Table of Content

20 February 2013, Volume 22 Issue 1

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The impact of different land use and management on community composition, species diversity and productivity in a typical temperate grassland

LI Yu-zhe, FAN Jiang-wen, ZHANG Liang-xia, ZHAI Jun, LIU Ge-fei, LI Jia

2013, 22(1):  1-9. 

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This article discusses the community differences including community composition, species diversity and productivity between six land use and manage patterns (fenced Stipa grandis lawn, fenced Leymus chinensis lawn, public grazing lawn, private grazing lawn, fired and fenced S. grandis lawn and artificial forage) in a typical tempered grassland in Xinlin Gol. The comparison was aimed to find out and to understand the influences and their mechanism that grassland use methods would bring to the community. Results were obtained by community investigation, and measurement of aboveground biomass and belowground biomass using harvest method and soil auger method in each plots. The above and below ground biomass decreased in grazed communities, and significantly increased in long-term fenced communities (P<0.05); but being fenced or not didn’t remarkably affect the community composition or species diversity. With the weakening of the grassland usage, the productivity and proportion of C3 plants gradually increased (P<0.05), the productivity of C4 plants remained steady and its proportion decreased. The past fire raised the species diversity and productivity and proportion of the C4 plant in the community in the grassland communities (P<0.05), significantly reduced the below ground biomass (P<0.05), and increased, but had rarely effect on the above ground biomass. The forage reclamation of grassland severely changed the community composition, significantly reduced the below ground biomass, but largely raised the above ground biomass, consequently resulting in higher the above/below ground biomass ratio compared to any surrounding natural grassland communities.

Influence of altitude on reproductive traits and reproductive allocation of different colours in Anemone obtusiloba populations

LI Bing, LIU Zuo-jun, ZHAO Zhi-gang, HU Chun, REN Hong-mei, WU Guo-qiang

2013, 22(1):  10-19. 

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Reproductive traits and reproductive allocation of three colours in Anemone obtusiloba at four different altitudinal gradients in the eastern Qinghai-Tibetan Plateau were examined. 1) With increased altitude, the investment proportion of the three flower colours of A. obtusiloba all increased in flowers but decreased in leaves. 2) Flower numbers of A. obtusiloba in all three colours decreased with an increase of altitude; but single flower area, single flower weight, floral display area and reproductive allocation all increased. 3) In the four altitudinal gradients,the individual size of the same colour flowers was significantly positively correlated with flower number, single flower weight, floral display area and reproductive investment. The single flower area was also positively correlated with other aspects, and showed that the altitude directly affected these reproductive traits. There was no significant correlation between reproductive allocation and individual size of the same colour flowers of A. obtusiloba. All these results suggest that there is an important effect of altitude on reproductive traits and reproductive allocation to different colours of A. obtusiloba. These reproductive colour traits and allocation of A. obtusiloba all increased reproductive fitness with an increase of altitude, but the altitude could not fully explain the change of resource allocation strategy of this alpine perennial.

Study on soil water in rhizosphere and root system distribution of Nitraria tangutorum on Loess Plateau

WANG Wen, JIANG Wen-lan, XIE Zhong-kui, ZHANG De-gang, GONG Xu-yin, KOU Jiang-tao

2013, 22(1):  20-28. 

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The soil water in rhizosphere and root system distribution of Nitraria tangutorum was studied in hilly area in north part of Lanzhou City on Loess Plateau. The result indicated that the soil water content in rhizosphere incresed and then decreased as the soil depth. The variation of soil water content within 0 to 40 cm layer was higher and it was lower within 160 to 300 cm layer. The soil water content within 40 to 80 cm layer was the highest. The root length and diameter of root system were 100 cm and 300 cm respectively. The root length was 1.32 times of plant height. The diameter of root system was 3.23 times of plant crown. The aboveground biomass was 1.46 times of underground. The effective roots were mainly distributed within 0 to 40 cm layer, and the effective root weight within 0 to 20 cm and 20 to 40 cm layers accounted for 58.69% and 22.96% of the total respectively. And for the effective root length, they were 59.65% and 23.20% respectively. The amount of effective roots decreased significantly as the soil depth. The 0 to 40 cm layer was very important for the water utilization and the horizontal distribution range of roots was 3 times of that in vertical range. This pattern of root distribution helps the water absorbtion of plant which depend the natural rainfall as the only water source on Loess Plateau.

Interactions of four PGPRs isolated from pasture rhizosphere

ZHANG Ying, ZHU Ying, YAO Tuo,QI Juan, RONG Liang-yan

2013, 22(1):  29-37. 

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Four PGPRs (plant growth promoting rhizobacteria) were isolated and screened from the rhizospheres of Medicago sativa, Trifolium repens and Trifolium pratense. Antagonistic reactions, the ability of solubilizing phosphate and the production of IAA (Indoleacetic Acid) by strains in both single and compound culture, together with the pH values of culture solutions and total contents of organic acid were tested. The ability to solubilize phosphate and produce IAA were determined by molybdenum-bule and Salkowski colorimetry. The relativity of isolated bacterial strains was analyzed. The results showed that there was no antagonistic reaction between different single strains so that compound strains could be utilized. In a bio-phosphorus culture solution, the Hsg+lhs11 compound strain had the highest increment of effective-phosphorus (536.2 mg/L), while the Hsg+ls1-3+lhs11 compound strain was second (475.6 mg/L). Effective-phosphorus increments gave additional effects of “1+1>2” in Hsg+lhs11 compound strains. Effective-phosphorus increased in Hsg+ls1-3+lhs11 compounding strains compared with single strain treatmenst (P<0.01), but there was no additional effect with “1+1+1>3” Hsg+ls1-3+lhs11 compound strains. In organic phosphorus culture solution, the lhs11 strain had the highest effective-phosphorus increment (11.11 mg/L), and Hsg+ls1-3+lhs11 compound strains was second (9.20 mg/L). The effective-phosphorus increment with the Hsg+ls1-3+lhs11 compound strains was higher than in other compounding treatments. There were linear correlations between effective-phosphorus increment and pH value, effective phosphorus increment and total content of organic acid, pH value and total content of organic acid. Single strains and compound strains both had the ability to produce IAA, between 0.212-9.331 mg/L. The IAA content in the Hsg+lhs11 compound treatment was higher than that of the single strain Hsg or lhs11 treatments (P<0.01), both of which presented a “1+1>2” additional effect. Consider the growth-promoting effects of different treatments, the Hsg+lhs11 compound strains and Hsg+ls1-3+lhs11 compound strains had better interaction effects so they have the potential to develop the optimal compound strain fertilizer.

A study on forage nutritional quality of Elymus nutans from different populations in the Qinghai-Tibet Plateau

ZHAO Yu-yu, HUANG De-jun, MAO Zhu-xin, NIE Bin, FU Hua

2013, 22(1):  38-45. 

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To study forage nutritional quality of Elymus nutans from different populations in the Qinghai-Tibet Plateau, production traits, crude protein (CP), water soluble carbohydrate (WSC), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of 45 E. nutans populations were investigated. There were significant differences in yield, CP, WSC, NDF and ADF between populations, and the four parameters were reccorded with an almost normal distribution. Fresh grass yield was 2 062.59-18 597.73 kg/hm², dry grass yield was 529.42-4 682.60 kg/hm²,CP was 13.88%-23.92%, WSC was 1.59%-6.03%, NDF was 57.34%-64.97% and ADF was 35.06%-47.23%. Coefficients of variation of yields were all over 62% and that of WSC was 31.19%. There were significant negative correlations between CP and both NDF and ADF, significant positive correlations between NDF and ADF, and significant negative correlations between WSC and NDF, and between yields and ADF. Based on these correlations, five E. nutans populations with high CP and WSC but low NDF and ADF were selected for future work.

