Table of Content

20 August 2009, Volume 18 Issue 4

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Dynamics of the above-ground standing biomass assets of typical grassland

LI Shi-mei, XIE Gao-di, ZHANG Cai-xia

2009, 18(4):  1-8. 

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Biomass is not only a carrier of material, but also a carrier of energy and value. It is an important index for evaluation of ecosystem structure and function. Based on existing observations at the Inner Mongolia Grassland Ecosystem Research Station and Haibei Alpine Meadow Ecosystem Research Station, the dynamics of the above-ground biomass assets of a Leymus chinensis+Stipa grandis community and a Kobresia humilis meadow were studied. The dynamic curves of above-ground biomass of these two communities were the single peak type, and the maximum above-ground standing biomass of the former was 197.21 g/m², while that of the latter was 307.75 g/m². The dynamic curves of above-ground standing energy of these two communities appeared the same shape as the above-ground biomass dynamic curves, whose peak value was 3 637.8 and 5 964.20 kJ/m², respectively. The accumulative rate of above-ground standing energy was positively correlated to accumulative rate of above-ground biomass. The biomass value curves of the L. chinensis+S. grandis community and K. humilis meadow were quite different from above-ground biomass curve and above-ground standing energy curves, and the peak values of above-ground biomass value of L. chinensis, S. grandis and K. humilis meadow were 584.95, 300.93 and 2 066.84 yuan/hm², respectively. During the process of biomass accumulation, grassland also produces a gas regulation value. The peak value for O₂ emission by the L. chinensis+S. grandis community and K. humilis meadow was 742.40 and 1 158.52 yuan/hm², respectively, while that of CO₂ fixation was 1 484.89 and 2 317.20 yuan/hm².

Species diversity of degraded vegetation in different age restorations in Horqin Sandy Land, Northern China

ZUO Xiao-an, ZHAO Ha-lin, ZHAO Xue-yong, GUO Yi-rui,
ZHANG Tong-hui, MAO Wei, SU Na, FENG Jing

2009, 18(4):  9-16. 

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Following a series of field investigations into vegetation characteristics in Horqin Sandy Land, the community composition and species diversity were analyzed along a restoration gradient of dune vegetations [non-fenced mobile dune, 11-year old dunes (mobile dune, semi-mobile dune, and semi-fixed dune), 20-year old fenced dunes (mobile dune, semi-mobile dune, semi-fixed dune, and fixed dune)] and scattered tree grassland. Vegetation cover, species richness and diversity increased with an increase in degree of fixed and fenced years of mobile dunes. The succession series of plant communities were: Pioneer plants of Agriophyllum squarrosum and a few annual plants (mobile dune stage) → Artemisia halodendrom shrub and annual, biennial herbs (semi-mobile dune and semi-fixed dune stages) → annual, biennial and perennial herbs (fixed dune stage). As the amount of grass and perennial herbs increased in the process of dune vegetation restoration, the structure of plant communities became complex and herbage quality was considerably improved.

Distribution pattern and dynamic population changes of Seriphidium transiliense seedlings in fenced enclosures in the northern Tianshan Mountains

LU Wei-hua, ZHU Jin-zhong, WANG Dong-jiang, JIN Gui-li, YU Bo

2009, 18(4):  17-26. 

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Spatial distribution pattern analysis was used to describe distribution patterns of Seriphidium transiliense seedlings. Seedlings had a clumped pattern of distribution in May and September both inside and outside the fenced area, but the degree of aggregation was different due to the spatial heterogeneity of the environmental conditions; the IWAOY regression and TAYLOR principle analyses of the spatial distribution of indicators in line gave the same results. The sampling area of S. transiliense seedlings was 4 m²; DCCA and correlation analysis showed that the number of seedlings was positively correlated with environmental factors, and that the seedling populations could be classified into four categories according to the habitat conditions. There were huge differences in the numbers of surviving seedlings at different times under different habitat conditions: Large numbers of seedlings germinated initially and there was a high mortality rate in the summer, characteristics of “explosive emergence” and “sudden death”. Peak seedling emergence was in April in all four habitat conditions and was followed by sharp decreases in July and August with almost no surviving seedlings. The high mortality rate and a strong focus in time, were mainly due to intensive environmental selection and to competition.

Influence of different ratios of herbage and shrubs on plant community characteristics for roadside deforestation and soil protection on the Bi-Tong Expressway

ZHANG Xiang-feng, MA Chuang, DONG Shi-kui, ZHANG Wen-hui, LIU Xin-cheng

2009, 18(4):  27-34. 

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The species composition, plant functional groups, community characteristics, and diversity index were investigated through building natural restoration. The Cynodon dactylon community and five kinds of mixture-planting plots of shrub and herbage on the Bi-Tong Expressway typical slope, and species similarity between different plots was analyzed. Plants of Leguminosae, Gramineae and Compositae occupied a fairly large proportion and played important roles in the reforestation plots. The mixture-planting plots of shrub and herbage could be divided into three patterns based on the change of dominate species. C. dactylon grassland (300-400 plants/m²), intergrowth land with C. dactylon and Medicago sativa(500-600 plants/m²), and M. sativa grassland (700 plants/m²). The density, coverage, height and biomass of reforestation communities tended to decrease and then increase as the density of herbage became higher. The maximum value was 700 plants/m². The species richness (Margalef index),plant diversity (Shannon-Wiener index), and Pielou evenness index tended to increase, to a density of 500 plants/m² then decrease. As the density of herbage became higher, species similarity between different plots and natural restoration tended to decrease and then increase, indicating that the composition of artificial restoration, not the herbage density, decided the community composition. The density had no serious effect on coverage, height, biomass and diversity of reforestation communities when the density was over 500 plants/m². The cost should be reduced and the optimum effect of restoration achieved by choosing the appropriate proportion of species and density.

