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Phosphorus is one of the most important nutrients for plant growth and development, and it is also indispensable for plant metabolism. Deficiency of P greatly limits crop growth in one-third to one-half of cultivated land in China. Symbiotic association between plants and arbuscular mycorrhizal fungi (AMF) is widespread, and is of particular importance to improving plant P uptake efficiency. This paper summarizes progress in the elucidation of the mechanisms of mycorrhizal fungi in the promotion of phosphorus uptake and utilization by plants, including aspects of mycorrhizal morphological features, physiology, biochemistry, and molecular biology. In addition, we discuss research on the potential of growth-promoting mechanisms of mycorrhizal fungi. AMF can form a dense network of hyphae in rhizosphere soil and root cortical cells, increase the absorptive surface areas of the root system, reduce nutrient transport distances, excrete phosphatase, organic acid, and protons, and dissociate insoluble phosphate and the specific expression of phosphate transporter genes.
The biological characteristics of Trichoderma rossicum strain GAU 1-X-2 were examined using different carbon and nitrogen sources, pH, temperature, and other factors. The results indicated that T. rossicum could grow under temperatures of 10-35 ℃ and pH of 5.0-12.0, with optimal conditions of 20 ℃ and pH 7.0, although the highest sporulation occurred at pH 8.0. Mannitol was the optimum carbon source for hypha growth, but dextrose was the best for spore production. Peptone was the optimum nitrogen source for mycelia, but conidiophores were not observed after six days in the seven nitrogen sources. The best mycelia growth and the largest sporulation occurred with 24 h of darkness. The lethal spore temperature was 68 ℃ for 10 min.
Biolog EcoPlates were used to analyse carbon source utilization by soil bacteria in different plant functional groups (Leymus chinensis, grass, legume, and forb) in the Songnen steppe. The results showed there were differences in carbon source utilization and bacterial metabolic activity among the four plant functional groups. Carbon source utilization of the soil bacteria community was the highest in the forb group, followed by grass and L. chinensis groups, and was lowest in the legume group. Carbohydrate and amino acids were used the most by soil bacteria in the four plants functional groups; however, phenolic acids and amines were poorly used in all plant functional groups. The Shannon-Wiener index, Pielou index, and the Gini index were the highest in the forb group and the lowest in the legume group. Redundancy analysis (RDA) showed that total N and organic matter were the major factors affecting carbon source utilization by soil bacteria in the forb and legume functional groups, and electrical conductivity, pH value, and moisture content were the major factors in the L. chinensis and grass groups.
As a critical synusia in steppe grasslands, annual plant functional groups can compensate for changes in community biomass and maintain its stability in wet seasons and across years. This compensation should be evident because they are more sensitive to precipitation than perennial plant functional groups, especially in grazing communities with low biomass of perennial plant functional groups. However, it is not clear how the compensation effects of the annual plant functional groups improve productivity and affect soil respiration (Rs) in grazing areas in the steppe. We conducted a 2-year grazing experiment, including light-grazing (L) and moderate-grazing (M) treatments, in a typical steppe in Inner Mongolia in 2012 and 2013. Above-ground biomass (AGB), under-ground biomass (UGB), Rs, and environmental factors were monitored during the growing season. We found that: 1) either compensation of the annual plant functional groups occurred in the AGB and UGB, or Rs was higher in the wet year (2012) than in the dry year (2013); 2) both compensation effects in the annual plant functional groups in the AGB and UGB and Rs were significantly greater in moderate-grazing than light-grazing; 3) Rs was positively correlated with both the AGB and UGB of the annual plant functional groups, as well as with soil temperature and moisture (P<0.001). This study showed that grazing utilization decreased biomass of the perennial plant functional groups, and the annual plant functional groups dramatically developed in wet seasons and years to compensate for loss in community biomass to improve productivity and maintain ecosystem stability, which as a principal biotic mechanism that affects the ecosystem carbon cycle in grasslands.
