf area, but increased the value of leaf dry mass content (y=0.170 5x+0.106 3, R2=0.506 5, P<0.001). There were negative relationships between plant height (y=-12.299x+410.3, R2=0.678 2, P<0.001), relative growth rate (y=-0.022 9x+0.624 7, R2=0.699 2, P<0.001), special leaf area (y=-61.171x+2 756.5, R2=0.595 6, P<0.001) and succession stage, but a positive relationship between leaf dry mass content (y=0.170 5x+0.106 3, R2=0.506 5, P<0.001) and succession stage. A negative relationship also emerged between above-ground net primary productivity (ANPP) and succession stage (y=-0.228x+7.386 7, R2=0.495 4, P<0.01). Plant height (y=0.014 7x+0.942 6, R2=0.457 5, P<0.01), relative growth rate (y=8.695 4x+1.869 9, R2=0.519 1, P<0.001) and special leaf area (y=0.002 4x+0.942 6, R2=0.361 7, P<0.01) all had significantly positive effects on ANPP, while leaf dry mass content had no significant effect on ANPP (y=-0.435 5x+6.797, R2=0.101 5, P>0.05). The plant height, relative growth rate and special leaf area could be used as predicting traits for ecosystem productivity response to succession in the alpine meadow. In the management and utilization of alpine meadow ecosystems, these three functional traits could be used to describe and predict ecosystem function response to environmental changes.
    A comprehensive evaluation of the productive performance of legume-grass mixtures under different mixed sowing patterns
    ZHENG Wei, ZHU Jin-zhong, Jianaerguli
    2012, 21(6):  242-251. 
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    The productive performance of legume-grass mixtures was analyzed with the grey correlative system in seven combinations of 6 species mixtures (Onobrychis viciaefolia, Medicago sativa, Trifolium pratense, Dactylis glomerata, Bromus inermis, and Phleum pratense), 5-1 species mixture (M. sativa, T. pratense, D. glomerata, B. inermis, and P. pratense), 5-2 species mixture (M. sativa, O. viciaefolia, D. glomerata, B. inermis, and P. pratense), 4-1 species mixture (M. sativa, T. pratense, D. glomerata, and B. inermis), 4-2 species mixture (M. sativa, O. viciaefolia, D. glomerata, and B. inermis), 3-1 species mixture (M. sativa, D. glomerata, and B. inermis), 3-2 species mixture (O. viciaefolia, D. glomerata, and B. inermis). Three sowing ratios were used to establish evaluation models of productive performance including forage yield, forage quality, interspecific compatibility and community stability. The productive performance of the 6 species mixture performed better than the other mixed sowing species combinations, whereas the productive performance was not significantly different between three sowing ratios. The combinations were divided into three groups based on performance: ecological stability, forage yield and forage quality. The 6 species mixture belonged to the ecological stability type and was characterized by its better performance in interspecific compatibility, community stability and forage yield. This type was recommended for sustainable use. The forage yield type included 5-2 species, 4-2 species, and 3-2 species mixtures, and was characterized by their better performance in forage yield but poorer performance in forage quality. This type could be utilized to provide large quantity roughage. The forage quality type included 5-1 species, 4-1 species, and 3-1 species mixtures, and was characterized by their better performance in forage quality but poorer performance in forage yield. This type could be utilized to provide high quality forage.
    Studies on the biological characteristics and dynamics of energy production of Miscanthus floridulus
    CHEN Hui-juan, NING Zu-lin, ZHANG Zhuo-wen
    2012, 21(6):  252-257. 
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    To obtain the greatest energy output of Miscanthus floridulus, the basic biological traits and biomass dynamics, including yearly dynamics of biomass and calorific value, the biomass characteristics and other indicators, were studied. M. floridulus grows slowly at the leaf-expansion stage and increasingly faster at the stem-elongation stage. The average growth rate was 2.12 cm per day at the ear sprouting stage and 2.52 cm per day at the flowering stage, after which, the growth rate decreased and then stopped. There was strong tillering ability with peaks in spring and autumn. The dark treatment was beneficial for seed germination. The annual average caloric value of different organs was: spike (18.27 kJ/g)>stem (17.76 kJ/g)>leaf (17.44 kJ/g). The annual average ash was in the order: leaf (7.03%)>spike (3.44%)>stem (2.55%). Although the biomass energy varied with the biomass change, the caloric value had little significant effect on it.
    Analysis of hyperspectral reflectance characteristics of three main grassland types in Xinjiang
    YANG Hong-fei, LI Jian-long, MU Shao-jie, YANG Qi, HU Xiao-xiao, JIN Guo-ping, ZHAO Wan-yu
    2012, 21(6):  258-266. 
