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2021 Vol.38(12)

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Temporal and spatial variation of drought in the Xilingol grassland based on the standardized precipitation index and standardized precipitation evapotranspiration index
MA Jingzhao, HAO Lu
2021, 38(12): 2327-2339. doi: 10.11829/j.issn.1001-0629.2021-0216
[Abstract](1114) [FullText HTML] (512) [PDF 1852KB](26)
As the main terrestrial ecosystem, grasslands have an important impact on global climate change. It is of great scientific significance to study the temporal and spatial distribution of grassland drought and explore the drought index with high applicability for drought monitoring and evaluation in this ecosystem. This study analyzed the spatial and temporal distribution characteristics of annual and seasonal meteorological droughts and the trends, mutations, and annual drought frequencies using the drought indices of the standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI), as well as the Mann-Kendall test, based on the monthly precipitation and monthly mean temperature data of the Xilingol League 9 meteorological stations from 1990 to 2019. The results showed that: 1) Both indexes identified an increasing trend of drought in the region, and the SPEI was more significant than SPI (P < 0.05). In spring, SPI showed a wetting trend, whereas SPEI showed a drought trend. Both indexes showed a significant drought trend in summer (P < 0.05) and showed a wetness trend in autumn and winter. 2) The drought range detected by SPEI was larger than that detected by SPI, and the drought was the most severe from the central to western part of the Xilingol League. 3) SPEI detected more severe drought events than the SPI. 4) There were no mutation points in either index. In general, SPEI has a better applicability than SPI in evaluating drought conditions in the Xilingol League.
The relationship between classification of herbaceous plant communities and environment in Kekesu Wetland, Xinjiang
YANG Fan, LIN Tao, XU Hailiang, LING Hongbo, LIU Xinghong
2021, 38(12): 2340-2349. doi: 10.11829/j.issn.1001-0629.2021-0239
[Abstract](1024) [FullText HTML] (437) [PDF 1351KB](17)
Kekesu Wetland is a typical wetland in arid and semiarid lands. In the study, we used unweighted pair-group method with arithmetic means (UPGMA), detrended correspondence analysis (DCA), and canonical correspondence analysis (CCA) to quantitatively categorize the herbaceous plant communities in Kekesu Wetland. The correlations of community composition and species diversity with environmental factors were explored. We also evaluated the relative impacts of different environmental factors on the spatial distribution of herbaceous wetland communities. Our results showed that the herbaceous communities in Kekesu Wetland could be categorized into ten types, including Carex spp. + Phragmites australis community, Achnatherum inebrians + Artemisia desertorum community, Phragmites australis + Galium aparine community, Phragmites australis community, A. inebrians community, Plantago asiatica + Poa annua community, Calamagrostis epigeios community, Elytrigia repens community, Stipa capillata community and P. annua community. The species richness ranges from 2.5 to 8.8, Simpson dominance index from 0.28 to 0.62, Pielou evenness index from 0.33 to 0.73, Simpson diversity index from 1.44 to 2.61 and Shannon-Wiener diversity index from 1.75 to 3.50 across the ten community types. The CCA ranking results confirmed that the distance from the rivers was the most significant factor that affected the distribution of the herbaceous plant communities in Kekesu Wetland. Overall, our study revealed the classification and distribution of plant communities in Kekeksu Wetland and their corresponding influential factors, which can serve as a theoretical basis for ecosystem conservation and ecological function promotion in Kekesu Wetland.