Effects of arbuscular mycorrhizal fungi (AMF) on growth and regrowth of bermudagrass under different P supply levels

YE Shao-ping, ZENG Xiu-hua, XIN Guo-rong, BAI Chang-jun, LUO Ren-feng, LIU Xin-lu

2013, 22(1):  46-52. 

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Effects of the arbuscular mycorrhizal fungi (AMF) Glomus mosseae and G. aggregatum, on the growth and regrowth of bermudagrass (Cynodon dactylon) when combined with P applications of 20, 40 or 100 mg/kg were examined in pot experiments. Both G. mosseae and G. aggregatum colonized roots of bermudagrass well and the colonization rate of G. aggregatum was higher than that of G. mossea. N concentration of shoots was positively correlated with P concentration (P<0.001), indicating a potential cooperative effect between N and P absorption in bermudagrass. Regrowth rate and shoot biomass were higher in mycorrhizal bermudagrass than in the control during four cutting periods. P application also benefited growth and regrowth of bermudagrass, especially at an application rate of 40 mg/kg. Thus, in order to enhance regrowth of bermudagrass, AMF inoculation and an appropriate supply of P will be needed for regrowth and nutrition absorption.

Effects of basal Se fertilizers on nutrition values of naked oats

GUO Xiao, JIE Xiao-lei, HU Hua-feng, LI Jian-ping, LI Ming, HUANG An-qun, SHI Zhi-fang

2013, 22(1):  53-59. 

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A randomized complete block design of 5 treatments with 4 replications was carried out at the Yellow River beach in Henan Province from 2008 to 2010. There were 20 plots each 7.5 m×2.0 m. The effects of basal Se fertilizer on nutrition values of forage and grain of naked oats was studied using basal Se fertilizer treatments of 0, 570, 765, 954, and 1 143 g/ha). 1) Safe amounts of Se fertilizer had no significant effect on the nutrition of hay and straw, and the safe amount to apply was from 570 g/ha to 765 g/ha. There was a significant effect on nutrition contents of hay and straw of naked oats with greater amounts. At an application rate of 954 g/ha Se fertilizer, there were significant increases of the contents of CP (crude protein), CF (crude fiber) and A (crude ash) [-7.34% (P＜0.05), 5.65% (P＜0.05) and 5.80% (P＜0.05) respectively] for hay, and increases of -7.16% (P＜0.05), 5.74% (P＜0.05) and 5.32% (P＜0.05) respectively for straw. With an increase of fertilizer amount, CP and NFE (non-nitrogen extract) decreased, while the contents of A, EE (ether extract), and CF increased. Se fertilizer had accumulation and saturation effects on naked oats. 2) Basal Se fertilizers had more apparent effects on the improvement of grain nutrition of naked oat. When application rates ranged from 570 g/ha to 765 g/ha, CP content increased significantly, but CF content decreased. When the application rate of Se fertilizer was over 954 g/ha, the content of EE increased significantly, but that of CF significantly decreased, while there were no obvious effects on the contents of CP and NFE.

A study on phenological phases of Astragalus membranaceus

JI Li-jun, XI Xu-dong, JIN Xiao-jun

2013, 22(1):  60-67. 

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To develop a good understanding of growth-development of transplanted Astragalus membranaceus, and an accurate division of phenological phases, A. membranaceus sleedings were studied by classification transplanting. Fixed-point and real-time observations were combined with comprehensive surveys in the field, to observe and compare the growth and development stages of different grade seedlings of A. membranaceus. The phenological phases of A. membranaceus were divided into five stages: emergence after transplantation, budding and flowering stage, elongation stage of roots, fruit maturation stage, and diameter of roots.

The responses of annual plant traits to rainfall variation in steppe and desert regions

YAN Jian-cheng, LIANG Cun-zhu, FU Xiao-yue, WANG Wei, WANG Li-xin, JIA Cheng-zhen

2013, 22(1):  68-76. 

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The responses of phenophase and morphological traits of four kinds of annual species in steppe and desert regions in Inner Mongolia to rainfall variation were analyzed by an experiment in which four precipitation gradients (5, 20,70 and 150 mm) were used to simulate effective rainfall in steppe and desert regions. The growing season of annual plant groups in these regions is usually 40 to 90 (<100) days. The growing season, plant height, leaf length, and biomass of annual plants increased with an increase of rainfall. The life history of annual plants can basically be completed with 5 mm effective rainfall, but their growth and propagation are best in 70 mm effective rainfall. The change of phenophase in Salsola collina was smaller than that of other annual short grasses, and was done by adjusting the length of the reproductive stage and reducing fruit bearing as a response to lack of rainfall. Annual short grass can adjust the length of every phenophase to adapt its growth and reproduction to rainfall variation. In the same conditions of rainfall, the growing time of annual short grass is relatively longer than that of S. collina but the latter showed stronger drought-avoidance ability, while annual short grass has stronger drought-resistance ability in its adaption strategies.

Anatomical structure of Stipa breviflora leaves and its relationship with environmental factors

KANG Sarula, NIU Jian-ming, ZHANG Qing, CHEN Li-ping

2013, 22(1):  77-86. 

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Stipa breviflora is the constructive species in desert steppe and plays an important role in grazing use and stabilizing desert grassland ecosystems. The characteristic of S. beviflora leaf structure with drought resistance can provide a good reference for grassland species. S. beviflora leaves from eight sites were paraffin wax sectioned and double-stained, then observed with an OLYMPUS CX41 microscope, and imaged by a CANON DS16275 digital camera. The area, thickness and density of corneum, vascular bundle, vascular catheter cavity of the main vein, palisade tissue, leaves, epidermal cells, and leaf trichomes were calculated with ArcGis. Six indicators (corneum thickness/leaf thickness, vascular area/leaf area, palisade tissue thickness/leaf thickness, the area of main vein vascular bundle catheter cavity/ mainvascular bundle, epidermal cell density and trichome density of leaf-like structures) from the eight sites were selected for CCA (canonical correspondence analysis) with climate data and the relationship between leaf structure and environmental factors was analyzed using Pearson analysis. Finally, the correlation between two similarity matrixes of leaf structure and genetics was calculated by a Mantel test. 1) The leaf structure of S. reviflora showed typical drought resistance; 2) Temperature was the dominant environmental factor for the differentiation structure of S. beviflora leaves, with moisture second; 3) There were significant correlations between the ratios of vascular area within leaf area, the main vascular bundle with the vascular bundle and annual mean temperature and the ratio of vascular area within leaf area and annual mean precipitation; 4) There was no significant correlation between two similarity matrixes of leaf structure and genetics.

Correlation analysis of phenotypic traits of Reaumuria soongorica seed in different natural populations in the Gansu Corridor

SU Shi-ping, LI Yi, CHONG Pei-fang, GAO Qian

2013, 22(1):  87-94. 

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Reaumuria soongorica, a drought-tolerant shrub typical of Tamaricaceae, is one of the dominant species in desert areas of northwest China. It functions as a key biotic barrier against desertification due to its strong sand fixation ability and is therefore critical for maintaining the stability of desert ecosystems. The Gansu Corridor (in west Gansu province), is the main distribution range of R. soongorica in China and is characterized by environmental harshness associated with long-term aridity, rare precipitation, high evaporation, extremely high temperatures in summer and freezing conditions in winter. As a consequence, variations in plant morphological traits in this area are primarily accounted for by abiotic factors. Variations in four phenotypic traits of seed including thousand-kernel weight (TKW), seed length, seed width, seed length/seed width in 10 natural populations of R. soongorica in the Gansu Corridor, China, were examined using variance (ANOVA), correlation analysis and cluster analysis to reveal the pattern of variability in seed phenotype. The four phenotypic traits of R. soongorica seeds differed significantly between populations (P<0.01), but showed no significant difference within populations. The average coefficient of variance (CV) between populations across the four traits was 0.019 3, ranging from 0.001 8 for seed length to 0.068 5 for TKW. The average coefficient of variance for each population was the highest for Zhangye1 (0.048 4) and the lowest for Jiuquan2 (0.006 6). The main source of variation was in groups, which accounted for more than 68% of the total variance. All traits were spatially correlated with longitude, latitude, and altitude. Cluster analysis (using Euclidean distances) for all four seed traits revealed that the 10 sampled populations can be grouped into four clusters. The understanding of the seed phenotypic traits of R. soongorica in different populations and the spatial variation in the Gansu Corridor will be fundamental for future research projects on the collection, conservation, genetic evaluation, and utilization of its germplasm. The results can help to design artificial supplementary regeneration and enhance population genetic diversity.

