Table of Content

20 June 2017, Volume 26 Issue 6

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Analysis of change in grassland area in the Heihe River basin over the past 30 years and prediction of future trends

ZHAO Yu-Hao, RONG Zhan-Lei, ZHANG Yu-Feng, YE Miao, JIANG Hui, ZHAO Chuan-Yan

2017, 26(6):  1-15.  DOI: 10.11686/cyxb2016294

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Grassland, is one of the most widespread vegetation types in the world, and accounts for nearly 20% of the global land surface. China has abundant grassland resources, and the second largest grassland area of any country. However, in recent years, China’s grassland ecosystem has suffered dramatic impairment through human activities and climate change. Grassland in the Heihe River Basin provides necessary resources for the livelihood of local communities. It is therefore important to monitor grassland change. In this study, we assessed historical grassland cover in Heihe River Basin using GIS technology and evaluated land use and land cover change (LUCC) since 1986. We also predicted the future grassland distribution pattern using a CA-Markov Model and land-use transfer matrix, reflecting change in spatial distribution and metabolic indices of grassland. In 1986, the total area of grassland in the Heihe River Basin was 32998 km², of which 4290 km² were classed as having high coverage, 6372 km² were classed as having medium coverage and 22336 km² were classed as having low coverage. In 2000, the grassland area was 23939 km², and areas with high, medium and low coverage were, respectively, 5509, 5540 and 12891 km². In 2011, the grassland area was 24273 km², and areas with high medium and low coverage were, respectively, 5561, 5715 and 12996 km². During the period 1986-2000, the area of grassland in the Heihe River Basin was considerably reduced and severe degeneration occurred. During this period, there was substantial transformation of grassland from high to medium coverage, from medium to low coverage, and from low coverage to unutilized land. During the period 2000-2011, the grassland area in Heihe River Basin increased slightly and transition between the three coverage classes was small. Finally, in 2022 the predicted grassland area of the Heihe River Basin is 24450 km² with, respectively, 5560, 5658 and 13232 km² with high, medium, and low coverage, respectively.

Retrieval of soil moisture information in Xinjiang using MODIS

LI Hai-Xia, YANG Jing, CHEN Ya-Ning, HAO Xing-Ming

2017, 26(6):  16-27.  DOI: 10.11686/cyxb2016331

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MOD13A2, MOD11A2 and field measurements were utilized to study soil moisture variation in Xinjiang during May and June. Relationships between NDVI (Normalized Difference Vegetation Index) and Ts (Land Surface Temperature), and EVI (Enhanced Vegetation Index) and Ts were investigated. The spatial pattern of the temperature vegetation dryness index (TVDI) and influencing factors were analyzed. Results: (1) NDVI-Ts and EVI-Ts follow the classic triangle relationship. (2) Soil moisture in Xinjiang was mainly dominated by drought conditions (0.6<TVDI<0.8); Spatially, Alta, the middle slope area of the Tianshan Mountains, and the south slopes of the Kunlun Mountains are characterized by extremely wet conditions, while the north Junggar basin and southern Tarim Basin are dry. (3) The TVDI of forested land was lowest in May while the TVDI of grassland was lowest in June; soil moisture generally increased with elevation. (4) For regions with high vegetation coverage, EVI based TVDI is more suitable than NDVI based TVDI for drought monitoring. (5) The land surface temperature was better able to reflect drought conditions compared to vegetation index.

A study of grazing intensity in the Hulunbuir grasslands using remote sensing

WANG Meng-Jia, SUN Rui, LIU Zhe, XIN Xiao-Ping, LIU Gang, ZHANG Lei, QIAO Chen

2017, 26(6):  28-36.  DOI: 10.11686/cyxb2016316

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The Hulunbuir meadow steppe, located in northeast China, is an important site for animal husbandry. The potential to further develop animal husbandry in this region is closely related to the growth of grass and to sustainable utilization of grasslands more generally. As a critical component of the grassland ecosystem, the intensity of grazing has become an important issue. In this study, remote sensing data, based on Landsat images, and Net Primary Productivity (NPP) data were collected from June to July 2014 and used to estimate grazing intensity in Xeltala pastures. Multi-image Landsat optical data was used to calculate aboveground biomass and biomass increments, while the NPP data was used to analyze grass growth. Unlike previous studies, this analysis used NPP data to take account of the heterogeneity of grassland conditions. The results indicate that this method is capable of accurately estimating grazing intensity, with a R² of 0.7996 when validated by measurements on the ground. Grazing intensity in the Xeltala pastures ranged from 1 to 2.5 Au/ha, with the latter being over-grazed. The local map suggested that heavy grazing areas were distributed around a small lake and in certain locations where abundant grass favoured concentrations of cattle. Light grazing areas, on the other hand, were located in enclosed places where the grass was reserved for winter supplies. Extending the study area to include the city of Hailaer, the grazing intensity map clearly demonstrated the variations between areas of light, moderate and over-grazing, with Hailaer in the southwest appearing as extremely lightly grazed compared to the northeastern meadows.