Classification and ordination of subalpine meadows in Wutai Mountains by artificial neural network methods

ZHANG Jin-tun, NIE Er-bao, XIANG Chun-ling

2009, 18(4):  35-40. 

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Artificial neural network theory and ordination are relatively new branches of mathematics that have recently been introduced to plant ecology. This work applied these two methods to study the subalpine high and cold meadows in the Wutai Mountains. SOFM clustering classified 78 quadrats into 8 community types, basically representing the associations of the high and cold meadows in the Wutai Mountains. This classification is meaningful in ecology. The SOFM ordination clearly reflected ecological gradients, indicating that altitude is the most important factor affecting the growth and distribution of meadow vegetation, while slope and aspect also have certain roles. SOFM clustering and ordination methods performed well in this application, and this study showed that the combination of these two methods is good for ecological analysis. The conservation of meadows in Wutai Mountains needs to be strengthened further.

Spatial variability of soil moisture and aboveground biomass of Medicago sativa under long term continuous planting

WANG Jun, LIU Wen-zhao, ZHONG Liang-ping, LI Yu-shan

2009, 18(4):  41-46. 

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Impacts of fertilization and sampling position on soil moisture and aboveground biomass of Medicago sativa were studied in a long term, in situ experiment. After 19 years continuous M. sativa planting, fertilization had no impact on M. sativa aboveground biomass. However, plant height declined and accumulation of aboveground biomass decreased towards the center of the experimental plot, like a biomass funnel. Differences due to sampling position were much bigger than those due to fertilization. Soil moisture in the layers below 1 m also resembled a moisture funnel and significantly correlated with M. sativa aboveground biomass, which indicated that subsoil moisture may be crucial to M. sativa growth in long term continuous plantings.

Dynamic changes in morphological and physiological characteristics and above-ground nutrients of Carex thunbergii after light grazing

DAI Ping-li, ZHOU Shou-biao, LIU Shou-feng, LIU Kun,YU Hai-bo,WANG Ji-ming

2009, 18(4):  47-53. 

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Leaf morphological and physiological characteristics and above-ground nutrients of Carex thunbergii were investigated after light grazing. 1) Height and fresh and dry weights of grass under light grazing were significantly lower than those of the CK during the first four phases of restoration but could be restored to the same level as that of the CK after about 40 d. There was no significant difference in population density, between light grazing and CK during the whole restoration process. 2) MDA content increased and reached a peak after the first week, then slowly declined until it was restored to the CK level after about 30 d. CAT and SOD enzyme activities initially increased then decreased to the CK level about one month later. POD activity was initially higher than that of the CK, then after a reduction there was a second increase followed by a slow decrease to the CK level. There were no significant differences in leaf chlorophyll content compared with those of the CK. 3) Above-ground crude fat and protein content increased with time and were considerably higher than those of the CK. Above-ground crude fiber content was initially significantly higher under light grazing than in the CK but significantly decreased with time until it reached CK level about 20 d later. It continued to decline and became lower than that of the CK. C. thunbergii has a strong restoration ability and has improved herb quality after light grazing.

Occurrence and output of all types of belowground buds of Leymus chinensis and the dynamics of formation and maintenance of aboveground shoots

ZHANG Ji-tao, XU An-kai, MU Chun-sheng, WANG Jun-feng

2009, 18(4):  54-60. 

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Seasonal variations of densities of all types of buds, parent and daughter shoots of Leymus chinensis were investigated. The origin of current year parent shoots was 80% from shoot buds and daughter axillary shoots, 15% from apical rhizome buds and daughter apical rhizome shoots, and 5% from axillary rhizome buds and daughter axillary rhizome shoots, from total buds and shoots formed during previous years. When parent shoots were growing, apical rhizome buds began to generate and spread horizontally to occupy niches during 20 May, one month earlier than axillary shoot buds and axillary rhizome buds. By 20 June, the horizontal apical rhizome buds started growing into vertical apical rhizome buds and finally into daughter rhizome shoots. Similarly, by 20 June, shoot buds and axillary rhizome buds occurred and finally developed into daughter shoots. Parent shoots of L. chinensis produced both a lower proportion of spreading shoots (i.e. apical rhizome buds and shoots, or axillary rhizome buds and shoots) and a higher proportion of clumping shoot (i.e. shoot buds and axillary shoots), resulting in a combined growth form. This enables L. chinensis to maintain an asexual propagation mechanism through continuous growth of buds, daughter shoots and parent shoots between and within years. Higher precipitation can promote the density of all types of buds, leading to an increase in density of daughter and parent shoots.

Pollen viability and stigma receptivity of nine species and five variety in Paris

DING Chun-bang, LI Qiang, LI Yan, ZHANG Li, YANG Rui-wu, ZHOU Yong-hong

2009, 18(4):  61-66. 

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Pollen viabilities of nine species and five varieties of Paris were evaluated using TTC(2, 3, 5-triphenyl tetrazolium chloride), while stigma receptivities were measured by a benzidine-H₂O₂ method. 1) Pollen viabilities of Paris species were lower than 50%, except for P. cronuistii, which was up to 52.8%; 2) Pollen viabilities were different between species, varieties, and populations; 3) Stigma receptivities were different between species, but the same among populations within a species; 4) Stigma of P. thibetica and P. bashanensis had no receptivity at all. Stigma receptivities were in positively related to pollen viabilities of P. axialis, P. delavayi, P. polyphylla, P. forrestii, P. delavayi var. petiolata, P. polyphylla var. chinensis and P. polyphylla var. stenophylla. However, there were no correlations in P. cronuistii, P. polyphylla var. yunnanensis, P. undulata and P. fargesii var. brevipetalata; 5) Anthers opened in the morning and closed at dusk each day during the blooming period.