Effects of different nitrogen levels on nitrogen fixation and seed production of alfalfa inoculated with rhizobia

MA Xia, WANG Li-li, LI Wei-jun, SONG Jiang-ping, HE Yuan, LUO Ming

2013, 22(1):  95-102. 

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Field plot and sand pot experiments were carried out to study the effects of four different nitrogen fertilizer levels (0, 50, 100, 150 kg/ha) and two ways of inoculating rhizobia (soaking seeds with rhizobia in autumn and furrow inoculating rhizobia in spring) on the nitrogen fixation ability, growth characteristics and seed yield of alfalfa by using a ¹⁵N natural abundance method. The field experiments were located at the grassland ecological research station in Hutubi County of Xinjiang Agricultural University during the growing seasons 2009 to 2010. The nodule numbers and nodule fresh weight were significantly improved by inoculating rhizobial strain ACCC17544, and attained the maximum percentage and amount of nitrogen fixation (77.8±0.508)% and (452.51±2.568) kg/ha respectively under the lower level of 50 kg/ha nitrogen application. Also, inoculating rhizobia promoted growth, increased above ground dry matter accumulation, number of branches, number of pods and seed yield of alfalfa. The seed yield obtained had an average increase rate of (59.7±0.118)% that was significantly more than those in uninoculated, no nitrogen fertilization and other nitrogen rate treatments. Nitrogen application above 50 kg/ha inhibited nodulation and the percentage and amount of nitrogen fixation were reduced. With increasing amounts of nitrogen fertilizer, the inoculating rhizobial efficiency for improving alfalfa growth were obviously weakened, and the biomass, number of pods, and extent of yield increase were reduced. Soaking seeds with rhizobia in autumn combined with nitrogen application of 50 kg/ha was the best combination for increasing seed yield in the field plot experiments. There was a significant positive relationship between the amount of rhizobial nitrogen fixation and seed yield.

Study on the diet composition and trophic niche of main herbivores in the Inner Mongolia Typical steppe——Taking Leymus chinensis community as an example

LIU Gui-he, WANG Guo-jie, WANG Shi-ping, ZHANG Ying-jun, WAN Xin-rong, HAO Shu-guang

2013, 22(1):  103-111. 

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In order to discuss the relations of grassland degradation and the diet composition and trophic niche of main herbivores (Ovis aries, Spermophilus dauricus, Oedaleus asiaticus) in the Inner Mongolia steppe, we research change of diet composition and trophic niche of main herbivores in the different grazing intensity in June-July 2003 by using n-alkane technique. The results showed that the richness of Leymus chinensis and Stipa krylovii decreased significantly with the increase of grazing intensity, while the proportion of Potentilla acaulis in the community increased at the same time. The proportion of Carex korshinskii ingested by O. aries increased significantly with the increase of grazing intensity, and Achnatherum sibiricum and Agropyron michnoi were not ingested by O. aries instead of P. acaulis. The proportion of L. chinensis ingested by S. dauricus inside fence more than outside fence significantly, but A. michnoi, C. korshinskii and P. acaulis were not ingested inside fence. There was no comparison of dietary in O. asiaticus between inside and outside fence due to having no capture it, but the proportion of S. krylovii ingested by O. asiaticus reduced significantly with the increase of grazing intensity, and instead of increasing the proportion of A. michnoi and P. acaulis. The same plant species of ingested were L. chinensis and C. squarrosa. Furthermore, the selected index of L. chinensis was highest. The tropic niche of O. aries was broadened with the increased grazing intensity, on the contrary S. dauricus and O. asiaticus, furthermore, the overlap of trophic niche among three herbivores were similar. In conclusion, an action of heavy grazing in Inner Mongolia steppe changed the L. chinensis community into the P. acaulis community, and this succession lead to the degradation of grassland. While the spoliating grassland resources by O. aries, S. dauricus, O. asiaticus have accelerated the process.

The carbon contents and the relationship with the calorific values of 67 plant species in Inner Mongolia grasslands

LONG Shi-you, BAO Ya-jing, LI Zheng-hai, GAO Wei, HONG Guang-yu, HUANG Shuo, ZOU De-xi

2013, 22(1):  112-119. 

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The carbon content is a metric of plant carbon storage, which reflects the ability to fix and store carbon element in photosynthesis of the green plants, is also one of important indexes to estimate carbon storage of ecosystem. The carbon contents, and their relationships with the calorific values of 67 plant species in three types from different climate zones of Xilin Gol Grassland (meddow steppe, typical steppe, desert steppe), Inner Mongolia were studied with the method of the field sampling and experimental determination, and the carbon content variation of different plant functional groups based on several classification method were studied at the same time. The aim is to provide theoretical basis for estimating scientifically carbon storage of grassland ecosystems. The results showed that the carbon content in the 67 species of plants were in normal distribution, the average value was (52.17±2.01)%, of all the species, the Salsola collina, a kind of annual forb, had the lowest value (43.79±1.37)%, and Thalictrum squarrosum, a kind of perennial forb, had the highest value (57.12±4.58) %. Among the groups classified by life forms, the order of average carbon content (%), from low to high, was: annuals and biennial plants (49.39±2.88)＜perennial fobs (52.31±1.65)＜sub-shrub (52.84±1.90) and perennial grasses (53.54±0.88). The carbon content of annuals and biennial plants were significantly lower than those of other groups (P<0.05), and there were no significant differences among the other three groups (P>0.05). The carbon contents (%) of the different plant groups based on water ecological types, followed the order: xero-mesophyte (50.01±4.36)＜mesophytes (51.80±1.92)＜wet-mesophytes (51.96±0.78)＜xerophytes (52.34±1.90) < meso-xerophytes (52.54±1.53). No statistically significant differences were found among these groups (P>0.05). Different families showed apparent difference in average carbon content (P<0.05), the lowest value was found in Chenopodiaceae, only (48.43±2.65)%. And there was a positive correlation between the carbon contents of 67 species and their calorific values (r=0.52, P<0.01).

Estimation model of aboveground biomass in the Northern Tibet Plateau based on remote sensing date

ZHOU Yu-ting, FU Gang, SHEN Zhen-xi, ZHANG Xian-zhou, WU Jian-shuang, LI Yun-long, YANG Peng-wan

2013, 22(1):  120-129. 

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Normalized difference vegetation indices (NDVI), enhanced vegetation indices (EVI) and land surface water indices (LSWI) were calculated based on MYD09A1 during 2010-2011 to estimate the aboveground biomass (ANPP) in the Northern Tibet Plateau using regression analysis. Air temperature, air moisture, soil temperature and soil moisture were compared in 2010 and 2011 when there was a great difference in aboveground biomass during the two years. Correlation analysis between aboveground biomass and vegetation indices showed that single factor regression model would be sufficient to reflect the relationship between aboveground biomass and vegetation indices. Regression analysis showed that both NDVI and EVI could be used to estimate aboveground biomass, however LSWI performed relatively poor. The simple linear regression model best reflected the relationship between vegetation indices and aboveground biomass while the power fitting was not quite as good as linear regression. The relationships between NDVI, EVI and aboveground biomass can be expressed by the linear regression equation: ANPP=115.478 NDVI (R²=0.956, P<0.001) and ANPP=174.225 EVI (R²=0.975, P<0.001). Results of verification showed that the power model had a better estimating capability than the linear model. When the power model was used to estimate ANPP, the relative error was 9.76% compared with 10.8% for the linear model. This difference demonstrated that the power model may be more robust in estimating the ANPP.