Effects of temperature and moisture treatments on microbial characteristics of arable and grassland soil in dry-hot valley
PENG Sili, WU Renjie, ZHANG Xin, GE Zhiwei, YANG Nan
2021, 38(12): 2350-2362. doi: 10.11829/j.issn.1001-0629.2021-0406
[Abstract](1043) [FullText HTML] (495) [PDF 1307KB](18)
In order to investigate the influences of temperature and moisture on soil microbial characteristics under different land use types, a laboratory incubation experiment using arable and grassland soils collected from Yuanmou dry-hot valley with a full factorial combination of three temperature levels (15 ℃, 25 ℃ and 35 ℃) and three moisture levels (40%, 60% and 80% water holding capacity-WHC) was conducted. Soil microbial respiration rate, cumulative respiration and microbial metabolic quotient (qCO2) after 7 d, 14 d and 28 d’s incubations, and soil bacterial community composition after 28 d’s incubation were measured. At each stage of the incubation, microbial respiration rate, cumulative respiration and soil bacterial community diversity (Shannon index) in grassland soil were significantly higher than those in arable soil, while microbial metabolic quotient in grassland soil was significantly lower than that in arable soil (P < 0.05). Soil respiration rate and cumulative respiration in both soils increased significantly with the temperature. The Q10 value at the middle stage of the incubation (14 d) was significantly higher than that at the early (7 d) and late (28 d) stages (P < 0.05). The water treatment had different effects on microbial respirations for different soils, and the cumulative respiration under 60% WHC was larger than those under the other two water treatments. ANOSIM similarity tests suggested that land-use type had a great effect on soil bacterial community composition (r = 0.715, P < 0.01). Compared to arable soil, the bacterial community structure in grassland soil was more sensitive to the temperature and moisture treatments. The relative abundances of dominant groups in grassland and arable soils varied differently with the temperature and water levels.
Cloning and functional validation of RtVAMP2-2 gene of Reaumuria trigyna
ZHANG Jian, WANG Caixia, WANG Yingchun, ZHENG Linlin
2021, 38(12): 2363-2371. doi: 10.11829/j.issn.1001-0629.2021-0423
[Abstract](1167) [FullText HTML] (430) [PDF 9679KB](14)
Reaumuria trigyna is a rare recretohalophyte. Its unique salt-gland structure plays a key role in its adaptation to saline desert environment, and vesicular trafficking is involved in the salt secretion process of the plant. In this study, RtVAMP2-2 gene involved in membrane vesicle trafficking was cloned based on the analysis of transcriptome data of R. trigyna under salt stress. The ORF of RtVAMP2-2 was 1 074 bp and encoded 357 amino acids. RtVAMP2-2 was localized to the plasma membrane, and its expression was induced by saline stress. Then RtVAMP2-2 was transferred into Arabidopsis thaliana for functional validation. The results showed that the transgenic Arabidopsis thaliana showed a salt-sensitive phenotype, and was speculated that the RtVAMP2-2 may have a negative regulatory effect on plant salt tolerance.
Effect of traffic stress on component traits and physiological metabolism of Euphorbia thymifolia
YANG Xiaoqin, MAO Rui, LIU Jinping, ZENG Xiaolin
2021, 38(12): 2372-2380. doi: 10.11829/j.issn.1001-0629.2021-0352
[Abstract](983) [FullText HTML] (411) [PDF 836KB](18)
Euphorbia thymifolia is a wild native turfgrass germplasm resource. To explore its trampling tolerance and response mode to different traffic frequencies, namely mild (3 times per month), moderate (5 times per month), and severe (10 times per month), trampling simulation experiments were performed on potted E. thymifolia for 20 feet each time. After a month of treatment, the parameters including component traits, antioxidant enzyme activity, osmotic substance content, and chlorophyll content were determined to analyze the effects of traffic on the growth and physiology of E. thymifolia. 1) The response sequence of leaf traits to traffic was as follows: leaf number > leaf length > leaf area > leaf width > leaf thickness; the response sequence of stem traits to traffic was as follows: secondary branch number > longest length > total length > first-level branch number > internode length; and the response sequence of root traits to traffic was as follows: main root length > adventitious root length > main root diameter > lateral root number > adventitious root number. 2) Mild traffic increased leaf area and secondary branch number, while moderate and severe traffic limited the growth and regeneration of roots, stems, and leaves. 3) Trampling significantly affected the activities of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and soluble protein (SP) content in stems and leaves (P < 0.05), but the physiological response and resistance of stems to traffic were stronger than those of leaves. Evaluated together, stems and leaves showed traffic tolerance. 4) By significantly increasing chlorophyll (Chl) content (P < 0.05), E. thymifolia reduced the influence of leaf number reduction caused by traffic on photosynthesis. Under traffic stress, the ratio of Chla/Chlb was relatively maintained, thus providing support for survival, growth, and resistance. In summary, the morphological and physiological metabolism of E. thymifolia adapted to different traffic frequencies to form traffic resistance, even at severe frequencies, leading to survival and growth. Therefore, E. thymifolia is suitable as a turfgrass for planting in steppingstone gaps.