A comprehensive evaluation of salt tolerance for germplasm and materials of Elytrigia at the seedling stage

MENG Lin, SHANG Chun-yan, MAO Pei-chun, ZHANG Guo-fang, AN Sha-zhou

2009, 18(4):  67-74. 

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Simulating salinity stress in a green house was used to study the relative water content(RWC), relative electrical conductivity rate(EC),content of free proline(Pro), K⁺/Na⁺, changes of relative growth rate, the salt-tolerant coefficient, the livability and time of salinity injury to death of Elytrigia. Materials of 34 germplasms and 8 species of Elytrigia collected from 21 countries were measured and analyzed at the seedling stage, and the salt tolerances were comprehensively evaluated. Eight indexes were all effective for evaluation of salt tolerance of germ plasm and materials of Elytrigia at seedling stage. Cluster analysis of salt tolerant indexes showed the 34 germ plasms and materials could be divided into three salt tolerant levels, e.g. strong (ER030, ER035, ER041, EE011, EE014, EE017, EE023, EE026, EE047, EH001, EH002, EPU02), medium (ER008, ER014, ER027, ER032, ER037, ER038, ER044, ER045, EE007, EE027, EJ001, EPO02, EPO03, EPO04), and the weaker (ER028, ER033, ER036, ER039, EE022, EJ003, EL001, EI022).

A comprehensive assessment of drought-resistance of three wild rocky-slope grasses

XIE Xian-jian, LAN Dai-ping, BAI Jing-wen

2009, 18(4):  75-80. 

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The drought-resistance of three native, rocky-slope grasses (Pogonatherum paniceum, Eriophorum comosum and Cynodon dactylon) were studied in a pot experiment. Indexes such as leaf area index, drying roots accumulation, leaf holding water ability, leaf relative conductance, soluble protein, chlorophyll were analysed and a comparison of the subordinate function values of each grass was used to decide the drought-resistance order of each grass. Drought-resistance of P. panideum was stronger than C. dactylon which was stronger than E. comosum. This is useful to provide a theoretical foundation for selecting and cultivating native slope-protecting vegetation adapted to rocky slopes.

Allelopathic effects of Eucalyptus grandis on Medicago sativa growing in different soil water conditions

ZHONG Yu, ZHANG Jian, YANG Wan-qin, WU Fu-zhong, FENG Mao-song, CHEN Xiao-hong

2009, 18(4):  81-86. 

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The responses of Medicago sativa to allelopathic effects of Eucalyptus grandis growing in different soil water conditions was studied using a bioassay method. The effects of E. grandis leaf extracts were examined on M. sativa seed germination and seedlings grown in different soil water conditions [75%, 55%, 40%, 30% FC (field water content)]. Regardless of water condition, E. grandis showed an obvious allelopathic effect on M. sativa. Leaf extracts of E. grandis significantly reduced the germination index of M. sativa, and the index was further reduced with a water reduction in soil used to grow E. grandis. E. grandis that grew in the lower soil water conditions (40% and 30% FC) had a higher concentration of leaf extract that significantly inhibited seedling growth in contrast to the lower concentration of leaf extract, which enhanced the seed germination rate of M. sativa. E. grandis that grew in high soil water conditions (75% and 55% FC) produced a low concentration leaf extract that significantly improved seedling growth of M. sativa, while the high concentration extract enhanced the seed germination rate. A high concentration leaf extract of E. grandis reduced leaf chlorophyll content and root activity of M. sativa seedlings. M. sativa showed a relatively strong resistance to E. grandis leaf extract treatments and could be chosen as a priority species for tree-grass combinations in E. grandis plantations.

Influence of different treatment with straw and straw’s thickness on forming-sod time and turf quality

GAN You-min, MENG Yu, ZHANG Jian-bo, ZHOU Yu-feng, WU Jia-hai, TANG Cheng-bin

2009, 18(4):  87-93. 

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Use square, regressive and rotation with 5 factors design, researched on the different straw and straw’s thickness that influence the days of forming-sod (TreatmentⅠ: straw+pig’s dejectas+accelerating-humus powder; TreatmentⅡ: straw+pig’s dejectas; Treatment Ⅲ: straw+urea+accelerating-humus powder; Treatment Ⅳ: straw+urea; and factor V: 10, 15, 20, 25 and 30 mm thickness). As the result, the mostly influence on the days of forming-sod is treatmentⅠ (straw), the second is straw’s thickness, the third is treatment Ⅲ. Others have little influence on this. In the limit of the turf quality, the best medium is 600 g of treatment Ⅰ, 600 g of treatmentⅡ, 0 g of treatment Ⅲ, 600 g of treatment Ⅳ, 20 mm of the straw’s thickness. The days of forming-sod of the medium are 36.33 d. And the weight value of turf quality is 108.61.

Estimation of photosynthetic pigment of Festuca arundinacea using hyper-spectral data

QIAN Yu-rong, YANG Feng, LI Jian-long, GAN Xiao-yu, YANG Qi, WANG Wei-yuan

2009, 18(4):  94-102. 

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Photosynthetic pigments of vegetation are a primary product and important materials that can indirectly reflect health status and photosynthetic capacity of vegetation. Hyper-spectral remote sensing provides the possibility for rapid, large-scale monitoring of vegetation chlorophyll change. In this study, canopy reflectance spectra and chlorophyll content of cool-season Festuca arundinacea were measured and their relationship analyzed. The top-five chlorophyll sensitive parameters were selected from 12 hyperspectral characteristic variables, and then used to establish a vegetation index model to estimate photosynthetic pigments. 1) The relationship between Chlb and the original spectrum was the best among the photosynthetic pigments: Chla, Chlb, Chls, and Cars. 2) The first derivative spectra gave a better relationship (correlation coefficient: -0.897) with vegetation photosynthetic pigments near 700 nm wavelength than the other two hyperspectrum forms {R and D[log(1/R)]}. Finally, after comparing the correlation between photosynthetic pigment concentrations and hyperspectral data, the most significant variables {R_g, Dλ₇₀₀, D[log(1/R₇₃₀)], RVI_b, R_ch, CARI} were selected from twelve variables to establish the regression model of photosynthetic pigments. All of these provide a theoretical basis for rapid, non-invasive detection of nutritional status and meadow quality of F. arundinacea.