A study on optimal grazing rates in Stipa purpurea alpine grassland in Northern Tibet

Ganjurjav, GUO Ya-qi, GAO Qing-zhu, DUAN Min-jie, WAN Yun-fan, LI Yu-e, DANJIU Luo-bu

2013, 22(1):  130-137. 

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Stipa purpurea alpine grassland is the most representative and important natural pasture of Northern Tibet but in recent years has suffered large-scale degradation, mainly from overgrazing. Optimization of S. purpurea alpine grassland grazing systems in Northern Tibet is a very important issue for local policy makers. Livestock feed intake is an evaluation method of grassland productivity and is one of the important tools of grassland management as it is a key factor in the grazing system. Grassland standing crops and the feed intake rate of Tibetan sheep are critical criteria for healthy and sustainable development of alpine grassland in Northern Tibet. Based on 5 years (2006-2010) of grazing in S. purpurea alpine grassland in Amdo County, Nagqu Region, Tibet Autonomous Region, the biomass of standing crops and net primary production of grassland and Tibetan sheep feed intake were studied using four grazing rates. In the first three years (2006-2008) of the experiment, the stocking rate was: 0 sheep/1.67 ha (CK), 2 sheep/1.67 ha (LG, light grazing), 3 sheep/1.67 ha (MG, moderate grazing), and 5 sheep/1.67 ha (HG, heavy grazing). In a later experiment (2009-2010), the grazing rate was doubled to 0 sheep/1.67 ha (CK), 4 sheep/1.67 ha (LG), 6 sheep/1.67 ha (MG), and 10 sheep/1.67 ha (HG). In the growing season of 6-9 months, based on the method of community investigation, the standing crops within 0.5 m×0.5 m quadrants were measured and the feed intake was calculated by the formula: Feed intake=Before grazing biomass-after grazing biomass+growth matter. There was no significant effect on standing crops of grazing intensity in the first study, but with the doubling of grazing intensity in the later experiment, the standing crops decreased with increased grazing intensity. The aboveground net primary production of the grazing area was larger than in the control pilot in 2006 but by 2010, in the control treatment it was significantly (P<0.05) larger than in the grazing treatment. The feed intake of Tibetan sheep was significantly negatively correlated with grazing intensity (P<0.05). The order of intake rate of sheep was: heavy grazing intensity>light grazing intensity>moderate grazing intensity. Comprehensive analysis of the results indicated that, in the light grazing treatment, not only was the biomass of standing crops and aboveground net primary production the largest, but also the feed intake of sheep was relatively high. We therefore consider that the optimal stocking rate of S. purpurea alpine grassland in Northern Tibet should be less than 4 sheep/1.67 ha.

Spatiotemporal variation of grassland vegetation NDVI in the middle and upper reaches of the Hei River and its response to climatic factors

ZHOU Wei, WANG Qian, ZHANG Chao-bin, LI Jian-long

2013, 22(1):  138-147. 

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Vegetation dynamics and its coupled relation with the climate is a hot spot in the study of how terrestrial ecosystems respond to climate systems. Analysis of grassland NDVI (normalized difference vegetation index) spatiotemporal dynamics and exploration of key climate factors has important significance for research of grassland cover change. Based on the RS, GIS and SPOT NDVI data and monthly meteorological data from 1999 to 2007, the spatiotemporal variation characteristics of grassland vegetation NDVI in the middle and upper reaches of the Hei River and the correlation between NDVI and four climate factors were analyzed. 1) The annual average NDVI and growing season NDVI increased in the middle and upper reaches of the Hei River. The area of grassland NDVI that increased accounted for 71.53% of the total grassland area, while that which decreased accounted for 19.43%. The grassland vegetation NDVI in typical steppe, alpine steppe and meadow of the Tuolai Mountain, Southern Mountain of Hexi corridor, Lenglong Ridge and the middle of the Hexi corridor increased, while the decreased regions were located in the zone between desert grassland and non-grassland of the Tuolai Mountain, Southern Mountain of the Hexi corridor and Lenglong Ridge. 2) The grassland vegetation NDVI of the Hei River shows a single peak curve within the yearly changes of different grassland types, and the value of NDVI reached a peak in July. 3) There was an extremely significant positive correlation between grassland NDVI and average temperature (R=0.942,P<0.01), and a significant correlation with average precipitation (R=0.922,P<0.05). The coefficient of correlation between grassland NDVI and relative humidity was positive but not significant, while the correlation with sunshine hours was negative. The limiting factor was different in the four grassland types. In recent years, with the shift from warm-dry to warm-humid climate in Northwest China, grassland vegetation coverage in the middle and upper reaches of the Hei River significantly increased and temperature was the important factor for grass growth.

Effects of climate change on household compound ecosystems and herders’ adaptation

LI Xi-liang, HOU Xiang-yang, Leonid Ubugunov, DING Yong, DING Wen-qiang, YIN Yan-ting, YUN Xiang-jun, ZHANG Yong

2013, 22(1):  148-156. 

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The household compound ecological system is the basic unit which responsed to climate change in the northern grasslands of China, and research on climate change adaptability is necessary to promote sustainable development in pastoral areas. With the guidance of grassland system theory and using questionnaire surveys, the response and adaptation of 599 households to climate change in Inner Mongolia, China were studied. 1) The methods of forage supply which including grazing land, mowing grassland, forage land and buying fodder in households are regionally different; 2) Extreme events, especially drought, are the key factors influencing the household compound ecological system, but there are different patterns of influence from heavy snow, sandstorms and strong winds; 3) Climate change influences the households mainly through pasture and livestock rather than soil, human and infrastructure; 4) Buying fodder and selling livestock are the main adaptive strategies. The response of the household compound systems to climate change occurs at the grassland and livestock-management interface where forage and livestock are the key nodes in the feedback process.

Extraction and analysis of hyper-spectral data from typical desert grassland in Xinjiang

QIAN Yu-rong, YU Jiong, JIA Zhen-hong, YANG Feng, Palidan Tuerxun

2013, 22(1):  157-166. 

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The hyper-spectral features (red edge, green peak, red valley) of typical desert grasslands in Xinjiang Fukang City were extracted from hyper-spectral lines through differential and Savitzky-Golay smoothing filter processing. The desert vegetations have absorption features, such as red edges and green peaks but the hyper-spectral curves are not clear because of the effect of the underlying surface showing through the sparse foliage of the low coverage desert vegetation; Due to the withered litter desert vegetation in October, the spectral reflectance effect of soil interference was too large, and compared with that in May, the red edge position showed the phenomenon of “red edge shift”. The NDVI (the normalized difference vegetation index) and RVI (ratio vegetation index) index values were lower in October. There were significant differences in red edge, green peak, red peak and vegetation index characteristics between grassland types, different seasonal desert vegetations, but NDVI and RVI were associated with strong correlations. Finally, the feature extraction and analysis of hyper-spectral data from typical desert grasslands in Xinjiang not only enriches the means of hyper-spectral data mining, but also provides a scientific basis for grassland classification based on hyper-spectral data.

Analysis of characteristics of the circular economy of grassland farming

TANG Jing, LIN Hui-long

2013, 22(1):  167-175. 