DNA fingerprinting of annual ryegrass strain of ‘Chuansi No. 1’ using SSR markers
CHENG Shaobo, SONG Yang, YANG Xunzhe, MA Xiao, ZHOU Yonghong, ZHANG Haiqin
2021, 38(12): 2381-2389. doi: 10.11829/j.issn.1001-0629.2021-0431
[Abstract](886) [FullText HTML] (358) [PDF 1060KB](15)
DNA fingerprinting of 23 varieties of annual ryegrass (Lolium multiflorum) were constructed using the SSR markers in this study. A total of 104 bands were amplified using 12 SSR primer pairs. The polymorphism information content (PIC) ranged from 0.392 to 0.822, with an average of 0.613. The Shannon index and gene diversity index ranged from 0.911 to 2.061 and from 0.407 to 0.838, respectively, with averages of 1.325 and 0.650, respectively. Cluster analysis showed that all the materials were divided into three branches. The first branch included a new line of ‘Chuansi No.1’ and its parental donor, in which ‘Chuansi No.1’ was clustered with ‘PI 611146’ and ‘Splendor’ as a small branch, and with ‘PI 283610’, ‘PI 283612’, and ‘PI 376875’ (‘G. Manawa’) as another small branch. The second largest branch was comprised of 12 nationally approved varieties, including ‘Gansi No.3’ and ‘Yancheng’. The third largest branch included five nationally approved varieties such as ‘Abundant’ and ‘Tetragold’. These results suggested that high genetic variation existed between the new line of ‘Chuansi No.1’ and the cultivated varieties of L. multiflorum used in this study. Primer 02-12E amplified unique bands on ‘Chuansi No.1’, which can be used for the rapid construction of fingerprints and molecular identification of this new line.
Karyotype analysis of six oat cultivars
Mubalake·Kuerbang, LEI Yingxia, WANG Hui, ZHOU Qingping
2021, 38(12): 2390-2396. doi: 10.11829/j.issn.1001-0629.2021-0241
[Abstract](977) [FullText HTML] (491) [PDF 1189KB](11)
To directly identify the number, size, and morphology of chromosomes in oat (Avena sativa), the chromosome karyotypes of six oat cultivars were analyzed by sectioning the root tips. The results showed that the chromosome number of six oat cultivars was 2n = 42, and all tested materials were hexaploids. Among them, the karyotype formula of ‘Yan Wang’, ‘Monica’, and ‘Qiang Shou’ was respectively 2n = 6X = 26m + 16sm (6sat), 2n = 6X = 22m + 20sm (4sat), and 2n = 6X = 22m (2sat) + 20sm (4sat), belonging to type 2B. The karyotype formula of ‘Qinghai 444’, ‘Mu Wang’, and ‘Jun Ma’ was respectively 2n = 6X = 28m (4sat) + 14sm, 2n = 6X = 22m (2sat) + 20sm (2sat), and 2n = 6X = 22m (2sat) + 20sm (4sat), and their karyotype type was 2A. All six oat cultivars contained satellites. The results of this study can provide a cytological basis for the identification of oat germplasm resources and research on genetic breeding.
