Table of Content

20 February 2012, Volume 21 Issue 1

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The nutritional value evaluation of artificial grassland in karst region in Yunnan-Guizhou Plateau

LI Tai-rong, YANG Xing-cheng, MA Ning

2012, 21(1):  1-9. 

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Artificial grassland is main rangeland in Karst region in Yunnan-Guizhou Plateau. In this paper, nutritional value and conversion efficiency of grasses of two artificial grasslands were tested through grazing test, feeding experiment, and digestion and metabolism trial. Testing under the same grazing pressure, grazing experiment showed that soil nutrients, trace elements and forage yield of Yongshan Artificial Grassland was significantly lower than Xundian Artificial Grassland, but no significant difference in nutritional content between the two artificial grasslands were detected. Feeding trial showed that grass usage efficiency by sheep on Yongshan Artificial Grassland was higher than Xundian Artificial Grassland, digestibility and deposition rate of mineral trace elements in sheep grazing on Yongshan Artificial Grassland were significant higher than Xundian Artificial Grassland. Digestion metabolic test showed that nutrient content including crude protein, crude fat, crude ash, crude fiber, nitrogen free extract in grasses of Xundian Artificial Grassland were higher than Yongshan Artificial Grassland. Comparison of digestive rate, feed intake and body weight gain of sheep gazing on the two artificial grasslands showed the same trend with nutrient content. The above results indicated that, a high conversion efficiency was produced by livestock grazing on Yongshan Artificial Grassland, where was a relatively barren field with a lower forage production than Xundian Artificial Grassland. According to the results, we proposed to feed on livestock after maturity of grasses, and supplementation of certain trace elements. At the same time, we proposed, grass and artificial grassland nutritive value evaluation needs not only the determination of its nutritional content, but also its final value, namely, animal weight gain, because conversion efficiency of livestock directly affects the efficiency of grassland animal husbandry. The output of artificial grassland can only be evaluated accurately by combination of nutrition value evaluation and livestock conversion efficiency estimation.

Response of distribution patterns of plant species diversity and biomass to permafrost changes

WANG Zeng-ru, YANG Guo-jing, HE Xiao-bo, YE Bai-sheng

2012, 21(1):  10-17. 

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With a background of global climate warming, the effects of permafrost changes on aboveground vegetation have attracted much attention. The effects of permafrost changes on distribution patterns of plant species diversities and biomass in the Dongkemadi River Basin (head water of Yangtze River) were investigated. 1) Species diversity indexes non-monotonically decreased as the depth of the permafrost active layer increased, and the maximal values of species diversity indexes occurred at about 2 m depth of the permafrost active layer (the Partrick index, Shannon-Wiener index and Simpson index are respectively 26.43±3.31, 2.06±0.38 and 0.83±0.08). 2) In terms of the vertical distribution of biomass, underground biomass was considerably larger than aboveground biomass, underground biomass occupied 63%-96% of the total biomass. 3) There was a significant correlation between biomass and depth of the permafrost active layer (R²=0.65, P<0.01 for aboveground biomass and R²=0.79, P<0.01 for underground biomass), and both aboveground and underground biomasses decreased as the depth of the permafrost active layer increased. 4) The depth of the permafrost active layer had a considerable influence on the vertical distribution of underground biomass at soil depths of 0-40 cm: when the depth of the permafrost active layer was about 1 m, there was little vertical variation of underground biomass; but there was an obpyramidal pattern when the depth of permafrost active layer was larger than 1.5 m. When the depth of this layer was larger than 3 m, the ratio of underground biomass with soil depths of 10-40 cm to total underground biomass increased as the depth of the permafrost active layer increased.

A study on root system development ability of alfalfa cultivars with different fall dormancy rates in the Guizhou area

XU Da-wei, HAN Yong-fen, LU Xin-shi, YAO Chun-yan

2012, 21(1):  18-23. 

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The abilities of different fall-dormancy alfalfa cultivars to develop root systems were studied in the Guizhou area to analyze their adaptabilities. Root neck diameter initially decreased but then increased as the fall dormancy rate increased. Root neck diameter of UC-1887 (FD10) was the largest (1.439 cm). Taproot length initially increased, then decreased with Pierce (FD8) having the longest taproots (59.75 cm). The number of secondary roots gradually, decreased:Vernal (FD2) had the most (19.33), and Pierce (FD8) the fewest (12.25). Taproot diameter, taproot volume, taproot biomass, lateral root volume, lateral root biomass, root system volume, and root system biomass tended to increase as the fall dormancy rate increased. First year underground root systems grew mainly in the 0-20 cm depth zone. The proportions of root system volume were 77.82%-92.35% and root system biomass rates were 75.14%-90.96%. Based on the integrated performance and cluster analysis of alfalfa with different fall dormancy rates, the fall dormancy rates of alfalfa with the greatest root system development ability ranged from 7 to 10.

Biomass and dynamic changes of nutritive value over different growth periods of Potamogeton crispus in Baiyangdian Lake

NING Guo-hui, XIE Jian-zhi, WANG Hua

2012, 21(1):  24-33. 

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Five sites were sampled to analyze the biomass and nutritive value of Potamogeton crispus at the stages of greening, exponential growth, bud emergence and decline. In the exponential growth phase, biomass increased: the contents of crude protein, crude fat, total P and β-carotene were the largest. From March to June, the contents of crude fiber, crude ash, calcium and Vc showed a gradually rising trend. May was the best time for harvesting P. crispus. The nutritive value contents of P. crispus were different at different sampling sites but over the whole growth period of P. crispus at all sampling sites, the contents of crude protein were more than 100 g/kg while those of crude fiber were less than 155 g/kg. The contents of crude fat were more than 12 g/kg and of crude ash were more than 140 g/kg. Ca and total P contents were more than 3.0 g/kg while those of Vc were more than 140 mg/kg, and the contents of β-carotene more than 310 mg/kg. The nutritive values of P. crispus were more than that of other hydrophytic feeds and it was the best feed for fish and domestic animals. The carotene contents of P. crispus could improve health value of eggs and the prospects for applications of P. crispus are very wide.

Effect of different nitrogen supply methods on yield and photosynthesis of maize under the alternative fallow high stubble about narrow row and wide row

LIU Chao-wei, ZHANG En-he, XIE Rui-zhi, LIU Wu-ren, LI Shao-kun

2012, 21(1):  34-42. 