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Circular economy characteristics of grassland agro-ecosystems in Sidunzi county were studied using emergy analysis. 1) The agro-ecosystem’s emergy flux of Sidunzi county was 121.007 6×10¹⁷ sej (solar enjoules), while the emergy flux of the grassland sub-system was 89.27×10¹⁷ sej giving a ratio of 73.77%, which was greater than those of cropping and woodland sub-systems. 2) Among these sub-systems, grassland agro-ecosystems had a proportionally lower emergy investment ratio and environment loading ratio, but had the highest solar emergy transformation rate and a relatively higher emergy-based sustainable index. 3) The potential production of agro-ecosystems could be greatly improved by system coupling between grassland agro-ecosystems and other sub-systems. These results demonstrate that grassland farming occupies a central position in material and emergy cycles within mega-agriculture systems and this is the primary point to realize in the agricultural circular economies. The implementation of grassland farming and extensive systematic coupling are the technical support for promoting development of agricultural circular economies and the inevitable way for adjusting Chinese agricultural structure.

Physiological responses in leaves of Reaumuria soongorica from different altitudes under osmotic stress

LI Chao-zhou, ZUO Li-ping, LI Yi, JIAO Jian

2013, 22(1):  176-182. 

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The different physiological responses and their mechanisms in the leaves of Reaumuria soongorica from two altitudes when under osmotic stress were studied. When the leaves of R. soongorica were seriously stressed, the leaves from the branches picked at the foot of the Jiuzhoutai mountain had a better water condition, higher contents of proline and soluble sugar, lower malondialdehyde (MDA) content and reactive oxygen level. The materials living at the foot of the mountain were better in hardness than those living on the top of the mountain. The interrelationship analysis among the above indexes showed that there were significantly negative relationships between the relative water content, water potential, the ratio of free water content with bound water content and MDA content, and O₂^-· production rate, and there was a significantly positive relationship between superoxide dismutase (SOD) activities and O₂^-· production rate. With an increase of osmotic stress, the material living at the bottom had better osmoregulation and antioxidative ability, and even lower level of lipid-oxidation. The main reason for the above differences may be the water content: the material living at the bottom of the mountain had higher levels of bound water, and better water retaining ability under deep osmotic stress. The relatively lower water content and water potential of the material living at the bottom could be one of the important reasons for the better osmo-regulation ability to deal with osmotic stress.

Physiological responses to PEG stress of Reaumuria soongorica seedlings from different geographical origins

CHONG Pei-fang, SU Shi-ping, LI Yi, SUN Zhao-cheng

2013, 22(1):  183-192. 

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The effects of different concentrations of PEG-6000 stress on relative permeatbility of plasma membrane, protective enzyme activity, and osmotic gulatory molecules in leaves of Reaumuria soongorica seedlings from Lanzhou, Wuwei, Zhangye and Jiuquan geographic origins in Gansu province were studied. Contents of proline (Pro) and soluble sugars (SS) in leaves initially increased but then decreased as the stress concentrations increased. The accumulation in plants from Wuwei was more than that in those from other origins. Contents of malondiadehyde (MDA) and relative permeability of plasma (RPP) increased as stress concentrations increased but the increased range in Wuwei origin plants was less than that of others, which indicated a stronger drought resistances than plants from the other origins. Protective enzyme activities such as superoxide dismutase (SOD), peroxide enzyme (POD) and catalase (CAT) increased initially but then decreased. POD and CAT activities of Wuwei origin plants were higher than those from other origins. There was a threshold of protective enzyme activity, and it was reduced when protective enzyme activity was out of the threshold level. Correlation analysis showed that there were significant positive correlations of relative permeability of plasma with MDA (P＜0.05), highly significant positive correlations with Pro and SS (P＜0.01), and significant negative correlations of relative permeability of plasma with SOD, CAT, and POD activity (P＜0.05). Drought resistance of R. soongorica from four geographic origins was in the following order Wuwei>Jiuquan>Zhangye>Lanzhou.

Solute accumulation and distribution traits of an alkali resistant forage plant Kochia sieversiana and physiological contribution of organic acid under salt and alkali stresses

MA Ying, GUO Li-quan, ZHANG Shu-fang, WANG Xiao-ping, SHI De-cheng

2013, 22(1):  193-200. 

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The accumulation and distribution characteristics of various solutes from Kochia sieversiana seedlings stressed by salt and alkali were measured to study the physiological mechanisms in different parts of K. sieversiana and their role in adaptability to salt-alkalinized soil, and to identify the contribution of organic acid to salt-alkalinized habitat adaptability. There were considerable differences in the distribution of various solutes from different plant parts such as young leaves, mature leaves, young stems, old stems and roots. Organic acid was distributed mainly in stems and leaves, especially in mature and functional leaves on which photosynthetic productivity was dependent. Distributions of Na⁺, K⁺ and Ca²⁺ in different plant parts were uniform on the whole indicating that there was no competition for Na⁺, K⁺ and Ca²⁺ for absorption and transportation. Special absorption mechanisms of K⁺ and Ca²⁺ and distribution characteristics of various solutes from K. sieversiana were very important to its adaptability to salt-alkalinized soil. Organic acid in different parts, especially in mature leaves of K. sieversiana, was the dominant element in osmotic regulation, ion balance and pH adjustment, and was a key substance for the adaptation to saline and alkaline conditions. There were different adaptive mechanisms to salt and alkali stresses in different parts of K. sieversiana plants.

Growth adaptation and Na⁺ and K⁺ metabolism responses of Leymus chinensis seedlings under salt and alkali stresses

LI Xiao-yu, LIN Ji-xiang, LI Xiu-jun, MU Chun-sheng

2013, 22(1):  201-209. 

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Two neutral salts (NaCl∶Na₂SO₄=9∶1) and two alkaline salts (NaHCO₃∶Na₂CO₃=9∶1) were used to simulate different salt and alkali stresses on organ growth and ion metabolism and their adaptation strategies in 35 d old potted seedlings of Leymus chinensis. The dry weight of all organs, clonal growth (rhizome daughter and tiller daughter shoots), photosynthesis and K⁺ contents decreased significantly while Na⁺ content and Na⁺/K⁺ ratio increased significantly, with increased salinity and alkalinity. Under a high concentration of 200 mmol/L, the change of all variables was higher under alkali than under salt stress. Under the two stresses, the biomass reduction of rhizomes was the largest and that of daughter shoots from rhizomes were higher than those from tillers. Under salt and lower alkali stresses, the changes of Na⁺, K⁺ contents and Na⁺/K⁺ ratio in rhizomes and roots were greater than those in stems and leaves. Under higher alkali stress, the Na⁺ content increased significantly in stems and leaves. In conclusion, L. chinensis was resistant to salt but not to alkali at the same concentration, especially at the higher concentration. Under salt and lower alkali stresses, L. chinensis had similar strategies of growth adaptation and Na⁺, K⁺ metabolism. Rhizome growth and daughter shoots were reduced to maintain development in situ and to compartmentalize the Na⁺ into rhizome and root to avoid stem and leaf growth damage. However, the high pH stress exceeded the carrying capacity of rhizome and root, leading to much Na⁺ transportation to stem and leaves, where it influenced photosynthesis and restrained growth. Either in growth adaptation or in Na⁺, K⁺ metabolism, the existence of rhizomes played a protective role to mitigate the harmful effects of salt or alkali stress on the other organs.

Effects of exogenous nitric oxide on photosynthetic and bioluminescent characteristics in ryegrass seedlings under osmotic stress

LIU Jian-xin, WANG Jin-cheng, WANG Rui-juan, JIA Hai-yan

2013, 22(1):  210-216. 