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    The arid desert meadow, Artemisia desert meadow, and lowland mountain meadow are three main grassland types of Xinjiang Uygur Autonomous Region of China. To assist the extraction of remote sensing data and dynamic monitoring of grassland, hyperspectral reflectance spectra were measured with a portable ground object spectrometer. The reflectance spectral characteristics were analyzed for the three main grassland types that are located on the northern side of the Tianshan Mountains in Fukang city. The canopy spectral reflectance of arid desert meadow was smaller than those of Artemisia desert meadow and lowland mountain meadow in the visible wavelengths (except for Ceratocarpus arenarius) while in the near infrared wavelengths, the spectral reflectance of C. arenarius, Peganum harmala and Haloxylon ammodendron was considerably greater than those of Artemisia desert meadow and lowland mountain meadow. Because of the difference between vegetation type and internal structure of leaves, the differences of spectral reflectance between different vegetations that belong to the same type were significant in the visible and the near infrared wavelengths. The value of the red edge position of H. ammodendron of arid desert meadow was greater than those of Artemisia desert meadow and lowland mountain meadow. The value of red and Sred of P. harmala in the Artemisia desert meadow was greater than those of arid desert meadow and lowland mountain meadow, while those of Carex liparocarpos was the smallest. PRI, OSAVI and MCARI were the greatest for arid desert meadow vegetation and the smallest for Artemisia desert meadow vegetation. NDVI was the greatest for lowland mountain meadow and the lowest for arid desert meadow. In addition, GNDVI was the greatest for lowland mountain meadow and the lowest for Artemisia desert meadow. In conclusion, hyperspectral remote sensing played a vital and significant role in monitoring grassland vegetation classification and remote sensing inversion.
    Analysis on competitive power of the agricultural product processing industry from Gansu province
    GUO Zhi-qiang, CHEN Qiang-qiang, MA Ding-chou, DOU Xue-cheng
    2012, 21(6):  267-274. 
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    An evaluation index system about competitive power of the agricultural product processing Industry was built consisting of 13 primary indicators. Taking Gansu province as a case, a comprehensive evaluation was carried out with this index system. The result showed that, the development of the agricultural product processing industries reflected the resources guiding development strategies. There was an obvious differentiation in competitive power of agricultural product processing industries. Namely that, the competitive powers of traditional agricultural product processing industries had been no longer in existence. However, those of the new type agricultural product processing industries were raised remarkably including livestock product and related products, beverage production, agriculture and sideline food production,which had become the main motive forces for agricultural economic development. It was inevitable for traditional agricultural product processing industries to change of development patterns and accelerate the transformation and upgrading. In additional the low market exploring, production and marketing becoming separated from each other and low utilization efficiency of resources were the main restraint factors for the agricultural product processing industries to improve the competitive power.
    Advance in studies of carbon cycling on alpine grasslands of the Qinghai-Tibetan Plateau
    QIN Yu, YI Shu-hua, LI Nai-jie, REN Shi-long, WANG Xiao-yun, CHEN Jian-jun
    2012, 21(6):  275-285. 
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    The Qinghai-Tibetan Plateau is susceptible to climate change and anthropogenic perturbation, due to its fragile ecosystems which play a vital role in mediating future global carbon cycling. To enhance our understanding of the carbon cycling of alpine grassland on the Qinghai-Tibetan Plateau, green-house gases emissions, changes of soil carbon pools, and modeling applications were reviewed in the context of global change, nitrogen deposition and human disturbances, based on research over the last decade. Generally, most attention has been focused on alpine steppe, alpine meadow, shrubland meadow steppe, swamp meadow and alpine wetland. Additionally, The mechanism of greenhouse gas emissions and the shift between source and sink of alpine grassland are summarised. Rising temperatures, grazing activity and nitrogen deposition all exerted significant impacts on greenhouse gas emissions and carbon cycling. However, the responses of carbon cycling to simultaneous changes of these factors is still unknown. On the basis of vegetation type, most recent carbon cycling models failed to incorporate the modulation between biotic and abiotic factors and their relationships. Finally, it was noted that the following four areas required special attention in future studies: 1) greenhouse gas emissions in the course of freeze and thaw cycles; 2) soil respiration observation during non-growing seasons; 3) coupled study on carbon cycling with plant phenology; and 4) the development of some suitable carbon cycling models for alpine grassland.
    Research progress in the ecosystem services function and value of grasslands
    LIU Xing-yuan, Mu Yue-ting
    2012, 21(6):  286-295. 