To assess the impacts of yak excreta and trampling on carbon dioxide (CO2) fluxes inatypical peat bog in the Bitahai wetland in the Northwest Yunnan Plateau, CO2 fluxes weremeasured in yak dung, yak trampled areas, yak dung intrampled areas (as an indicator of the interaction of yak dung and yak trampling), and control areas during the summer grazing season in 2015. The results showed that yak grazing significantly affected the emissions of CO2 of peat bogs in the Bitahai wetland. The fluxes of CO2 from different grazing treatments were characterized by yak dung>yak dung and trampled>control>yak trampled(P<0.05). During the experimental period, the average amount of CO2 fluxes from yak dung, yak dung and trampled, control, and yak trampled areaswere14.38, 9.48, 4.71, and 2.60 μmol·m-2·s-1, respectively. Fluxes of CO2 in the control area had a significant positive correlation with the temperature of the upper 10 cm soil (P<0.05). In contrast, fluxes of CO2 in yak dung, yak trampled, and yak dung and trampled areas had no correlation with the upper 10 cm soil temperature. These results indicated that yak dung improvedthe fluxes of CO2 in peat bogs, but yak trampling had the opposite effect. Yak grazing decreasedthe effect of soil temperature on the fluxes of CO2 in peat bogs.
A synthetic evaluation method for soil fertility was investigated based on unascertained mathematical theory, attribute mathematical theory, and the unascertained attribute measurement analysis method (UAMA). A synthetic evaluation and classification of soil fertility in urban green spaces was postulated. Firstly, the evaluation indexes and their classification standards, and the grades for soil fertility status were determined for the evaluation of urban green space soil fertility. Secondly, the unascertained attribute measurement functions of each index were constructed to compute the unascertained attribute measurement value of the single index and the synthetic unascertained attribute measurement value. Finally, the evaluation of soil samples from urban green spaces was conducted using the confidence criteria to determine the status and classification of soil fertility. The UAMA method in this paper was tested based on the fuzzy comprehensive method for two soil fertility samples, and the entire-array-polygon indicator method, matter-element extension method, and improved artificial neural network method for 13 soil fertility samples. The consistency rates were 100%, 84.62%, 92.31%, and 100% between the UAMA method and fuzzy comprehensive method, entire-array-polygon indicator method, matter-element extension method, and improved artificial neural network method, respectively. Case studies indicated that the UAMA method used in this paper was feasible and reasonable, and it provided a new method for the evaluation of urban green space soil fertility.
To more accurately determine vegetation information for the mid-lower reaches of the Tarim River in an arid desert region, we used MODIS data to calculate commonly used vegetation indices (VIs, normalized difference vegetation index [NDVI], difference vegetation index [DVI], enhanced vegetation index [EVI], ratio vegetation index [RVI]). We combined remote sensing data using Image J software to acquire a vegetation coverage, and compared them with actual measurements. We concluded that they were significantly correlated. Next, we made a vegetation coverage map via Image J and vegetation indices in a 2D scatter plot using regression analysis. Finally, we chose the most suitable VI among the four VIs. The study showed that each VI was positively correlated with vegetation coverage. The goodness of fit between VIs and vegetation coverage was ranked: NDVI, EVI, RVI, and DVI. Thus, we suggest the use of NDVI as the VI.
To investigate the effects of citric acid and EDTA-Na2 on growth and characteristics of absorption and transportation of Pb and six essential nutrient elements (N, P, K, Ca, Mg, and Fe) of Coleus blumei exposed to Pb pollution, an experiment was conducted with eight treatments, including the control, 6 mmol·L-1 Pb pollution, and 6 mmol·L-1 Pb pollution mixed with 1, 5, or 10 mmol·L-1 citric acid or 1, 5, or 10 mmol·L-1 EDTA-Na2 on potted C. blumei plants. Compared with that in the control, Pb pollution caused a decrease in dry weight, water content, and root dehydrogenase activity. Except for N content in roots, and Ca content in leaves and roots, the contents of other nutrient elements were lower in plants exposed to Pb than in the control, whereas the accumulation amount of Pb increased. In contrast, under other conditions, such as the treatments of Pb pollution mixed with the addition of 1, 5, or 10 mmol·L-1 citric acid or 1, 5, or 10 mmol·L-1 EDTA-Na2, significant decreases in dry weight, water content, and root dehydrogenase activity were observed. Changes in Pb content, the accumulated amount of Pb, and content of six nutrient elements varied with different treatments. C. blumei accumulated more Pb in shoots (leaf and stem) under the lower concentration treatment (1 mmol·L-1) of citric acid than EDTA-Na2, but the higher concentration treatment of (5 and 10 mmol·L-1) citric acid showed the opposite trend. Therefore, it was concluded that the suitable concentration of citric acid or EDTA-Na2 could enhance the Pb absorption ability of C. blumei.