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The regulating effect of nitric oxide (NO) on photosynthetic physiological response of herbage under osmotic stress, was studied in a hydroponic experiment. The effect of the exogenous NO donor sodium nitroprusside (SNP) on the photosynthetic pigment content, gas exchange and chlorophyll fluorescence parameters, and bioluminescence intensity in leaves of ryegrass (Lolium perenne) under osmotic stress simulated by 15% PEG-6000 were investigated. The stress from 100 μmol/L SNP significantly increased photosynthetic pigment contents, net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), stomatal limited value (L_s), PSⅡ maximal photochemical efficiency (F_v/F_m) and actual photochemical efficiency (Φ_PSⅡ), but reduced intercellular CO₂ concentration (C_i), PSⅡ excitation pressure (1-q^P), non-photochemical quenching (NPQ), ultra-weak luminescence intensity, fluorescence intensity and phosphorescence intensity in ryegrass seedling leaves. The addition of haemoglobin (Hb), a NO scavenger, reversed the effects of SNP, but application of 100 μmol/L sodium nitrate or nitrite (the decomposition products of NO or its donor SNP) or sodium ferricyanide (an analog of SNP) had no significant alleviation effects on osmotic stress. NO may alleviate the damage of osmotic stress to the leaf photosynthetic apparatus by increasing photosynthetic pigment and light-energy utilization, and decreasing bioluminescent intensity, thus improving photosynthetic efficiency of the ryegrass seedlings under osmotic stress.

Effects of submergence on the antioxidative enzymes and carbohydrate contents of Paspalum distichum

TAN Shu-duan, ZHU Ming-yong, ZHANG Ke-rong, ZHU Jia-wen, WEI Gao-xia, ZHANG Quan-fa

2013, 22(1):  217-224. 

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Submergence is one of the major abiotic stresses, primarily through restriction in the diffusion of oxygen and carbon dioxide in plants. A complex anti-oxidative defensive system plays an important role in defending anoxia or hypoxia stress. In this study, the physiological responses in antioxidative enzymes and carbohydrate contents of Paspalum distichum to different submergence times were investigated. 1) The activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and glutathione reductase (GR) in roots increased with increased submergence duration and depth, implying an integrated pathway involving CAT, SOD, POD, GR, and APX for protection against the detrimental effects of activated oxygen species under submergence. 2) Total soluble carbohydrate and starch contents of shoots and roots decreased with increased submergence depth and duration, and the decrease was progressive and proportional to the magnitude of the submergence stress. The soluble carbohydrate of submerged plants necessary for survival can be replenished from starch hydrolyzation and this was critical for the survival of submerged P. distichum.

A study on resistance and purifying ability of SO₂ on four warm-season turfgrasses

WANG Li-hua, LI Xi, LIU Wei, GAN You-min

2013, 22(1):  225-233. 

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The influence of sulfur dioxide (SO₂) on four warm-season turfgrasses [centipedegrass (Eremochloa ophiuroides), zoysiagrass (Zoysia japonica), bahiagrass (Paspalum notatum), bermudagrass (Cynodon dactylon)] were studied using fumigation to apply five SO₂ treatments: CK (Natural state), S1 (1.5 mg/L), S2 (2.25 mg/L), S3 (3 mg/L) and S4 (3.75 mg/L). There was a negative correlation between total chlorophyll and SO₂ concentration but positive correlations between soluble protein, malondialdehyde, proline, peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), leaf sulfur content and SO₂ concentration; The soluble protein content increased except for bermudagrass. By the fuzzy membership function, the resistance of four turfgrasses to SO₂ was in the order: bermudagrass＞zoysiagrass＞bahiagrass＞centipedegrass; and the purifying ability was in the order: zoysiagrass＞bahiagrass＞bermudagrass＞centipedegrass.

Flavonoid compounds in the petals of Hosta

LIU Ni-na, LI Xiao-dong, ZHANG Jin-zheng, WANG Liang-sheng, SUN Guo-feng, LIN Qin-wen, XU Yan-jun

2013, 22(1):  234-244. 

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The flavonoid composition of five Hosta species and 85 Hosta cultivars was investigated by HPLC-DAD for the first time to expand the applications of Hosta. Qualitative and quantitative analysis methods for total flavonoids in flowers of Hosta were used as a basis for the quality control of Hosta. A combination of powerful tools (HPLC-DAD and HPLC-MSⁿ), were used to characterize seventeen kinds of flavonoid including kaempferol 3,7-di-O-glucoside, kaempferol 3-O-glucosyl-7-O-rutinose, isorhamnetin 3,4-di-O-glucoside, kaempferol 3-O-quinoylglucoside, kaempferol 3-O-sinapoylglucoside, kaempferol 3-O- ascorbicoylglucoside, kaempferol 7-O-neohesperidoside, kaempferol 3,7-di-O-hexoside, kaempferol 3-O-glucosyl-7-O-rhamnoside, luteolin 7-O-neohesperidoside, quercetin 3-O-glucoside, quercetin 3-O-glucuronide, kaempferol 3-O-robinobioside, kaempferol 3-O-glucoside, kaempferol 3-O-glucuronide, kaempferol 3-O-pentose, and kaempferol 7-O-glucoside. The flavonoid contents of 90 kinds of Hosta flowers were compared and the high-value species were selected.

Vertical distribution characters of soil organic carbon and soil enzyme activity in alfalfa field with different growing years

WU Xu-dong, ZHANG Xiao-juan, XIE Ying-zhong, XU Kun, YANG Jing

2013, 22(1):  245-251. 

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Through comparing the concentration and inventory of soil organic carbon (SOC) and soil enzyme activity under different plant ages (1, 3, 4, 5 to 8 years) of alfalfa at the foot of Helan mountain in Ningxia, the SOC and soil enzyme activity vertical distribution characters were explored. 1)With the increase of soil depth and plant time, from 0 to 100 cm soil mean SOC concentration were 4.519,4.865,5.120,5.348 and 3.334 g/kg from 1 to 8 years, the soil profile SOC concentration mainly showed a significant accumulation in the 0 to 40 cm depth, accounted for 69.7%, 65.8%, 73.8%, 70.0% and 67.2% from 0 to 100 cm, but it sharply declined below 40 cm;2)0-100 cm soil mean SOC density were 1.148, 1.217, 1.231,1.398 and 0.840 kg/m² from 1 to 8 years, and the surface soil (0-40 cm) accounted for about 54.8% to 61.8%, the highest SOC content and its density was five-year alfalfa, the order of the concentration and density of SOC in the 0-100 cm soil layer were 8 years (19.9 g/kg and 5.04 kg/m²)<1 year (27.7 g/kg and 6.77 kg/m²)<3 years (29.7 g/kg and 7.26 kg/m²)<4 years (30.4 g/kg and 7.38 kg/m²)<5 years (32.2 g/kg and 8.53 kg/m²). 3) Three kinds of soil enzyme activity decreased with the increase of soil depth and plant time, the soil surface (0-10 cm) and subsurface (10-20 cm) enzyme activity decreased significantly, soil enzyme activity was mainly concentrated in the 0-20 cm depth, showed the surface gathering.

Effects of glycerol on energy balance and concentration of glucose in the liver during the peripartum period in dairy cows

WANG Cong, LIU Qiang, ZHANG Yan-li, ZHANG Shuan-lin, PEI Cai-xia, BAI Yuan-sheng, SHI Zhou-ge, LIU Xiao-ni

2013, 22(1):  252-259. 