Effects of land use regimes on soil physical and chemical properties in the Longzhong part of Loess plateau

LI Xiao-dong, WEI Long, ZHANG Yong-chao, GUO Ding, LI Xu-dong, FU Hua

2009, 18(4):  103-110. 

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In this study we analyzed soil physical and chemical properties in croplands which were cultivated under traditional tillage for at least 50 years and grasslands which had been restored from cropping for 20 years in the Loess Plateau in Gansu Longzhong. 1) Different land uses resulted in significant differences in soil organic carbon (SOC), total nitrogen, total phosphorous, available phosphorous, soil bulk density and soil pH. In surface soil (0-10 cm), SOC contents were significantly higher in grasslands than those in croplands, while total nitrogen was not significantly different. In the soil layers from 20 to 100 cm, SOC and total nitrogen contents were significantly (P<0.05) higher in croplands than those in grasslands. The soil total phosphorous was higher in croplands than that in grasslands but not significantly so. In the soil profile down to 100 cm, the C/N ratios in croplands were much higher than those in grasslands, except for the 0-10 cm layer. The soil pH in grasslands was significantly (P<0.05) higher than that in croplands in each layer. The soil bulk densities in the grasslands were higher than in croplands, except for the 10-20 cm layer. 2) The SOC and total nitrogen decreased with soil depth in grasslands, but this was only found in the soil layers below 30 cm in croplands; In the upper 30 cm soil layers, SOC increased with depth. Total phosphorous did not show significant differences in different soil layers in grasslands while in croplands, the changes of total phosphorous showed the same trends as those of SOC and total nitrogen. The available phosphorous contents decreased with soil depth in both grasslands and croplands while the soil pH was the reverse. 3) In both grasslands and croplands, soil organic carbon, total nitrogen, total phosphorous and available phosphorous showed significant negative correlations with soil BD and soil pH. There were significant positive correlation between soil BD and soil pH. Significant positive correlations were also found between SOC, total nitrogen, total phosphorous and available phosphorous.

A preliminary study on the relationship between soil urease activity and soil fertility in the grazing grasslands of Yongchang county, Gansu province

HOU Yan-hui, ZHOU Xue-hui, JIAO Ting, LIU Rong-tang, LI Xing-fu

2009, 18(4):  111-116. 

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The relationship between soil urease activity and soil fertility in the grazing grasslands of Yongchang county of Gansu province was studied from 2007 to 2008. There were significant differences in the urease activities of different grazing grasslands, and these activities were more intense in the surface layer than in the deeper layers. The soil urease activities showed significant positive correlations with organic matter content, total nitrogen, available nitrogen, and available potassium, but a significant negative correlation with soil pH value. Path analysis showed that the sequence of soil fertilities based on their direct acting coefficients to soil urease activity was: Total nitrogen>available potassium>available nitrogen>available phosphorus>soil pH value>organic matter. The organic matter does not affect urease activities directly, but acts indirectly through its effect on total nitrogen. Total nitrogen directly affects urease activity. Other factors like soil available nitrogen, available phosphorus, and available potassium do not directly affect urease activity, but indirectly affect ti through total nitrogen. Both direct and indirect effects of soil pH value are limited and soil pH value is not a major factor affecting urease activity.

Varieties of soil microorganisms decomposing Betula luminifera fine roots and Hemarthria compressa roots

RONG Li, LI Xian-wei, ZHU Tian-hui, ZHANG Jian, YUAN Wei-yang, WANG Qiao

2009, 18(4):  117-124. 

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Fine root decomposition often plays an important role in maintaining soil fertility and mass nutrient cycling in soil ecosystems. As irreplaceable decomposers of fine roots, soil microorganisms are closely linked to bioelement components. Birch (Betula luminifera)-grass (Hemarthria compressa) is a successful forest and grass compound model for converting farmland to forest and is beneficial to the development of the environment and economy. There is a lack of information on quantities of soil microbes in relation to fine root decomposition and few published reports on soil microorganisms in birch-grass plantations. Therefore, soil microbial amount and dominant microbial groups during decomposition of fine roots and grass roots were investigated in order to obtain an understanding of the mechanisms of fine root decomposition. Birch fine roots and grass roots from a birch-grass compound model in converting farmland to forest in Hongya, Sichuan, were used in a 120-d laboratory incubation experiment. The roots were mixed with the same soil in the following five treatments: 1) 0-1 mm birch fine roots, 2) 1-2 mm birch fine roots, 3) grass roots, 4) 0-2 mm birch fine roots+grass roots, and 5) no roots (CK). Treatments of addition of fine roots (and grass roots) significantly increased soil microbial content. The ranked orders of total microbial content were: Treatment 4＞treatment 3＝treatment 1＞treatment 2 (P＜0.05). Fungi played a more important role in fine root decomposition than bacteria and actinomycetes. Eight dominant microbial groups were isolated and identified. Pseudomonas, Trichoderma, and Actinoplanes played the most important role at the initial phase of fine and grass root decomposition, while Bacillus, Aspergillus, Penicillium, Streptomyces, and Nocardia dominated the later phase of decomposition. Regular fluctuations were not observed during the first 120 d of the decomposition processes but after 120 d eight dominant microbial groups increased significantly (P＜0.05). The different treatments with birch fine roots and grass roots greatly influenced soil microbial amount and the dominant microbial groups in root decomposition.

