Table of Content

20 June 2015, Volume 24 Issue 6

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The definition, analysis and relevant description of several professional vocabulary

REN Ji-Zhou

2015, 24(6):  1-4.  DOI: 10.11686/cyxb20150001

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Rate and causes of degradation of alpine grassland in the source regions of the Yangtze and Yellow Rivers during the last 45 years

DU Ji-Zeng, WANG Gen-Xu, LI Yuan-Shou

2015, 24(6):  5-15.  DOI: 10.11686/cyxb2014302

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Alpine grassland is the main vegetation type in the source regions of the Yangtze and Yellow Rivers, and accounts for about 70% of the total area in this region. As a result, maintenance of ecosystem balance, water cycling and soil-atmosphere exchanges in these regions critically depends on the status of the local alpine grasslands. With current global changes such as climate change, and increased human population in the region, alpine grassland in this region has been subject to increasing grazing pressure with significant changes resulting. These environment and regional economic changes have attracted widespread attention. In this research, alpine grassland degradation in the source regions of Yangtze and Yellow Rivers was quantified by analysis of images obtained by aerial photography in 1969 and TM remote sensing data captured in 1989, 2000, 2007 and 2013. In addition, with the inclusion of climatic observation data and data on human factors, the causes of the degradation were analyzed by principal component analysis and the gray correlation method. The results show that the alpine grassland degradation is characterized by reducing coverage, and increasing fragmentation and desertification. The total area of mid-cover alpine grassland and high-cover alpine grassland has decreased by 16.33% from 1969 to 2013. With a trend to increase in periodic drought, the total area of alpine meadow has decreased by 3.75% during the same time. Fragmentation and separation of alpine grassland units in the landscape has been occurring and also shrinkage and disappearance of patches. The rate of degradation increased very rapidly after the 1980s, and reached its maximum in 2000, but has been consistently decreasing since 2000. Climatic drought caused by a warming trend has been the main driver for alpine grassland degradation in the source regions of Yangtze and Yellow Rivers, and overstocking and unreasonable human activity were important contributing factors, intensifying the degradation.

Characteristics of precipitation interception in soil and water conservation forests of the Northeast black soil areas of China

SUI Yuan-Yuan, XU Xiao-Hong, ZHANG Yu, OU Yang, YAN Bai-Xing, WANG Pei-Jiang, CUI Hai-Feng, CUI Bin

2015, 24(6):  16-24.  DOI: 10.11686/cyxb2014305

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A study of forests for soil and water conservation has been undertaken to learn the effect of canopy interception on water circle, allocation and utilization in the Northeast black soil areas of China. Field monitoring data was used to investigate precipitation interception in two forest types [Larix gmelinii (LG) and Quercus mongolica-Larix gmelinii (QM-LG)] in the Xingmu small watershed of Dongliao County, Jilin Province. During the 15 rainfalls from May to September 2013, throughfall accounted for 72.0% and 67.4% of LG and QM-LG total precipitation respectively. Stemflow made up 2.6% and 2.7% of total rainfall and 25.3% and 29.8% of interception respectively. Interception percentages in the two forests varied from 8.9% to 73.5%. Compared with LG, QM-LG had higher interception efficiency. 8 rainfall events generated surface runoff for LG at 3.52 mm and QM-LG at 3.40 mm. Monthly throughfall and interception in the two forests ranked as August>July>June>May>September, and stemflow as July>August>June>May>September. Monthly interception percentages in the two forests were the highest in September (44.5% and 49.0%) and the lowest in July (20.4% and 25.2%). Throughfall, stemflow and interception had significant linear associations with total rainfall. Stemflow increased slightly with light rain and more significantly when rainfall was above 30 mm. Interception percentages gradually decreased with increases in precipitation. Throughfall in LG and QM-LG was significantly positively correlated with rainfall intensity. Stemflow and rainfall intensity could be fitted with logarithmic curve. However, the relationship between rainfall intensity and interception or interception percentage was not significant. The interception percentage of the two forests was more than 50% when rainfall intensity was equal to or less than 2.65 mm/h.

Assessment of above-ground Biomass of Grassland using remote sensing,Yili, Xinjiang

ZHANG Xu-Chen, ZHU Hua-Zhong, ZHONG Hua-Ping, CHENG Yao-Dong, JIN Gui-Li, SHAO Xiao-Ming

2015, 24(6):  25-34.  DOI: 10.11686/cyxb2014478

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The relationship between the above-ground biomass of grassland vegetation in Yili, Xinjiang (assessed with cut quadrats) and the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), altitude, annual precipitation, annual mean temperature, accumulated temperature and dryness and wetness indices was analyzed using regression. Subsequently, an ArcGIS interpolation method was used to map the spatial distribution of above ground biomass of the grassland. There was a strong relationship between above-ground biomass and the independent factors assessed; the multiple regression coefficient (R²) was 0.85 and the RMSE was 216.56 kg/ha. It was concluded that the simulation data used in the study could be used to reliably monitor and assess grassland productivity and dynamics.