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A field experiment was designed to investigate the effects of five N supply methods (no fertilizer, one fertilizer application, basic+jointing fertilizer, basic+jointing+earing fertilizer, slow release fertilizer) on grain yield, photosynthesis, leaf area index (LAI) and photosynthetic active radiation (PAR) of maize (Zea mays) under the alternative fallow high stubble about narrow rows and wide rows. In terms of tillage and fertilizer interaction, the yield of basic+jointing+earing fertilizer of narrow row and wide row treatment (11 709.3 kg/ha) was higher than that of other treatments by 7.05%-30.29% except for one fertilizer and basic+jointing fertilizer of conventional treatment. At flowering to filling stage, the best treatments were basic+jointing+earing fertilize and slow release fertilizer of narrow row and wide row treatment (29.65-34.16 μmol/m²·s). Generally, stomatal conductance, transpiration rate of several fertilizer applications were higher than a single fertilizer application in a narrow row and wide row treatment, but intercellular CO₂ concentration was the opposite. The mean transmittance of narrow row and wide row treatment was higher than that of conventional treatment by 3.60%-10.64% and the basic+jointing+earing fertilizer was the lowest in narrow row and wide row treatments. The LAI of narrow row and wide row treatment was lower than conventional treatment except for the basic+jointing+earing fertilize and slow release fertilizer. The results of this study suggest that basic+jointing+earing fertilizer of the narrow row and wide row may be the best management strategy because of its relatively higher grain yield, and improved photosynthesis and transmittance.

Effect of Rhizobium inoculation on crop growth and nitrogen nutrition of a pea/maize intercropping system

GUO Li-zhuo, ZHANG Hu-tian, HE Ya-hui, CHAI Qiang, HUANG Gao-bao

2012, 21(1):  43-49. 

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A Rhizobium inoculation experiment was conducted in a pea/maize intercropping system to investigate the changes of nodulation, nitrogen (N) fixation, N absorption, and crop growth. Nitrogenase activity of Rhizobium in pea nodules was increased significantly by intercropping and inoculation with ACCC16101 (R₁) and XC3.1 (R₂). Nodule weights of intercropped pea increased by 19.0%-120.4% after inoculation with these two Rhizobium strains. ACCC16101 had little effect on N absorption and dry matter accumulation of either pea or maize. In an intercropping system inoculated with XC3.1, N and dry matter accumulation of these two crops were considerably improved and seed yields of pea and maize increased by 16.9% and 19.1%, respectively. XC3.1 is suitable for inoculation in a pea/maize system.

Production and N nutrient performance of wheat-maize-soybean relay strip intercropping system and evaluation of interspecies competition

YONG Tai-wen, YANG Wen-yu, XIANG Da-bing, CHEN Xiao-rong, WAN Yan

2012, 21(1):  50-58. 

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The aim of this paper was to study the variation of interspecies competitiveness in two relay strip intercropping system: wheat-maize-soybean and wheat-maize-sweet potato. The character of biomass accumulation and nitrogen uptake were examined for five cropping systems using years of field experiment. The cropping systems included three sole cropping systems (wheat-soybean, wheat-sweet potato and maize) and two relay strip intercropping systems (wheat/maize/soybean and wheat/maize/sweet potato). Land equivalent ratio (LER), aggressiveness (A), and nutrition competition ratio(NCR) were introduced as indexes to evaluate the interspecies competitiveness in each treatment. The results showed that there was obvious relay strip intercropping advantage (LER>1, A_wc<0, A_cs>0, NCR_wc<0, NCR_cs>1) in the wheat-maize-soybean relay strip intercropping system, maize occupied the dominant niche for the whole growing stage in the relay strip intercropping systems, and the interspecies competitiveness of wheat and soybean were lower than that of the maize. Comparing with the sole cropping systems and wheat-maize-sweet potato relay strip intercropping system, the grain yield and nitrogen uptake, total biomass and total nitrogen uptake above ground of crops were increased significantly at both flowering (or spinning) and maturity stages in the wheat-maize-soybean relay strip intercropping system. The values of biomass and nitrogen uptake for the relay strip intercropping system were greater than the sole cropping systems, and that of soybean stubble were greater than sweet potato stubble. The total economic returns of crops in the wheat/maize/soybean relay strip intercropping system was higher 28.02% than those of crops in the wheat/maize/sweet potato relay strip intercropping system.

Competitive effects between Medicago sativa and Achnatherum inebrians

HUANG Xi, LI Chun-jie, NAN Zhi-biao

2012, 21(1):  59-65. 

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Through studying the effects of interspecific competition between Medicago sativa and Achnatherum inebrians, the results indicated the total biomass, relative yield and competitive balance index of M. sativa were significantly higher than those of A. inebrians, the relative yield total was significantly lower than 1. The relationships mentioned above become more obvious with decreasing of experimental plant community densities. The total biomass of A.inebrians at the densities of 4, 8 and 12 plants/pot in mixture decreased by 38.5%, 41.4% and 56.0% compared to those in monoculture, respectively. However, the total biomass of M. sativa at the same density between monoculture and mixture showed no significant difference.The relative competitive ability of M. sativa was higher, it will be a promising strategy for replacement control of A.inebrians by using M. sativa as a competitor.

Response of the ground arthropod community to exclosure of desert steppe in semi-arid regions

LIU Ren-tao, LI Xue-bin, XIN Ming, MA Lin, LIU Kai

2012, 21(1):  66-74. 

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The National Range Resources Monitoring Station in Yanchi county of Ningxia was used for an investigation on the community structure of ground arthropods, vegetation and soil properties, and on the response of ground arthropods to exclosure of desert steppe in semi-arid regions. There were obvious effects of exclosure on ground vegetation and soil properties, especially in terms of plant density, vegetation height and coverage, which were all significantly (P<0.05) higher under exclosure than non-exclosure. Totally, there were 26 groups and 28 families of 7 orders captured; the faunal group that came up in CK and exclosure at the same time was Blaps (Carabidae) for the dominant group, together with 13 common groups. Also, there was an active response of ground arthropods to exclosure, with higher density, group richness and diversity of arthropod community on exclosure grassland than on non-exclosure grassland, but the differences were not significant (P>0.05). It is suggested that short-term exclosure (five years) had different ecological effects on ground vegetation and arthropods in desert steppe. From correlation analysis, there was a negative correlation of group richness and Shannon index with soil bulk density (P<0.05), but positive for Simpson index with soil bulk density (P<0.05). The soil bulk density was the main factor for the difference of arthropod community structure under exclosure compared with non-exclosure. In addition, different response models were shown for each arthropod group to the selection of habitats between exclosure and non-exclosure.

Analysis of grassland resources in southwest China

HUANGFU Jiang-yun, MAO Feng-xian, LU Xin-shi

2012, 21(1):  75-82. 

