Table of Content

20 October 2012, Volume 21 Issue 5

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The characteristics of soil and vegetation of degenerated alpine steppe in the Yellow River Source Region

ZHOU Hua-kun, ZHAO Xin-quan, WEN Jun, CHEN Zhe, YAO Bu-qing, YANG Yuan-wu, XU Wei-xin, DUAN Ji-chuang

2012, 21(5):  1-11. 

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In recent years, the alpine steppe in the Yellow River Source Region has shown obvious trends of degradation and desertification. We studied the different plant communities, biomass and soil characteristics of the Stipa purpurea alpine steppe at different degradation stages. With an increase of alpine steppe degradation, the vegetation coverage, grassland quality index and the proportion of excellent aboveground biomass forage gradually declined and the grassland similarity index decreased. As degradation increased, the plant diversity index and evenness index trend were both single-peak type curves. With increased degradation, grass aboveground biomass was significantly reduced and that of forbs was significantly increased at the beginning, but it was reduced during the mid-late period. The sedge above-ground biomass was not influenced by grassland degradation. The below-ground biomass of alpine steppe plant roots in the 0-20 cm soil profile was increasingly reduced as soil depth increased while the root biomass changed into an inverted “V” type. The “V” shape, with increased degradation, the relationship between species richness and productivity converted significant positive correlation of soil organic matter, available phosphorus, nitrate nitrogen, available potassium and soil compactness concentrations were reduced. With the succession of alpine grassland degradation, soil degradation became more serious. In the severe degradation stage, desert plants appeared, and the landscape developed a desert appearance.

The effect of different grazing systems on aboveground biomass and interspecific relationships in desert steppe

FANG Kai, SONG Nai-ping, WEI Le, AN Hui

2012, 21(5):  12-22. 

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The best grazing system characteristics in desert steppe were probed in a controlled grazing experiment in desert grassland under 9-year exclosure in Yanchi county, Ningxia province and the effects of different grazing systems on aboveground biomass of pasture and interspecific relationships were studied. Results showed that, 1) The grazing intensities had different effects on aboveground biomass of pasture in different growing seasons, and the biomass was lower in moderately grazed, fenced plots than in continuously grazed ones throughout the growing season. 2) The environment had a great impact on aboveground biomass which was lower in fenced than in rotationally grazed plots with different intensities under adequate natural conditions, while fenced plots had more biomass in rotationally grazed plots under high temperature, drought environments. The grassland of rotationally grazed plots with moderate intensity showed better anti-stress ability than ungrazed. 3) Grazing reduced the temporal heterogeneity of aboveground biomass in desert steppe throughout the growing season, however the spatial heterogeneity of aboveground biomass was complex: it had different responses in different grazing systems and different growing seasons. 4) The interspecific relationships and those between communities were not changed by continuous low intensity grazing, while continuous grazing with heavy intensity not only increased the resource competition between different communities but also caused varying degrees of regressive succession in three communities. The four-course system with moderate intensity was the best grazing system in this area, as it eased the resource competition at the interface between communities and also improved the forward succession of Stipa bungeana. Therefore, the desert steppe could be protected and restored by regulating the grazing systems.

Effect of 3-year fencing on soil seed banks of three alpine grassland communities

DENG Bin, REN Guo-hua, LIU Zhi-yun, SHANG Zhang-huan, PEI Shi-fang

2012, 21(5):  23-31. 

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In the Yellow River source region of the Qinghai-Tibet Plateau, we selected three different alpine grassland communities (shrub grassland, Kobresia pygmaea degraded grassland and black-soil) through three years of enclosure. Microscopic examination was used to research the size of soil seed banks, species composition, spatial distribution and correlation between vegetation and soil seed banks. The results showed that: 1) The density of soil seed banks within and outside the fence of K. pygmaea degraded grassland, black-soil and shrub grassland respectively were (9 938±1 780) and (15 330±1 827) seeds/m², (4 074±459) and (3 640±486) seeds/m², and (9 879±1 453) and (12 899±1 695) seeds/m², respectively but only the K. pygmaea degraded grassland within and outside the fence had significant differences. 2) The number of species in soil seed banks in the three alpine grassland communities within and outside the fence was not significantly different, but the proportion of grass and sedge seeds in the soil seed banks were greater within than outside the grassland fence which increased the proportion of native vegetation in the soil seed bank. 3) The Shannon-Wiener diversity index, Simpson diversity index and Pielou evenness index of the soil seed banks had the same pattern in each community and: black-soil>shrub grassland>K. pygmaea degraded grassland: K. pygmaea degraded grassland>black-soil>shrub grassland by the Margalef richness rules. The range of Sorensen similarity index between soil seed banks and vegetation in the three alpine grassland communities was 0.32-0.64 in the sequence and black-soil>K. pygmaea degraded grassland>shrub grassland, and within>outside. 4) Soil seed banks were mainly in the 0-5 cm soil layer with an average proportion of 88.56% of the total soil seed bank. While the overall differences within and outside the fence of the three grassland communities were not significant, the proportion of black-soil soil seed numbesr in the 5-10 cm layer was significantly greater than those of the shrub grassland and K. ygmaea degraded grassland. Thus grassland enclosure improved grassland soil seed bank status, had a greater significant effect for degraded grassland, and played an important role in grassland maintainance and recovery.

Effects of NaCl stress on seed germination of four desert plant species

YANG Jing-ning, WANG Yan-rong

2012, 21(5):  32-38. 

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The seeds of four important desert plants:Haloxylon ammodendron, Reaumuria soongorica, Ceratoides lateens, and Suaeda glauca were collected from the Alashan arid desert, Inner Mongolia. A series of laboratory tests were conducted to study the effects of salt stress on seed germination using NaCl solutions ranging from 0 to 1.8 mol/L, and on germination recovery under optimum conditions after presoaking in NaCl solutions. Germination and radical growth of the four desert plants were subject to different degrees of inhibition with increasing NaCl concentration. In conclusion, the higher the salt concentrations, the greater the inhibitory effects and a slight salt stress improved the germination percentage and index of S. glauca and germination percentage of C. latens. The highest threshold concentrations of NaCl for germination were 1.8 mol/L (H. ammodendron), 0.6 mol/L (R. soongorica), 0.9 mol/L (C. latens), 0.5 mol/L (S. glauca). H. ammodendron therefore had the strongest salt tolerance, and S. glauca the weakest. Under optimum conditions, the seeds presoaked in NaCl solutions could recover their germination capability after the salt stress was relieved. Seeds presoaked for a longer time suffered a greater impact from salt stress, even completel suppression of germination. Presoaking a short time significantly improved germination percentage and index of R. soongorica and also stimulated the radical growth of H. ammodendron, R. soongorica, and C. lateens, but the radical growth of S. glauca was always suppressed by presoaking.

Effects of simulated salt stress on seed germination, seedling emergence and growth of Ulmus pumila

LIU Bing-xiang, WANG Zhi-gang, YANG Min-sheng, LIANG Hai-yong

2012, 21(5):  39-46. 

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The effect of salt stress on seed germination, seedling emergence, growth and the photosynthetic performance of Ulmus pumila were studied to supply a theoretical basis for salt-tolerant germplasm selection in U. pumila. With an increasing concentration of salt stress, germination rate and germination index decreased, and the time of seedling germination was significantly delayed. The rate of emergence, planting percent and survival rate of seedlings decreased with an increase of salt concentration and salt stress reduced the growth of seedling height and root length of U. pumila. Because salt tolerance is weak in the seedling stage, a large number of seedlings died under salt stress. With an increase in salt stress, yields or flux ratios (φ_Po, Ψ_o and φ_Eo), phenomenological energy fluxes(ABS/CS_M, TR_O/CS_M and ET_O/CS_M). Density of reaction centers (RC/CS_O and RC/CS_M), performance indexes (PI_ABS and PI_CSM) and driving force per unit area basis (DF_CSM) decreased, while absorption flux per CS (ABS/CS_O), quantum yield for energy dissipation (φ_Do) and dissipated energy flux per CS (DI_O/ CS_M) increased. The reason that seeds of forest plant seedlings cannot grow when under salt stress is that salt tolerance is weak in the seedling stage, resulting in low planting percent and death of seedlings under salt stress.