The compensatory growth of plant community, synusia and species under different clipping intensity

WANG Li-Hua, LIU Wei, WANG Jin-Niu, GAN You-Min, WU Yan

2015, 24(6):  35-42.  DOI: 10.11686/cyxb2014473

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The species of different layers in community have various responses to clipping, which crucially affect the compensation ability of the whole community and its productivity. Thus, this study aims to investigate the compensatory effects of grassland community and different layer of species, and three clipping intensities were conducted in Qishan pasture of Chongqing in the growing season. The study found that, 1)community aboveground biomass recovered more quickly at moderate clipping rate than that at high clipping rate, while the aboveground relative growth rate (RGR) reached the highest at the high clipping rate; 2)at the end of growing season, RGR of the top layer reached maximum at moderate clipping intensity, and the middle layer of RGR was reached maximum at high clipping intensity; 3)the moderate clipping intensity appropriated the over-compensatory growth for the tall plants, however, the high clipping intensity was suitable for the middle species; 4)at the moderate clipping rate, the total community biomass was positively correlated with biomass of top layer species, however, there were positive correlations between biomass of top and middle layer species and community biomass at high clipping rate, but no significant relationship was found between community biomass and the lower layer species biomass at the moderate and high clipping rate; 5)for the dominant species, Miscanthus floridulus, Dactylis glomerata and Trifolium repens presented the similar biomass change patterns with those at synusia level. The results demonstrate that the plants at different synusia level shave species-specific responses to clipping removal with different intensity. Moderate clipping intensity was appropriate for the over-compensatory growth of the tall pants, while the high clipping intensity was suitable for middle species. In conclusion, clipping intensity should be adopted according to the fragments of layers’ characteristics and that can be advantageous for grassland productive potential.

Effects of film mulching on growth and crown and root characteristics of alfalfa in an alpine meadow

YU Xiao-Jun, JING Yuan-Yuan, XU Chang-Lin, SHI Shang-Li, ZHANG Jian-Wen, CHEN Lu-Jun, YANG Hai-Lei, XIAO Hong

2015, 24(6):  43-52.  DOI: 10.11686/cyxb2014295

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The lack of cold-resistant alfalfa varieties and appropriate cultivation techniques has greatly restricted the development of dry land alfalfa production and animal husbandry in alpine areas. This study compared four establishment treatments; plastic film mulching on ridges and furrows (A); film mulching parallel to the ground (B); film mulching on ridges and furrows+soil cover (C) and standard ridge and furrow planting (D). The study was conducted in an alpine region at Tianzhu. The growth characteristics of alfalfa were assessed in year 1 and crown and root characteristics in year 2. Treatment ‘A’ significantly (P<0.05) increased alfalfa growth in the 1st year (249.37 kg/hm²) compared to all other treatments. Total root volume (9.288 cm³/plant) root surface area (466.287 cm²/plant), root biomass (7.76 g/plant), root length (85.55 cm), root diameter (8.36 mm) and lateral root number (26.27) of treatment A were significantly higher than that of all other treatments (P<0.05). Crown bud numbers, crown diameter, root volume, root surface area and root biomass of treatments B and C were not significantly different but were significantly higher than treatment D (P<0.05). There were no differences in tap root depth, diameter and root biomass between treatments B, C and D. The present study showed that film mulching on ridges and furrows greatly improved alfalfa crown diameter, crown bud numbers, tap root depth, root volume, root surface area, root biomass and forage yield indicating considerable potential for the use of this technique in alpine areas.

Effects of exogenous nitrogen forms on root characteristics of alfalfa at different growth stages

LIU Xiao-Jing, YE Fang, ZHANG Xiao-Ling

2015, 24(6):  53-63.  DOI: 10.11686/cyxb2014269

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This paper reports research on the effect of exogenous nitrogen on the root characteristics of “Gannong No. 3” Alfalfa at different growth stages. Samples were cultivated for the whole growth period using the sand culture method under the condition of complete nutrient solution. Three exogenous nitrogen forms (nitrate nitrogen, ammonium nitrogen and nitrate nitrogen) were investigated; with the ammonium nitrogen solution at 1∶1 and the others are three solution levels (CK, 105, 210 mg/L). Results showed that under different forms of nitrogen treatment, the root biomass, root surface area, root volume, root activity, root nodule number, nodule weight, and nitrogenase activity of alfalfa are significantly higher than that of CK. With increasing nitrogen levels, there were increases in the proportions of alfalfa root biomass, root surface area, root volume, root activity, root nodule number, nodule weight and nitrogenase activity. The effects are in the following order: NO₃^- -N and NH₄⁺ -N mixed culture the highest, followed by NH₄⁺ -N and with NO₃^--N the lowest. The impact on root average diameter was not large. The maximum values were reached by NO₃^-+N H₄⁺ with a concentration of 210 mg/L. In terms of the whole growth stage, root biomass, root surface area, root activity, root nodule number, nodule weight and nitrogenase activity were significantly different during the seedling, budding and flowering stages. However, differences during seed podding and podding were not significant.