We used Sedum aizoon to determine the growth index, relative conductivity, malondialdehyde (MDA) content, antioxidant enzyme activity, proline content, soluble protein content, chlorophyll content, and chlorophyll fluorescence parameters following low temperature stress (0, 5, 10, and 25 ℃) for 2, 4, 6, 8, and 10 d after inoculation with arbuscular mycorrhizal fungi (AMF). The results showed that mycorrhizal colonization abilities and mycorrhizal dependency were significantly (P<0.05) inhibited by low temperature. Low temperature stress significantly inhibited the growth of S. aizoon, and the plant height, stem diameter, and root length growth were significantly greater than in the normal control. The growth effect was greater under 0 ℃ temperature stress, and total dry weight was 75.38% greater than that of the non-AMF treatment. Under low temperature stress, relative conductivity, MDA content, and proline increased as temperature decreased and the stress time increased. Superoxide dismutase(SOD) activity, peroxidase(POD) activity, catalase(CAT) activity, and soluble protein showed a decreasing trend after an initial increase. Furthermore, chlorophyll content and Fv/Fm declined. Compared with the non-AMF treatment, AMF inoculation significantly inhibited the increase in relative electric conductivity and MDA content, significantly improved antioxidant enzyme activity, such as SOD, POD, and CAT, and induced greater soluble protein and proline content. It also indicated that Fv/Fm in AMF plants was significantly higher than that in the non-AMF plants. Therefore, AMF could greatly enhance the low temperature tolerance of S. aizoon and reduce damage from low temperature stress.
As a common and dominant species in heavy metal contaminated soils in southern China, Bermuda grass can be potentially used for Cd phytoremediation. The growth response following exposure and tolerance to Cd, as well as accumulation of Cd of 10 Bermuda grass genotypes were studied under hydroponic culture conditions with 1.5 mmol·L-1 of Cd. The results indicated that under Cd stress conditions, all of the Bermuda grass genotypes appeared to show symptoms such as slow growth, drawl plant, yellow and wilting leaves, and poor root growth. Differences in the degree of damage in different genotypes were significant. Among them, three genotypes (WBD242, WBD245, and WBD193) exhibited less severe damage in turf quality, chlorophyll content, and transpiration rate under Cd stress. These three genotypes showed the strongest Cd accumulation ability (119.0, 177.0, 124.2 mg·kg-1 in aboveground parts, respectively), which surpassed the putative criteria for hyper-accumulation plants expected to be used for phytoremediation of severe Cd contaminated soil. However, we also found that two other accessions, WBD144 and WBD147, showed the highest translocation capacity for Cd, but with weaker Cd tolerance, which could be applied for phytoremediation of slightly polluted area. Our findings could be used as guidance for future studies on phytoremediation and reconstruction.
Ten wild ornamental grasses were subjected to osmotic stress of approximately 0 to -1.3 MPa created with polyethyleneglycol (PEG-6000). As the osmotic stress decreased, the germination rare, germination potential, germination index, plumule length, and radicle length first increased and then decreased, however, fresh weight of seedling gradually decreased; in addition to Pennisetum alopecuroide (Ningxian), Pennisetum alopecuroide(Lingtai), and Eragrostis ferruginea(Lingtai), the vigor index of other germplasm gradually decreased. Osmotic stress at -0.1 MPa promoted germination of seeds of all the ten wild ornamental grasses, their germination rate, germination potential, germination index, plumule and radicle length reached the maximum values at this osmotic stress level, and the initial germination days of Achnatherum splendens(Lanzhou), Achnatherum splendens(Wuwei), Eragrostis ferruginea(Lingtai), Deschampsia cespitosa(Tianzhu) were one day shorter than the control. Beyond -0.5 MPa,the germination of these ten wild ornamental grass seeds was severely suppressed. Furthermore, beyond -1.3 MPa, seeds of all these varieties did not germinate at all. Using the subordinate function analysis to evaluate drought resistance, the varieties were ranked as follows: Achnatherum splendens (Lanzhou)>Pennisetum alopecuroide (Ningxian)>Achnatherum splendens (Wuwei)>Pennisetum alopecuroide (Lingtai)>Achnatherum splendens (Sunan)>Carex rochebrunii (Weiyuan)>Deschampsia cespitosa(Weiyuan)>Deschampsia cespitosa (Tianzhu)>Carex nubigena (Weiyuan)>Eragrostis ferruginea (Lingtai).