Physiological response of six alpine grass varieties to drought stress and their drought resistance evaluation
LIN Yaping, YANG Chenghang, SU Jiahao, MA Qing, BAO Aike
2021, 38(12): 2397-2405. doi: 10.11829/j.issn.1001-0629.2021-0078
[Abstract](973) [FullText HTML] (413) [PDF 991KB](21)
Screening excellent drought resistant grass varieties is an important prerequisite for the rapid restoration of desertification grassland in alpine regions. In this study, six grass varieties mainly used in grassland restoration in alpine area were used as materials for pot experiment under drought stress, and the responses of shoot biomass, leaf moisture status, cell membrane permeability, chlorophyll content, superoxide dismutase and peroxidase activity of above varieties to drought stress were analyzed, the drought resistance of 6 grasses was evaluated comprehensively by subordinate function method. The results showed that drought stress inhibited the growth of six grasses, which showed that the leaf tissue water content and chlorophyll content decreased, the cell membrane permeability and the activity of antioxidant enzymes increased. Elymus sibiricus ‘Tongde’, E. sibiricus ‘Qingmu No. 1’ and E. breviaristatus ‘Tongde’ could maintain high antioxidant enzyme activities and grew better under drought stress. The order of drought resistance among 6 grasses was as follows: E. sibiricus ‘Qingmu No. 1’ > E. sibiricus ‘Tongde’ > E. breviaristatus ‘Tongde’ > Poa crymophila ‘Qinghai’ > Poa pratensis var. anceps ‘Qinghai’ > Festuca sinensis ‘Qinghai’. This study suggested that E. sibiricus ‘Qingmu No. 1’, E. breviaristatus ‘Tongde’, and E. sibiricus ‘Tongde’ were more suitable for planting in desertification grassland in alpine regions.
Effects of three plant growth regulators on the photosynthetic indicesindexes of giant juncao under different drought stress conditions
LI Sutao, CHEN Siqi, LI Yan, SHI Wenjiao, SU Dewei, LIN Hui, LUO Hailing, ZHOU Jing
2021, 38(12): 2406-2420. doi: 10.11829/j.issn.1001-0629.2021-0329
[Abstract](936) [FullText HTML] (453) [PDF 1327KB](15)
Using giant juncao seedlings as an experimental material, we measured the rates of net photosynthesis (Pn), transpiration (Tr), stomatal conductance (Gs), and water-use efficiency (WUE) using CIRAS-3. We analyzed the effects of different concentrations of the growth regulators methyl jasmonate (MeJA), 3-indoleacetic acid (IAA), and zeatin (ZT), applied via foliar spraying, on the photosynthetic indices of giant juncao subjected to drought stress induced by 15% PEG. The results revealed that under drought stress alone, plant growth was significantly reduced, and there were significant reductions in Pn, Tr, Gs, and WUE compared with control plants. However, spraying stressed plants with different concentrations of MeJA, IAA, and ZT resulted in significant increases in Pn, Tr, Gs, and WUE after spraying with 25 μmol·L−1 MeJA, 510 μmol·L−1 IAA, and 6 μmol·L−1 ZT compared with stressed control, and these were established to be the optimal concentration of the respective growth promoters Furthermore, by spraying plants with 25 μmol·L−1 MeJA, 510 μmol·L−1 IAA, and 6 μmol·L−1 ZT under different levels of drought stress and at different periods of time, we found that the optimal time for applying MeJA was during the second half of the stress period, between 8 and 24 h after stress onset. In contrast, application of IAA and ZT during the first half of the stress period, between 1 and 8 h, was found to be the most effective. In conclusion, this study revealed the effect mechanism of MeJA, IAA and ZT on photosynthetic indexes of giant juncao under drought stress, which provided a reference for studying its response mechanism to giant juncao under drought stress.
Comparative experiment on the production performance of four Sorghum bicolor × S. sudanense cultivars in the Chengdu Plain
DING Qiong, XIE Guanqi, ZHANG Huan, BAN Qiqin, LU Xiaowen, WANG Xiaoshan, HUANG Linkai
2021, 38(12): 2421-2428. doi: 10.11829/j.issn.1001-0629.2021-0208
[Abstract](1005) [FullText HTML] (430) [PDF 913KB](23)
To screen for high yield and high-quality Sorghum bicolor × S. sudanense cultivars in the Chengdu Plain. Field experiment of four cultivars were conducted in the Chengdu Plain from 2018 to 2020. The phenological phase, agronomic traits, and hay grass yield were measured; only the grass yield was measured for three years, and others were measured in the first year. Seven growth indexes were comprehensively evaluated by the grey relational degree analysis method. The results showed that in terms of growth characteristics, ‘Shucao No. 1’ and ‘Jicao No. 2’ had the highest plant height. The leaf number, tiller number and leaf width of ‘JC-009’ were the highest, and ‘JC-009’ had the highest hay yield and the lowest stem/leaf ratio. The comprehensive evaluation of the four cultivars using the grey relational degree indicated that ‘JC-009’ was more suitable for planting in the Chengdu Plain.