The correlation between soil physical and chemical properties and soil microbes in different types of Nitraria dune

XI Jun-Qiang, YANG Zi-Hui, GUO Shu-Jiang, WANG Qiang-Qiang, ZHANG Jian-Hui, WANG Duo-Ze

2015, 24(6):  64-74.  DOI: 10.11686/cyxb2014315

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In order to explore soil-forming processes and to provide basic data for oasis ecological construction, a study has been undertaken that correlates soil microbes with soil physical and chemical properties in different Nitraria sand dunes in the oasis-desert ecotone of Minqin. Results showed significant differences in soil clay, silt, fine sand and coarse sand content among fixed, semi-fixed and flowing sand dunes. Soil nutrients showed a positive correlation with soil clay, silt and fine sand. However, they were negatively correlated with coarse sand. Correlations decreased with increasing soil particle size. The quantity of soil microbes in semi-fixed sand dunes was clearly higher than in fixed and flowing sand dunes. The ecotone exhibits alkaline soils. The older the sand dune the greater the content of organic matter, total nitrogen, total phosphorus, total potassium, hydrolytic nitrogen, potassium, available phosphorus and CaCO₃. In addition, soil microbes were significantly correlated with the physical and chemical properties of different ages of sand dune, especially bacteria and actinomycetes, which showed a prominent negative correlation with pH value. Soil organic matter had a significant positive correlation with the quantity of these microbes.

Soil microbial community diversity under four vegetation types in the Qilian Mountains, China

ZHU Ping, CHEN Ren-Sheng, SONG Yao-Xuan, LIU Guang-Xiu, CHEN Tuo, ZHANG Wei

2015, 24(6):  75-84.  DOI: 10.11686/cyxb2014272

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Soil microbes are an important component of soil ecosystem playing a key role in nutrient and energy cycling. The variation of soil microbial community diversity under cushion plants, alpine meadow, swamp meadow and alpine shrub along an elevation gradient in mid the altitude zone of the Qilian Mountains was measured using the BIOLOG-ECO technique.The results showed that the soil microbial activity assessed using well color development (AWCD) varied in the order: swamp meadow>alpine meadow>alpine shrub>cushion plants. Soil microbial communities in swamp meadow had the highest soil microbial activity; the carbon source utilization mode of soil microbial communities was similar under alpine meadow and swamp meadow. Correlation analysis indicated that the Shannon-Wiener index (H) was significantly correlated (P<0.05) with soil organic carbon and total nitrogen. Simpson’s (D) and Mclntosh’s (U) indices were significantly (P<0.05) correlated with soil total nitrogen. Redundancy analysis (RDA) on microbial communities constrained by different soil factors showed that soil organic carbon, soil pH and total soil nitrogen were important factors determining the rate of metabolism of carbon substrates in soils. The results of this study suggested a basis for further investigation of the relationships between vegetation diversity and soil microbial community diversity.

Effects of saikosaponin on in vitro fermentation parameters and bacterial quantity

PAN Long, NIU Jun-Li, BU Deng-Pan, DU Hong, CHENG Jian-Bo, SUN Xian-Zhi, WANG Xiu-Min, QIN Jun-Jie, YUAN Yao-Ming, ZHANG Xing-Kai

2015, 24(6):  85-91.  DOI: 10.11686/cyxb2014213

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An experiment was conducted to investigate the effects of saikosaponin (SSA) on in vitro fermentation parameters and bacterial quantity. Four treatments consisting of supplemental SSA at 0, 0.25, 0.5, and 1.0 g/kg dry matter (DM) were combined with 0.5 g total mixed ration (TMR), 50 mL basal media and 25 mL rumen fluid obtained from ruminally cannulated, lactating Holstein dairy cows. The treatments were randomly assigned to 5 of 20 incubation bottles. Cumulative gas production (GP) was continuously monitored by an automated trace gas recording system (AGRS-III, Beijing) at 39℃ during the 48 h incubation. Relative content of the bacterial community in the in vitro culture fluid was analyzed by real-time quantitative PCR. The results revealed that SSA at 0.25 g/kg could increase dry matter degradability (DMD, P=0.08), total gas production (GP, P<0.05) and the concentration of acetate, propionate and total volatile fatty acids (TVFA) (P<0.05). Adding SSA at 0.5 and 1.0 g/kg level did not affect GP kinetics and DMD, while it increased the concentration of acetate and TVFA (P<0.05). The supplement of SSA increased the relative quantity of Ruminococcus albus and Streptococcus bovis (P<0.05), but decreased the content of Prevotella brevis and Ruminobacter amylophilus (P<0.05). Therefore, SSA supplementation improved gas production, increased VFA concentrations and the quantity of major microbial species in the in vitro culture fluid, which indicates that SSA may be beneficial for the manipulation of rumen microbial fermentation in vitro.