Alien invasive plants in Northeast China grasslands have posed serious threats to economies and ecosystems. Thirty-eight alien invasive plants were identified in Northeast China grasslands based on field surveys, herbarium information, and literature reviews. They belonged to 35 genera of 12 families. Alien invasive plants were mainly those belonging to Compositae, Gramineae, Solanaceae, Amaranthaceae, and Leguminosae. These five families included the main alien invasive species in Northeast China grasslands, accounting for 81.58% of total invasive plants. Farmland, grasslands, roadsides, and watersides were the main habitats of alien invasive plants in Northeast China grasslands. Based on analysis of invasion pathways, the number of alien invasive plants by intentional introduction was nearly equal to the number by unintentional introduction. In light of the situation regarding alien invasive plants in this area, control strategies were postulated, including controlling alien invasive plants of key families, controlling alien invasive plants in main habitats, cutting off invasion pathways, and adopting scientific control measures. Because the situation of alien invasive plants is very similar in Northeast China and China as a whole, the control strategies can be used throughout China.
Hormonal priming is an important component of seed priming. It has great significance for seed germination, seedling growth, stress tolerance and yield increase. Based on the current research situation, we summarized the concept and application range of hormonal priming, illustrated the positive effects of hormonal priming on plant growth. Furthermore, biochemistry and molecular mechanism of seed hormonal priming were explained. In addition, we pointed out that hormonal concentration, priming time and drying conditions are the most important factors that constraint the priming effect. To improve the research in the future, priming mechanism should be intensively studied based on the genomics and proteome approach, and increase the use of hormonal priming in grass species.
The hyperaccumulator Carex putuoshan was used as cloning material for the phytochelatin synthase (PCS) gene, and to characterize its expression following heavy metal stress. The results showed that the cDNA of CpPCS was 1 461 bp in length, and it encoded 486 amino acids with a molecular weight of 53.86 kDa and pI value of 6.12. As compared to other plants, the amino acid sequence similarity was approximately 63%. Phylogenetic analysis of PCS proteins from different species showed those of C. putuoshan were most closely related to those of Oryza sativa and Triticum aestivum. Real-time quantitative PCR analysis indicated that CpPCS and CePCS (Carex oshimensis 'Evergold') genes were expressed in the leaves. The CpPCS and CePCS genes were up-regulated in Pb and Zn treatments. Additionally, we investigated CpPCS structure, phylogenetic relationships, and gene expression patterns. Our results indicated that CpPCS might play an important role in heavy metal stress, and could be further utilized in plants.
After three years of screening 541 common vetch (Vicia sativa) accessions from National Plant Germplasm System (NPGS), 33 accessions with high, moderate and low pod shattering rate were selected for the further study. In the present study, the pod shattering rate, the pod horizontal cracking mechanical force and vertical cracking mechanical force of these 33 common vetch accessions were analyzed and measured by a digital mechanical force gauge (HANDPI, HP-50) to provide accurate and rapid evaluation method for screening non-shattering accessions. The results showed that the cracking mechanical force of accessions with high pod shattering rate was significantly lower (P<0.01) than that of accessions with low pod shattering rate. The horizontal cracking mechanical force of common vetch pods was significantly lower (P<0.01) than the vertical cracking mechanical force of them. The accessions with horizontal cracking mechanical force greater than the 9.286 N were low shattering accessions, meanwhile the accessions with horizontal cracking mechanical force less than 2.163 N were high shattering accessions. These results indicated that pod horizontal cracking mechanical force measured by digital mechanical force gauge could accurately reflect the pod crack characteristic of different accessions and provided reference for the pod shattering characteristics.