Mixed silage of potato pulp and corn straw affects growth performance, ruminant environments and blood biochemical parameters of mutton sheep

WANG Dian, LI Fa-di, ZHANG Yang-dong, BU Deng-pan, SUN Peng, ZHOU Ling-yun

2012, 21(5):  47-54. 

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This study was conducted to determine the effects of mixed silage with potato pulp and corn straw on growth performance and blood biochemical parameters of mutton sheep. 40 healthy White-Suffolk cross sheep with body weight of (47.45±6.38) kg were randomly allocated into 4 treatments with 10 replicates per treatment and 1 sheep per replicate. The feeding trial lasted 70 days. Four treatment included: 1)control group (Ctrl), 40% basal diet +60% corn silage; 2) test group 1 (S15), 40% basal diet +45% corn silage+15% mixed silage; 3) test group 2 (S30), 40% basal diet +30% corn silage+30% mixed silage; 4) test group 3 (S45), 40% basal diet +15% corn silage+45% mixed silage; The result showed that the averaged daily gain of S45 group was increased by 14.29% compared with Ctrl group (P<0.05). No significant differences were observed in the dry matter intake (P>0.05). The ammonia-N content was significantly decreased in S15, S30 and S45 groups than that in Ctrl group by 18.92% (P<0.01), 30.17% (P<0.01) and 33.03% (P<0.01), respectively. No significant differences were observed in acetate content, propionate content, butyrate content, acetate percentage, propionate percentage, butyrate percentage, the ration of acetate to propionate and the ration of acetate to propionate and butyrate (P>0.05). On the zero, twentieth and fortieth day of the trial, no significant differences were observed in serum total protein (P>0.05). On the sixtieth day of the trial, the serum urea nitrogen content was significantly increased in S15 and S45 groups than that in S30 and Ctrl group (P<0.05). On the sixtieth day of the trial, the serum glucose contents of S45 group was improved compares with the other three groups (P<0.05). In conclusion, the mixed silage with potato pulp and corn straw can increase serum urea nitrogen content and decrease the ammonia-N content of mutton sheep. Therefore, the study suggests that it is feasible when mixed silage with potato pulp and corn straw replaced 75% yellow corn silage in the mutton sheep diet.

Nutritional evaluation of fennel straw and shell on sheep

LIU Ting, ZHENG Chen, LI Fa-di, MA You-ji, YUAN Jiu, WANG Xiao-juan, GUO Jiang-peng, HAO Zheng-li, LI Chong

2012, 21(5):  55-62. 

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Six Gansu alpine sheep with an average weight of 28 kg were fitted with permanent rumen fistulas to investigate the nutritional value of fennel (Foeniculum vulgare) straw and shell on sheep in a 3×3 Latin square design. The digestibility of dry matter, nitrogen, organic matter, neutral detergent fiber, acid detergent fiber, calcium, phosphorus of fennel straw and shell were 61.63% and 62.11%, 64.66% and 66.47%, 62.50% and 62.63%, 72.72% and 71.53%, 68.28% and 67.25%, 20.35% and 23.19%, 35.03% and 31.98%, respectively. The nitrogen retention rate and digestive energy were 49.53% and 52.09% (fennel), and 9.51 and 9.86 (shell) MJ/kg respectively. Sheep digestibility of fennel straw and of shell were higher than those of other roughages. When feeding fennel straw to sheep there were significant differences in the molar ratio of acetic acid, propionate, and butyrate, and of pH and the ratio of acetic acid to propionate in rumen fluid (P<0.05). There were no differences in total volatile fatty acids or in molar ratio of other acids and nitrogen in rumen fluid (P>0.05). When feeding fennel shell to sheep, there were significant differences in the molar ratios of acetic acid, butyrate and other acids in rumen fluid (P<0.05). There were no differences in pH, total volatile fatty acids, nitrogen content, the ratio of acetic acid to propionate and molar ratio of propionate in rumen fluid (P>0.05).

Effects of transgenic alfalfa on soil microorganisms

YAN Li-ping, LIU Cui-lan,LI Li, LI Shuang-yun, YANG Qing-shan, SUN Chao, LIANG Hui-min, ZHANG Ying, ZHANG Zhao-yun, XIA Yang

2012, 21(5):  63-68. 

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A field release of transgenic alfalfa and non-transgenic alfalfa grown under normal agricultural practice was monitored for changes in total bacterial, actinomycetic and fungal populations in 2009 and 2010. Classical plate counting and PCR technology were adopted to investigate the amounts of microorganisms and horizontal gene transfer. We found that three kinds of soil microorganism appeared with identical trends within different months and different years. ANOVA and multiple comparison analyses revealed that there was no significant difference in terms of the microorganism numbers between both individual plants and between the amounts of cultured soil microorganisms in the rhizosphere soil of the transgenic alfalfa and non-transgenic alfalfa. No alien target DNA was detected from PCR products of total soil DNA, and strains DNA amplified with specific primers of BADH. Our preliminary results indicated that there are still no significant effects of transgenic alfalfa on the soil microorganism system.

Agrobacterium-mediated transformation of maize shoot apical meristem by introducing fused gene Chi-linker-Glu and bar

FANG Yong-feng, LI Yong-sheng, PEN Yun-ling, WANG Fang, WANG Wei, MU Yan-zhao, WANG Han-ning

2012, 21(5):  69-76. 

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Most maize disease are caused by fungi pathogens, such as northern leaf blight, southern leaf blight, ear and stalk rots, and so on. In normal years, this disease makes maize yield lost by 10% and this percentage may be increased by 30%-40% in its popular years. However, it is very difficult for conventional breeding to develop an elite maize material with the resistance to all the fungi disease. Therefore, we can use transgenic method to transfer some genes related to the resistance of these disease into maize in order to obtain resistance materials. Chitinase and β-1,3-glucanase are two important enzymes which play a key role in the hydrolysis reaction of fungal cell wall, so it is useful in the control of fungi disease, meanwhile, the herbicide resistant gene bar are usually used as a selectable marker in maize transformation.The purpose of this research is to introduce the fused gene of chitinase and β-1,3-glucanase and bar as well into elite maize inbred Zheng58 for improving its resistance to fungi disease. The wounded shoot apical meristem (SAM) of germinated seedlings were used as the material for Agrobacterium mediated transformation. We report here: 1) An optimized transformation system for Agrobacterium mediated transformation of shoot apical meristem, using the optimal concentration of bacterial culture (the value of OD₆₀₀ was 0.6) for infection, addition of 150 μmol/L acetosyringone (AS) in the bacterial suspension, the whole infection process was carried out in a vacuum desiccators with a negative pressure of 50 kPa for 12 minutes. 2) Identified by herbicide screening procedure and PCR detection, 13 transformed plants were obtained among the 32 herbicide-resistant plants, and the overall transformation was 2.6%.The preliminary evidences showed that the foreign genes had been introduced into the maize genome. This method circumvented the long period of tissue culture step and limitation of different seasons, in addition, many elite inbred lines which are recalcitrant in callus induction can be efficiently transformed by this method.