Comprehensive character evaluation of 12 wild legume forage germplasms in Tibet
PENG Yan, MA Sujie, SUN Jingyuan, WANG Xiangtao, SUN Lei, WEI Xuehong
2021, 38(12): 2429-2439. doi: 10.11829/j.issn.1001-0629.2020-0707
[Abstract](851) [FullText HTML] (375) [PDF 1131KB](12)
To alleviate the problems of lack of high protein forage during the cold season in alpine grazing area of Nyingchi in Tibet, a comprehensive introduction evaluation of 12 legume forage germplasms was conducted. The grey relationship analysis, membership function analysis, similar priority ratio analysis, principal components analysis were used to evaluate the production performance and nutritional value of these using the weighted analysis method. Using the simple correlation analysis, we analysed 13 main traits: growth duration, plant height, growth rate, fresh dry weight ratio, dry weight ratio, crude protein, crude fat, crude fiber, crude ash, dry matter, nitrogen-free extract, calcium, phosphorus and fresh yield to explore the effects of main traits on fresh yield. The results showed that the different wild legume forages had different adapt ability to Nyingchi environment according to their agronomic characters. The phenological period of Vicia amoena was longest at 174 d, and the yield was highest at 4 665.89 kg·ha−1. The plant height of V. tibetica ‘Qiangna’ was highest (114.75 cm). The average growth rate, fresh dry weight ratio, crude protein, crude ash, calcium of V. angustifolia ‘Dangxiong’ was the highest at 1.60 cm·d−1, 6.89, 20.81%, 13.58%, 1.35%, respectively. The crude fat of V. tibetica ‘Chayu’ was the highest at 8.85%. The nitrogen-free extract, dry matter of V. tibetica ‘Bamadang’ was the highest, being 43.33%, 97.78% respectively, and the crude fibre was the lowest (20.12%). The phosphorus contents of Lablab purpureus ‘Shannan’ was the highest (2.76%). Plant height and growth rate; crude ash and fresh dry weight ratio were of 12 wild legume forages significantly positive correlation. The optimal wild legume forages suitable for utilization in Nyingchi were Vicia angustifolia ‘Dangxiong’ , Vicia amoena and Vicia tibetica ‘Chayu’, based on comprehensive evaluation. The results of this research play an important role in solving the forage shortage and promoting the sustainable development of Nyingchi grassland animal husbandry.
Effects of different growth periods on the quality of ‘118’ forage millet silage
ZHAO Muqier, WANG Zhijun, JIA Yushan, ZHANG Yonghu, WEN Rui, BAO Jian, Gegentu
2021, 38(12): 2440-2448. doi: 10.11829/j.issn.1001-0629.2021-0138
[Abstract](958) [FullText HTML] (442) [PDF 846KB](19)
To determine the optimal growth period of forage millet (Setaria italica) silage, a random block design was adopted in this study, using ‘118’ forage millet varieties as test varieties. They were harvested during the filling period, milk maturity period, and wax maturity period to prepare small package silage. After 60 days of anaerobic fermentation, the nutrient composition, fermentation quality, and microbial composition were compared. The result showed that: 1) As the growth period progressed, dry matter content in the silage gradually increased, while the crude protein content and soluble carbohydrate content showed a decreasing trend, and the soluble carbohydrate content in the milk maturity period was higher. 2) After 60 days, the number of lactic acid bacteria in silage increased, with the highest number being observed in the treatment group in the milk maturity period. There were a certain number of molds, yeasts, and general aerobic bacteria in each treatment group. 3) The pH value in different growth periods was relatively high and the lactic acid content was low, but the presence of butyric acid was not detected. 4) The membership function value method was used for comprehensive evaluation, and the evaluation results were in the order: milk maturity > dough stage > filling period. Although there were differences in silage quality at different growth stages, it did not reach the standard of high-quality silage. The addition of exogenous silage additives was an effective means to improve the silage quality of forage millet and reduce nutrient loss.