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Based on a rangeland resources survey of China (Branch of Animal Husbandry and Veterinary Services affiliated to the Agricultural Department of China, 1996), grassland statistics of China (2009) related literature and field investigations, the natural grassland resources, winter-fallow paddy fields and forest grassland were studied. 1) The natural grassland area in southwest China was 35.58×10⁶ ha (32.59% of the total land area). Available grassland area was 29.04×10⁶ ha (>70% of the total natural grassland area). 2) Grassland resources types were divided into four regions: tropical humid shrubby tussock region, subtropical humid tussock region, subtropical subhumid tussock region, temperate humid plateau tussock meadow region. 3) The Karst area of southwest China was 52.23×10⁶ ha (29.50% of the land area), covering 292 counties. The rocky desertification area was 11.11×10⁶ ha (21.27% of the karst region), covering 88 severely rocky desertification counties. 4) The available farming-fallow crop area was 961.46×10⁴ ha, and the utilized farming-fallow crop area was 193.11×10⁴ ha (20.09% of the available farming-fallow crop area). Utilized winter-fallow paddy field grassland area totaled 118.58×10⁴ ha (12.33% of the available farming-fallow crop area and 61.40% of the utilized farming-fallow crop area). 5) Shrubby tussock and sparse forest tussock of southwest China was 1 894.84×10⁴ ha (29.81% of the grassland area and 36.06% of the available grassland area).

Ecological analysis and classification of Stipa breviflora communities in the Inner Mongolia region: the role of environmental factors

WANG Feng-lan, ZHANG Yan-nan, YANG Yan, HAN Yan-jun

2012, 21(1):  83-92. 

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Environmental characteristics, spatial heterogeneity, and biological interactions are key factors that affect ecological communities. We studied how environmental factors and spatial patterns influence the structure of Stipa breviflora communities in the Inner Mongolia region. First, we used the two-way indicator species analysis (TWINSPAN) algorithm to summarize variation in species composition and group 202 study plots. Second, we investigated the effects of three environmental and three spatial factors, together with their interaction, on the structure of S. breviflora communities by using detrended canonical correspondence analysis (DCCA). 1) The target plant communities were classified into 16 groups at the fourth level of division by TWINSPAN; 2) The first two DCCA axes, which corresponded to gradients of temperature and precipitation, respectively, explained most of the variation in community structure (75.3%). Based on these results different S. breviflora communities were arranged into an ecological series; 3) When analysed together, 70.7% of the total variance in S. breviflora community structure was explained by all environmental factors and 55.6% by all spatial factors. When these factors were examined separately, only 29.5% and 11.4% of the total variance were explained respectively, while 44.2% was simultaneously explained by the two groups of factors, and 17.9% was explained by other undetermined factors. Our study contributes to other researchers’ findings and strongly supports the conclusion that the degree to which environmental factors control the structure and spatial distribution of plant communities is determined by complexity of the vegetation pattern. The explanatory power of plant community structure by environmental factors decreases with the increase in complexity of vegetation cover.

A study on community ecology and the restoration and reconstruction strategy of Tuohu wetland in the Anhui provincial nature reserve

CHEN Ming-lin, TU Chuan-lin

2012, 21(1):  93-102. 

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Wetland is one of the most important living environments and is an ecological landscape with the most abundant biodiversity in the world. Recently, with rapid development of society and economy, as well as over-exploitation and irrational utilization to wetland resources, the structure and function of the wetland ecosystem has suffered grievous disturbance and destruction. This has limited the social economy to sustainable development so it is very important and urgent to protect and restore wetlands. The community characteristics of the Tuohu wetland in the Anhui provincial nature reserve were analyzed using the methods of participatory rural appraisal (PRA), biodiversity investigation, TWINSPAN classification and DCA ordination, the environment situation, plant biodiversity. 1) The Tuohu wetland ecological environment had obviously degenerated; 2) The aquatic community structure, of Potamogeton crispus, appeared to be simple; 3) There were three rare and endangered plant species in the nature reserve, i.e. Nelumbo adans, Glycine soja, and Trapa incise. The results of DCA ordination both tested and verified the results of the TWINSPAN classification, and the ordinate and abscissa of DCA ordination indicated the gradient variety of habitat associations. Based on the characters of the water body and aquatic ecological system, some suggestions for policy & rule of law, technology solutions, conservation strategies, and development mode were addressed in this paper.

Study of the photosynthesis characteristics and physical signs of four plants at the desert-oasis ecotone

AN Gui-xiang, LI Hai-feng, YUAN Na

2012, 21(1):  103-111. 

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The photosynthesis characteristic and the water potential of four plants:Tamarix ramosissma, Haloxylon ammodendron, Calligonum caput-medusae and Elaeagnus angustifolia were studied in the same environment at the desert-oasis ecotone of Moyu county in the south fringe of Takelamkan Desert in August of 2010, we analysed and compared the physiology characteristics of the four plants. 1) Among the four plants, light response curves are basically the same trend, showed that photosynthetic rate (A) rapidly increases with the photosynthetic active radiation (PAR) increases, when the PAR reached light saturation point, appear decline trends;as C₄ plants, C. caput-medusae and H. ammodendron have higher light saturation point (LSP) and light compensation point (LCP), which embodies the advantage of the high photosynthesis of C₄ plants; however, other parameters of photosynthesis, such as A_max, and R_day, are not in complete accord; 2) H. ammodendron has a lower early morning and midday water potential, indicating that H. ammodendron rely mainly on water recovery capability at night to cope with drought environment;dawn water potential had a highly significantly except C. caput-medusae and E. angustifolia (P<0.01), midday water potential also had a highly significantly except T. ramosissima and E. angustifolia (P<0.01); 3) Changes of proline and soluble sugar are similar, the content in C. caput-medusae is higher than the other three plants(P<0.05);The E. angustifolia has the highest content of MDA, while the content in C. caput-medusae and H. ammodendron are lowest; the content of MDA is differed significantly except H. ammodendron and C. caput-medusae (P<0.05); 4) Based on the analysis in the relevant membership function using the average of four plants for drought resistance in this order, the results show that: the four plants in the order of drought resistance is H. ammodendron>T. ramosissima>E. angustifolia>C. caput-medusae.

Effects of salinization stress on growth and the antioxidant system of tall fescue

FAN Rui-ping, ZHOU Qin, ZHOU Bo, JIANG Hai-dong

2012, 21(1):  112-117. 

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The effects of different concentrations of NaCl (0, 50, 100, 200, 300 mmol/L) on growth and on the antioxidant enzyme system of tall fescue (Festuca arundinacea) were studied. The biomass and MDA content were not significantly affected when tall fescue were stressed by 50, 100 mmol/L of NaCl as compared with the control, but the biomass of tall fescue was significantly reduced and MDA content increased significantly when stressed by 200 and 300 mmol/L of NaCl. The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) initially increased but then decreased with duration of NaCl treatment. The higher the concentrations of NaCl, the more the enzyme activities were reduced. Contents of AsA and GSH gradually decreased while carotenoid content increased initially but with prolonged duration of NaCl treatment, concentration of the three antioxidants decreased, especially at the 200 and 300 mmol/L concentrations.