Influence of simulated rotational grazing on the forage production of spring wheat, oats and rye in the Yellow River irrigation area

CHENG Hui, CHANG Sheng-Hua, CHEN Xian-Jiang, HOU Fu-Jiang

2015, 24(6):  92-98.  DOI: 10.11686/cyxb2012423

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Changes in the growth and nutrition content of cereals (spring wheat, oats and rye) under simulated rotational grazing utilization (SG) were studied in the Yellow River irrigation area. The results showed that under SG the forage yields of oats were 38.8% and 9.9% more than that of rye and spring wheat respectively. The total above-ground yields (grain and straw) of spring wheat and rye when used as grain production (GP, traditional utilization method) were 37.5% and 35.0% higher than when they were used as SG, while there was no significant difference in rye yields across the two utilizations. Crude protein yields of the three small grain crops were significantly higher under SG than GP. Crude fat contents of spring wheat and rye were higher under SG than GP, but crude fat yields of oats were lower under SG. Compared with GP, crude fiber contents of the three small grain crops under SG decreased by 42.9%, 53.0% and 21.9% respectively. Grazing resulted in an increase of water soluble carbohydrate contents and lower NDF, ADF and crude fiber contents when compared with GP. On the whole, the three small grain crops have higher feed evaluation scores when they were used as SG and the score of rye was highest.

Isolation and identification of low temperature-tolerant lactic acid bacteria from legume silages in Tibet

YANG Xiao-Dan, YUAN Xian-Jun, GUO Gang, CUI Zhao-Ming, LI Jun-Feng, BAI Xi, BA Sang, SHAO Tao

2015, 24(6):  99-107.  DOI: 10.11686/cyxb2014312

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The objectives of this study were to identify lactic acid bacteria with desirable attributes by isolating and identifying lactic acid bacteria (LAB) from legume silages in Tibetan Plateau. A total of 6 homofermentiative lactic acid bacteria were isolated from alfalfa (Medicago sativa) and common vetch (Vicia sativa) silage. Strains LCG9, CG35 and AG11 were identified as Pediococcus pentosaceus, strains LCG3 and LAG1 as Lactobacillus plantarum and strain LA3 as Lactobacillus curvatu. Conventional microbial identification methods and 16S rRNA sequencing analyses were used to identify different strains. The selected strains were grown in a range of conditions; temperature 5-20℃, pH 3.0-8.0 and NaCl 3.0% and 6.5%. LCG9 and AG11 grew weakly at 5℃ while LCG9 and AG11 were inactive at pH 3.0 and pH 8.0. LCG3 was identified as the best strain to use as a silage additive in Tibet due to its unique tolerance of low temperature, high lactic acid production and rapid reproductive rate.

The relationship between seasonal forage digestibility and forage nutritive value in different grazing pastures

LIANG Jian-Yong, JIAO Ting, WU Jian-Ping, GONG Xu-Yin, DU Wen-Hua, LIU Hai-Bo, XIAO Yuan-Ming

2015, 24(6):  108-115.  DOI: 10.11686/cyxb2014140

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The digestibility of dry matter in forages collected from Maqu alpine meadow, swampy meadow, Pingshan lake desert steppe of Zhangye in Gansu and temperate steppe in Xinjiang was analyzed using the nylon bag method in 5 rumen-fistulated sheep. The digestibility of forage dry matter in alpine meadow and swampy meadow in high altitude areas was significantly higher than that of herbage from desert steppe of low altitude areas. In addition, the digestibility of forage dry matter in alpine meadow and swampy meadow tended to rise in spring to a peak in June and then decline in late season, while the opposite trend was observed in Pingshan lake desert steppe of Zhangye. In contrast, the digestibility of forage dry matter in Xinjiang temperate steppe exhibited a declining trend as herbage progressed through flowering, seed set, and hay stages of growth. As expected, forage dry matter digestibility was significantly positively correlated (P<0.01) with forage crude protein (CP) content, and significantly negatively correlated (P<0.01) with ADF and NDF in alpine meadow. That is, forage growth stage was negatively correlated with CP content and DMD, but was highly positively correlated with DM, ADF, and NDF (P<0.01). The study indicated that the forage from alpine meadow in June, July and August had very high nutritional content, and is ideal to meet the energy needs of maintenance and growth, for grazing livestock.