Responses of soil respiration to extreme low temperature and hydro-thermal factors in dryland region with different cropping patterns in southwest China

ZHOU Quan, XING Yi, MA Shu-Min, ZHANG Xiao-Duan, CHEN Jiao, SHI Chao, WANG Long-Chang

2017, 26(6):  37-44.  DOI: 10.11686/cyxb2016377

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An increased frequency of extreme climate events is one of the important characteristics of global climate change. Extreme low temperatures not only affect agricultural production, but also affect agricultural carbon emissions. Soil respiration, is the main source of agricultural carbon emission. However, there has been a lack of detailed study of soil respiration at extremely low temperatures. Through measuring soil respiration and hydro-thermal factors under low temperature in winter, we analyzed the response characteristics of soil respiration in the extreme low temperature environment. There were 6 treatments: TA (no straw mulching+Chinese milk vetch monoculture), TR (no straw mulching+rape monoculture), TAR (no straw mulching+rape intercropping with Chinese milk vetch), SA (straw mulching+Chinese milk vetch monoculture), SR (straw mulching+rape monoculture), SAR (straw mulching+rape intercropping with Chinese milk vetch). Results showed, soil respiration and root respiration reached to maximum in the SAR treatment. Chinese milk vetch significantly increased the soil temperature, soil moisture and soil electrical conductivity in the depth of 10 cm. In addition, compared with ordinary low temperature environment, the extreme low temperature environment decreased significantly the soil respiration and root respiration, increased significantly the temperature sensitivity of soil respiration (Q₁₀ value) from 0.31 to 1.19, and changed the relationship between soil respiration and soil electrical conductivity. At the same time, the proportion of root respiration in the TA and TAR treatments were increased by 12.07% and 8.15%, however, the proportion of root respiration in the SA, SR and SAR treatments were decreased by 28.55%, 38.87% and 24.80%.

Returning effects on tobacco potassium uptake and soil potassium availability in grain amaranth-tobacco intercropping system

WU Kai, CHEN Guo-Jun, YAN Hui-Feng, ZHANG Yong-Chun, WEN Liang, ZHANG Chao, SUN Yan-Guo, LIU Hai-Wei, SHI Yi

2017, 26(6):  45-55.  DOI: 10.11686/cyxb2016456

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Two field experiments were conducted to explore the influence of grain amaranth (Amaranthus hypochondriacus) and tobacco intercropping on tobacco growth and potassium uptake during 2014 and 2015. The experiment during 2014 included three treatments, (a) planting tobacco only; (b) tobacco and amaranth intercropping, amaranth was cut and burried into soil after 45 day growth; (c) tobacco and amaranth intercropping, but did not cut and burry. There were 4 treatments during 2015, (d) planting tobacco only; The other 3 treatments were all tobacco and amaranth intercropping, (e) one row of tobacco with 2 rows of amaranth; (f) one row of tobacco with 4 rows of amaranth; (g) one row of tobacco with 6 rows of amaranth. We analyzed tobacco dry matter accumulation, tobacco potassium concentration, potassium uptake, soil available potassium and soil slow-release potassium in the three intercropping systems. The results showed that, compared with treatment (a), amaranth intercropping without returning to the field (treatment c) increased dry matter accumulation in tobacco roots. Potassium concentration showed no significant changes, while potassium content increased by 70%. Dry matter accumulation reduced by 11% and 14% respectively in stem and leaves, while potassium contents were 0.11% and 0.12% lower and potassium concentration 16% and 12% lower. For the treatments with amaranth returning to the field, the highest potassium concentration in leaves was recorded. The different intercropping systems showed different amounts of dry matter accumulation, potassium content and potassium concentration. Dry matter accumulation and potassium contents in root, stem, upper leaves and middle leaves increased in the 2 rows (e) and 4 rows (f) treatments and decreased in the 6 rows (g) treatment. Dry matter accumulation in the upper and middle leaves was lower in treatment (e) than (f), but the former's potassium concentration and potassium content were higher. The concentration of soil available potassium in the tobacco rows increased in the intercropping systems, but the concentration of soil slow-release potassium did not change. The intercropping systems without grain amaranth returning showed lower soil available potassium concentrations than those with amaranth returning. Among the treatments in the amaranth returning system, the growth in soil available potassium was largest in treatment (g), which increased by 91% and 35% when returned after 20 and 60 d respectively. Soil available potassium increased by 54% and 23% in (f) over these periods. The analysis of apparent potassium flow showed different results for the various amaranth returning systems. About 42%-52% of potassium was uptaken by the tobacco in treatments (e) and (f), while only some 17% was absorbed in treatment (g). This study suggests that the most favorable planting pattern is the amaranth-tobacco intercropping system with 2 rows of amaranths and returning amaranth to the field after 45-55 d growth.