Effects of saline sodic stress on growth and physiological responses of Lolium perenne

GUO Hui-juan, HU Tao, FU Jin-min

2012, 21(1):  118-125. 

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The effects of saline sodic stress on growth and physiological responses of perennial ryegrass (Lolium perenne) were investigated in a greenhouse hydroponics experiment. Relative transpiration rate, shoot height, root length, water content, chlorophyll content, malondiadehyde (MDA) content were measured together with the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) of perennial ryegrass seedlings treated with one of five pH levels and distilled water. As pH values increased, relative transpiration rate, shoot height, root length, water content, and chlorophyll content were significantly reduced compared with the control, while the ratio of root to shoot initially increased but then decreased. MDA contents increased (from 7.0 nmol/g FW to 30.0 nmol/g FW) with an increase of pH. At pH=9.1, SOD activity was the highest (8.4 U/mg protein). CAT activity was highest (118.5 U/min·g protein) at pH=6.5 and then declined at higher pH values. POD was lowest at pH=6.5 but increased as pH values increased.

Selection and physiological identification of somaclonal variants for increased drought resistance of centipedegrass

LIU Ming-xi, LU Shao-yun, GUO Zhen-fei

2012, 21(1):  126-132. 

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Centipedegrass (Eremochloa ophiuroides) is an important warm-season turfgrass species, originated from China, but its drought resistance needs to be improved. In this paper selection and identification of somaclonal variants of centipedegrass for increased drought resistance were investigated. Embryogenic calli were subject to a long-term subculture for 24 months for induction of somaclonal variation. Five individual variants with improved drought resistance were selected and identified. Their physiological responses to drought were further measured. Relative water content (RWC), ion leakage, and malondialdehyde (MDA) content decreased after drought stress by withholding irrigation, but higher RWC and lower levels of ion leakage and MDA were in the drought-resistant variants than the control plants. There was no significant difference in proline content and superoxide dismutase (SOD) and catalase (CAT) activities between the variants and the wild type control plants prior to drought treatment. After withholding irrigation for 6 d, all plants showed increase in proline content and SOD and CAT activities, while lower content of proline and higher activities of SOD and CAT were in the variants than the control plants. It is suggested that the increased drought resistance in the five variants is associated with their higher levels of SOD and CAT activity under drought stress.

Effects of nitrogen form on the photochemical efficiency of PSⅡ and antioxidant characteristics of Jerusalem artichoke seedling under salt stress

WANG Lei, LONG Xiao-hua, HAO Lian-xiang, LIU Zhao-pu

2012, 21(1):  133-140. 

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In order to study the effect of different nitrogen form on the physiology of Jerusalem artichoke seedling under the salt stress, a sand cultural study was carried out under the nitrogen nutrition (NH₄⁺/NO₃^- as 4/1, 1/1 and 1/4) and salt stress. 1) The treatment of low concentration of salt stress had a little effect on the inhibition of plant growth, but high concentration of salt stress could remarkably inhibit Jerusalem artichoke growth. Under the same salt concentrations, the dry weights, relative moisture content, plant height and leaf area of Jerusalem artichoke increased with the proportions of NO₃^--N augment.2)With the increasing of salt concentration, PSⅡ system was significantly damaged, but the increasing of the proportions of NO₃^--N could reduce the damage degree of the PSⅡ system and improve ΦPSⅡ, Fv, Fv/Fm, Fv/Fo, Fm/Fo and q_P. Especially, nitrogen nutrition had the highest light use efficiency at the ratio of NH₄⁺/NO₃^- as 1/4. For example, under 100 mmol/L NaCl stress, compared with the treatment at the ratio of NH₄⁺/NO₃^- as 4/1, ΦPSⅡ, Fv, Fv/Fm, Fv/Fo, Fm/Fo and q_P of the treatment at the ratio of NH₄⁺/NO₃^- as 1/4 increased by 1.03, 1.15, 1.05, 1.26, 1.20 and 1.05 times, respectively.3)Too much salt supply could cause the imbalance of plant cell osmotic, however, under the same salt concentration, the increasing of the proportions of NO₃^--N could significantly promote soluble sugar and soluble protein production and the transfer to the roots, then maintained the balance cell osmotic effectively under salt stress.4)Under the salt stress, the membrane lipid peroxidation usually occurred in plants cells, but the proportions of NO₃^--N augment could promote the SOD, POD, CAT and APX activity which had a function of eliminating reactive oxygen species, then alleviated membrane damage which the excessive accumulation of reactive oxygen species caused in cell. For example, under 100 mmol/L NaCl stress, compared with the treatment at the ratio of NH₄⁺/NO₃^-as 4/1, SOD, POD, CAT and APX activities of the treatment with NH₄⁺/NO₃^- as 1/4 were improved by 1.19, 1.08, 1.18 and 1.11 times, respectively. So with respect to NH₄⁺-N, the increase of the proportions of NO₃^--N was more conducive to increase the accumulation of dry matter and water content, improve the activity of intracellular protection enzyme, maintain the stability of PSⅡ system and cell osmotic balance, then enhanced the resistance of Jerusalem artichoke to salt stress.

Effect of different amounts of potassium fertilizer on the growth, nutrient uptake and quality of Lanzhou lily

LIN Yu-hong

2012, 21(1):  141-148. 

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Using N (150 kg/ha) and P (150 kg/ha) as basal fertilizer in dry conditions in a field experiment, the effects of different levels of potash fertilizer (0, 112.5, 225.0 and 337.5 kg/ha) on the growth, nutrient accumulation and quality of Lanzhou lily were studied. The average annual production of one-year, two-year, and three-year old Lanzhou lily increased (52.3±22.7)%, (132.0±52.0)% and (71.3±38.3)%, respectively in response to potassium. Total sugar and crude starch content of Lanzhou lily increased by an average of (4.1±1.92)% and (9.3±5.02)% respectively under potassium fertilizer treatment compared with no potassium fertilizer, while the soluble sugar, crude fiber and crude protein contents decreased (7.9±5.61)%, (7.5±6.91)% and (8.5±5.64)%. There were significant (P<0.05) positive correlations between total sugar and crude starch contents of lily and potassium fertilizer amount, but significant (P<0.05) negative correlations between crude fiber content and potassium fertilizer amount, and a significant (P<0.01) negative correlation between protein content and potassium fertilizer amount. Potassium is one of the main factors that affects yield and quality of Lanzhou lily.

Effect of different waterlogging stress conditions on growth and some physiological characteristics of Amorpha fruticosa

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

2012, 21(1):  149-155. 