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    Grasslands not only maintain the integrity of natural ecosystem structure and act as an ecological safety barrier, but they also play an important role in supporting animal production and in inheriting grassland culture. Ecological services function is one of the key aspects of grassland research, and its value, through quantitatively evaluating ecological services function and value of grassland ecosystem, is the key for assessing the importance of ecological services of grassland ecosystem. This paper reviews the previous research on grassland ecosystem services function and its services value, the methods for evaluating ecological services, and presents domestic and overseas study conditions in this field. On this basis, some problems in previous studies were analyzed from research method, content and scale of ecological services function and its values, and a future potential study was proposed for grassland ecosystems.
    Research progress on alfalfa salt tolerance
    ZHANG Li-quan, ZHANG Feng-ying, HASI Agula
    2012, 21(6):  296-305. 
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    Alfalfa (Medicago sativa) is one of important legume forages worldwide. However, the growth range of alfalfa is limited due to its sensitivity to soil salinity, and breeding salt-tolerant alfalfa cultivars is one approach to reducing the deleterious effects of soil salinity on alfalfa production. This article has reviewed the salt-tolerance physiology, genes induced by salt stress and salt-tolerant breeding of alfalfa. The further researches on salt-tolerance alfalfa have also been discussed.
    Research on characteristics and relationship of soil heat and moisture in summer on alpine grassland in Yellow River source region
    ZHANG Juan, LI Xiao-dong, LI Feng-xia, ZHOU Bing-rong
    2012, 21(6):  306-314. 
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    On the basis of observed data, the spatial-temporal variation characteristics, relationship and interactions between soil temperature,water and soil heat flux are studied. The results shows that there exit same trend everyday on soil moisture in summer at alpine grassland in Yellow River source region. Soil moisture exit same trend in each month in summer. The average maximum value of soil moisture was 17.58 m3/m3, and reached in July 4 in each soil layer. The average minimum value of soil moisture was 6.83 m3/m3, and appeared in August 9 in each soil layer. The maximum value appeared from 16 to 17 O’clock, which was 15.26 m3/m3 in 10 cm soil layer from June to August. The minimum value appeared 8 O’clock, which was 14.49 m3/m3.The minimum value appeared 22 and 0 O’clock, which was 15.56 m3/m3 in 30 cm soil layer from June to August. The minimum value appeared from 11 to 13 O’clock, which was 15.32 m3/m3. Soil temperature exit same trend in each month in summer, soil moisture affected by soil temperature. The average maximum soil temperature value was 17.59℃, which appeared in July and August. The average minimum soil temperature value was 4.57℃, which appeared in June 1. Soil heat flux showed a sine curve change from July to August in 10 and 30 cm soil layer. The maximum and minimum values of soil heat flux were 67.35 and -21.62 W/m2 in 10 cm soil layer. The maximum and minimum values of soil heat flux were 21.33 and -2.73 W/m2 in 30 cm soil layer. Soil heat flux was more sensitive than soil temperature. Soil heat flux was declined with soil temperature decreased. The soil heat flux was negative, indicating that during this time soil heat transfer from soil to the atmosphere. The soil heat flux was positive, soil heat transfer from the atmosphere to the soil. Daily evapotranspiration was calculated by the formula of Penman and analyzed relationship with climatic factors. Wind speed was significantly affected on daily evapotranspiration, and wind speed and relative humidity were major factors on daily evapotranspiration change.
    Effect of intrusion volume of Imperata koenigii on relative competitiveness and traits of young Festuca arundinacea turf
    LIU Jin-ping, YOU Ming-hong
    2012, 21(6):  315-320. 
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    Imperata koenigii was artificially planted into young tall fescue (Festuca arundinacea) turf. The tillering, depth and meristematic capacity of roots, and biomass were determined. Root and shoot competitiveness of the two species and traits of young tall fescue were studied. The intrusion volume of I. koenigii had a significant effect on the relative yield of root and shoot, total relative yield, and attack index of F. arundinacea. There was an antagonism between the two species. Direct competition for the same resources existed between the roots. I. koenigii had obvious competitive advantages because of its positive attack power of roots and shoots. The invasion of I. koenigii significantly affected the tillers and height of F. arundinacea. There was a significant negative correlation between turf quality of F. arundinacea and intrusion volume of I. koenigii, and a significant positive correlation between turf quality of F. arundinacea and other indexes except plant height. Weed control, inhibition of plant height, meristem promotion and competitiveness increment were basic requirements and necessary means to improve the quality of tall fescue turf.