Effect of drying-wetting condition on attenuation-recovery of soil shear strength of bio-embankment on sloping farmland comprising purple soil

DING Wen-Bin, HE Wen-Jian, SHI Dong-Mei, JIANG Guang-Yi, JIANG Ping, CHANG Song-Guo

2017, 26(6):  56-67.  DOI: 10.11686/cyxb2016298

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During rainfall the soil in bio-embankments undergoes a drying-wetting-re-drying process which may potential influence the shear strength and stability of bio-embankment soil. This study investigated the attenuated recovery of soil shear strength in a mulberry bio-embankment under drying-wetting conditions. The main purpose of the study was to undertake a comprehensive study of mulberry hedge root distribution before and after rainfall (rainfall 0-9 d), the wetting and drying process in bio-embankment soil, physicochemical changes and the influence of roots on soil shear strength. The results show: (1) Roots with root diameter ≤1 mm were concentrated at shallow depths (0-20 cm), while the roots with 2 mm <root diameter≤5 mm were mostly found at 20-40 cm soil depth. (2) There were significant differences (P<0.05) in soil bulk density, soil porosity and soil water of different vertical layers before and after rainfall. In the 30-40 cm soil layer soil bulk density increased after a dry-wet cycle by 5.47%-5.88%, reaching a maximum value 5 days after wetting (1.39, 1.37, 1.44 g/cm³). Soil porosity initially increased and then decreased during a dry-wet cycle. (3) Soil cohesion and internal friction angle responded to an increase in soil water content; initially there was a large decrease in both traits. The correlation between cohesion and soil water content was 0.68, and the correlation between internal friction angle and soil water content was 0.73. (4) Mulberry root diameter classes influenced soil cohesion, internal friction angle and shear strength. Root length density and root surface area density were significantly, positively correlated. Soil cohesion and internal friction angle showed a linear decreasing trend with increasing soil water content. Bio-embankments can improve soil structure, soil aeration, soil nutrient content and reduce soil bulk density, and increase soil porosity, crop growth, development and yield on sloping land.

Examination and comparison of the physiological characteristics of ten Calligonum species in a desert environment

PAN Hang, FENG Ying, WANG Xi-Yong, LI Yan

2017, 26(6):  68-75.  DOI: 10.11686/cyxb2016334

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Desertification is a serious issue and especially so in Xinjiang, where it is a significant threat to ecosystem security. As plants play an important role in the prevention and control of desertification, screening suitable species for restoration projects is an important task. Calligonum is a dominant species in the desert region of Xinjiang and its resistance to drought and salt stress has been thoroughly researched. However, there are few quantitative analyses comparing the resistance of different Calligonum species. In this study, ten Calligonum species grown in the Turpan desert botanical garden were selected and their physiological characteristics analysed. Seven physiological indexes were measured. Species’ differences were examined using variance analysis, while their resistance was evaluated using principal component analysis. The results showed that the species’ physiological indexes in the same habitat showed significant differences (P<0.01). Superoxide dismutase (SOD) and peroxide enzyme (POD) contents were the lowest for C. caput-medsae, C. arborescens and C. pumilum, all of which showed poor resistance. Proline content was the highest for C. junceum, with strong resistance. H₂O₂ content was the highest for C. pumilum, which is not conducive for normal cell metabolism. The combined resistance analysis produced the following species’ order: C. junceum>C. ebi-nurcum>C. densum>C. leucocladum>C. klementzii>C. cordatum>C. rubicundum>C. arborescens>C. caput-medsae>C. pumilum. Calligonum species have different resistance mechanisms with different protective enzyme contents. These results are confirmed by the ecological distribution of Calligonum in Xinjiang. This experiment thus provides a scientific basis for screening and introducing Calligonum species to remedy desert conditions.

Initial assessment of sixteen perennial grass species in the upper Datong River

JING Mei-Ling, MA Yu-Shou, LI Shi-Xiong, WANG Yan-Long

2017, 26(6):  76-88.  DOI: 10.11686/cyxb2016388

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To identify potentially suitable gramineae species which could be used to enrich grassland on recovering black-soil flood zone in the upper Datong River in the Qilian Mountains, Qinghai Province, 16 forage species suitable for cultivation on the Tibetan Plateau were assessed in 2012. Phenology, yield and nutritional value of all species were studied in a replicated trial arranged in a randomised block design over a 3 year period. Phalaris arundinacea Sp.Pl. was not able to survive the winter. Elymus sibiricus cv. Qingmu No.1, E. sibiricus cv. Tongde, E. sibiricus cv. chuancao No.2 were unable to completed their life cycles. Among the remaining species, the aboveground biomass was highest in E. sibiricus cv. Qingmu No.1 (479.13 g/m²) followed by Elymus nutans cv. Aba. The seed yield of E. nutans cv. Aba was higher than that of any other species (98.30 g/m²). Forage quality, Kengyilia thoroldiana had high nutritional value in 2013-2014. Thus, the height, aboveground biomass, underground biomass, seed yield and quality of 15 forage species were analyzed by membership function. E. nutans cv. Aba, Poa pratensis var. anceps cv. Qinghai, Poa pratensis cv. Qinghai, Festuca sinensis cv. Qinghai and Elymus sibiricus cv. Tongde were identified as the most useful species; they adapted well to environmental conditions in the upper Datong River.