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The changes of growth and physiological characteristics of Amorpha fruticosa seedlings under different waterlogging stress conditions were studied by carrying out a water soaking treatment. The nutritive growth had no obvious change although a mass of aquatic adventitious roots and specialized lenticels grew in a short time to adapt to the different waterlogging stresses. Chlorophyll contents in leaves and photosynthetic rate decreased differently in different flooding treatments: the main factor in surface submergence and semi-submergence waterlogging was the reduction of stomal condunctance, while the main factor in the nearly submerged waterlogging was the increase of intercellular CO₂ concentration. Root activity of the surface submerge waterlogging treatments decreased insignificantly, while it fell by 58% between in the semi-submerge waterlogging treatments and the control group, and 51% between the nearly submerge waterlogging treatments and the control. Soluble sugar and proline contents in waterlogging treatments were all more than that in the control while the semi-submerge waterlogging treatments had the highest contents of them with the quantity 22.43 mmol/L and 570 μg/g respectively, and had obvious change with the control group (P<0.05), while MDA content showed no change. A. fruticosa could adapt to waterlogging stress by the growth of many aquatic adventitious roots and specialized lenticels and by accumulating osmotic adjustment substances. A. fruticosa had strong waterlogging tolerance ability and could be planted in wet land.

Effects of different soil moisture on growth and physiological characteristics of Astragalus sinicus

ZHANG Wei-guang, CAO Wei-dong

2012, 21(1):  156-161. 

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Five treatments (25%-30%, 50%-55%, 75%-80%, 95%-100% of field moisture capacity and submergence) were installed to study the effects of soil moisture on growth and physiological characteristics of Astragalus sinicus. Growth and accumulation of the nutrients absorbed by A. sinicus were greatest at 75%-80% of field moisture capacity, which was the best fit to growth. Disease symptoms of water stress were shown by A. sinicus at 25%-30% of field moisture capacity and at submergence. Compared with the 75%-80% of field moisture capacity treatment, superoxide dismutase (SOD), peroxidase (POD), catlase (CAT) activities and malondialdehvde (MDA) contents in leaves of A. sinicus and the minimal fluorescence (Fo) all increased significantly, while the maximal fluorescence (Fm), variable fluorescence (Fv), light energy transformation efficiency of PSⅡ(Fv/ Fm) and activity potential of PSⅡ(Fv/Fo) declined significantly as did the yield and accumulation of nutrients absorbed. SOD, POD, and CAT activities, MDA content and chlorophyll fluorescence parameters did not change significantly in the three treatments (50%-55%, 75%-80% and 95%-100% of field moisture capacity) which therefore showed that A. sinicus could normally grow at 50%-100% of field moisture capacity.

Variability of nitrogen, phosphorus, potassium and lead concentration of nine predominant herbaceous plant species in a lead-zinc mining tailing

ZHANG Shu-jin, LI Ting-xuan, ZOU Tong-jing, XIONG Jian

2012, 21(1):  162-169. 

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The co-relationships between nitrogen, phosphorus, potassium, and lead concentrations of nine predominant herbaceous plant species in the Sanhe lead-zinc mining tailings were studied and the distribution characteristics within the growth period were explored. 1) The concentrations of nitrogen, phosphorus and potassium in shoots of plants were higher than in roots and they all decreased with the extension of the growth stages. 2) None of the plant species accumulated lead above 1 000 mg/kg (criteria for hyperaccumulator of lead) in the shoots. However, the roots of Athyrium wardii can uptake a great deal of lead, and the maximum concentration and accumulation concentration were 15 542.1 mg/kg and 41.81 mg/plant, respectively. 3) In addition to the later growth, the shoot concentrations of nitrogen and potassium with lead of the nine predominant herbaceous plants in mining tailings showed significant positive correlations (0.750^* and 0.773^* respectively) but there were no significant correlations between the concentrations of nitrogen, phosphorus, potassium and lead. 4) The lead concentration of shoots in early growth stages had no significant relationship (P<0.05) with that of roots. However, in vigorous and late growth stages, the correlations between the lead concentrations of shoots and roots in the same, or in different growth stages were significant or highly significant (P<0.01) respectively.

The construction of genetic linkage frame map in tetraploid Medicago using RAPD markers

SUN Juan-juan, YAO Ting-ting

2012, 21(1):  170-175. 

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Using random amplified polymorphic DNA (RAPD) molecular genetic markers analyze the F₂ population of 94 plant individuals. The F₂ segregating population derived from a self-pollinated F₁ hybrid individual of the cross Medicago sativa×Medicago falcata. The genetic analyses were performed by using maximum-likelihood equations and related computer programs. The genetic map comprises 74 markers, and contains 8 linkage groups covering 1 261.5 cM, with an average distance of 24.73 cM between markers. This genetic linkage map provides an entry point for the construction of saturated tetraploid alfalfa molecular genetic map and further development of alfalfa molecular genetic research.

Cloning and analysis of the dehydrin (DHN) gene from Galega orientalis

Nikolay D, SUN Gui-zhi, GAO Hong-wen

2012, 21(1):  176-183. 

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Using rapid amplification of cDNA ends (RACE) method, a cDNA clone encoding dehydrin (GoDHN) was isolated from a cDNA SSH (suppression subtractive hybridization) library induced by salt stress from Galega orientalis. The full-length of cDNA sequence was 1 169 bp and included an 843 bp open reading frame. Molecular weight of this protein was 28.71 kDa. Results of real-time PCR indicated that the expression of quantity of GoDHN was higher in leaves and stems than in roots. Abiotic stress, such as NaCl and PEG, all induced the expression of GoDHN. Application of the exogenous hormone ABA also up-regulated mRNA accumulation. The expression of GoDHN increased with the induction time. These results indicated that the DHN gene may be involved in regulation of stress-resistance in G. orientalis. Construction of a pCAMBIA1302-DHN vector formed a basis for gene transformation.

Optimization of a chromosome mounting technique and karyotype analysis of Thymus mongolicus

YANG Ning, TAN Yong-xia, LI Qiao-xia, JIA Ling-yun, CHEN Xi-lian, LIU Xiao-rui

2012, 21(1):  184-189. 

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The karyotype of Thymus mongolicus was analyzed using a chromosome mounting technique. The best sampling time was between 8:45 am and 9:15 am, the best pre-treatment was 0.04% colchicine and 0.002 mol/L 8-hydroxyquinoline mixture (1∶1) for 2-3 h, and the dyeing treatment was 1 h with modified carbolic acid-magenta. Karyotype analysis of T. mongolicus showed that the chromosome number is 24 and the karyotype formula is 2n=2x=24=20m+4sm. Ten pairs are metacentric (m) and 2 pairs are submetacentric (sm). The karyotype of T. mongolicus is 2A and the karyotype asymmetry coefficient is 59.63%.