To provide evidence for the feasibility of artificial seed banks for ecological restoration of fluctuation zone, a flooding experiment was conducted in which the variation in seed viability, protein content, soluble sugar content, and starch content for Cynodon dactylon, Hemarthria sibirica, Pycreus globosus artificial seed banks was tested. The flooding experiment included 0, 5, 6, 7, 8, and 9 month flooding treatments that simulated the flooding rhythms at different altitudes in the Three Gorges Reservoir region. The results showed that all three artificial seed banks had good sustainability under short-term submersion. Seed viability of the three artificial seed banks remained relatively high after submersion for 5~6 months. Seed activity of the C. dactylon seed bank ranked the highest among the three seed banks. However, seed activity of all artificial seed banks decreased dramatically after submersion for 7 months and decreased further with increasing submersion time. The seed activity of C. dactylon, H. sibirica, and P. globosus declined by 34.2%, 43.0%, and 63.8%, respectively, when submersed for 9 months. Submersion also induced significant reductions in protein, starch, and soluble sugar content of seeds (P<0.05). A dramatic decline occurred when seed banks were submersed for 7 months. The C. dactylon seed bank had the best sustainability, followed by H. sibirica and P. globosus. An additional correlation analysis indicated that there were significant negative linear correlations between submersion time and seed viability for H. sibirica and P. globosus seed banks. Seed nutrients also exhibited a negative linear correlation with the viability of seed banks, with the degree of correlation depending on the species.
Characteristics contributing to hay yield and adaptability of Aksu white sweet clover (Melilotus albus) were analysed and compared among four Melilotus cultivars and four wild Melilotus germplasm resources. The experiment was conducted at the campus experimental station of the Animal Science College, Tarim University, located in Alar, Xinjiang (40°54'21'' N, 81°30'20″ E). The results showed that the squaring and initial bloom stage of Aksu white sweet clover was on the 64th and 75th day after emergence, respectively. The number of growth and development days was very short and its hay yield was 5 874.23 kg·hm-2, which was 18.76%~67.20% greater than that of the control group. Plant height and the fresh-dry ratio were 125.27 cm and 4.23, respectively, which were greater than those of the control group, indicating better hay yield characteristics. Its water-holding and summer survival rate was 65.00% and 99.00%, respectively, indicating good adaptability to the megathermal and arid climate of the Aksu area. The comprehensive performance score ranked first among the tested accessions, which demonstrated it had potential to be transformed into wild varieties.
We took samples along the elevation gradient using the combined method of quadrats and belt transects, and we analysed subalpine meadows in the Xiaowutai Mountain Nature Reserve using quantitative ecological methods. TWINSPAN and RDA were used to analyse the relationship between vegetation and environmental variables. Species diversity indexes were used to explain the relationships between the changes inspecies diversity and environmental factors. The results showed that TWINSPAN classified all samples into nine groups representing nine plant communities. RDA ordination clearly reflected the relationships between the distribution patterns of subalpine meadow communities and environmental gradients. The distribution pattern of communities was obvious in the first axis and second axis gradient. The first axismainly represented the relationship with slope aspect, soil temperature, elevation, soil thickness(P<0.01), and soil moisture gradients(P<0.05). In addition, the second axis mainly represented the relationship with slope and soil thickness(P<0.01). The statistical significance of the effect of each variable was tested by a Monte Carlo permutation test, and slope aspect, elevation, and slope were significantly related to species data(P<0.05). The three environmental factors played an important role in the community distribution pattern. The Patrick richness index declined with increasing elevation, and showed an increasing trend with increasing slope aspect and soil temperature. The Shannon-Wiener diversity index exhibited a declining trend with increasing soil thickness. The Pielou evenness index exhibited an increasing trend with increasing altitude and soil moisture, and decreased with increasing slope aspect and soil temperature. The Simpson dominance index showed a slightly decreasing trend with increasing slope, and an increasing trend with increasing soil thickness.