Effects of gibberellin on the germination of Reaumuria soongorica seeds under salt stress

NIU Song-Fang, WANG Li-Juan, LIU Bing-Ru

2017, 26(6):  89-97.  DOI: 10.11686/cyxb2016288

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Reaumuria soongorica, an extreme xeric shrub and a dominant species in desert and semi-desert areas, has low levels of reproductive through germination. This shrub could be an important species for vegetation restoration and the improvement of eco-environments in western China. A study has been undertaken to investigate the effect of interactions between gibberellin (GA) and different salinity conditions on seed germination in R. soongorica. Using petri dish techniques, the treatments studied were germination under H₂O (control), various concentrations of NaCl to explore saline stress (100, 200, 400, 600 mg/L; treated group 1), a range of GA concentrations (50, 100, 150, 200, 250, 300 mmol/L, treated group 2) and their combined interaction (treated group 3). The results showed that seed germination percentages continuously decreased with increasing salinity, while germination uniformity increased with rising salt levels. With increasing NaCl concentrations, the length of the R. soongorica’s radicle and germ gradually decreased, and radicle length significantly decreased (R²=0.9452). With increasing concentrations of GA, germination percentage, the germination index and germination speed all at first decreased and then increased, with a threshold reached at 200 mg/L. With NaCl concentrations of more than 50 mmol/L, germination energy gradually decreased with increasing GA applications. There were no significant differences between the length of R. soongorica’s radicle and germ under different concentrations of GA. This research shows that while salt stress inhibits seed germination, GA enhances the germination percentage and index under highly salt-stressed conditions (more than 100 mmol/L). GA applications could thus be used to promote the establishment and growth of R. soongorica in desert and semi-desert regions.

Effects of nitrogen application on seed yield and nitrogen accumulation in alfalfa (Medicago sativa)

CHEN Ling-Ling, REN Wei, MAO Pei-Sheng, WU Ren-Tu-Ya, WANG Sheng-Nan, LIANG Qing-Wei

2017, 26(6):  98-104.  DOI: 10.11686/cyxb2016265

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To investigate nitrogen (N) uptake, N fertilizer management and N utilization in alfalfa (Medicago sativa) seed crops a field experiment with four N treatments (0, 45, 90, and 135 kg N/ha) and two alfalfa cultivars, Aohan and Gongnong No.1 was established to compare the effects of N application on seed yield, seed quality, N harvest index and the dynamics of N accumulation and distribution in alfalfa plants. The results showed that the seed yield and N harvest index were decreased while the pod setting rate, seed weight per plant, 1000 seed weight and seed quality of both cultivars were increased with increased N application. The dynamic changes of N accumulation and distribution were influenced by cultivar. The optimum N application rate for Aohan was 45 kg N/ha at the budding stage and 90 kg N/ha at the podding stage whereas the optimum N application rate for Gongnong No.1 was 45 kg N/ha at flowering stage and 45 kg N/ha at podding stage. The initial results confirmed the value of N fertilizer application and the regulation of N fertilizer requirements in alfalfa seed crops in the Chifeng area, and provided useful information for the determination of appropriate N fertilizer use in alfalfa seed crops.

Construction of RNAi expression vector of CYP86A gene in halophyte Puccinellia tenuiflora

WANG Pei, CUI Yan-Nong, GAO Li, WANG Suo-Min

2017, 26(6):  105-110.  DOI: 10.11686/cyxb2017076

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The salt-excluding halophyte Puccinellia tenuiflora exhibits a highly suberized endodermis in the root, which may contribute to its salt tolerance. In this study, the RNAi target fragment of CYP86A, a key gene in suberin biosynthesis, was amplified by RT-PCR from roots of P. tenuiflora seedlings under salt stress. Then based on the intermediate vector pHANNIBAL and the plant expression vector pART27, the RNAi plant expression vector pARC, which contained inverted repeats of PtCYP86A and was driven by the 35S promoter, was constructed successfully by restriction enzyme digestion, ligation and In-Fusion cloning. The work might be a good basis for further investigating the roles of roots suberization in Na⁺ exclusion in P. tenuiflora by RNAi technique.