Phylogenetic relationships and maternal donor of Hystrix and Leymus species as revealed by chloroplast atpB-rbcL sequences

LIU Jing, ZHANG Hai-qin, FAN Xing, SHA Li-na, ZENG Jian, ZHOU Yong-hong

2012, 21(5):  77-85. 

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The phylogenetic relationships and maternal donor of species in the genera Hystrix and Leymus were investigated by analysing the chloroplast atpB-rbcL sequences for five taxa of Hystrix, 22 species of Leymus (NsXm), together with two species of Elymus (StH) and 17 related diploid species from 8 genera. Maximum Parsimony (MP) and Bayesian Inference (BI) were used for phylogenetic analysis. 1) H. patula was closely related to Elymus, and the maternal donor of H. patula was the St genome; 2) H. duthiei and H. duthiei ssp. longearistata were closely related to the Eurasia Leymus, and the maternal donors of them were the Ns genome from Psathyrostachys; 3) H. coreana and H. komarovii were closely related to the Leymus species in North America, and their maternal donors could be the Xm genome. Thus, it is reasonable to transfer H. patula from Hystrix to Elymus, and to combine H. duthiei, H. duthiei ssp. longearistata, H. coreana, and H. komarovii into Leymus.

Study on the transferability of maize SSR and sugarcane EST-SSR markers to Miscanthus (Poaceae)

LU Yu-fei, JIANG Jian-xiong, YI Zi-li

2012, 21(5):  86-95. 

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Miscanthus germplasm resources are fundamental to breed its new varieties better suitable for being utilized as energy crop. In order to screen the effective microsatellite molecular markers prior to the relevant genetic analysis for Miscanthus, we studied the transferability of 382 maize SSR primer pairs and 100 sugarcane EST-SSR primers pairs using the accessions from all the 7 species of Miscanthus in China. The screening included two sections, which were preliminary screening to obtain those primer pairs which were preliminarily considered to be effective, and the PCR amplification for all 84 accessions using these primer pairs. The number of 39 (10.21%) maize SSR primer pairs and 13 (13.00%) sugarcane EST-SSR primer pairs were obtained through screening, respectively, whose amplification bands were reproducible, strong and polymorphic, and could be exactly scored across all 84 accessions. A total of 250 amplification bands were produced by the 52 primer pairs, of which 220 bands were produced in Miscanthus. Of the 220 bands, 206 (93.64%) were polymorphic with an average of 3.96, and some of them were specific, which were only possessed by some taxon or taxa in the genus. The genetic similarity (GS) ranged from 0.588 to 0.988 based on the all 250 amplification bands. UPGMA clustering analysis showed that Miscanthus in China was divided into two groups on the level of GS=0.68. The former contained Miscanthus nepalensis, M. nudipes, and M. paniculatus, and the latter comprised of M. sinensis, M. floridulus, M. sacchariflorus, and M. lutarioriparius. On the level of GS=0.82, M. sinensis and M. floridulus constituted one subgroup, and M. sacchariflorus and M. lutarioriparius constituted another subgroup. On the level of GS=0.88, M. sinensis and M. floridulus were separated with each other. The results preliminarily showed that there was rich genetic diversity among all the taxa of Miscanthus in China. The genetic similarity among M. sinensis, M. floridulus, M. sacchariflorus, and M. lutarioriparius ranged from 0.780 to 0.988, which indicated there were small genetic distances among them. However, there were relatively long genetic distances between the group consisting of M. nepalensis, M. nudipes, and M. paniculatus, and the other group comprised of M. sinensis, M. floridulus, M. sacchariflorus, and M. lutarioriparius, which implied that M. nepalensis, M. nudipes, and M. paniculatus should be given appropriate consideration when selecting parents in the course of genetic improvement and breeding of Miscanthus from China in order to broaden the genetic basis of varieties.

Genetic diversity of Miscanthus floridulus revealed by morphological characters and SSR markers

XUE De, XIAO Liang, AI Xin, DENG Nian-dan, JIANG Jian-xiong, QIN Jing-ping, CHEN Zhi-yong, LIU Shu-ling, YI Zi-li

2012, 21(5):  96-106. 

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In this study, a total of 25 morphological characters and 33 SSR markers were used to reveal the genetic diversity in 53 accessions of Miscanthus floridulus germplasms from China. All of 25 morphological characters displayed significant difference in these M. floridulus germplasms, with a coefficient of variation ranging from 6.53% to 69.82%, in which the dry weight per plant, the third-class branch number of panicle and the second-class branch number of panicle were with the highest CV values and were the major factors responsible for morphological variation. Clustering analysis based on morphological data showed that 53 M. floridulus germplasms were divided into three groups, and most of which were clustered into the third group. SSR analysis showed that 26 of 33 primer pairs were polymorphic which generated a total of 81 DNA fragments, with 74 of which being polymorphic. The polymorphic information content (PIC) for each SSR primer ranged from 0.086 to 0.374 with an average of 0.245, the genetic similarity coefficients from 0.693 2 to 0.965 9, the gene diversity of Nei’s (H) 0.258 7, and the average information index of Shannon (I) 0.400 4. SSR marker clustering analysis based on SSR data indicated that there was no direct correlation between the genetic distance and the geographic distance for M. floridulus germplasms. Both SSR and morphological analyses suggested a higher genetic diversity existing in the M. floridulus germplasms.

The genetic diversity of three ecological Medicago ruthenica germplasms revealed by ISSR and SSR

LI Hong-yan, LI Zhi-yong, SHI Wen-gui, CAI Li-yan, ZHANG Jing-ping

2012, 21(5):  107-113. 

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Quantitative and classification was based on germplasm collection and utilization. The genetic diversity of 14 wild Medicago ruthenica was assessed by screening with 18 pairs of SSR and 18 ISSR primers. SSR primers amplified 109 clear polymorphic bands, and the polymorphism rate was 80.09% with a similarity coefficient ranging from 0.669 to 0.885. ISSR primers amplified 125 polymorphic bands and the polymorphism ratio was 87.08% with a similarity coefficient ranging from 0.448 to 0.811. UPGMA (Unweighted Pair Group Method with Arithmetic mean) cluster analysis based on two markers showed that part of the M. ruthenica material grouped into one group. Mantel tests showed that the genetic similarity of two markers had a significant correlation (r=0.019 6, t=0.121 2). Compared with yellow M. ruthenica genetic diversity levels, those of M. ruthenica were higher. The genetic difference was highest in M. ruthenica var. oblongifolia.

Analysis of genetic diversity in Salix oritrepha from different altitudes in Gansu Qilian Mountains using SSR markers

GUO Min, MA Yan-jun, LI Yi

2012, 21(5):  114-121. 

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Genetic diversity and genetic structure of Salix oritrepha (about 180 individuals in total) from nine altitudes on the Qilian mountains were analyzed by SSR (simple sequence repeat) markers. Fifteen highly stable and repeatable SSRs (selected from 47 SSRs of Populus) detected a total of 211 alleles of which 176 (85%) were polymorphic. At the species level, the Shannon index (I) was 0.419 2, Nei’s gene diversity index (H) was 0.279 6, the coefficient of gene differentiation (Gst) was 0.093 5, and the gene flow (Nm) was 4.848 7. There was more genetic differentiation within altitudes than between altitudes. All of the results include P, H, and I showed that S. oritrepha has a high genetic diversity in the Gansu Qilian mountain. Cluster analysis showed a direct correlation between genetic distance and geographic distance. Genetic diversity of S. oritrepha was notably affected by the latitude and altitude: the higher the altitude gradient, the more abundant the genetic diversity of S. oritrepha.