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To observe the effects of glycerol on energy balance, blood parameter, glucose and adipose concentrations in the liver during the peripartum period in dairy cows, multiparous Holstein dairy cows with similar body weights (674.6±13.8 kg), lactation numbers (2.5±0.5), corrected milk yields in the last lactation (7 412±15 kg) and expected calving dates (23.8±0.3 d) were allocated into four treatments at random. Graded levels (0, 100, 200, and 300 g/d) of glycerol were supplemented in the four treatments from day 19 peripartum. Body condition score at 7, 21 and 35 d postpartum was increased, body weight loss from 7 to 35 d postpartum was reduced, energy balance at 14 d peripartum and 7, 21 and 35 d postpartum was improved significantly (P<0.05) by the 200 g/d and 300 g/d treatment compared with the 0 g/d treatment. Cows receiving 200 g/d and 300 g/d glycerol had a higher insulin concentration at 14 d peripartum and higher plasma glucose and insulin concentrations at 7, 21 and 35 d postpartum than the 0 g/d treatment (P<0.05). They had lower plasma NEFA and β-hydroxybutyrate at 7, 21 and 35 d postpartum than the 0 g/d and 100 g/d treatment (P<0.05) while 200 g/d and 300 g/d glycerol supplementation increased the contents of glycogen and key regulatory enzymes of gluconeogenesis in the liver compared with the 0 g/d glycerol treatment (P<0.05). Glycerol supplementation was beneficial to peripartum cows in enhancing the gluconeogenesis and improving energy balance status. The optimum dose was about 200 g per cow per day.

Genetic diversity analysis of Agropyron germplasm resources by ISSR

ZENG Liang, YUAN Qing-hua, WANG Fang, WANG Yu

2013, 22(1):  260-267. 

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The genetic diversity of 33 Agropyron materials from both at home and abroad was analyzed by ISSR (inter-simple sequence repeats) markers. Eleven primers were selected from 93 primers which had clear polymorphic bands. A total of 84 bands of which 59 were polymorphic were obtained from the 33 materials. On average, each primer amplification site was 7.64. The genetic similarity coefficient of varieties was between 0.083 and 0.706, and showed rich genetic diversity. UPGMA cluster analysis gave a genetic similarity coefficient of 0.52 for boundaries and the 33 materials were divided into four types, with basic clustering in accord with geographical origin and regional distribution.

Cloning of a S-adenosyl methionine synthetase gene from Cleistogenes songorica and its expression under drought stress

KONG Ling-fang, ZHANG Ji-yu, LIU Zhi-peng, WANG Yan-rong

2013, 22(1):  268-275. 

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To identify more genes for the improvement of drought-tolerance in plants, Cleistogenes songorica was used to investigate differential gene expression under drought stress. A full-length cDNA of the S-adenosyl methionine synthetase (SAMS) gene was isolated from C. songorica. It was named CsSAMS1 and was 1 399 bp in length and encoded 397 amino acids with the three typical domains of SAMS. The CsSAMS1 protein was a hydrophilic protein with no transmembrane domain but with an α-helix spatial structure constituting a random coil. Multiple alignment analysis based on amino acids of SAMS genes from kindred plants indicated that SAMS was very conserved between different species with 92%-99% similarity in amino acid level. CsSAMS1 had the highest similarity with that of Oryza sativa (99%). The expression patterns of CsSAMS1 under drought were investigated by semi-quantitative and real-time quantitative RT-PCR analysis. The results showed that drought stress induced a large amount of gene expression in roots, but there was no significant change in leaves. The CsSAMS1 gene was induced by drought stress, and it is a basis for further study on genetic improvement of grass drought resistance.

In vitro mutation induction by NaN₃ in ryegrass variety “Blue Heaven” and RAPD analysis for its variation

LI Jie-qin, WANG Li-hua, ZHAN Qiu-wen, DONG Hai-feng, LIU Jing-liang, LI Wan-xiang

2013, 22(1):  276-281. 

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The ryegrass (Lolium multiflorum) variety “Blue Heaven” were treated by sodium azide (NaN₃). After selecting from M₂ generation and identification of M₃ generation, we obtained 60 mutants with the most significant variation traits. Two panicle mutants were chosen to identify by molecular markers. 100 RAPD (randomly amplified polymorphic DNA) random primers were used to analyze check (CK) and 2 panicle mutants. The results showed that 60 plants with stable variation traits were obtained from M₂ mutant lines. 21 panicle mutants were obtained and it was the most among these mutant types. 2 panicle mutants were compared with CK. Only one top spike on CK, 2 panicle mutants have more top spikelets. And mutants No.2 and CK have not secondary branch per panicle. Therefore, mutant No.1 has 5 secondary panicle braches. 45 RAPD primers can be amplified among the three materials. In addition, the three materials can be differentiated by 3 RAPD primers. So there were difference between CK and the 2 panicle mutants on molecular level.

Research on micromorphology of leaf epidermis of three species of Vetiveria zizanioides

LIU Jin-xiang, ZHANG Ying, LI Ting-ting

2013, 22(1):  282-287. 

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The leaf epidermal characters of 3 species of Vetiveria zizanioides were observed and compared under light and scanning electron microscopes. The results showed that leaf epidermis consisted of long cells, short cells, stomas, micro-hairs, prickle-hairs, macro-hairs and mastoid process. The long cells were rectangle, with shallow or deep wavy anticlinal walls. The short cells has dumbbell, cruciform and nodular types. The stomata were tandem and triangular or dome shaped subsidiary cells. The leaves distributed ad- and abxially epidermis of micro-hairs and mastoid process. The lower epidermis also have prickle-hairs and macro-hairs. The leaf epidermal were covered with thick cutin and strip upheaval. The study could clarify that the same characteristic of microstructure of cotyledon epidermis of V. zizanioides, and the difference in species, so it could provide morphological evidence for stress resistance and taxonomy.

Allelopathy of the invasive plant Alternanthera philoxeroides to radish and lettuce

ZHANG Zhi-zhong, SHI Qiu-xiang, SUN Zhi-hao, LAN Mao-feng

2013, 22(1):  288-293. 

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Alternanthera philoxeroides is a worldwide weed. After invasion of A. philoxeroides, the local ecosystem can be irreversibly damaged and agricultural production seriously affected. Allelopathy is an effective chemical weapon in the invasion process of exotic weeds. With radish (Raphanus sativas) and lettuce (Lactuca sativa) as receptor materials, the allelopathic effect of plant aqueous extract of A. philoxeroides was studied using a Petri dish bioassay. In this process, plant protective enzyme activity was also measured to clarify the allelopathic mechanism. Seed germination rates of lettuce and radish showed significant allelopathic inhibition which gradually increased with an increase of the A. philoxeroides plant aqueous extract concentration. This inhibition in lettuce was significantly greater than in radish. A. philoxeroides plant aqueous extracts caused a general inhibition of the radish and lettuce seedlings growth. Inhibition on radicle growth was significantly greater than on the hypocotyl. At low concentrations (0.01 g/mL), A. philoxeroides plant aqueous extracts promoted growth of hypocotyls but as the concentration increased, this promotion gradually diminished. Radish and lettuce hypocotyl growth were significantly inhibited at a concentration of 0.04 g/mL. The degree of inhibition of radicle length and fresh weight gradually increased with increasing concentrations. The radicle growth of radish and lettuce seedlings was almost inhibited at a concentration of 0.04 g/mL. The degree of inhibition of plant fresh weight in lettuce was more serious than in radish. Changes in protective enzyme activity were more complex. Superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities increased at low concentrations but as the concentration increased, SOD activity gradually decreased, while POD and CAT activities initially decreased and then increased. Malondialdehyde (MDA) content of radish and lettuce seedlings increased with increased concentrations of A. philoxeroides plant aqueous extracts and the increase rate was slightly higher in radish than in lettuce. However, the MDA content increases at low concentrations were not significant. With a concentration of 0.04 g/mL of A. philoxeroides plants aqueous extract, MDA contents in both radish and lettuce seedlings increased rapidly. Compared with the control, the increased rate of MDA content in radish and lettuce seedlings were 116.67% and 98%, respectively.

Absorption capacity of nitrogen and phosphorus of aquatic plants and harvest management research

YU Hong-bing, YANG Zhi-jian, XIAO Run-lin, ZHANG Shu-nan, LIU Feng, XIANG Zuo-xiang

2013, 22(1):  294-299. 