To determine vegetation community diversity and stability in different habitat regions of the Nanhaizi wetland in Yanchi County, Ningxia Autonomous Region, vegetation surveys were conducted in July 2016. Firstly, the moving split-window technique was applied to the quantitative determination of ecotone. According to the result, the research area was divided into wetland regions, ecotone, and arid regions. Then, diversity indexes (species diversity index, community dominant concentration index, community evenness index, and species richness index) were used to analyse plant community diversity of different habitat regions in different transect lines. The M.Godron stability determination method was used to analyse plant community stability in different habitats. The results showed: 1) The ecotone boundary could be clearly delineated with six quadrats of east and west transect lines, and eight quadrats of south and north transect lines. 2) Species diversity index, community evenness index, and community dominant concentration index of the four transect lines all followed the order of ecotone>arid region>wet region, whereas the species richness index was ordered as wet region>arid region>ecotone. 3) As compared to that of the other two habitat regions, the ecotone had the highest stability of vegetation, but the least species. The M.Godron stability followed the order of wet region>arid region>ecotone. The research showed that the moving split-window technique could be used to quantitatively determine small-scale wetland-grassland ecotones.By analysing the data and making comparisons, we found a negative correlation between vegetation diversity and stability.
Spatial patterns of Dactylis glomerata were sampled using the contiguous grid quadrat method at various altitudes in the eastern and western sections of the Northern Tianshan Mountains and analysed using the variance to mean ratio, negative binomial parameter, index of clumping, index of aggregation, and Cassie's index. The results showed that the distribution was aggregated in both the eastern and western sections of the Northern Tianshan Mountains. The degree of aggregation of D. glomerata was moderate in the eastern section, but was moderate at an altitude of 2 000 m and high at 1 800 m and 2 200 m in the western section. There were one or two peaks in the scale of the distribution pattern of D. glomerata in the different regions. The minimum area of aggregation was 0.4 m2 and the largest area was 5 m2. Peaks in aggregation appeared in block of 4, the block of 8, the block of 32, the block of 64 at different altitudes. Finally, mean crowding exhibited an increasing trend as density increased.
We examined the effects of soybean molasses adsorbed to different substrates on the ruminal environment of dairy cows. Three Chinese Holstein dairy cows (all the same age, and three parity) with an average body weight of (500±50) kg were allocated three dietary treatments in a 3×3 Latin square design. The cows were fitted with the permanent ruminal fistula, the three experimental diets were similar except that some wheat bran (replaced 15% of corn meal by adsorbed soybean molasses with wheat bran) or soybean hull (replaced 10% of wheat bran and 5% corn meal by adsorbed soybean molasses with soybean hull). The results showed that the molasses that were adsorbed to soybean hull and wheat bran significantly increased the pH value of the rumen compared to the control group (P<0.01). However, there was no significant difference (P>0.05) between the pH values of the rumens of cows fed diets containing molasses adsorbed to soybean hull and wheat bran. The wheat bran diet resulted in significantly lower ruminal NH3-N concentrations than the control diet (P<0.05), however, no differences were observed between soybean hull and control diets (P>0.05). Furthermore, no significant differences (P>0.05) were observed in individual volatile fatty acid (VFA) (acetate, propionate, isobutyrate, butyrate, isovalerate, and valerate) concentrations or the acetate/propionate (A∶P) ratio between the control and treatment groups. However, the ruminal total VFA concentration in cows of the soybean hull molasses group did show a lower trend than that observed in the control group, whereas ruminal total VFA concentration in cows of the wheat bran molasses group had a tendency to increase. These results suggest that it would be efficient that feed soybean hull molasses to replace 15% of corn meal instead of 10% of what bran and 5% corn meal in dairy cattle. Molasses adsorbed to both wheat bran and soybean hull have the ability to maintain ruminal homeostasis, although wheat bran is a better adsorption substrate than soybean hull.
This study was conducted to investigate the effects of different levels of betaine and rumen-protected fat on production performance, blood parameters, and rumen fermentation in Hu sheep. We used a 2×3 dual-factor experiment, consisting of three levels of betaine(0,4, and 8 g·d-1) and two rumen-protected fat concentrations (0, and 2.4%). In the experiment,48 3 month-old Hu sheep lambs were randomly arranged into six groups with eight duplicates of one sheep. The experiment included three periods: an acclimation period of 10 days, a pre-trial period of 7 days, and a trial period of 50 days. Dietary 2.4% rumen-protected fat significantly reduced the production performance, final weight, and carcass weight (P<0.05), whereas it remarkably improved plasma triglycerides and cholesterol content of Hu sheep fat-tail weight (P<0.05). Dietary betaine had no effect on blood parameters, production performance, slaughter performance, and blood parameters of Hu sheep (P>0.05). Betaine and rumen-protected fat had no interaction effect on production performance or blood parameters of Hu sheep. Dietary 2.4% rumen-protected fat could significantly reduce the digestibility of NDF and ADF (P<0.05), with no obvious impact on DM, OM, or CP digestibility, rumen fermentation, or different types of fatty acids of Hu sheep (P>0.05), whereas dietary betaine had no significant effect on nutrient digestibility, rumen fermentation, or different types of fatty acids (P>0.05). There was no interaction effect on rumen fermentation or nutrient digestibility (P>0.05). The results suggest that under the conditions in this study, betaine had no regulatory effect on fattening production of Hu sheep, whereas rumen-protected fat played a role through ingestion, fat metabolism, and decomposition of fibre. Dietary 2.4% rumen-protected fat reduced fattening production of Hu sheep. In actual production, rumen-protected fat is inadvisable as a dietary additive to influence high meat production.