Genetic diversity and genetic relationships among three species of Medicago sativa complex in Xinjiang Province of China

LI Fei-fei, CUI Da-fang, YANG Hai-jun, DENG Chao-hong, LI Qing-yan

2012, 21(1):  190-198. 

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The genetic diversity and the genetic relationships among 10 populations of Medicago falcata, M. varia and M. sativa, belonging to the M. sativa complex were studied by using 15 pair of SSR primers and 10 ISSR primers. The results showed that population VG of M. varia had the highest percentage of polymorphism bands (PPB), Shannon’s information index (I) and Nei’s genetic diversity index (h) of 10 populations in SSR results; population FH of M. falcata had the 3 highest indices in ISSR results; population FH had private bands in SSR and ISSR results, which indicated VG of M. sativa and FH of M. falcata had the highest genetic diversity and thus need to be protected further. Three species could be distinguished clearly by UPGMA cluster analysis and combined their distribution in Xinjiang area, our study supported their classification at the species level.

Effect of addition of silicon on seed emergence and growth of tall fescue (Festuca arundinacea) under the different soil moistures

Effect of addition of silicon on seed emergence and growth of tall fescue

2012, 21(1):  199-205. 

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The water and fertilizer coupling benefits the health growth of turf grasses and reduces the irrigation water to some extent. A pot experiment was conducted to determine the effect of addition of silicon on seed emergence and growth of tall fescue (Festuca arundinacea) under the different soil moistures. This study showed that the soil moisture ranging from 45% to 60% of field water capacity was suitable for seed emergence of tall fescue, and the minimal requirement for soil moisture was 75% of field water capacity for plant growth of tall fescue when addition of silicon was unavailable. Addition of silicon enabled seed emergence of tall fescue to become fast, that addition of silicon shortened the time of seed emergence, increased the survival seedling rate, encouraged the plant height and leaf length to grow, and increased the biomass of shoots and roots when soil moisture was 60% of field water capacity or over it. However, addition of silicon did not affect the growth of tall fescue when soil moisture was 45% of field water capacity or below it, implying that the beneficial effectiveness of addition of silicon on tall fescue growth was strongly regulated by the soil moisture environment. This study also showed that tillers per plant, height, leaf length, and total biomass of plants between +Si (addition of silicon) treatments with 60% of field water capacity and -Si (control) treatments with 75% field water capacity was not significantly different, suggesting that addition of silicon reduced the minimal requirement for soil moisture for health growth of tall fescue, and benefited the saving irrigation water.

Switchgrass seeds germination and seedling growth and development with different concentration of Agrobacterium tumefaciens

XU Kai-jie, YAN Ming-xian, CHAI Guai-qiang, SUN Feng-li, LIU Shu-dong, XI Ya-jun

2012, 21(1):  206-212. 

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With the switchgrass strains (Xiji No.1, Xiji No.2, Xiji No.3) as the dominated factors, the concentration of Agrobacterium tumefaciens as the deputy factors, the effect of switchgrass seed germination and seedling physio-biochemical characteristics were studied, using A. tumefaciens-soaking method. The results showed that the interaction effect between the strains and the concentration was not significant; The effects of A. tumefaciens on switchgrass strains were different, and the Xiji No.3 was more insensitive to A. tumefaciens than the other strains. With the concentration of A. tumefaciens increased, the switchgrass seed germination rate, the seedling plantingpercent and chlorophyll content showed downtrend, and the seedling POD activity, CAT activity and MDA content showed uptrend, and the seedling SOD activity initially increased but then decreased. To sum up, the most appropiate concentration of A. tumefaciens may be under 1.2 OD₆₀₀ in switchgrass seeds soaking.

Effects of salicylic acid on seed germination and physiological characters of cauliflower seedlings under salt stress

WANG Yu-ping, DONG Wen, ZHANG Xin, YANG Qian, ZHANG Feng

2012, 21(1):  213-219. 

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Effects of salicylic acid on salt stress-induced injuries were investigated during the stage of seed germination and seedling growth of cauliflower (Brassica oleracea var. botrytis). Under the stress, presoaking the seeds with 0.5-1.5 mmol/L of salicylic acid increased the germination percentage, germination energy, germination index and relative α-amylase activity of cauliflower. Among the treatment of salicylic acid, 1.0 mmol/L had the best effect. The results also showed that treatment with 0.5-1.5 mmol/L of salicylic acid during the stage of seedling growth under salt stress increased the plant height, stem diameter, leaf area, chlorophyll contents, free proline and water dissolved-carbohydrate contents, the activities of superoxide dismutase (SOD) and peroxidase (POD), and decreased the content of malondialdehyde (MDA), suggesting that the exogenous SA (salicylic acid) could effectively mitigate the injuries of salt stress and increase salt-tolerance of cauliflower seeds and seedlings by increasing α-amylase activity, osmotic regulation and antioxidation. The best treatment concentration of salicylic acid was 1.0 mmol/L. When the concentration of SA was beyond 2.0 mmol/L, no mitigation effect was observed on the seeds germination and growth of seedling under salt stress.

A preliminary study on fermentation technology in the manufacture of fuel alcohol using annual ryegrass

DAI Ying, GUO He-rong, ZHANG Xing-long, LI Qiang

2012, 21(1):  220-228. 

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The fermentation technology of fuel alcohol manufacturing transformation was studied using an annual ryegrass (Lolium multiflorum) variety for abundant material. It was pretreated with 1% H₂SO₄ and 10% NaOH then hydrolyzed by Trichoderma viride. The relative optimum conditions of program 1 (a volume ratio of Saccharomyces cerevisiae to Pichia pastoris of 7∶3) were a 10% concentration of the yeasts at 37℃, pH 5.5 for 48 h. For program 2 (a ratio of S. cerevisiae, P. pastoris, and Aspergullus niger of 7∶3∶2) a 12% concentration of the mixture at 37℃, pH 5.5 was tested for 48 h. The concentration of strains and the fermentation temperature were the more important factors in both programs. For pretreatments with H₂SO₄ and NaOH, program 2 achieved relatively higher alcohol conversion rates (8.36% and 8.39%, respectively) but there was no significant difference.

A discussion on applications of vegetation index for estimating aboveground biomass of typical steppe

ZHANG Yan-nan, NIU Jan-ming, ZHANG Qing, YANG Yan, DONG Jian-jun

2012, 21(1):  229-238. 