Ultrastructural characteristics of compatible Pseudopeziza medicaginis interaction with alfalfa leaf

SHI Juan, WANG Hua-rong, ZHONG Shao-lin

2012, 21(5):  122-127. 

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Ultrastructural characteristics of the compatible interaction between Pseudopeziza medicaginis and alfalfa was studied using transmission electron microscopy (TEM). When P. medicaginis invaded host tissue, the hyphae directly penetrated the host cell wall and formed intracellular hyphae with growth in the cell and expansion into the adjacent cell. Hyphal penetration of host cell walls was assisted by greater vacuole pressure. Hyphae within host cells were wrapped by invagination of the host plasma membrane and mycelium and plasma membrane were always isolated and there was deposition of electron dense, dark material between host plasma membrane and cell wall. Pathogen hyphae continued to expand in the host plasma membrane region with a corresponding expansion in the host cell’s, plasma membranes which separated the host protoplast and from the mycelium. The hyphae separated from the plasma membrane to form a hyphal sheath. With an increase in the amount of infection, the region of host plasma membrane that was not penetrated was gradually degraded as P. medicaginis infected chloroplasts and other organelles. First, the mycelial sheath connected to the chloroplast and other organelle membranes, then the degradation of grana lamellae structure and degraded organelle tissues were deposited along the mycelium and around the cell wall. At a later stage of infection, the mycelium expanded both intra and extracellularly, but the hyphae in degraded cells had thick cell walls and the host cells filled with a lot of black material and crystalline particulate matter.

Comparison of SRAP and SSR markers for hybrid identification of switchgrass (Panicum virgatum)

ZHANG Jing, HUANG Lin-kai, ZHAO Bing-yu, ZHANG Xin-quan, YAN Hai-dong, JIANG Xiao-yang

2012, 21(5):  128-133. 

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To provide a scientific basis for hybrid identification of switchgrass (Panicum virgatum) and cross-pollinating plants, we compared the identification efficiency and accuracy of SRAP and SSR markers. Switchgrass hybrid individuals (165) and their parental lines of switchgrass were tested by both methods. Compared to SRAP markers, the codominant SSR technique was more efficient. One pair of SSR primers (primer 23) detected all hybrids effectively and the percentage of polymorphic bands was 100%. SRAP required six primers to identify hybrids. The percentage of polymorphic bands of SRAP was 40% lower than that of SSR.

Genetic analysis of morphological characters of zoysiagrass

GUO Hai-lin, CHEN Xuan, XUE Dan-dan, LIU Jian-xiu

2012, 21(5):  134-143. 

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The heredity of morphological characters, including density, turf height, leaf length, leaf width, leaf length/width, internode length, internode diameter, and internode length/diameter, in two F₁ populations of J36×Z039 and Z039×J36 was analyzed by major gene and polygene mixed genetic models to reveal the genetic mechanisms of these characters of zoysiagrass. The range of variation for each character in reciprocal progenies was far beyond that of their parents. The widest variation was in density, followed by internode length/diameter, internode length, leaf length/width, turf height, internode diameter, leaf length, and leaf width. Significant differences were observed between two reciprocal crosses for turf height, leaf length, leaf width, leaf length/width, internode diameter and internode length/diameter, which suggested that there could be maternal genetic phenomenon for these characters in zoysiagrass. However, no significant differences were found between two reciprocal crosses for density and internode length. The density from the reciprocal cross J36 ×Z039 was controlled by two additive-dominance-epistasis major genes model (B-1), and the heritability of major genes of positive and negative crosses were 93.67% and 63.22%, respectively. A no major gene model (A-0) was the most suitable model for turf height, leaf length, leaf width, leaf length/width, internode length of reciprocal crosses, internode diameter of negative crosses and internode length/diameter of positive crosses. Internode diameter of positive crosses and internode length/diameter of negative crosses of J36 ×Z039 were controlled by one major gene model.

A novel method for building of traffic tolerance experiment of turf grass

XIAO Bo, SONG Gui-long, XU Li-xin, HAN Lie-bao

2012, 21(5):  144-152. 

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A novel method for investigating traffic tolerance of turf grass was built on the basis of the invention of a portable traffic simulator and a new approach for traffic treatment. Four traffic treatments (non-traffic, light traffic, moderate traffic and severe traffic) were used in the method for the experiment of traffic tolerance of perennial ryegrass (Lolium perenne), and five indexes, including visual rating, coverage, chlorophyll content, leaf water content and fresh weight of aboveground biomass of turf grass, were measured at 1, 3, 7, 10, 14 and 21 day after traffic treatments. Results showed that five indexes of perennial ryegrass showed different changes under different degree of traffic stress. The value of all indexes declined obviously with increasing intensity of traffic under all kinds of traffic treatments except that chlorophyll content was higher than CK (non-traffic) under light traffic. Values of all indexes began to increase after 3 days from traffic treatment and kept rising with increasing days. Under light traffic and moderate traffic, the value of all indexes reached to CK level at 7 d and 14 d after traffic treatments, respectively. However, the value of all indexes under severe traffic did not reach to CK level at 21 d after traffic treatments. Correlation between visual rating and coverage, chlorophyll content, leaf water content and fresh weight of aboveground biomass were analyzed and highly close relationships were found at 7 d after traffic treatments (P<0.01). The correlation coefficients were the highest at 14 d after traffic treatments. Therefore, 14 days after traffic treatments may be an important period for physiological regulation of perennial ryegrass in response to traffic stress. The results can provide theoretical basis for further in-depth research about the mechanism of traffic tolerance of turf grass.

A study on utilization of recycled clippings on a golf course

SHI Pei, LI Rui-jun, ZHANG Ju-ming

2012, 21(5):  153-159. 

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Utilization of clippings as a recycling resource on a golf course were studied using a composting experiment with turf-grass clippings mixed with chicken dung organic fertilizers at ratios of 100%∶0%, 90%∶10%, 80%∶20%, and 70%∶30%. Microbial inocula were added to improve clippings for reuse on golf courses. The composting maturity was determined by testing temperature, pH, and germination index during composting and matured composts were analyzed for nutrient content. The four matured composts mixed with fine sand at a ratio of 1∶1 were evaluated as turf growing media using Zoysia japonica cv. Lanyin No.Ⅲ and measuring turf-grass density, coverage, chlorophyll content, aboveground biomass, and underground biomass. Clippings mixed with 20% organic fertilizer were suitable for composting, but needed 21 days to be well matured with an appropriate pH, good fertility, and safety. The compost mixed with sand significantly increased the turf quality, so that the golf course clippings could be reused as a resource for turf growing media.

The effects of climate change on dryland wheat production under different tillage systems

LI Guang, LI Yue, HUANG Gao-bao, LUO Zhu-zhu, WANG Qi, LIU Qiang, YAN Zhen-gang, ZHAO You-yi

2012, 21(5):  160-168. 

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In order to explore the influence mechanism and regulation of climate change on wheat yields, the parameters of APSIM model were firstly modified and then verified according to the data collected from field experiment. APSIM model was used to survey the effect and sensitivity of elevated CO₂ concentration and temperature on wheat yield under 3 tillage systems. The results show the relationships between wheat yield and the CO₂ concentration were quadratic parabola that shows an increased change and the yield will coincide with the diminishing return when CO₂ concentration increase. Meanwhile, the increasing effect of wheat yield of no tillage with stubble mulching (NTS) is greater than that of conventional tillage (T) and no tillage (NT). The relationships between wheat yield and temperature were quadratic parabola. Wheat yield and temperature of T and NT show a decreased change of quadratic parabola, and the contribution of temperature to the yield will coincide with the superimposed decreasing effect. Wheat yield and temperature under NTS show inflection point type change of quadratic parabola, temperature threshold is 0.94℃. Sensitivity of wheat yield to interaction of temperature and CO₂ concentration is divided to insensitivity, positive sensitivity and negative sensitivity. Sensitivity under NTS treatment changes little. In 3 tillage systems, the increasing effect of wheat yield caused by elevated CO₂ concentration can compensate for the yield reduction due to high temperature under NTS treatment, and there exists better interaction effect between CO₂ concentration and temperature. Preferably NTS can deal with the change of temperature and CO₂ concentration better, and it can reduce the negative effect of climate change.