Effects of additives and crop ratio on quality of mixed naked oat (Avena nuda) and alfalfa (Medicago sativa) silage

GE Jian, YANG Cui-Jun, LIU Gui-He, YANG Zhi-Min, BAI Xue-Mei

2015, 24(6):  116-124.  DOI: 10.11686/cyxb2014400

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This experiment evaluated the effects of two additives and of crop mix ratio on quality of silage made from mixtures of naked oats and alfalfa, in order to provide guidelines for optimisation of quality. Freshly cut herbage of naked oats and alfalfa was mixed in ratios by weight of 1∶1, 2∶1, and 1∶2 and either 0.4% formic acid (FA) or 2% sucrose (S) were added, or no additive included. The fermentation quality and nutritional composition were assessed after 60 days by measurement of sensory factors (colour, odour, texture), nutritional properties (CP, WSC, NDF, ADF, Ash), pH, volatile fatty acids, ammonia N (NH₃-N) and total N (TN), among others. For sensory characters, a 2∶1 crop mix ratio of naked oats and alfalfa resulted in better silage quality score than the other two crop mix ratios, regardless of additive, while silages with either 0.4% FA or 2% S added tended to have lower pH and had significantly lower NH₃-N than silages without additive (P<0.05). Silage made from a 2∶1 mix of naked oats and alfalfa also had higher lactic acid content (1.45%-1.83% DM) than the other two crop mix ratios (0.84%-1.14% DM), while propionic acid and butyric acid were not detected in analysis of the 2∶1 naked oats∶alfalfa crop mix, whereas these acids were detected in other mixtures. However, CP of silages increased with proportion of alfalfa from 11.9% CP at 2∶1 naked oats∶alfalfa to 14.6% CP at 1∶2 naked oats∶alfalfa. The effects of additives on silage nutritional properties were not statistically significant. However, the two additives changed volatile fatty acid profiles and resulted in a significant increase in % DM as lactic acid compared to silage without additive. In addition there was a significant decrease in % DM as acetic acid (mean 0.62%), compared to control silages (mean 1.00%) (P<0.05). In summary, silage made from a mixture of naked oats and alfalfa exhibited improved nutritional quality and the addition of either 0.4% formic acid or 2% sucrose also benefited the fermentation process and silage quality.

Effects of crop growth stage and wilting time on the feeding and fermentation quality of Italian ryegrass (Lolium multiflorum) silage

DONG Chen-Fei, DING Cheng-Long, XU Neng-Xiang, ZHANG Wen-Jie, CHENG Yun-Hui, GU Hong-Ru

2015, 24(6):  125-132.  DOI: 10.11686/cyxb2014286

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The objective of this study was to investigate the feeding and fermentation quality of Italian ryegrass (Lolium multiflorum) cut at different growth stages and wilted for various lengths of time, so as to formulate scientifically based guidelines for optimal wilting time when making silage. One Italian ryegrass variety, Musashi, was used in this study, and there were six wilting treatments (0, 1, 2, 3, 4, 5 h) at booting and flowering stages, with the feeding quality and fermentation quality analyzed. The nonstructural carbohydrate (NSC) content decreased with time during wilting, but water soluble carbohydrate (WSC) which was the main component of NSC, showed an intital increase in WSC during the first hour of wilting to a high of 10.62% after 1 h, then declined, when cut at booting stage. When cut at flowering stage the WSC content during the wilting period increased to a high of 14.46% after 3 h and then decreased. Fermentation-related data for cutting at booting stage were: pH reached its lowest point, 4.05, after 3 h and then increased; the NH₃-N content decreased with increased wilting time; the lactic acid (LA) content initially increased and then decreased, with a high point of 8.49% after 3 h. Corresponding values for cutting at flowering stage were: the pH value increased with wilting time; NH₃-N content initially increased to a high of 2.03 mg/g after 2 h wilting; the LA content decreased slowly at first to 4.56% after 3 h wilting, and then sharply decreased to 1.38% after 5 h wilting. Considering that the ideal for silage making is higher WSC and LA content and lower pH and NH₃-N content, based on these data the optimal wilting time for Italian ryegrass at booting stage would be 3 h, while at flowering stage it would be 2 h.

The effect of diet with different crude protein levels on growth performance, meat quality and serum parameters in Huai pigs

HUO Yong-Jiu, ZHAN Jin-Shun, YU Tong-Shui, ZHU Jian-Ping, ZHAO Guo-Qi

2015, 24(6):  133-141.  DOI: 10.11686/cyxb2014310

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The aim of this experiment was to study the effect of dietary crude protein level on growth performance, meat quality and serum parameters of Huai pigs. Forty-eight Huai pigs (half males and half females) with similar body weight were randomly divided into 3 groups, and fed with low (11.96%), medium (13.04%) or high protein (14.16%) diets. Each treatment group had 4 replicates with 4 pigs in each replicate. The trial lasted for 138 days. The key results were: 1) No significant difference was seen among the three groups in final body weight, average daily feed intake, average daily gain and slaughter traits. However, the ratio of feed to gain in the high protein group was significantly higher than for the remaining two groups (P<0.05); 2) The pH value, color score, driage, DM, crude protein, and ash in muscle and intra-muscular pressure showed no significant difference among the three groups, whereas the content of crude fat and cholesterol in muscle were significantly increased in the high protein group (P<0.05); 3) There was no significant difference between the three groups in fatty acid, linolenic acid or arachidonic acid levels. The content of linolenic acid in the muscle of the high protein group was significantly higher than that in the low protein group (P<0.05), while arachidonic acid content of muscle was significantly lower in the high protein group than in the remaining groups (P<0.05); 4) The serum albumin levels of animals in the low protein group were significantly higher than those of medium protein group, and blood urea nitrogen in serum tended to increase with increased protein level in the diet (P<0.1). In conclusion, the medium protein diet with 13.04% crude protein was optimal for growth performance, meat quality and serum parameters during the final stage of pig fattening.