Effects of different conservation tillage on amount and distribution of soil ammonifying bacteria, nitrobacteria and nitrogen-fixing bacteria

ZHAO You-yi, CAI Li-qun, WANG Jing, ZHANG Ren-zhi

2009, 18(4):  125-130. 

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Field experiments were conducted in Dingxi, in the western Loess Plateau, on the effects of tillage on soil ammonifying bacteria, nitrobacteria and nitrogen-fixing bacteria under a rotation system with spring wheat and pea. The treatments were conventional tillage and three conservation agriculture patterns: Conventional tillage (T), conventional tillage with stubble incorporation (TS), no till with no straw cover (NT), no till with straw cover (NTS) The amount of soil ammonifying bacteria, nitrobacteria and nitrogen-fixing bacteria from high to low was NTS, TS, NT, and T in the 0-5, 5-10, and 10-30 cm depths of soil under two rotation fields. The amounts of soil ammonifying bacteria in NTS at these three depths was 76.21%,146.92%,67.82% respectively, higher than that in NT. Soil nitrobacteria and nitrogen-fixing bacteria initially increased, then decreased in all treatments in spring wheat fields. However, soil nitrogen-fixing bacteria decreased with soil depth, while nitrobacteria initially increased, then decreased in pea fields. Ammonifying bacteria decreased with soil depth in NTS and TS, but initially increased, then decreased in NT and T.

The effects of lactic acid bacteria inoculation on the fermentation quality and aerobic stability of king grass silage

LIU Qin-hua, ZHANG Jian-guo, LU Xiao-liang

2009, 18(4):  131-137. 

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The effects of moisture contents (high, moderate and low) and lactic acid bacteria inoculation (LA, LB and LA+LB) on the fermentation quality and aerobic stability of king grass silage were investigated. All the silages were well preserved. The fermentation quality of king grass silages with moderate moisture content were better than those with high and low moisture content. LA inoculation did not significantly influence the fermentation quality of king grass silage, but the fermentation quality of king grass silages with high and moderate moisture contents was improved. LB or LA+LB inoculation increased the pH value (P<0.05) and acetic acid content, but decreased lactic acid content, the rates of lactic acid to acetic acid and lactic acid to total acid (P<0.01). When the silages of king grass were exposed to the air, the aerobic stability of LB and LA+LB inoculated silage were best.

Genetic variation of Dactylis glomerata germplasm from Southwest China detected by SSR markers

XIE Wen-gang, ZHANG Xin-quan, MA Xiao, HUANG Lin-kai, ZENG Bing

2009, 18(4):  138-146. 

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Simple sequence repeat (SSR) molecular markers were applied to detect the genetic variation of 110 individuals of 11 Dactylis glomerata accessions from Southwest China(Sichuan province, Yunnan province,Guizhou province and Chongqing city). 1) 21 primer pairs were selected for SSR analysis and 143 polymorphic bands were found with an average of 6.8 bands per primer pair. The percentage of polymorphism bands (PPB) was 90.7%, the polymorphism information content (PIC) ranged from 0.17(A01F24) to 0.45(A01E02) with an average of 0.33, and the Shannon’s information index of diversity (I) ranged from 0.046 3 to 0.347 7, showing considerable genetic diversity between all the accessions. 2) The AMOVA analysis showed considerable genetic variation within accessions (63.39%) rather than between them (21.93%). There was no significant genetic variation between diploid and tetraploid groups. 3) UPGMA clusters based on average Nei’s genetic identity divided 11 accessions into two groups: 3 diploid accessions (YA2006-3, YA2006-4, YA02-101) collected from Chongqing and Guizhou were classified into group I and the remaining 8 accessions were classified into group II. In most cases, materials from the same region and ploidy level were in the same group thus showing a geographical distribution of genetic diversity of the tested materials.

Genetic analysis of green period of Zoysia

GUO Hai-lin, CHEN Xuan, XUE Dan-dan, ZHENG Yi-qi, WANG Zhi-yong, LIU Jian-xiu

2009, 18(4):  147-153. 

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Two Zoysia F₁ segregating populations of the reciprocal crosses of Z136 and Z039 were obtained, and the heredity of the green period in two F₁ populations (Z136×Z039 and Z039×Z136) was analyzed by the major gene and polygene mixed genetic model to show the underlying genetic. The variation in range of green period of both crosses was 178-261 and 188-253 d, well beyond that of either of their two parents (248 and 231 d). The average green period of reciprocal crosses were 223.6 and 216.8 d and the significant differences between the two reciprocal crosses further indicated three were maternal genetic effects for the green period in Zoysia. Second, there was a large difference in the genetic models between the two reciprocal crosses: The effect of maternal genetic and of environment were both significant to the green period. No single major gene model (A-0) was the most suitable for the green period of Z136×Z039, but the green period of the reciprocal cross Z039×Z136 were controlled by two equal additive major genes. The most suitable model is B-4 and the heritability of major genes of the green period of reciprocal crosses was 94.35%.

Genetic relationship analysis of Zea species using RAPD markers

TANG Qi-lin, WANG Pei, LU Yan-li, ZHENG Ming-min, LIU Jian, RONG Ting-zhao

2009, 18(4):  154-160. 

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Randomly amplified polymorphic DNA (RAPD) was used to identify the polymorphisms and relationships between 14 genotypes of maize and its wild relatives (teosinte). A total of 136 primers were screened from 340 random decamer primers, and a total of 5 303 DNA bands were amplified, of which 4 500 were polymorphic. Genetic similarities among the cultivars ranged from 0.570 to 0.809 and in wild species, from 0.767 to 0.809 in the same genotypes, and from 0.570 to 0.745 between different genotypes. A consensus tree indicated that the genus Zea can be classified into two sections: Zea and Luxuriantes. Section Zea consists of four subspecies: Z. mays ssp. mays, Z. mays ssp. mexicana, Z. mays ssp. parviglumis and Z. mays ssp. huehuetenangensis. Section Luxuriantes is composed of Z. diploperennis, Z. luxurians and Z. perennis, as well as Z. nicaraguensis. Z. nicaraguensis was genetically closer to Z. luxurians than to other teosintes. In conclusion, polymorphism information obtained using RAPDs in a set of genotypes is useful for the assessment of genetic relationships and could be useful in taxonomic classification programs.