Effect of irrigation and nitrogen supply levels on water consumption, grain yield and water use efficiency of spring wheat on no-tillage with stubble standing farmland

LIU Qing-lin, ZHANG En-he, WANG Qi, WANG Tian-tao, LIU Chao-wei, YIN Hui, YU Hua-lin

2012, 21(5):  169-177. 

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In the Shiyang River basin, the environmental deterioration caused by excessive nitrogen (N) and irrigation application in agricultural ecosystems has received much attention in recent years. A combination of careful irrigation and N management is needed to improve grain yield and water use efficiency (WUE) in the arid oasis agricultural area of Northwest China. A field experiment was conducted to investigate the effects of different irrigation and N application rates on water consumption, grain yield and water use efficiency on no-tillage farmland with standing stubble in the oasis region of the Shiyang River basin, Gansu province. The experiment followed a completely randomized split-plot design, taking flood irrigation (conventional irrigation 327 mm), 20%water-saving irrigation (261 mm), 40%water-saving irrigation (196 mm) and N fertilizer application rates (0, 140, 221, 300 kg N/hm²) as the main-plot and split-plot, respectively.Under the experimental conditions, irrigation supply increased the soil water content in 80-120 cm depth measured 24 h before irrigation and in 0-80 cm depth measured 24 h after irrigation. Nitrogen application has no significant effects on the soil water content in 0-120 cm depth. Soil water storage and water consumption rate were increased with amount of irrigation. The soil water storage in the treatments without nitrogen application was significantly higher than that with nitrogen application. Nitrogen application did not significantly affect water consumption rate. When the rate of N application was 221 kg/N hm², the grain yield (6 365 kg/hm²) and WUE (14.51 kg/hm²·mm) were reached the maximum among other N treatments across irrigation regimes. Spring wheat (Triticum aestivum) grain yield were increased with the amount of irrigation. The increases of grain yield in traditional irrigation were 8.2% and 32.2% when compared with 20% water-saving irrigation and 40% water-saving irrigation. The differences of WUE between different irrigations were not significant.

Effects of different film mulching on photosynthesis, transpiration rate and leaf water use efficiency of maize

GAO Yu-hong, NIU Jun-yi, XU Rui, WANG Yan, LI Chang-jiang, QI Di

2012, 21(5):  178-184. 

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To clarify the maize (Zea mays) yield-increasing mechanism of whole film mulching, two lines of furrow sowing were done in arid and semi-arid areas. Field experiments were carried out in 2009 to study the effects of five methods of film mulching on photosynthesis rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), leaf water use efficiency (LWUE) and grain yield. The Pn and Tr were highest at the bell-mouthed stage with single-peaked curves. The Pn, Gs, LWUE and grain yield under whole film mulching of two lines of furrow sowing (QS) were significantly higher than those of mulching lines of furrow sowing (QL), semi-film mulching two lines of furrow sowing (BS), semi-film mulching of tiling bunch sowing (BP) and no film mulching of bunch sowing (CK). The Gs was significantly positively correlated with Pn and Tr, while Pn was significantly correlated with Tr. The grain yield was significantly positively correlated with Pn, Gs, LWUE from seeding stage to bell-mouthed stage and Tr from bell-mouthed stage to milking stage. The results also showed that the QS treatment improved grain yield by 24.17%, 27.15%, 44.52% compared with QL, BS, BP and CK respectively and is currently the optimum pattern for maize film mulching in the Longdong area.

Relationships of dominant species root activity, plant community characteristics and soil micro-environment in artificial grassland over different cultivation periods

ZHANG Li, WANG Chang-ting, LIU Wei, WANG Qi-lan, LI li, XIANG Ze-yu

2012, 21(5):  185-194. 

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Three river source regions were contrasted with heavily degraded grassland (black soil patch) by studying, the root activity of Elymus nutans (the dominant species), plant community quantity characteristics, soil physicochemical properties and activities of six soil enzymes over six and ten years of artificial grassland. The relationship of root activity of the dominant species, community quantity structure and soil micro-environment of artificial grassland were analysed. The biomass of grass became the largest part of the plant community and legumes began to invade in six year old artificial grassland. The biomass of grass in ten year old artificial grassland was lower than that of the six year artificial grassland, in which the biomass of forbs became the largest component of the plant community. There was an immense invasion of legumes, and sedges also began to emerge. Soil physicochemical properties had marked changes in artificial grassland. Soil moisture, organic matter, total nitrogen, available nitrogen, total phosphorus and available phosphorus increased while soil bulk density, temperature and pH value decreased. The activities of invertase, alkali phosphatase, protease and urease of six year and of ten year artificial grassland increased but the polyphenol oxidase activity was reduced. The catalase activity was not obviously changed. Plant community characteristics were positively related to soil moisture, organic matter, available nitrogen, total phosphorus and hydrolysis enzymes whereas plant community characteristics were negatively related to soil bulk density, pH value and polyphenol oxidase. The root activity of E. nutans was negatively related to soil compaction, soil moisture, pH value, protease, alkali phosphatase, polyphenol oxidase. Analysis showed that the variation trend of root activity of E. nutans in 6 year artificial grassland was more than that in 10 year artificial grassland. The changes in soil micro-environment led to increasing plant competition for soil resource utilization. The root activity of plants changed with the different species composition and biomass distribution of the plant community.

Effect of growth inhibitors on biomass structure, energy distribution and lodging rates for populations of Elymus sibiricus

LIU Jin-ping, YOU Ming-hong

2012, 21(5):  195-203. 

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The population of Elymus sibiricus was sprayed at the jointing or booting stage with various concentrations of paclobutrazol or chlormequat chloride. The biomass structure, energy accumulation and distribution, and the lodging rates of populations were determined and analyzed at the full flowering stage. After spraying growth inhibitor, there was a highly significant effect between traits and biomass of components, which led to a highly significant influence between aboveground and underground biomass structure (P<0.01). Growth inhibitor had significant effects on the energy value of leaves and stems, but little effect on energy value of roots and inflorescence(P＞0.05). A highly significant influence was found between biomass and energy distribution of populations, with the influence in the sequence inflorescence＞stem＞leaf＞root. At the jointing stage, application of chlormequat chloride was beneficial for increasing biomass and energy in the stem and leaf but at the booting stage, it was beneficial only for biomass and energy in the stem. Application of paclobutrazol helped distribute biomass and energy to the inflorescence and at the jointing stage the effect was significantly stronger than at the booting stage. Growth inhibitors may significantly elevate root biomass and reduce the lodging rate of populations. Paclobutrazol could be applied at the jointing stage for seed production, while chlormequat chloride could be sprayed at the booting stage for forage production. At the booting stage, 200 mg/L chlormequat chloride increased fresh grass yield by 10.22%, and 200-600 mg/L paclobutrazol at the jointing stage significantly raised potential seed production.

Effect of fertilization on biomass of alfalfa in returned farmland in semiarid loess hilly area

CAI Guo-jun,ZHANG Ren-dou,CHAI Chun-shan

2012, 21(5):  204-212. 