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Remote sensing technology emerged in the early 1960s and was widely used in grassland yield estimation. Estimation of the relationship between vegetation index and biomass on different scales was always used to complete the conversion from points to surface. Fourteen vegetation indices which were commonly used in grassland yield estimation were selected to establish regression models of vegetation index-dry weight and vegetation index-fresh weight in typical grassland in Baiyinxil, Xilinhaote, Inner Mongolia. The DCA analysis of 14 vegetation indices showed that: 1) It was feasible to use fresh weight and dry weight in remote sensing estimation of grass biomass, and that although dry weight was better than fresh weight, for reasons of experimental conditions, fresh weight had a wider range of applications. 2) The first and second axis of DCA analysis represent the effects of soil and atmosphere with soil the most important factor that affected vegetation index; DCA divided 14 vegetation indices into 4 categories, and the category which generally excluded the influences of soil and atmosphere (e.g. NDVI, SAVI and MSAVI) were the best. 3) Empirical dates showed that while the biomass was lower than 370 g/m², the yield estimation model was a simple unitary linear model, but when it was between 370 and 720 g/m², the simulation results of the linear and the exponential model were both very good. When the biomass was greater than 720 g/m², the exponential model was the best yield estimation model. Therefore, as the range of biomass increases, the yield estimation model should be gradually changed from a simple linear model to an exponential model.

Modelling light use efficiency of alpine meadows on the Northern Tibetan Plateau based on the MODIS algorithm

WU Jian-shuang, ZHOU Yu-ting

2012, 21(1):  239-247. 

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Light use efficiency (LUE) is defined as the ratio of primary production to absorbed photosynthetically active radiation (APAR) by a vegetation canopy and it reflects the capability of using luminous energy. Quantitative analysis of the temporal and spatial variations of primary production is based on the quantitative analysis LUE and is an important component of quantitative analysis of the global carbon cycle. Therefore, quantitative analysis of the global vegetation LUE is an important component of quantitative analysis of the global carbon cycle. The LUE of alpine meadows on the Northern Tibetan Plateau were modeled based on the MODIS LUE algorithm in 2004-2005. Daily minimum air temperature (Tamin) and vapor pressure deficit (VPD) were used to calculate the temperature attenuation scalar (T_scalar) and water attenuation scalar (W_scalar), respectively. Based on correlation analysis and multiple stepwise linear regression analysis, the T_scalar might explain more seasonal variations of LUE than the W_scalar. Modeled LUE values were about 14.97% and 16.57% larger than observed LUE values in 2004 and 2005, respectively. However, there was no significant difference between modeled LUE and observed LUE. This means that the LUE model based on the MODIS algorithm had high accuracy to model LUE of alpine meadows on the Northern Tibetan Plateau. Correlation analysis showed that the correlation coefficient between observed LUE and Tamin was larger than that between observed LUE and mean air temperature. This indicated that Tamin was better than mean air temperature in quantitative analysis of the LUE seasonal change. The LUE model based on the MODIS algorithm accurately quantified the LUE of alpine meadows on the Northern Tibetan Plateau.

Response of urinary purine derivatives excretion to yeast RNA infusion levels in the yak abomasum

WANG Hu-cheng, YE De-he, ZHOU Jian-wei, LONG Rui-jun

2012, 21(1):  248-253. 

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Three castrated yaks fitted with T-shaped abomasum cannulae were used to study the recovery rate of urinary purine derivative after abomasum infusion with incremental amounts of purine bases. As the infusion RNA levels increased, excretion of urinary allantoin (564-1 426 μmol/kg BW^0.75), total purine derivative (629-1 507 μmol/kg BW^0.75) and the ratio of allantoin to total purine derivative (0.90-0.95) increased linearly (P<0.01), although excretion of uric acid, creatinine and nitrogen were not significantly (P>0.05) affected by infusion levels. The relationship between daily urinary purine derivative excretion (Y, mmol/d) and exogenous purine supply via abomasums infusion (X, mmol/d) was Y=0.85X+33.02 (R²=0.96), suggesting that 85% of the supplied exogenous purine was excreted in the urine of the yaks.

A review of mountain grazing-paths and vegetation spatial heterogeneity

LIU Jin-xin, GONG Yuan-bo, ZUO Qin, CHEN Lin-wu, FANG Jian-jia, LIU Shan-shan

2012, 21(1):  254-261. 

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Vegetation spatial heterogeneity was changed by mountain grazing-paths and by grazing along the grazing-paths. Mountain grazing-paths were defined as settled movement ways, ascending or descending, and comparatively fixed trails of foraging and trampling of livestock on the mountain sides. Their formation and distribution are summarized based on published literature at home and abroad. This paper mainly reviews the interaction mechanisms between mountain grazing-paths and vegetation spatial heterogeneity. As a linear corridor, mountain grazing-paths provide channels and habitats for species diffusion; they divide patch landscapes, affect plant boundary dynamics, and also impact on vegetation spatial heterogeneity at different scales. There is mutual influence between livestock selective grazing along grazing-paths and vegetation spatial heterogeneity and vegetation spatial heterogeneity change by livestock trampling and excretion. Foraging, trampling and excretion of livestock play a comprehensive role in soil changes and indirectly affect the spatial distribution of vegetation. Mountain grazing-paths have theoretical and practical values in the study of animal behavior and grazing ecology. Furthermore, they could be a basis for monitoring vegetation degeneration and controlling grazing capacity.

An integrated orderly classification system of natural wetland and its application in China

WANG Chong, LIN Hui-long

2012, 21(1):  262-272. 

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Based on previous research on classification methods, this paper raises 6 principles that the classification system should obey. Drawing lessons from the comprehensive and sequential classification system of grassland (CSCS) proposed by Ren Ji-zhou et al, we suggest an integrated orderly classification system of natural wetland (IOCSNW) based on bioclimate- basement material- vegetation. The first level of the IOCSNW is class, and the classification indicators are depth of stagnant water and the years accumulated temperature above 0℃(∑θ) - these are quantified indicators. The second level is subclass, and the indicator is the basement material. The third level is type: emerging type, floating leaf type, submerged type, and floating type. According to bioclimatic and other indicators, the IOCSNW recognizes 21 wetland classes. The five largest areas of the wetlands classes are the frigid and shallow surface water wetland class (ⅠB), cool temperate and shallow surface water wetland class (ⅢB), cold temperate and shallow surface water wetland class (ⅡB), frigid and deep surface water wetland class (ⅠA) and warm temperate and shallow surface water wetland class (ⅣB). They occupy 79.75% of natural inland wetlands of China. These classes are distributed in the provinces of Qinghai, Tibet, Xinjiang, Gansu, Sichuan, Inner Mongolia, Jilin and Heilongjiang. While the warm and shallow surface water wetland class (ⅤB), tropical and shallow surface water wetland class (ⅦB), tropical and deep surface water wetland class (ⅦA), subtropical and shallow surface water wetland class (ⅥB), and cold temperate and deep surface water wetland class (ⅡA) are the smallest classes in area (they occupy only 0.83% of the total area) and are distributed in the provinces of Anhui, Hubei, Yunnan, Guangdong, Guangxi, Hainan, Guizhou and Qinghai. Twenty of the 21 classes occur in China since our data shows no wetlands of the tropical and seasonality surface water wetland class (ⅦC). Since the retrieval graph of the wetlands adequately embodies the genetic relationship of the natural inland wetlands, it lays the foundation to predict the succession of natural wetlands classes in a background of global warming and drying.