Genome-wide identification and characterization of the cinnamyl alcohol dehydrogenase gene family in Zoysia japonica

SHI Jing-Ang, ZHANG Bing, XIAO Xiao-Lin, MA Jing-Jing, YANG Xiang-Yang, LIU Jian-Xiu

2017, 26(6):  111-119.  DOI: 10.11686/cyxb2016442

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Cinnamyl alcohol dehydrogenase (CAD, EC1.1.1.195) is a key enzyme in the lignin biosynthesis pathway. By using NADPH as a cofactor, CAD catalyzes cinnamyl aldehydes to alcohols and plays an important role in plant development and stress responses. This study identified 16 CAD genes in Zoysia japonica. Phylogenetic and structural analyses of these genes were conducted. Semi-quantitative RT-PCR indicated that 5 ZjCAD genes were specifically expressed in leaves. Lignin histochemical staining and expression analyses of ZjCAD genes in different cultivars and a wild accession further showed that the expression pattern of ZjCAD6 was positively correlated with leaf lignin contents. These results indicate that ZjCAD6 may be the key gene that regulates lignin biosynthesis in the leaves of Z. japonica. The full length of the ZjCAD6 gene is 2736 bp, and is comprised of three introns and four exons. The 1074 bp open reading frame of ZjCAD6 encodes 357 amino acids. ZjCAD6 protein contains two Zn²⁺-binding motifs and a NADP(H)-binding motif, which is vital for its catalytic activity. Our results provide an important reference for further study of both lignin content's molecular mechanisms and the tensile strength of Z. japonica leaves.

Influence of Scrophularia ningpoensis-tobacco intercropping on bacterial community structure in soil

ZHANG Dong-Yan, WANG Jun, YANG Shui-Ping, ZHANG Xue, LIU Jing, ZHAO Jian, HE Da-Min, YANG Hong-Jun, MO Jing-Jing, GOU Jian-Yu, ZHAO Xin-Mei, JIANG Wei, DING Wei, CHEN Da-Xia

2017, 26(6):  120-130.  DOI: 10.11686/cyxb2016507

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To explore the influence of Scrophularia ningpoensis and tobacco planting on bacterial community structure in soil under different planting patterns, we used Illumina MiSeq technology to identify bacteria in soil. It was found that the richness and diversity of bacterial species in S. ningpoensis soil tended to be higher than in tobacco soil, but differences were not statistically significant. Crop species and planting pattern both affected the abundance and the order of dominant bacteria. At phylum level, presence of Saccharibacteria in tobacco soil was significantly higher than that in S. ningpoensis soil, whereas presence of Gemmatimonadetes in S. ningpoensis soil was significantly higher than that in tobacco soil. Bacteroidetes occurrence also varied between different planting patterns. At genus level, taxa significantly more common in tobacco soil than in S. ningpoensis soil, included unclassified Xanthomonadaceae, norank Saccharibacteria, uncultured Gaiellales, and norank SC-I-84. Meanwhile, for S. ningpoensis soil, significantly more common taxa (than in tobacco soil) included norank GR-WP33-30, norank JG30a-KF-32, Gemmatimonas, Candidatus_Solibacter, uncultured Nitrosomonadaceae, norank C0119, norank Subgroup_6, norank DA101_soil_group, norank BIrii41, Anaeromyxobacter, unclassified Xanthomonadales, uncultured Methylophilaceae, and norank JG37-AG-20. Planting pattern had almost no effect on genera detected. Principal component analysis also showed that crops had a greater influence than planting patterns. In summary, soil bacteria community structure differed between tobacco and S. ningpoensis crops, and was also affected to a lesser extent by planting pattern. Hence, in an intercropped field the microbial community displays spatial heterogeneity determined by the crop species.

Microbial composting and detoxification of Ageratina adenophora

YANG Hong-Jun, DU Ru-Wan, WU Ye-Kuan, WAN Jian, WANG Yong, ZHAO Jiang, LIANG Yong-Jiang, ZHANG Chang-Hua, YUAN Ling

2017, 26(6):  131-138.  DOI: 10.11686/cyxb2016308

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Ageratina adenophora, the most harmful invasive plant in China, is toxic to animals, plants, and microbes. This paper describes work to develop a technique for composting A. adenophora in situ and evaluation of the decomposition effect to provide information on the effective elimination and resource utilization of this harmful plant. This study investigated the composting of Ageratina adenophora using incubation with Pseudomonas putita, Clostridium thermocellum, addition of urea and CaSO₄, and covering the stack with plastic film. Biological toxicity was evaluated at the end of bio-composting. The high temperature period (50.0-64.5 ℃) lasted for 22 days and detection of toxin in petroleum ether extracts decreased from 3.15 g/kg to 0.37 g/kg. After 80 days of bio-composting, and A. adenophora plant material was well decomposed. The compost contained 8.42% humic acids. The pH, organic matter and heavy metal concentrations of the compost matched the NY/525-2011 state standard. No effects on growth in wheat were detected following gavage of A. adenophora compost extract (ACE) with a large amount of water. Similarly, no pathologic changes in the main organs (heart, liver, kidney and lungs, mice) were detected either. Wheat seed germination, seedling vigor index and seedling height were increased by 8.65%, 28.79% and 23.69%, respectively compared with control (water soaked) seeds, when seeds were soaked seeds with ACE. In an incubation experiment, addition of bio-compost into soil increased microbial biomass carbon and nitrogen, and dehydrogenase activity compared with with untreated soil used as a control or soil which had received a chemical fertilizer treatment. This indicates that ACE promoted microbial growth, reproduction, and activity of soil. In summary, bio-composting successfully decomposed and detoxified A. adenophora herbage, and was able to produce organic fertilizer for agriculture, thereby effectively and economically eliminating and utilizing this invasive plant.