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For increasing the aboveground biomass of alfalfa (Medicago sativa) in returned farmland and prolonging its degradation time, the mixed fertilization experiment of nitrogen and phosphate fertilizer was conducted two times in 2007-2008, on alfalfa grassland that has been planted for five years in Longtan catchment, Anding district, Dingxi city. The result showed that nitrogen fertilizer has no obvious effect on increasing the growth conditions and biomass of alfalfa. However, phosphate fertilizer has significant influence on promoting the alfalfa’s growth and increasing biomass. And the mean biomass of fertilized alfalfa in 2007 and 2008 was 1.62 and 1.15 times the biomass of control alfalfa respectively. The highest biomass of alfalfa was appeared when phosphate fertilizer rate was highest of 12 kg/667 m². The mean fresh biomass of alfalfa can achieve 18 240 kg/ha on seventh year. The growth conditions and biomass of alfalfa on sunny-slopes was better than that on shady-slopes,and its mean fresh and dry biomass were 1.49 and 1.43 times the biomass of shady-slopes respectively. In the semiarid loess area with 400 mm annual precipitation, the biomass of alfalfa harvest was mainly produced by the 1st harvest and it accounted for about 75% of annual biomass, whereas the biomass of 2nd harvest was small and accounted for about 25%. So twice per year for alfalfa harvest is optimized in this area.

Characteristic of four trace elements in soil and dominant plants form degraded grassland, enclosed grassland on the north bank of Qinghai Lake

LI Tian-cai, CAO Guang-min, LIU Qing-hai, ZHOU Guo-ying, SHI Sheng-bo, ZHANG De-gang

2012, 21(5):  213-221. 

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In order to study on the relationship between plant shapes and copper, zinc, iron, manganese and other trace elements, so we selected degraded grassland on the north bank of Qinghai Lake as our test sample and fence enclosure as control, through investigated of the types of grass plots and analyzed copper, zinc, iron, manganese and other trace elements in typical plants. The results showed that the contents of copper, zinc, iron, manganese and other trace elements have an accumulation of the plants on degraded grassland compared with that on enclosed grassland, and have a negative correlation between plant shapes-height and ground with biomass. Such as: in Lanniwan, Cu were 10.480 and 7.275 mg/kg in plant form degraded grassland and enclosed grassland, but in soil Cu were 13.99 and 24.19 mg/kg, plant height was 13.3 and 17.3 cm, respectively. In degraded grassland, the correlation coefficient between the plant height and Cu, Zn was -0.987 3 and -0.986 6, respectively. Trace elements nutrient-accumulation in plant form degraded grassland is the result of degraded and also one of the cause grassland accelerated degradation. It is also an “emergency” response for mineral elements nutrition needs change.

Morphological variation of space mutation in alfalfas

YANG Hong-shan, CHANG Gen-zhu, BAO Wen-sheng, CHAI Xiao-qin, ZHOU Xue-hui

2012, 21(5):  222-228. 

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Placing crop seeds in recoverable satellites to induce novel variety has become an important technique for space mutation breeding. The effects of space mutation on contemporary (SP₁) test materials of four alfalfas were tested in the spacecraft ‘ShenZhou No.3’. Four alfalfa contemporary test materials were planted in Lanzhou and after two years field observation we found 7 types of mutation variation such as multifoliator plants (6), big area plants (11), fast-growing plants (14), a white flowered plant (1), disease resistance plants (7), quick growing plants (7), and dwarfing-strong branch plants (2). As far as the rules of heredity and variation are concerned, different types of mutation were expressed in the different breeds and varieties. The mutations were not random and irregular variations were associated with the varieties own characteristics. Confirmation of the genetic stability of the variations is a necessary next step in the generation of molecular markers and observations in the field.

A study on spatial-temporal characteristics of grassland degradation using the Markov model

LIU Ai-jun, WANG Bao-lin, CHEN Xi-mei, YANG Sheng-li, ZHENG Shu-hua

2012, 21(5):  229-236. 

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The spatial and temporal features of grassland cover conversion (GCC) serve as a useful input for understanding the desertification process and degradation of grassland caused by anthropogenic activities and extreme natural events in general. Thematic Mapper data (TM 30 m) were used to detect and map degraded grassland features both spatially and temporally. Two data sets of TM 30 m data were collected from the years 2000 to 2010. Supervised classifications were developed for each of the GCC change detection of the three cases (degradation,desertification, and salinization). To address this situation, the field data were used to test the GCC detection of change results presented in this paper. The GCC change detection methods worked reasonably well and detection accuracy of deserted and salinized output was >90% although degraded output identified only 75% of the covered pixels within the ground observed perimeter polygons. The applications presented in this paper also evaluated the transition matrix between 2000 and 2010 of each of the three change detections,and predicted dynamic characteristics of grassland using the Markov model. The results showed that for the next decade, and even for a further ten years, the grassland will develop positively with a reduced trend of degradation and desertification. The research also indicated, it is credible to use remote sensing technology combined with the Markov model in analyzing the dynamic characteristics of grassland cover changes.

Cationic distribution and transportation in different organs of Pennisetum purpureum cv. Sumu No.2 seedling under sea-salt stress

LIU Zhi-wei, ZHONG Xiao-xian, CHANG Pan-pan, LIU Wei-guo

2012, 21(5):  237-247. 

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With prolonged stress time under different sea-salt concentrations, Na⁺, K⁺, Ca²⁺, Mg²⁺ distribution and transportation in roots, stems and leaves of Sumu No.2 Napier grass seedlings were analyzed and compared with those of N51(CK). Na⁺ content increased but K⁺, Ca²⁺, Mg²⁺ content and the ratios of K⁺/Na⁺ decreased in all organs of Sumu No.2 and N51 as the sea-salt concentration increasd. With increasing time under 10 g/L sea-salt concentration stress, the Na⁺ content in roots of Sumu No.2 was higher than those of N51. Under 4-10 g/L sea-salt concentration stress, the Na⁺ content in stems of Sumu No.2 was significantly lower than that of N51, and that in leaves of Sumu No.2 was lower than in N51; the K⁺ content in roots and stems of Sumu No.2 was significantly higher than those of N51, while the K⁺ content in leaves of Sumu No.2 and N51 were not the same; The ratios of K⁺/Na⁺ in leaves of Sumu No.2 were higher than in N51; The transport selectivity of S_K⁺/Na⁺ (stem/root)of Sumu No.2 was 1.02-2.19 times that of N51, except that Sumu No.2 was lower than that of N51 after 7 d stress with 4 g/L sea-salt concentration. It appears that a major characteristic of the salt tolerance mechanism in Sumu No.2 seedlings is a high transport selectivity of S_K⁺/Na⁺ (stem/root)that can intercept more Na⁺ in roots and selectively transport more K⁺ from root to stem resulting in a higher K⁺/Na⁺ ratios in stems and leaves under sea-salt stress.

Effects of 6-BA, GA₃ and IBA on photosynthetic pigment content and related enzyme activities of Lilium casa blanca

ZHAO Li, PAN Yuan-zhi, ZHU Qiao, YUE Jing, MI Shi-hong

2012, 21(5):  248-256. 