Allelopathic effect of extracts from the fibrous roots of Coptis chinensis on Lactuca compositae, Vigna radiate and Brassica rapa pekinensis

WANG Ya-Qi, CHEN Dan-Mei, YUAN Ling

2015, 24(6):  142-149.  DOI: 10.11686/cyxb2014287

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A study has been undertaken of the allelopathic effect of extracts from fibrous roots of Coptis chinensis (ERC) on seed germination and seedling growth in Lactuca compositae, Vigna radiate and Brassica rapa pekinensis. Seeds of the three species were cultured in plates with various concentrations of ERC and germination rate, young seedling growth and related physiological indexes were measured. There was no significant effect of ERC on seed germination rate and index at low concentrations (200 mg/L), but seed vitality decreased and seedling biomass and root vitality dropped greatly. As the concentration of ERC increased to>400 mg/L, seed starch and protein hydrolyses were inhibited and the contents of free amino acids, soluble sugars and soluble phosphorus decreased, resulting in poor germination. When ERC concentration reached 800 mg/L, roots deformed concomitantly with brown color, root hair disappearance and the curling-up of root tips to leave the ERC solution. Nitrate reductase activity and chlorophyll concentration also decreased in the leaves. As a result, seedling growth was stunted. Stronger inhibition of ERC on L. compositae was observed than on V. radiate and B. rapa pekinensis. The results thus show that allelopathic chemicals contained in root exudate and residual of C. chinensis could inhibit seed germination and seedling growth in these three plants. This inhibition could result in poor growth and yield reduction of consequent crops after intensive cultivation of C. chinensis.

Research on allelopathy of aqueous extract from Tagetes patula to four garden plants

HUANG Yu-Mei, ZHANG Yang-Xue, LIU Qing-Lin, HUANG Sheng-Lan, LIU Pan

2015, 24(6):  150-158.  DOI: 10.11686/cyxb2014496

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In order to provide scientific theoretical basis for the application of Tagetes patula in the garden plants configuration, the aqueous extracts from Tagetes patula was used to search the allelopathic effects on seed germination and seedling growth of Dianthus chinensis, Achillea millefolium, Orychophragmus violaceus, Celosia cristata using petridishs with filter papers. Results showed that the aqueous extracts from Tagetes patula had significant allelopathic effects on seed germination and seedling growth of four garden plants. The aqueous extracts from Tagetes patula inhibited seed germination of D. chinensis, O. violaceus and C. cristata, on the contrary, inceased seed germination of A.millefolium in a degree. The extracts also inhibited seedling growth of D. chinensis at all concentrations, but promoted at the lower concentrations and inhibited at the higher ones the seedling growth of O. violaceus and C. cristata.The inhibition was the most intensive by treatment with 100.0 mg/mL of the aqueous extracts. Whereas, the growth of A.millefolium was promoted significantly at 12.5, 25.0, 50.0 mg/mL, and inhibited only by treatment with 100.0 mg/mL. The chlorophyll content in these four garden plants were reduced by 23.46%, 42.56%, 14.75% and 58.28%, when the aqueous extracts concentration was 100.0 mg/mL. The extracts increased the activities of peroxidase (POD) of O. violaceus and C.cristata at the lower concentration, while decreased the activities of POD at 100.0 mg/mL. The activity of POD of D. chinensis declined at all concentrations, while A.millefolium declined earlier then ascended later. The content of MDA of D. chinensis and C.cristata ascended at all concentrations, whereas A. millefolium and O. violaceus declined earlier then ascended later. It implied that T. patula had different allelopathic effects on different garden plants and “concentration effect” was found in this research.

Effects of pod pre-treatments on the germination traits of Hedysarum polybotrys seeds

SUN Yun-Bo, CHEN Xiang, CHEN Yuan, ZHOU Chuan-Meng, BAI De-Tao

2015, 24(6):  159-167.  DOI: 10.11686/cyxb2014274

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Plant pod seeds of Hedysarum polybotrys were used in a germination test in order to explore the effect of seed pre-treatment methods. Several methods, such as soaking the peeled seeds, and soaking and stewing the unpeeled seed pods for 12 h, were compared with non-soaked, dry seed pods as a control. Results under natural illumination at 18-20℃ showed that germination dynamics in all pre-treatments followed S curve patterns that fitted to a logistic equation. Germination started days 2-6 and finished days 14-19. The pre-treatments showed significant differences in germination traits. The peeled and soaking pre-treatment and the soaking and stewed unpeeled-seed pods pre-treatment delayed peak germination by two days. The peeled and soaking pre-treatment significantly expedited germination while the unpeeled and stewing pre-treatment prolonged germination duration. All the pre-treatments for 12 h significantly improved germination quality compared with the control. The control had a germination rate of 34.7%, germination power 4.0% and germination index 1.865. The results for the peeled and soaked seeds were 80.7%, 54.0% and 7.083 respectively, that for the unpeeled stewed seed pods 64.0%, 13.3% and 3.462 respectively. The results thus show that pre-treating seeds by soaking or stewing can significantly improve germination quality. Improvements were highest in the peeled pre-treatment, where seeds showed over 80% germination rate.