Biological characteristics of the Angelica sinensis anthracnose causal agent, Colletotrichum dematium

YANG Cheng-De, BIAN Jing, CHEN Tai-Xiang, CHEN Xiu-Rong, WANG Han-Qi, YANG Xiao-Li, WANG Yang

2017, 26(6):  139-144.  DOI: 10.11686/cyxb2016295

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The biological characteristics and substrate requirements of Colletotrichum dematium were studied using traditional culture techniques to provide a basis for understanding the occurrence of outbreaks of Angelica sinensis anthracnose. It was found that the temperature range over which mycelium growth and conidial germination of C. dematium occurred was from 10 ℃ to 35 ℃, with an optimum temperature of 25 ℃. Mycelium growth occurred from pH 5 to pH 12, and the optimum pH value was 11. Conidia were produced from pH 8 to pH 11, and the optimum pH value for conidia production was 10, while the optimum for conidial germination was pH 7. The mycelium of C. dematium grew best on media with more abundant carbon and nitrogen supply, but were inhibited by mannitol, D-galactose and chloralose. Mycelium growth and conidial germination were not sensitive to light. Conidia required a relative humidity of 95% or more for germination, and liquid water was the most suitable medium for conidial germination (P<0.05). Sucrose solution promoted conidial germination, but potato solution inhibited germination.

Screening of inhibitory bacteria for prevention and treatment of fungal diseases of Medicago sativa

HU Jin-Ling, WANG Zhi-Gang, XU Na, DANG Shu-Zhong, LI Yan-Zhong

2017, 26(6):  145-152.  DOI: 10.11686/cyxb2016293

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The inhibitory effect of two bacteria on 9 alfalfa pathogens were tested on PDA medium using the confrontation method; the taxonomic status of each pathogen species were determined using morphological and molecular criteria. The bacteria identified were Bacillus amyloliquefaciens and Streptomyces kanamycin. The inhibitory effect of Bacillus amyloliquefaciens ranged from 24.02%-71.11%, with the greatest effect shown against Cercospora medicaginis (71.11%), Stemphylium botryosum (64.76%) and Fusarium roseum (60.55%). The inhibitory range of Streptomyces kanamycin was similar (49.95%-76.90%) with greatest effect against Colletotrichum trifolii (76.90%), Phoma medicaginis (70.94%), Stemphylium botryosum (68.01%) and Leptosphaerulina briosiana (60.99%). Bacillus amyloliquefaciens and Streptomyces kanamycin showed varying degrees of antagonism to different alfalfa pathogenic fungi indicate that they have promise as biological control agents for a variety of Medicago sativa foliar diseases, suggesting further development should be undertaken.

Analysis of the degradation of corn stalk fermented by complex bacteria composed of two Bacillus amyloliquefaciens strains

LI Hong-Ya, LI Wen, LI Shu-Na, WANG Shu-Xiang, LI Meng, TIAN Miao-Miao, ZHU Bao-Cheng

2017, 26(6):  153-167.  DOI: 10.11686/cyxb2016498

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In order to obtain a complex bacteria agent that can be used in the fermentation of corn stalk and improve its quality as silage, two Bacillus amyloliquefaciens strains with high lignocellulose-degrading ability were mixed to make a complex agent whose degradation effect could be studied. The microstructure and degradation products of corn stalk inoculated with the complex bacteria agent were analyzed using FTIR, ¹H-NMR, SEM and GC/MS. Fermentation tests showed that the microbial agent efficiently degraded lignocellulose in corn straw. When the agent was inoculated for 24 days, the degradation rate of lignin, cellulose and hemicellulose reached 48.4%, 30.5% and 41.4% respectively. FTIR and ¹H-NMR spectrum analysis showed that the main linking covalent bonds, such as β-O-4 and β-β linkages between the lignin monomers, the bonds connecting the lignin to cellulose and the carbohydrate bonds in lignocellulose’s molecular structure, were all broken. The complete destruction of plant tissue structure was also observed with electron microscope scanning. GC/MS analysis of low-molecule substances in the fermented corn stalk showed that the lignin was degraded into small molecular aromatic compounds, including amphetamine and phenylpropionic acid, monomers produced by the depolymerization of lignin, and benzyl alcohol and benzoic acid esters, which are degradation products of lignin phenyl propane monomers. GC/MS analysis of carbohydrate degradation products showed that the complex bacteria could not only convert cellulose, hemicellulose and other macromolecule carbohydrates into reducing monosaccharides, such as glucose, xylose, mannose and galactose, but that it could also metabolize these monosaccharides into glycol, glycerol and short-chain fatty acids. In conclusion, these results show that the complex bacteria agent effectively degrades lignocellulose and could be widely used to convert corn stalk into high quality forage.