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Effects of plant regulators on photosynthetic pigment content and enzyme activity in leaves of Lilium casa blanca (Lily) were studied using an orthogonal design [L₁₆(4⁴)] of 6-BA, GA₃, IBA, and bulb soaking time. Experimental data was analyzed by ANOVA and correlation analysis. In different periods,the contents of chlorophyll a, chlorophyll b, and chlorophyll a+b in leaves were significantly higher than those in the CK. During the whole growth period, these photosynthetic pigment contents were highest when GA₃ was 150 mg/L, IBA was 40 mg/L, 6-BA was 60 mg/L and soaking time was 40 min. They increased to maximum at the squaring stage or initial bloom stage, and then decreased slightly or strongly. The activity of superoxide dismutase (SOD), and of catalase (CAT) was enhanced. Both SOD and CAT stayed at a high level when GA₃ was 150 mg/L, IBA wais 40 mg/L, 6-BA was 60 mg/L and soaking time was 40 min. However, the content of maloaldehyde (MDA) in leaves was lower than that of the control, and the upward trend of MDA in leaves became less. The MDA content was lowest when the experimental condition was GA₃ 100-150 mg/L, IBA 40-60 mg/L, 6-BA 60 mg/L and soaking time was 40 min. Analyses showed that the best combination of plant regulators was GA₃ 150 mg/L, IBA 40 mg/L, and 6-BA 60 mg/L with a soaking time of 40 min.

Research of high temperature stress on the morphological and physiological changes in Scaevola albida ‘Mauve Clusters’ cutting seedlings

XU Na-ting, LIU Yu-min, LIU Ya-min, HE Bing-hui

2012, 21(5):  257-263. 

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The morphological and physiological changes was researched with Scaevola albida ‘Mauve Clusters’ cutting seedlings as materials in order to explore the physiological response and adapting mechanism of Mauve Clusters under high temperature stress in this study. Results showed that high temperature had certain influence on the morphological characteristics of Mauve Clusters. With the temperature rised, injury indices increased gradually, and continuous high-temperature stress could make Mauve Clusters wither or even death. When relieving from stress, most plants could recover by themselves. With temperature rised and time prolonged, chlorophyll and carotenoid content were significantly reduced, while MDA and proline content appeared a tendency of slight increase-surging-slight reduction, at the same time, SOD activity rised slowly, and CAT activity firstly increased and then sharply deceased. At the temperature of 35℃ and 40℃, there were little effect on Mauve Clusters cutting seedlings growth. Under the temperature of 45℃ for 1 to 2 days, Mauve Clusters would suffer certain thermal damage, but could restore through self-regulation, when for 3 days, only 45% plants could live through self-regulation, and 55% plant withered or even dead. Under the environment of high temperature, there were significant correlations among injury indices, chlorophyll, MDA, proline, SOD and CAT, which suggested that these physiological indexes could regulate the high temperature damage, and those physiological indexes could be used as heat resistant identification index of Mauve Clusters.

Nutrient structure of Amorpha fruticosa

LIU Xue-yun, ZHOU Zhi-yu, GUO Xia, WANG Rui, LIANG Kun-lun

2012, 21(5):  264-273. 

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The nutrient structure of Amorpha fruticosa was studied during the growing season by analysing the nutrient contents of leaves, stems and roots of different diameter for C, N, P, K, Ca, Mg, Fe, Mn, Cu, and Zn. 1) The nutrient contents of N, P and K were the inverse of stem and root diameter (they reduced as the diameter increased). The highest contents were in the leaf, stem and thin roots. 2) There was no specific pattern of Ca, Mg, Fe, Mn, Cu, and Zn contents with stem and root diameters. 3) The correlation between trace elements was poorer than that between trace elements and macro-elements. Most correlation element pairs were in the stem, followed by the leaves, then roots. N, P, and K had the most relationships with other elements but C, Zn and Ca had fewer. 4) There was more organic carbon, N, Ca, Mn and Cu in the leaves than in the stems and roots of A. fruticosa during the whole growingh season. The order of macro-element content in leaves was C＞N＞K＞Ca＞Mg＞P, and the order of trace element contents was Fe＞Mn＞Zn＞Cu.

The effects of N,P,K, and Ca on plant growth and nutrient content of Lily leaves

ZHU Qiao, PAN Yuan-zhi, ZHAO Li

2012, 21(5):  274-284. 

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The effects of different fertilizations on plant height, leaf number, leaf area, and chlorophyll and on nitrogen, phosphorus, potassium, calcium changes in leaf indexes of potted lilies were studied using an orthogonal design to explore fertilizer requirements and provide a basis for standardizing cultivation of lilies. 1) Nitrogen fertilizer had significant effects and was generally highly significantly positively correlated with plant height, leaf area and chlorophyll content. Plant height, leaf number, leaf area and chlorophyll were highest when nitrogen was 300 mg/kg. Phosphorus and calcium were positively correlated with plant height, leaf number, leaf area and chlorophyll content. Leaf area and chlorophyll content were highest when phosphorus was 100-150 mg/kg, potassium was150 mg/kg, and calcium was 120 mg/kg. 2) During the whole growth period, total leaf nutrient content was highest when nitrogen was 200-300 mg/kg, phosphorus was 100 mg/kg and potassium was 0-150 mg/kg. There was an increase to a maximum at budding or initial bloom stages, and then either a slight or a strong decrease. Under different fertilization ratios, the contents of leaf nutrition differed significantly after the budding stage. 3) The best combination was: N, 300 mg/kg; P, 100 mg/kg; K,150 mg/kg; and Ca, 120 mg/kg. This ratio led to optimal growth conditions, highest growth speed, best leaf quality, highest leaf nutrient content and longest period of P, K, and Ca accumulation of the Lily.

Antioxidant activities in vitro of different polar solvent extracts of Asarum himalaicum

HE Quan-lei, MIAO Fang, LI Chun-ling

2012, 21(5):  285-290. 

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The antioxidative activities in vitro of different solvent extracts of Asarum himalaicum were studied to provide more information for future research on the medicinal value of A. himalaicum. The powdered material of A. himalaicum was extracted with 50% ethanol refluxing extraction and the ethanol condensate was evaporated to dryness under vacuum on a rotary evaporator. The condensate was then extracted with Petroleum ether, ethyl acetate or n-butanol or water at the same volume to get four different extracts. The four extracts were then examined for their antioxidative activities by DPPH (1,1-diphenyl-2-plcrylhydrazyl), Fenton, NBT (nitrotetrazolium blue chloride) reduction and Fe²⁺ chelation. The results suggest that the four solvent extracts of A. himalaicum had a certain degree of antioxidant activity, and the activity had a positive correlation with the concentration of the extract. The ethyl acetate extract had higher activity in scavenging DPPH·(IC₅₀ =0.376 mg/mL) and O₂^-· (IC₅₀=0.297 mg/mL Hile the n-butanol extract had the highest ·OH scavenging capacity (IC₅₀=0.776 mg/mL). The water extract was the most powerful for chelating metal ions (IC₅₀=0.026 mg/mL) and was more powerfull than that of BHT (2, 6-di-tert-butyl-4-methylp-henol) (IC₅₀=0.373 mg/mL). This study has shown that the ethyl acetate extract, n-butanol extract and water extract of A. himalaicum have remarkable free radical scavenging activities, and the water extract can be selected as a new metal ion chelating reagent.

Multi-phase kinematic analysis of Gramineae leaf development

WANG Wei-guang, WANG Xian-guo

2012, 21(5):  291-301. 

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Plants vary widely under different environmental conditions. A general kinematic framework of grass leaf growth between different species or genotypes that is variable or has plasticity under different conditions is an important approach to better understanding plant plasticity at the organ level, tissue level, and/or cellular level. The identity of the components of multi-phase kinetic models depends on theoretical considerations that allow reinterpretation during leaf growth processes, as well as growth between subsequent leaves, tiller production and whole-plant growth. During recent decades, physiological and morphological aspects of the kinetic approach provide a series of acute quantitative analyses to investigate the relationship between the regulation of molecular mechanisms and macroscopic results during grass leaf growth. This review introduces multi-phase kinematic models as a new perspective in determining variation in grass leaf growth. The growth plasticity of grass leaves from a multi-phase kinematic perspective is discussed together with its role in some molecular regulations and further potential for molecular biology and grass science of the kinematic modeling approach.