The effect of maize||soybean intercropping on root morphology on the Loess Plateau
REN Yuanyuan, LI Zhaoyi, YAN Minfei, ZHANG Suiqi
2021, 38(12): 2449-2459. doi: 10.11829/j.issn.1001-0629.2021-0417
[Abstract](785) [FullText HTML] (355) [PDF 1025KB](8)
It is of great significance to understand the mechanism of high yield and high efficiency of intercropping system, by studying the effect of intercropping patterns on soil water content and root morphology in dryland rain-fed regions. Maize (Zhengdan 958, M1 and Yuyu 22, M2) and soybean varieties (Zhonghuang 24, S1 and Zhonghuang 13, S2) were intercropped at 2 ꞉ 2 row proportion (M1S1, M1S2, M2S1, M2S2) to analyze crop yield, root morphology and soil water content under different maize-soybean intercropping systems. The results showed that: The yield under M1S1 intercropping was higher than other intercropping systems. The root surface area density, root volume density and root weight density of maize under M1S1intercropping were higher by 40.6%, 62.4% and 71.9% than those of M2S1 intercropping. The root surface area density and root volume density of soybean under M1S1 intercropping increased by 39.7% and 29.4% compared with M1S2 intercropping. The increase in root surface area density, root volume density, root weight density by soil water content of maize and soybean under M1S1 intercropping was by 1.5 ~ 2.9, 3.1 ~ 3.3, 3.3 ~ 4.9, and 1.1 ~ 1.4, 1.5 ~ 2.4, 1.3 ~ 2.0 times greater than those in M1S2, M2S1, and M2S2. Therefore, M1S1 intercropping could effectively increase the growth rate of root morphology, which is beneficial for crop growth and increased yield of crops in dryland areas.
Effects of artificial grass on improving soil quality and agronomic traits of chestnuts in a Castanea henryi orchard
YU Jinlin, YOU Longhui, XU Huichang, YOU Huiming, CHENG Fensheng, NIE Sen, YE Gongfu, LI Jianmin, HUANG Yonglai, HUANG Aizhen
2021, 38(12): 2460-2470. doi: 10.11829/j.issn.1001-0629.2021-0372
[Abstract](903) [FullText HTML] (432) [PDF 1325KB](17)
This research evaluated the benefits of green manure for soil quality recovery, compared with those of traditional clear tillage and chemical herbicide application methods, in a Castanea henryi orchard in the typical red soil hill region of Fujian. A randomized block design was adopted, with each block having an area of 0.3 ~ 0.5 ha. The experimental site was cleared of natural weeds, trialed with two grass species (Vulpia myuros, VM; Lolium perenne, LP) and three legume species (Vicia villosa, VV; Astragalus simicus, AS; Chamaecrista rotundifolia, CR) as green manure crops, and treated with glyphosate spraying (GS) and clearing tillage treatments (CT), with three replicates of each. The physical and chemical properties, microbial biomass carbon and nitrogen of soils, and agronomic traits of chestnut in the five green mature and the two control treatments in the C. henryi orchard were analyzed. It was found that: 1) Compared with the CT and GS treatments, the soil quality of all grass cultivation treatments was significantly (P < 0.05) improved. In 0 − 10 cm and 10 − 20 cm soil layers, the contents of alkali-hydrolyzable nitrogen and microbial biomass carbon (MBC) of the VM treatment were the highest. The contents of alkali-hydrolyzable nitrogen were 74.14 and 54.87 mg·kg−1; the contents of microbial biomass carbon (MBC) were 1.42 and 1.15 g·kg−1. The contents of exchangeable calcium and magnesium of the LP treatment were the highest. The contents of exchangeable calcium were 128 and 93.39 mg·kg−1; the contents of magnesium were 114.95 and 66.28 mg·kg−1, respectively. The VV treatment had the highest microbial biomass nitrogen (MBN) content, which were 47.68 and 30.89 mg·kg−1, respectively. 2) Compared with that of the CT and GS treatments, the contents of starch, soluble sugar, protein, fat, phosphorus, potassium, calcium, and magnesium in the fruits of green manure crops were all increased. The transverse and longitudinal diameters of chestnut in the VM treatment were 26.6 mm and 33.1 mm, the weight of a single fruit was 13.54 g, which was significantly higher than that of CT and GS treatments, and the per unit yield of chestnut was higher than that of CT and GS treatments, which were 59.44% and 111.25%, respectively. 3) Mantel test and random forest analysis showed that MBN, soil hydrolyzed nitrogen, and exchangeable magnesium were not only the key factors affecting the agronomic traits of chestnut fruit, but also the most important factors affecting the yield of chestnut. In conclusion, grass cultivation can improve the soil quality of C. henryi garden, improve the agronomic characteristics of C. henryi fruit, and increase income for chestnut farmers. In this research, the VM treatment had the best performance and could be the best choice for ground management of C. henryi orchards in southern China.