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In order to investigate the fact how harvesting aquatic plants affects the removal of nitrogen and phosphorus. Canna glauca, Hydrocotyle vulgaris, Sparganium stoloniferum, Myriophyllum verticillatum and Juncus effusus were selected for the study in ecological ditch, absorption capacity of nitrogen and phosphorus were tested and each plant was divided into harvested and non-harvested plots. The results showed that, seasonal dynamics of the uptake of total nitrogen and phosphorus by aquatic plants changed in a single-peak curve, C. glauca is highest, the absorption capacity peak value of nitrogen and phosphorus were 75.97 and 13.52 g/m², respectively; Removing biomass, total nitrogen and phosphorus of aquatic plants through repeated cutting were several times single cutting, the changes in the range of 3.62-6.72 times. In addition to S. stoloniferum, the harvest can improve the removal rate of nitrogen and phosphorus in sediment of other aquatic plants. Compared with the non-harvested plot, the harvest can improve the removal rate of sediment total nitrogen and phosphorus in the following order: C. glauca>M. verticillatum>H. vulgaris>J. effusus>S. stoloniferum. Therefore, appropriate harvest measures can not only transfer nutrients of plants, but also conducive to the recovery and growth of plants and improve the removal rate of sediment total nitrogen and phosphorus.

Mechanisms of heavy metal accumulation in plants: a review

HUANG Bai-fei, XIN Jun-liang

2013, 22(1):  300-307. 

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Pollution by heavy metal contamination caused by recent human activities such as industry, agriculture and mining practices has attracted great attention worldwide. The mechanisms of heavy metal accumulation in plants have been one of the worldwide hotspots of study. Heavy metal enters plants from the soil solution through the rhizodermis. It traverses the root via symplasmic or apoplasmic pathways and then enters the xylem where it is transported to the shoot. Many genes, such as the ABC transport system gene and P-type ATPase gene, are associated with heavy metal transport and accumulation. This article reviews the role of different parts of the plant in heavy metal accumulation and translocation and the genes related to heavy metal transport. Future research fields ont heavy metal transport in plants is also suggested.

A study on carbon storage administration in alpine Kobresia humilis meadow in relation to influence of human activity

LIN Li, LI Yi-kang, ZHANG Fa-wei, GUO Xiao-wei, CAO Guang-min

2013, 22(1):  308-314. 

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Alpine Kobresia meadow is the main vegetation type in the Qinghai-Tibetan Plateau. Grassland degradation is one of the prominent problems in this area. The distribution of organic carbon storage in plants, soil and the plant-soil systems, and variation characteristics of the organic carbon sinks in different grassland degradation succession stages were studied. A spatial series instead of time series method was used and the alpine Kobresia meadows degradation succession series were selected. They were gramineae-forbrich communities: A Kobresia humilis community, a normal Kobresia pygmae community phase, a K. pygmae community mattic epipedon crazing phase, a K. pygmae community mattic epipedon collapse phase and a herb-black soil stage. The organic carbon storage in aboveground plant parts significantly decreased from (145.9±6.7) g/m² to (84.9±5.5) g/m² (P<0.05), while that of the plant underground parts of the K. pygmae community mattic epipedon crazing phase was the highest with a value of (3 011.6±114.3) g/m². The lowest was (121.6±14.9) g/m² in the herb-black soil stage. The normal K. pygmae community has the largest soil organic carbon storage capacity (16 805.94±856.5 g/m)² which was higher than that of the herb-black soil stage (8 255.152±671.5 g/m²) which had the lowest organic carbon storage in this kind of grassland degradation succession series. The highest organic carbon storage occurred in three phases, namely, normal K. humilis community, K. pygmae community phase and K. pygmae community mattic epipedon crazing phase, but there was no significant difference in the organic carbon storage capacities between these three phases. The alpine Kobresia meadows recovery series were artificial pasture vegetation succession series. After 14 years of artificial pasture cultivation, the plant organic carbon storage capacity in aboveground, underground and total plant system were 3.3 times, 2.7 times and 2.9 times respectively of the herb-black soil stage, while the plant-soil system organic carbon storage capacity increased from (8 550.8±169.7) g/m² to (13 648.8±28.7) g/m². The K. humilis community is the optimum stage in alpine Kobresia meadows degradation succession series, because the plant-soil system in this stage retains the highest organic carbon storage, higher livestock loading and system stabilization, and it can be the optimum stage for carbon storage administration. It is an effective method to cultivate artificial pasture in herb-black soil stage for its obvious improvement of the organic carbon storage capabilities in plant, soil and plant-soil system, while the cultivated artificial grassland can also offer more edible forage for livestock. Choosing a proper stage and restoration methods to carry out the corresponding administrative management in the degradation ecosystem in alpine K. humilis meadow can result in the best ecological service ability and production ability.

Effects of exogenous fibrolytic enzymes on the enzyme activities and fermentation characteristic of Chinese wildrye by mixed ruminal microorganisms in vitro

ZHUANG Su, DING Li-ren, ZHOU Jian-guo, WANG Tian

2013, 22(1):  315-322. 

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Three levels of mixture of cellulase and xylanase supplementations (0, 10.0 and 50.0 mg, respectively) and two pretreatment time (0 and 24 h) in triplicate were used to determine the effects of the mixture enzyme on the enzyme activities and fermentation characteristic of Chinese wildrye by mixed ruminal microorganisms in vitro. Fibrolytic enzymes increased (P<0.05) activities of xylanase and endoglucanase at 0 and 8 h and exoglucanase activity at 0 h postincubation in fermentation fluid. In addition, the enzyme activities increased with exogenous enzyme preparation level. However, the exogenous enzyme preparation did not affect the enzyme activities at 24 and 48 h of incubation. The content of acetic acid at 24 and 48 h, the total volatile fatty acids content at 8, 24, 48 h incubation and the cumulative gas production at end of incubation were increased (P<0.05) by the enzyme treatment. Exogenous enzyme had no effects the concentrations of valeric acid and isovaleric acid during incubation (P>0.05). The results suggested that the exogenous fibrolytic enzymes enhanced the activities of xylanase, endoglucanase and exoglucanase in the fermentation fluid in early incubation, finally increased total volatile fatty acids output and improved rumainal fermentation characteristic in vitro.

Influence of breed on postweaning litter growth and litter feed efficiency of meat rabbits

ZHANG Xiang-yu, LI Cong-yan, KUANG Liang-de, ZHENG Jie, ZHANG Cui-xia

2013, 22(1):  323-327. 

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The major factors influencing post-weaning litter growth and litter feed efficiency were analyzed with the General Linear Model (GLM) using 909 meat rabbits, from 173 litters representing 5 breeds (New Zealand White, Californian, Flemish Giant, Chinchilla, and Fujian Yellow). Breed and number weaned per litter had a significant effect on litter weaning weight at 5 weeks, litter weight gain, litter market weight at 10 weeks, average market weight, litter feed intake, and litter feed efficiency (P<0.01). Month of birth had a significant (P<0.01) difference on litter feed intake and on litter weaning weight and litter market weight (P<0.05). Litter weaning weight, litter weight gain, litter market weight and average market weight were heavier and litter feed intake was higher in Flemish Giant litters than in other breed litters (P<0.05). However, the five traits mentioned above were lower in Fujian Yellow litters than in other breed litters. The overall linear covariate of litter size at weaning was related positively to litter weaning weight, litter feed intake, litter weight gain, litter feed efficiency and market weight at 10 weeks and regressions were significantly different (P<0.01). The main effects of breed, number weaned per litter and month of birth were important sources of variation for post-weaning litter traits and litter feed efficiency. The results provide evidence in support of using Flemish Giant as a terminal sire breed.