Cloning of tobacco citrate synthase cDNA and construction of its light inducible plant expression vector

HU Qing-quan, WANG Qi-feng, LI Kun-zhi, CHEN Li-mei, YU Yong-xiong

2009, 18(4):  161-167. 

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Medicago sativa is one of the most highly valued forage legumes. Aluminum toxicity is the main problem in the acid soils that are widely distributed in south China, and this restricts extending the use of M. sativa in this district. The aluminum-tolerance of plants can be enhanced by excretion of organic acid by increasing organic acid synthase gene activity. In this study, a cDNA for the cs gene (encodes citrate synthase) was amplified by RT-PCR from tobacco and subcloned into a T cloning vector to yield pMD18-cs. Sequence analyses confirmed that the insertion fragment in pMD18-cs contained the full length of cs cDNA. Using the promoter for the Rubisco small subunit gene (a light inducible promoter) and the binary vector pPZP211, a light inducible plant expression vector pPZP211-PrbcS-cs was constructed. It can be used for genetic engineering to enhance the aluminum-tolerance of M. sativa in order to extend the use of M. sativa in south China.

Studies of chemical control of Pedicularis verticilata with 2,4-D butyl ester and the effect on grassland vegetation

ZHANG Xiao-yan, HU Yu-kun, JI Cheng-dong, GUO Zheng-gang, GONG Yan-ming

2009, 18(4):  168-174. 

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The herbicide 2,4-D butyl ester was used to control Pedicularis verticilata efficiently. The best time for control of P. verticilata was florescence and the concentration was 0.066 mL/m². The grassland vegetation ecological environment was obviously improved after spraying 2,4-D butyl ester herbicide. P. verticilata was entirely or partially controlled and the high quality forage Elymus multicaulis became dominant. The harmful grassland weed Gentianella turkestanorum was inhibited to some degree. In summary, grassland quality was efficiently improved.

Occurrence of Pythium root rot in turf grass and identification of the pathogen

GU Li-jun, XU Bing-liang, LIANG Qiao-lan, XUE Ying-yu

2009, 18(4):  175-180. 

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In 2007 and 2008, Pythium root rot of turf grass was surveyed in 13 district of Lanzhou City. The incidence in the most seriously affected fields was 83.33% with a disease index of 36.67. The disease caused three types of symptoms on the turf grasses depending on: Leaf tip blight, leaf middle shrink and rhizome-brown rot. The chief pathogen, based on morphology, cultural characteristics, and pathogenicity, was identified as P. aphanidermatum with an isolation frequency of 100% from rhizomes. The incubation period for P. aphanidermatum is 14-15 h at 35℃ with a relative humidity of 90%.

A primary study on the pathogenesis of Pythium aphanidermatum to Lolium perenne

XU Jiao, XU Wen-chao, KANG Zhan-hai, ZHENG Hui, ZHANG Jin-lin

2009, 18(4):  181-186. 

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In a stuy on the pathogenesis of Pythium aphanidermatum to Lolium perenne, the chlorophyll content, β-carotene content, PSⅡ, the MDA content, superoxid anion radical content, hill activity, root activity and relative water content were examined. Chlorophyll,β-carotene was destroyed, F_v/F_m, and F_m became lower but the F_o of NuspeedⅡwas not changed, while the F_o of Inspire became higher. The MDA content and superoxid anion radical content became higher and the hill activity became lower when the concentration of toxin increased, and root activity and relative water content were also affected.

Effects of magnesium propionate supplementation on body condition, lactation performance and metabolic parameters in early lactation Holstein dairy cows

LI Hong-yu, LIU Qiang, WANG Cong, YANG Xiao-min, HE Dong-chang, GUO Gang

2009, 18(4):  187-194. 

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The effects of magnesium propionate on lactation performance and metabolic parameters in early lactation Holstein dairy cows were evaluated using thirty-six multiparous Holstein dairy cows. They were blocked by lactation number, corrected milk yield in last lactation, and expected calving date, then designated into four treatments (0, 50, 100, and 150 g/d) of magnesium propionate supplement in a randomized block experiment. Average feed intake, milk fat percentage, milk protein percentage, milk lactose percentage and milk dry matter percentage were not affected by magnesium propionate supplementation (P>0.05). Milk yield, feed efficiency, body condition and metabolic parameters of cows supplemented with magnesium propionate at 100 and 150 g/d were significantly (P<0.05) better than the controls as were energy balance and concentrations of glucose and insulin in the cow’s plasma. With magnesium propionate supplements of 100 and 150 g/d, the concentrations of non-esterified fatty acids and β-hydroxybutyrate in plasma of cows were lower than those of the controls (P<0.05). The concentrations of urine ketones were significantly (P<0.05) lower than in cows with a magnesium propionate supplement of 50 g/d and of the controls. The optimum dose of magnesium propionate supplementation was 100 g/d.

Vertical distribution and diversity of butterflies in the northern slopes of Qilian Mountains and Hexi Corridor

XIE Zong-ping, NI Yong-qing, LI Zhi-zhong, LI Xiao-ming

2009, 18(4):  195-201. 