Salinity tolerance evaluation and mechanisms in bermudagrass (Cynodon spp.)

CHEN Jing-bo, LIU Jian-xiu

2012, 21(5):  302-310. 

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Bermudagrass (Cynodon spp.) is an important warm season turfgrass, forage, and soil and water conservation plant. Evaluation of salinity tolerance in bermudagrass cultivars and wild resources indicates that they are salinity-tolerant, can grow in saline soil, but there are significant genetic differences in the genus Cynodon. Salinity tolerance of bermudagrass is often less than that of saltgrass, manilagrass and seashore paspalum, but greater than Japanese zoysiagrass, rhodes grass, buffalo grass, centipedegrass and tall fescue. Na⁺ and K⁺ ion regulation and osmoregulation have been studied as mechanisms of salinity tolerance and bermudagrass has been found to reduce salt ions accumulation in shoots by means of salt glands secreting salt ions, ion selective transportation, stomatal regulation, and accumulation of osmotica such as betaine, proline, and soluble sugar. Finding key genes and their expression for ion selective absorption, transportation, distribution, synthesis of organic osmotica are important research directions in the future.

Research on effects of soil erosion on vegetation development and succession of plant resistance to erosion

JIAO Ju-ying, WANG Ning, DU Hua-dong, WANG Dong-li

2012, 21(5):  311-318. 

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The relationship between vegetation and soil erosion deserves more attention due to its importance to science and practical applications. While most available information is on the mechanisms and benefits of vegetation for soil erosion control, the interference of soil erosion in plant development and vegetation succession is poorly documented as is the plant’s resistance to soil erosion. Soil fertility and soil water decline during the erosion process reduces seed activity and production and the seeds on the soil surface will be redistributed or lost during soil erosion. While the seeds of some species have special appendages which can help the seeds persist in the soil, seed germination and seedling establishment are the vulnerable stages in plant life. Seed germination and seedling survival are restricted when soil water and fertility are reduced during the erosion process. Simultaneously, the over land flow and sediment redistribution also affect seed germination and seedling survival thus redistribution of seeds, water and sediment will influence the distribution of seedlings and the vegetation. Plants are selected by the environments and develop with the environments, so only some species can grow in habitats stressed with serious soil erosion. Soil erosion works on the environment and different stages of the plant life. Thus the process of vegetation succession is also influenced by soil erosion. In conclusion, plant growth and development are influenced by soil erosion and may express many traits that resist soil erosion. Eroded habitats are colonized by specially adapted plants. We consider that effective soil erosion control strategies in a region can be developed, only if the level of interference of soil erosion in vegetation development and succession and the traits and capacities of different plant’s resistance to erosion are fully considered.

Variation of phenology and bulbs of Fritillaria unibracteata along altitudinal gradients

CHEN Wen-nian, CHEN Fa-jun, XIE Yu-hua, WANG Yu, DUAN Hui-guo, QI Ze-min

2012, 21(5):  319-324. 

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To provide theoretical support for artificial cultivation of Fritillaria unibracteata, and to lay a foundation for protection of its wild resource, the effects of altitudinal height on phenology and bulbs of the species were studied. In this study, three locations (low, medium and high) were established along altitudinal gradients on a mountain slope of the eastern Tibetan Plateau, and a transplant experiment was carried out. In this experiment, 30 turfs in which individuals of F. unibracteata grew were transplanted between the high and the low location. Ecological factors at each location, such as snowmelt timing, soil water content, air temperature and soil pH were tested. In addition, phenological phases including plant emergence, first flowering, peak flowering and consenescence were observed at three day intervals, and bulbs at each location were weighed in September,2009. The results showed that phenological phases and most ecological factors given above were significantly different between locations. Snowmelt timing at the low location was nearly a month earlier than that at the high location and soil water content at the low location was 30.3% lower than that at the high one. Air temperature was 2.7℃ (March), 3.0℃ (April) and 5.3℃ (May) higher at the low location than that at the high location. However, pH at all locations did not differ. All phenological phases appeared first at the low location, second at the medium location and finally at the high location. Compared with the low location, phenological phases at the high location were 14-25 d later. Single bulb weight at the low location was the heaviest, reaching 282.4 mg. With an increase of elevation, weight of single bulbs decreased. At the high location, single bulb weight was only 217.4 mg, a decrease of 23.1% compared with the low location. That the phenology and bulb weight changed with altitude was further confirmed by the results of a transplant between high and low locations. Individuals transplanted from the low to high location always showed consistent traits with those originally at the high location, and vice versa. Changing trends of phenology and bulbs with altitude was mainly affected by length of snow free period, air temperature and soil water content. In conclusion, altitude exerted a strong influence on phenology and bulbs of F. unibracteata.

Optimization of SRAP-PCR system on Vicia amoena using orthogonal design and selection of primers

LIU Ying, WANG Xian-gou, ZHANG Ju-ming, LIU Fang

2012, 21(5):  325-330. 

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An orthogonal design was used to optimize a SRAP-PCR system with 4 factors (Mg²⁺, dNTP, primer and Taq polymerase) at 3 levels plus the concentration of template DNA. The optimized SRAP-PCR system for Vicia amoena was: 2 μL 10×PCR buffer (Mg²⁺ free), 30 ng template DNA, Mg²⁺ 2.0 mmol/L, dNTP 0.2 mmol/L, primer 2.0 μmol/L, Taq DNA polymerase 1.5 U in a total of 25 μL reaction solution. Each factor had a different effect on the results of PCR. Primer concentration had the greatest effect and dNTP concentration had the least effect. The optimized SRAP-PCR system was tested on three V. amoena germplasm and was shown to be consistent and reliable. Twenty pairs of primer combinations with abundant polymorphisms were selected from 98 pairs of primer combinations. The optimized SRAP-PCR system and polymorphism primer combinations provide a basis for molecular genetic research on V. amoena.

Ammonia volatilization from marsh soils of typical floodplains with different flooding frequencies

GAO Hai-feng, BAI Jun-hong, HUANG Lai-bin, WANG Guo-ping, HUANG Chen, LIU Pei-pei

2012, 21(5):  331-336. 

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Ammonia volatilization was monitored to investigate the ammonia loss in alkaline wetlands. In-situ airflow enclosure was used to measure the amount of ammonia volatilization of marsh soils in 5 typical zones [including permanently floodplain (B), 1-year floodplain (O), 5-year floodplain (F), 10-year floodplain (T), 100-year floodplain (H)] which are divided by different flooding frequencies along the vertical direction of the river channel in different floodplain wetlands of the Xianghai National Nature Reserve, Jilin Province, in different growing seasons (July, September, and November 2010). The highest ammonia volatilization rate (1.155 mg/m²) was observed in September (0.651 mg/m²) followed by November, while the lowest rate was in July (0.175 mg/m²). There were significant differences in the amount of ammonia volatilization in different sampling seasons. However, no significant differences were observed in ammonia volatilization rates between sites in July. The values of ammonia volatilization appeared “U” style with increasing flooding frequencies in September (i.e. the ammonia volatilization rates were higher in those zones near or far away from the river channel than those in the middle zones). However, the ammonia volatilization rates were higher in both the 5-year and 10-year floodplains in November. Grazing was one of the important factors that influenced increased nitrogen losses through ammonia volatilization from alkaline wetland soils.