Maqu is a typical ecologically fragile area in the Tibetan Plateau, and is very sensitive to the impacts of various natural and human factors. To elucidate the reasons for grassland degradation and achieve sustainable utilization of grassland resources in Maqu, it is important to analyse the influences of various human factors on grassland degradation, and the underlying mechanisms. We used MODIS-EVI data and related social statistics from 2004 to 2013 to detect the temporal patterns of grassland degradation in Maqu. The distribution of grassland degradation gradually moved from the northwest at high altitudes to the southeast at low altitudes in Maqu. We used quantitative and qualitative methods to analyse the impact of human factors on various spatial differences in grassland degradation. We found that: 1) The impact of human activities on grassland degradation was relatively large, and the inter-annual rate of change in grassland vegetation where the distance to settlements of herders was 1-3 km was relatively high, and degradation was particularly serious near settlements after implementation of the “pastoral settlement project” in Maqu in 2008; 2) The intensity of use of grassland resources was the primary reason for degradation; overgrazing and high livestock density in various areas was significantly negatively correlated with the inter-annual rate of change in grassland vegetation; 3) From the perspective of game theory, we analysed herders' motivation for overgrazing under the current popular operational mode of the joint household, and found that implementing certain policies of eco-compensation and strengthening supervision could change their game strategy, and ultimately achieve a “do not increase grazing capacity” as the optimal strategy of the new “Nash equilibrium”; 4) Through field surveys, we found that herder production style and life style changed in recent years; implementation of housing projects for herders, construction of roads and other infrastructures, fencing, and rodent infestation, among other factors, seriously damaged grassland vegetation in Maqu.
The aim of the study is to analyze the relative resource carrying capacity and its sustainable development status of pastoral areas in the past 10 years from 2009 to 2014, applying the model of geo-relative resource carrying capacity, taking Gansu Province as a reference area. The results showed that: 1) The grassland have surplus population and economic overload in Maqu, Luqu, Xiahe, Zhuoni and Tianzhu,which belongs to the economically developed areas of animal husbandry. The population and economy of grassland in Hezuo and Diebuare both overloaded and densely populated. The animal husbandry is more developed in these areas. 2) Sunan, Subei and A Kesai could be seen as the economically less developed areas with relatively abundant grassland resources and small population density, indicating a greateconomic development potential of animal husbandry. 3) Water resources are the key contributors to the relative resources carrying capacity, population and economy; 4) The relative resource carrying capacity of grassland in Gansu is quite different. The imbalance of water and soil resources is a potential threat to the sustainable development of pastoral areas. This study will provide reference for the rational use of the resources, the optimization and adjustment of the development mode, the formulation of future development strategy and direction, and the improvement of self-development capacityin pastoral areas. The paper finally forms a coordinated development of population, resources and environment, as well asregional social economy.
Taking cultivation of students’ ability of innovation and exploration as the basic point, the article elaborated the course construction and approaches on Seed Biology of Seed Science and Engineering in Gansu Agricultural University, from the perspectives of perfecting the teaching material system, strengthening the construction of teaching staff, enriching the teaching content, improving the teaching mode, reinforcing the practice teaching and improving the comprehensive assessment way of the course assessment. Through curriculum construction and reform, not only the students’ learning enthusiasm and initiative were aroused, but also their ability to analyze problems and solve problems was enhanced. Teachers’ teaching ability was raised as well. Finally, the “teaching” and “learning” win-win situation would be achieved.