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Based on vegetation, altitude, climate and soil of the northern slopes of Qilian Mountains and Hexi Corridor, the habitats of butterflies were classified into five types. The butterflies faunal composition and trait of vertical distribution were surveyed, in addition to an analysis of diversity of butterfly communities in different habitat types. Butterfly communities consisted of 128 species belonging to 74 genera in 8 families, and the diversity index decreased in the order: Mountain forest steppe, mountain steppe, subalpine shrub meadow, corridor oases and wilderness, and alpine sparse vegetation, which are consistent with richness but not completely with evenness index. The combination of the Shannon-Wiener index and G-F index provides a comprehensive measure to evaluate community diversity. Furthermore, the lower coefficients of species similarity among different habitats has been found.

Integrated influence of experimental trampling and simulated precipitation on fractal dimension of soil particle size distributions in the steppes of Huanxian County in Eastern Gansu Province, China

LIN Hui-long, REN Ji-zhou

2009, 18(4):  202-209. 

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Soil particle size distributions in the 0-15 cm soil layer were analyzed in a two-factor (experimental trampling and simulated precipitation) controlled field experiment of 16 treatment combinations. The characteristics of soil particle size distributions were reflected in progressively coarser textured soils from low to high trampling intensities. Precipitation also regulates the process of soil particle size formation. The fractal dimension of soil particles were calculated using a fractal model and soil particle size distribution was negatively correlated with trampling intensity. However, reduced average fractal dimension size was related to precipitation. In a precipitation sequence of dry, natural precipitation, moderate rainfall, and abundant rainfall, the fractal dimension values declined in the sequence 4.33%, 2.61%, 1.34%, and 1.23 respectively. Fractal dimension values were determined by the interaction between precipitation and trampling. Because of high fractal dimension values, soils are susceptible to grazing-induced erosion, and could become desertified if not properly managed. Calculation of fractal dimension is a reliable indicator in monitoring grazing-induced erosion processes and predicting desertification. Therefore, soil fractal dimension measurement could be meaningful for evaluating grazing-induced erosion and the formation of desertification processes.

An approach for monitoring snow depth based on AMSR-E data in the pastoral area of Northern Xinjiang

YU Hui, FENG Qi-sheng, ZHANG Xue-tong, HUANG Xiao-dong, LIANG Tian-gang

2009, 18(4):  210-216. 

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Using 445 temporal AMSR-E brightness temperature and snow depth data measured by 20 meteorological stations during the three snow seasons from December to March in 2002 to 2004 in Northern Xinjiang, we systematically analyzed the approaches of screening samples and impact factors for establishing a snow depth model. Through regression analysis of horizontal and vertical polarization brightness temperature differences in the 18 and 36 GHz bands, and of snow depth values, a snow depth model was established based on the AMSR-E brightness temperature data in northern Xinjiang. Accuracy of the model was evaluated: 1) AMSR-E brightness temperature differences were seriously affected by temperature, snowmelt, rain, wet snow and deep frost layers, of which the most important factor was deep frost layers. 2) There was a significant correlation between snow depth (y) over 2.5 cm and the vertical polarization brightness temperature difference at 18 and 36 GHz. The equation was SD=0.49(Tb_18V－Tb_36V)+8.72, and the correlation coefficient was up to 0.65. 3) The average error was -7.1 cm and average absolute error was 7.1 cm and RMSE was 7.7 cm when snow depth was 3-10 cm. When snow depth was between 11 and 30 cm, the average error was 1.8 cm, average absolute error was 4.9 cm, and RMSE was 9.1 cm. When the snow depth was over 30 cm, average error was 8.9 cm, average absolute error was 9.4 cm, and RMSE was 18.1 cm. 4) The snow depth model is more accurate than the Chang algorithm in Northern Xinjiang. It showed a good agreement between the simulated and measured snow depth values when the surface was covered by middle depth snow. However, the model’s accuracy was lower when the surface was covered by fallow or deep snow. Basically, the model can reflect the trend of snow depth variation in Northern Xinjiang, but it has a low accuracy for fallow or deep snow, and needs to be improved in the future.

Mechanisms and effects of agro-pastoral system coupling in the Inner Mongolian ecotone

LV Yu-hua, ZHENG Da-wei

2009, 18(4):  217-223. 

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In the Inner Mongolian section of the agro-pastoral ecotone of northern China, development of the transferred fattening and agro-pastoral coupling pattern has been enhanced by its high economic benefit. The increase of net income by this pattern has mainly contributed to the price increase per unit weight, the body weight increase of individual animals, and the slaughter rate increase of livestock in the agricultural region comparing with those in the pastoral region. The net profit of raising sheep with transferred fattening pattern was 20 times that of the local fattening pattern. The net profit of raising beef cattle with transferred fattening pattern was 6.5 times that of the local fattening pattern. There was hardly any forage cultivation in agricultural households before the system coupling, while the proportion of team pasture plants has reached 20%-36% after system coupling. The benefits of the transferred fattening and agro-pastoral coupling pattern can be summarized as: 1) unifying the grassland pastoral system and agricultural cultivation system; 2) reducing the over-loaded livestock carrying capacity in the pastoral region; 3) increasing the under-loaded herbivorous livestock carrying capacity in the agricultural region; 4) promoting the grassland enclosure and house raising practices in pastoral regions; 5) expediting the restoration of agricultural fields back to pastoral land.

Research on the temporal-spatial differences of carbon sources and sinks of farmland ecosystems of Hexi oasis in Gansu

XIE Peng, LIN Hai-ming, HUANG Gao-bao, WANG Long-qiang, CHAI Qiang

2009, 18(4):  224-229. 