The phylogenetic significance of fruit structures in Chinese Peucedanum of Apiaceae

WANG Miao-Yuan, LIU Mei, CHENG Xin-Yu, WANG Yu-Ting

2015, 24(6):  168-176.  DOI: 10.11686/cyxb2014512

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The fruit structures of the sections Eleganitia, Bracteolata, Oreoselinum, and Selinoides in the genus Peucedanum were deeply studied in the paper. The results show that fruits of the genus usually have single cellular trichome. The median and lateral ribs are usually not prominent, but marginal ribs form wings. The small rib duct occurs in many taxa. Vittae are present in the furrow (1-4) and commisure (2-14), and short and drowf vittae are observed in some species. The commisure is as wide as the mericarp width and with two opposite carpophores. The endosperm is often flat at the commissural side. The spherical crystals occur in the mesocarp. The fruit structures are similar in different sections and the Peucedanum should be a more natural group, and the further study is needed to know if the genus should be divided into sections. The fruits of Peucedanum terebinthaceum differ from the other taxa, which have thick marginal wings and large vascular bundles, and it is supported here that the molecular research moved the Peucedanum terebinthaceum out from the genus.

Cloning and Expression Analysis of a Leucoanthocyanidin Reductase (LAR) Gene from Onobrychis viciifolia cv.Gansu

CHEN Chun-Yan, MA Hui-Ling, DONG Wen-Ke

2015, 24(6):  177-187.  DOI: 10.11686/cyxb2014452

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A leucoanthocyanidin reductase (LAR) gene was cloned using RT-PCR from Onobrychis viciifolia (sainfoin) cv. Gansu, and the level of LAR gene expression was analyzed in different plant organs. The LAR gene sequence from O. viciifolia cv. Gansu shared a high level of similarity (98.34% homology) with an O. viciifolia LAR gene in GenBank (accession No: HM152980). However, the coding sequence of amino acids is obviously different from those in other genera of the Fabaceae. The open reading frame (ORF) comprised 1089 bp, encoding 362 amino acid residues. The sequence of the LAR gene from the present study was submitted to GenBank with the accession number KP013623. LAR expression differed between plant organs of O. viciifolia cv. Gansu. LAR expression was highest in leaves, followed by flowers and fruit, and was lowest in stem tissues, which corresponded to concentration of condensed tannins in different organs of O. viciifolia cv. Gansu. It is inferred that LAR gene expression is in some way involved in condensed tannin accumulation in O. viciifolia cv.Gansu. These results provide fundamental information and a method for exploring the regulation mechanism of condensed tannin accumulation.

Relationship between arbuscular mycorrhizal fungi and individual plant and their effects on plant productivity and species diversity of plant community

YANG Gao-Wen, LIU Nan, YANG Xin, ZHANG Ying-Jun

2015, 24(6):  188-203.  DOI: 10.11686/cyxb2014316

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Arbuscular mycorrhizal fungi (AMF) are important components of terrestrial ecosystems, able to form mycorrhizal symbioses with about 80% of all terrestrial plant species. AMF play an important role in determining plant diversity and productivity through their influence on plant nutrient uptake and the ability to mediate plant-plant interactions. We reviewed the literature on AMF to identify the research gaps concerning the relationships between AMF and individual plants, interplant plant interactions and plant diversity and productivity focusing on three aspects. Firstly, we analyzed AMF-plant interactions and the factors influencing these interactions and developed a conceptual model illustrating the effect of soil available phosphorus levels on the mycorrhizal contribution to plant growth. Secondly, we summarized the effects of AMF on plant-plant interactions and seedling recruitment. Thirdly, we analyzed the effects of AMF on plant diversity and productivity, and developed two conceptual models to predict the effects of soil nutrient levels on the mycorrhizal contribution to plant diversity and productivity. Our results could be applied to forage production and grassland management to provide scientific support for the introduction of AMF when establishing pasture and for conservation biodiversity in native grassland. Suggested research priorities are outlined.