Effect of different tillage treatments on soil respiration of winter-wheat farmland in oasis irrigated area Northwest China

YU Ai-zhong, HUANG Gao-bao, CHAI Qiang

2012, 21(1):  273-278. 

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Based on a long-term field experiment, the effects of no-tillage with wheat stubble mulching (NTS), no-tillage without wheat stubble mulching (NT) and conventional tillage (T) on soil respiration of winter wheat were studied in oasis irrigated area, Northwest China. The results showed that soil respiration rates appeared in single-peak curve during diurnal and seasonal changes under three tillage treatments. The maximum of diurnal soil respiration rate under NTS treatment occurred at 15: 00,but those of NT and T treatments occurred at 14:00. The peak value of seasonal soil respiration rate under three tillage treatments occurred at anthesis stage of winter wheat (early June). The average of soil respiration rates of NTS and T treatments were 43.01% and 33.33% higher than that of NT treatment, respectively. The sensitivity of soil respiration to soil temperature (Q₁₀) was 1.93-3.00 and was NT＞NTS＞T. Soil respiration was not significantly sensitive to soil water content. It was suggested that soil respiration under different tillage was mainly controlled by soil temperature in this area.

Effect of trophic status of cultivation solutions on allelopathic inhibition of Microcystis aeruginosa by Alternanthera philoxeroides

YE Liang-tao, QIAN Jia-zhong, ZUO Sheng-peng, LI Shu-ping, CHEN Ya-qiong

2012, 21(1):  279-284. 

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Three water solutions with different trophic status (distilled water, BG11 nutrient solution and eutrophic water) were used to study the allelopathic effects of living and dead plants of the invasive species Alternanthera philoxeroides at different growth phases on Microcystis aeruginosa in a hydroponics experiment. pH and ORP (oxidation-reduction potential) were measured in cultivation solutions from living plants and decomposed solutions from dead plants of A. philoxeroides. 1) Under different trophic status of culture media, A. philoxeroides had an inhibitory potential and living and dead plants at different stages could significantly inhibit M. aeruginosa at the lag phase. Dead plants had a stronger inhibitory effect on M. aeruginosa than living plants. Living plants had allelopathic effects, in the order: distilled water＞eutrophic water＞BG11 nutrient solution, while for dead plants the order was: eutrophic water＞BG11 nutrient solution＞distilled water. 2) The two kinds of plant materials gave similar allelopathic inhibition of M. aeruginosa. The inhibitory effect initially increased (for all three trophic water bodies), and then terminated at a steady state. The highest inhibitory rates of living and dead plants at 70.7% and 91.7%, respectively, were at the 5th day. 3) The physical-chemical properties of exudates from living plants and decomposed dead plants were notably different, and pH values and ORP were related to various factors such as duration and types of solutions and materials. These findings will provide theoretical references for utilization and management of invasive plants and its further application in water-bloom algal control.

Rice stem and leaf nutrient contents and effects of stubble heights on the nutrient contents of rice straw

CHEN Ming-xia, HUANG Yan-fang, CUI Wei-dong, FENG Fan, LIU Qin-hua, ZHANG Jian-guo

2012, 21(1):  285-290. 

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The utilization of rice straw has increased with the rapid development of animal husbandry. Feeding value of rice straw varies with the variety. The agronomic traits of five rice varieties (Taiyou 99, Yuxiang 203, Fengyou 22, Peizataifeng and Ⅱyou 368) and their nutrient contents and dry matter digestibility of stem and leaf were measured, and the effects of different stubble heights on the nutrient contents of their straw were investigated. Fengyou 22 had a higher feeding value than the others based on the agronomic traits, crude protein content and digestibility. Leaves of rice had more crude protein and crude ash, less nitrogen free extract and lower dry matter digestibility than stems. Stubble heights of rice straw had less effect on the nutrient contents. In order to increase straw yield, rice should be harvested at 3-5 cm from the ground.

Effects of subsurface drip irrigation on alfalfa growth and seed production

MENG Ji-meng, LI Wei-jun

2012, 21(1):  291-295. 

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To increase the output and profitability of alfalfa seeds, subsurface drip irrigation (SDI) was introduced into a production experiment of alfalfa seeds. Through the study of salt distribution of SDI in the soil and the growth characteristics of alfalfa, the possible uses and effectiveness in alfalfa production were explored. The biggest moisture content of SDI was 65%-80% of the soil moisture (W1) and the biggest radius was 50 cm horizontally and 20 cm vertically enabling water to reach the roots of alfalfa. The W1 root weight was significantly (P<0.01) higher (25.09 g) than that of the other treatments and the root weight sequence was W1＞CK (flooding irrigation)＞W2 (50%-65% of the soil moisture)＞W3 (35%-50% of the soil moisture). The seed yield of W1 was significantly (P<0.01) higher (909.62 kg/ha), than that of the CK (611.39 kg/ha). The application of SDI in alfalfa production could increase seed yields.

Cloning of a 4CL gene fragment and construction of a RNAi expression vector of Pennisetum purpureum

HUO Song, CHEN Hui, ZHU Qiong-hua, XIE Xin-ming

2012, 21(1):  296-311. 

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Pennisetum purpureum is a perennial resource plant and widely cultivated in tropical and sub-tropical regions. A pair of specific primers was designed to assess the effect of down-regulated expression of the 4-coumarate: CoA ligase (4CL) gene on lignin composition of P. purpureum cv. Huanan, using the 4CL gene sequence of P. purpureum cv. Mott (accession No: GU997597.1). An interference fragment of 374 bp was obtained by PCR amplification with the above primers and it was cloned into the pCR^/GW/TOPO^ vector by TOPO cloning to obtain pENTER-4CL. The corresponding fragment on destination vector pCB2004B was then replaced by the interference fragment of pENTR-4CL by LR reaction to form the RNAi (RNA interference) expression vector pCB2004B-4CL. The Agrobacterium-mediated transformation of the expression vector was carried out using the freeze-thaw method, and the expected fragments appeared in the PCR products using bacterial liquid as a template. This study was a basis for research on the 4CL function of P. purpureum by RNAi technology.