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Temporal-spatial differences of carbon sources and sinks of farmland ecosystems of Hexi oasis in Gansu in 1949-2005 were studied. 1) Carbon absorption of farmland ecosystems showed an increasing trend from 243.9 thousand tons in 1949 to 2 983.7 thousand tons in 2005, a net increase of 2 739.8 thousand tons (a 12.23 fold increase). 2) Carbon emissions from the farmland ecosystem of the Hexi oasis in Gansu in 1949-2005 showed a rapid, increasing trend from 2.5 thousand tons in 1949 to 757 thousand tons in 2005, a net increase of 754.5 thousand tons (a 302.8 fold increase). Fertilizer use played a leading role, and showed a rapid increase. Carbon emissions from agricultural machinery were low on the smooth terrain. 3) There was an increasing trend of net carbon sink in the farmland ecosystems of the Hexi oasis in Gansu in 1949-2005. Carbon absorption was more than carbon emission of these farmlands and farmland ecosystems had a large carbon sink capability. However, the increasing speeds of carbon emissions compared with carbon absorption do not give a reason for optimism.

Effect on physiological characteristic of Medicago sativa under saline-alkali stress at seeding stage

ZHANG Yong-feng, LIANG Zheng-wei, SUI Li, CUI Yan-ru

2009, 18(4):  230-235. 

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Under different saline-alkali stress, the physiological biochemistry response of Medicago sativa Gongnong No.1 leaves were studied. The content of soluble sugar and proline were increased with saline-alkali concentration increasing, could be up to 87.16% and 753.49 μg/g respectively; The rate of bound water increases gradually when increasing saline-alkali concentration, but the rate of free water had no remarkable change, the rate of bound water/free water was 0.94; Water retaining capacity of isolated leaves decreased 12%-48%, when increasing saline-alkali concentration.

Analysis of the nutritional composition in different plant parts of yacon

LIU Jian, LI Jing-wei, LAN Hai, YANG Yong, ZHENG Ming-min

2009, 18(4):  236-240. 

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The sugar, crude fat, amino acids and mineral elements from different parts of Smallanthus sonchifolius were analyzed. The content of sugar in root, stem and leaf were very high, accounting for 73.20%, 16.66% and 14.24%, respectively, especially the content of FOS in root was abundant, reached 58.86%; the total content of amino acid in root was 259.82 mg/100 g and the vitamin was 3.54 μg/g; the content of crude protein and mineral element in leaf and stem were also very high. Therefore, the stem and leaf of S. sonchifolius were not only the sources of protein for human, but also good forage for domestic animals, which showed a potential to develop and utilize.

The impact of plant pathogenic fungi on soil seed banks

HOU Jin-wei, NAN Zhi-biao

2009, 18(4):  241-250. 

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The impact of plant pathogenic fungi on soil seed banks is one of the new research areas developed during the last 20 years internationally. Progress in research in this field was reviewed in this paper. So called “seed bags burial+seeds treated with fungicides” method has been employed in the majority of experiments reported in the world literature. Compared with untreated soil seed banks the survival rates have been increased or the loss rates have been reduced, of soil seed banks treated with fungicides and buried in a variety of habitats. However,the fungicide effects varied with habitats or plant species tested. Seeds from small seeded plant species or aged seeds are more vulnerable to the fungi. Seeds containing chemical defense substances showed better persistence of seed banks due to better resistance to the invasion of pathogenic fungi. The impact of pathogenic fungi on seed banks is related closely to soil abiotic factors, including soil moisture, soil temperature, and seed burial depth, and soil biotic factors. Plant pathogenic fungi showed more severe negative effects on seed banks in humid conditions than those under drier ones, on ones in shallow soil or with high density than in deeper soil or lower density ones. Fungivores and non-pathogenic bacteria can protect seeds against pathogenic fungi in soil. Suggestions on improvement of current research methods are proposed based on the advantages and disadvantages of the existing methods. Further development in research in the field are suggested.

Polyphenol oxidase activity and its relationship to the soil main fertilizer factor in west Songnen alkali grassland

YUE Zhong-hui, WANG Bo-wen, WANG Hong-feng, YAN Xiu-feng

2009, 18(4):  251-255. 

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Polyphenol oxidase (PPO) activity and its relationship to the main soil fertility factors in west Songnen alkali grassland were examined. PPO activity was higher in bare and sparse vegetation spots, but lower in lush vegetation spots. The seasonal dynamics of PPO activity varied in different spots. PPO activity was highly correlated with fertility factors except for potassium nutrition and the most important factor was total salt. PPO activity could be used to show changes of total salt, pH value, total N, available P and organic matter.

A study on a model of turf quality evaluation based on reflectance spectroscopy

XU Yue-fei, JIN Jing-wei, SUN Xiao-ling, ZHOU He

2009, 18(4):  256-259. 

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Chlorophyll is an important pigment of turf color and it is an intrinsic factor for turf quality evaluation. The relationship between spectral properties of two turf communities and their chlorophyll contents were measured using reflectance spectroscopy with natural illumination. Results were analyzed by the partial least squares method. The model of chlorophyll content used reflectance spectroscopy in the range of 400-700 nm and gave a correlation coefficient between estimated values and real values of 0.937, with a relative standard deviation of 3.2%. A linear model of the partial least squares method with turf color was developed with a smaller RMSE (RMSE=0.26). Reflectance spectroscopy provides a new method for rapid turf quality evaluation in landscape engineering.

Genetic analysis of Lolium multiflorum hybrids and their progenies detected using SRAP markers

JI Yang, ZHANG Xin-quan, MA Xiao, CHU Xiu-juan, LI Fang, MENG Yu

2009, 18(4):  260-265. 

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Using sequence-related amplified polymorphism (SRAP) molecular markers, 70 samples containing 12 annual Lolium multiflorum hybrid combinations and their progenies were analyzed to study polymorphism and to detect true or false hybrid seeds. 1) Ten primer pairs produced 101 polymorphic bands, averaging 10.1 bands per primer pair. The average percentage of polymorphic bands was 77.1%. Samples had relatively high molecular genetic polymorphisms so it was feasible to identify the parents and hybrids. 2) Electrophoretic bands of the 62 hybrids identified by SRAP were consistent with results of different hybrid combinations. Progenies with the marker bands of the male but not the female parents were found in 48 progeny which were therefore true hybrids.