Evaluation of energy requirement in Gansu Alpine Fine-Wool pregnant ewes

ZHANG Chang-Ji, LI Cheng, ZHANG Yong, GUO Wu-Jun, ZHANG Li-Ping, GUN Shuang-Bao

2017, 26(6):  168-175.  DOI: 10.11686/cyxb2016301

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Combining the dry matter intake, nutrients digestibility and production data in seasonal pastures, the factorial method was used to estimate the energy and protein requirements of Gansu Alpine Fine-Wool sheep ewes. It was found that ewes’ metabolic energy requirement for maintenance was 6.58 MJ/d, and the protein requirement for maintenance was 108 g/d. Metabolic energy requirement for early pregnancy ewe was 12.54 MJ/d, crude protein requirement was 125 g/d, while metabolic energy requirement for late pregnancy ewe was 12.86 MJ/d, and the crude protein requirement was 146 g/d. Calcium, phosphorus and salt requirements of ewes were, respectively, 8.22-9.61 g/d, 4.98-5.87 g/d, and 9-16 g/d, respectively.

Isolation and identification of facultatively anaerobic cellulolytic bacterium in the rumen of Tibetan yaks (Bos grunniens)

LI Jun-Feng, YUAN Xian-Jun, DONG Zhi-Hao, Seare Tajebe Desta, CHEN Lei, BAI Xi, BAI Yun-Feng, SHAO Tao

2017, 26(6):  176-184.  DOI: 10.11686/cyxb2016315

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This study aimed to isolate and identify facultatively anaerobic cellulolytic bacterium in the rumen of yaks and to provide a basis for studying new types of silage additives. Fresh ruminal fluid was collected from Tibetan yaks and highly cellulolytic facultatively anaerobic bacteria were screened out by using Congo red staining and liquid secondary screening culture media. Cellulolytic bacteria strains were identified based on their morphological, physiological and biochemical characteristics, as well as by 16S rRNA analysis. Time course profile of growth and enzyme production by strain JF85 was obtained. The degradation efficiency of rice straw was examined by evaluating cellulose, hemicellulose and lignin contents under a range of condition. Strain JF85 was identified as Enterococcus faecalis. This strain grew well across a wide range of conditions: temperatures of 15-55 ℃, pH levels of 3.0-7.0 and NaCl levels of 3.0% and 6.5%. It exhibited the maximal endoglucanase activity (0.41 U/mL) and filter paper activity (0.13 U/mL) after 36 hours of incubation. In simulated fermentation, compared to the control, adding the JF85 strain significantly decreased the dry matter, cellulose and hemicellulose contents of rice straw after 14 days of inoculation (P<0.05). JF85-treated rice straw showed its highest water soluble carbohydrate content after 7 days of inoculation. However, there were no significant differences in lignin contents among all treatments. Applications of the JF85 strain, with its highly cellulolytic abilities and tolerance of acid and salt, have the potential to significantly improve the production of silage.

Using maturity to predict forage yield and nutritional quality of forage cereals in the Jingtai Oasis

DUAN Qian-Wen, CHENG Hui, HOU Fu-Jiang

2017, 26(6):  185-194.  DOI: 10.11686/cyxb2016311

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The yield and nutritional quality of spring wheat, oats and rye in the Jingtai Oasis was assessed in a trial planted in 2010. Measurements included calendar time and production data to harvest maturity, crude protein, crude fat, neutral detergent fiber, acid detergent fiber, ash and soluble carbohydrate content. The relationships among time to maturity and feeding value traits were also determined. The result showed that yield and nutritional quality of forage was able to be predicted by growth duration. Feed value and crude protein yield resulting from simulated grazing were assessed as significantly higher than making hay from the forage. The results provided a scientific basis for the production of cereal forages in an oasis environment.

The eco-physiological responses of invasive plants to defoliation in grassland: patterns, mechanisms and research prospects