Effects of nitrogen input on CH₄ production, oxidation and transport in soils, and mechanisms: a review

HU Min-Jie, TONG Chuan, ZOU Fang-Fang

2015, 24(6):  204-212.  DOI: 10.11686/cyxb2014313

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Methane is an important component of carbon output in anaerobic soil. Minor changes to the soil carbon cycle will cause significant changes in the metabolic processes involving methane, which in turn can be markedly affected by exogenous nitrogen input. With increase in anthropogenic nitrogen inputs, exogenous nitrogen becomes an important factor in soil methane production, oxidation, and transmission processes. Methane emissions are regulated by nitrogen availability. Nitrogen inputs can change the background environment and methane emission mechanisms in soil, and consequently influence methane emission fluxes. Research into effects of nitrogen input on CH₄ production and the mechanisms of N effects on oxidation and transport processes in soils are reviewed in this paper. The important findings in the literature are: 1) The effects of nitrogen input on CH₄ fluxes in soils can be positive, negative or neutral, due to the range of effects of added N on methane production, oxidation, and transport processes; 2) The effects of nitrogen input on methane production processes are controlled by methanogenic substrates and methanogenic microbial activities. Nitrogen input provides rich substrates for methane production by increasing soil organic carbon content. The changes in the physical and chemical properties of substrates and vegetation cover make this effect complicated. Nitrogen input can also either promote or inhibit the activity of methanogens, depending on the form of nitrogen supplied; 3) The effects of nitrogen input on methane oxidation processes mainly arise from stimulation or inhibition of the activities of methanotrophs; 4) The effects of nitrogen input on methane transport processes depend mostly on the number of aerenchyma vessels and on transport efficiencies, and the degree of dependence varied greatly in different ecosystems. Overall, the effects of nitrogen input on soil CH₄ production, oxidation, and transport process are complicated and the mechanisms are uncertain. Future research should focus on the effects of nitrogen input on the critical processes determining methane emissions, on investigation of the effects of nitrogen input on microbial community structures, abundance and activities, and on collaborative research in a range of ecosystems. The goal of future research should be to determine the contribution of various ecosystems to global methane emissions at specific levels of nitrogen input.

Seasonal change patterns in the production and mortality of fine roots in cotton and alfalfa

REN Ai-Tian, LU Wei-Hua, YANG Jie-Jing, MA Chun-Hui

2015, 24(6):  213-219.  DOI: 10.11686/cyxb2014319

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Roots have two functions, “source” and “sink”, which are important for substance and energy exchange between plants and soil. Understanding these processes requires studies of the dynamics of fine root growth and mortality. This study reports on the growth, death and turnover of fine roots in cotton (Gossypium hirsutum) and alfalfa (Medicago sativa) using minirhizotron techniques over different seasons. The fine root growth rate [G, cm/(cm³·d)], death rate [M, cm/(cm³·d)] and the ratio of growth to death (R) were determined. Results showed that the average standing crop of cotton in the growing season is 8.0 mm/cm³, with that of alfalfa being 14.8 mm/cm³ in 2011 and 8.0 in 2012. The average G and M of cotton in the growing season are 0.056 and 0.011 mm/(cm³·d) respectively, with those of alfalfa being 0.026 and 0.007 mm/(cm³·d) in 2011 and 0.041 and 0.028 in 2012. The G of cotton decreased rapidly from the end of May to mid-July, increased from mid-July to early September and then decreased. The G of alfalfa showed a consistent trend in 2011 and 2012, peaking from mid-June to mid-July and from early August to early September. The M of both cotton and alfalfa decreased from mid-June to mid-July and then increased to reach the maximum by the end of the growing season. The R of cotton and alfalfa decreased gradually from May to October, with cotton R>1 and alfalfa R<1. The estimated turnover rate is different according to whether it is calculated in terms of maximum or mean biomass. Mean biomass calculations increased turnover rates by about 22% compared with maximum biomass. During the growing season, the standing crop and G of cotton and alfalfa showed unimodal and bimodal peaks respectively, but the M of both rose continuously. At same time, cotton had a higher turnover rate to meet water and nutrient requirements.

Evaluation of the nutritional value of goat forages in Shandong Province

YUAN Cui-Lin, YU Zi-Yang, WANG Wen-Dan, ZHU Feng-Hua, WANG Li-Hua, LIN Ying-Ting, YU Jing-Jing, LI Bin

2015, 24(6):  220-226.  DOI: 10.11686/cyxb2014280

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This experiment was conducted to evaluate the nutritional value of common forages fed to goats sampled from 17 cities in Shandong Province. A total of 109 samples from 10 species were used to analyze common forage value and gross energy (GE). Forage attributes measured included in vitro dry matter digestibility (IVDMD), digestible energy (DE), metabolizable energy (ME) and crude protein (CP). An acceptability index of all forages was calculated using voluntary dry matter intake. The results revealed that the nutritional value of goat forage cannot be accurately evaluated by conventional nutrient analysis. Digestible energy was highest in alfalfa hay followed by Secale cereale hay, sweet potato vine, Chinese wild rye, peanut stem, corn stalk silage, dried corn stalk, rice straw, soybean straw and wheat straw. IVDMD and DE were significantly negatively correlated with NDF and ADF, while IVDMD was positively correlated with CP.