ZHAO Wei, WANG Yan-Jie, LI Ya-Ge

2017, 26(6):  195-202.  DOI: 10.11686/cyxb2016368

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Invasion of a grassland ecosystem by an alien plant usually results in loss of biodiversity, reduced vegetation productivity, and habitat deterioration of the grassland. A better understanding of the eco-physiological characteristics of the invasive plant is crucial for controlling these plant species effectively. As cutting is a commonly chosen method for controlling invasive plants both in China and elsewhere, this article reviews the eco-physiological patterns and mechanisms whereby invasive plants respond to defoliation. The main conclusions are as follows: (1) Defoliated invasive plants tend to adopt a compensatory photosynthesis pattern to ensure or improve their photosynthetic capacity. (2) A powerful stem/leaf regenerative ability of defoliated invasive plants can compensate rapidly for the loss of photosynthetic organs and above-ground biomass. (3) Change in the microbial community structure of soil after defoliation is more beneficial to the growth of defoliated invasive plants than to the native vegetation. (4) The defoliated invasive plants are able to utilize more efficient and diversified resource allocation strategies than the native vegetation to promote their regeneration. (5) A greater energy is distribution to the reproductive organs can help defoliated invasive plants maintain their population stability. (6) The tolerance to defoliation differs depending on the developmental stage of the invasive plant. Based on the above findings, we also analyze the advantages and disadvantages of cutting as a control treatment and make suggestions for controlling invasive plants using this method. In particular, researchers should focus on identifying the molecular mechanisms used by invasive plants to respond to defoliation, and on how invasive plants respond to global changes in the grazing rangeland, so as to develop efficient scientific methods for their control.

Effect of warm-shed feeding on liveweight loss and lambing performance of ewes during the winter-spring period

ZHANG Xiao-Qing, KEMP David, MA Yu-Bao, JIANG Chao

2017, 26(6):  203-209.  DOI: 10.11686/cyxb2016318

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The objective of this study was to determine the effect of warm shed housing on liveweight loss of ewes and on their lambing performance in winter-spring period. One hundred and twenty ewes, from two adjacent local farmers in Taipusi Banner of Xilinguole, Inner Mongolia, were used in winter-spring of 2011, 2012 and 2013. The animals were randomly assigned to two treatment groups: housing in a traditional shed+grazing (TS, control), and housing in a modified warm shed+no-grazing (WS). In summer all animals grazed pasture during the day and were housed in a traditional unheated shed overnight. During winter and spring the ewes in the TS treatment were again grazed on pasture each day and housed in the traditional shed each night, while the ewes in the WS treatment were not sent out to graze during the day. The ewes and their lambs in each treatment were fed the same amounts of supplements of hay and concentrate per day throughout the experiment period. The liveweight loss of ewes in the WS treatment was 22 g/day lower (P=0.005), and their liveweight 1.6 kg higher (P=0.004) at the end of the period, than for sheep in the TS treatment. In all three years the weight loss was greater in December and January than in February and March, and was significantly less (P<0.001) in 2012 and 2013 than in the first year of the experiment (2011). More lambs were born in the warm shed than in the traditional unheated shed (P=0.020), and lambs born in the warm shed also had a higher liveweight (P=0.0005) and daily weight gain (P=0.0001). The lamb weight gain and birth weight were also significantly higher in the later years of the experiment (P<0.001). As the shed temperature increased lambing, survival and twinning rates continuously increased. These results demonstrate that sheep housing in a warm shed during winter and spring will improve animal performance and household incomes and reduce grazing pressure on already degraded grasslands. Importantly, keeping animals in a warm shed in the cold season will assist herders to change from a traditional ‘animal survival’ mind set to a production oriented attitude. Thereby, we recommend sheep sheds should have a thermal time (degree-days)>-40 ℃·d or have an air temperature>2 ℃ during the cold season in pastoral regions of Northwest China.

Effects of high concentrate diet on microbial fermentation and biogenic amine formation and absorption in the rumen and cecum of goats

LI Hong-Wei, LIU Jun-Hua, HUO Wen-Jie, ZHU Wei-Yun, MAO Sheng-Yong

2017, 26(6):  210-216.  DOI: 10.11686/cyxb2016305

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This study was conducted to evaluate the effect of high concentrate diets on ruminal and cecal fermentation and biogenic amines production and absorption in the gastrointestinal tract of goats. Six goats fitted with permanent rumen fistula were randomly divided into low concentrate group and high concentrate groups for an experiment that lasted 24 days. The results showed that, compared with the low concentrate group, high concentrate diets increased the concentrations of total volatile fatty acid, acetate, propionate, butyrate, total branched chain fatty acid, tyramine, putrescine, histamine, methylamine and tryptamine (P<0.05). Ruminal pH and the ratio of acetate to propionate decreased (P<0.05). A high concentrate diet also improved the levels of acetate, propionate, total volatile fatty acid and the five biogenic amines in cecal digesta (P<0.05). Compared with the control group, the concentrations of biogenic amines contents were higher in the high concentrate group in rumen and cecal vein blood (P<0.05). Correlation analysis revealed that the biogenic amines contents of tyramine, putrescine, methylamine and tryptamine in rumen fluid and rumen vein blood were significantly positively correlated (P<0.05). In addition, significant correlations of the five amines contents were observed between cecal digesta and cecal vein blood (P<0.05). These results show that high concentrate diets significantly affect ruminal and cecal fermentation, indicating that high concentrate feeding might increase ruminal and cecal epithelial permeability and thus stimulate the absorption of biogenic amines from rumen and cecum.