Expression of the eg gene of cellulase from cattle rumen in Lactobacillus and analysis of enzymatic properties
ZOU Aiai, WEI Yaqin, YANG Yuze, CAO Lei, SUN Kangyongjie, WAN Xuerui, WANG Chuan
2021, 38(12): 2471-2480. doi: 10.11829/j.issn.1001-0629.2021-0001
[Abstract](1267) [FullText HTML] (436) [PDF 1383KB](14)
In order to construct highly expressing endoglucanase genetically engineered bacteria, the whole genome of the microorganism in bovine rumen juice was used as a template in this study, and the eg fragment was obtained by PCR amplification In order to construct genetically engineered bacteria with high endoglucanase expression, we used the whole genomes of microorganisms in bovine rumen juice as a template. We obtained a fragment containing the eg gene of cellulase by PCR amplification, which was cloned into the expression vector pMG36e to yield the expression vector pMG36e::eg. Recombinant plasmids containing the pMG36e::eg construct were electrotransduced into lactic acid bacteria (Lactococcus lactis NZ9000) to obtain an L. lactis NZ9000/pMG36e::eg recombinant strain, and the fermentation supernatant of the recombinant strain was concentrated using the 10% trichloroacetic acid/acetone precipitation method. Enzyme activity of the recombinant endoglucanase was determined using the 3, 5-dinitrosalicylic acid (DNS) and Congo red staining methods, total enzyme activity was determined using the filter paper enzyme activity (FPA) method, and enzymatic properties were examined. A gene of approximately 1 500 bp was cloned from a bovine rumen microorganism and the molecular weight of the encoded enzyme was approximately 50 kDa. Congo red staining analysis revealed that the recombinant enzyme caused a clear 2.32 cm zone of hydrolysis. The enzyme activity of the recombinant protein was 12.401 9 U·mL−1 based on the DNS method and 12.246 9 U·mL−1 using the FPA method. Furthermore, the recombinant protease has enzymatic activity on CMC-Na, filter paper, microcrystalline cellulose, and absorbent cotton. Enzyme activity was found to be optimal at a temperature of 90 °C and pH 6. Metal ions, including Cu2 + , Mn2 + , Ba2 + , Zn2 + , and Co2 + , were found to promote activity of the recombinant enzyme, whereas Fe2 + inhibited recombinant endoglucanase activity. In this study, we thus demonstrated the stable high-efficiency expression of the cellulase eg gene in L. lactis NZ9000, the practical utilization of which will contribute to improving the nutritional value of silage and digestibility of cattle feed.
Screening of polymorphic microsatellite markers in the plateau zokor based on transcriptome sequencing
LIU Qianqian, TAN Yuchen, YAO Baohui, KANG Yukun, SU Junhu
2021, 38(12): 2481-2489. doi: 10.11829/j.issn.1001-0629.2021-0052
[Abstract](1160) [FullText HTML] (492) [PDF 1069KB](11)
The second generation of high-throughput sequencing technology was used for transcriptional sequencing of the brain tissue of the plateau zokor (Eospalax baileyi). Microsatellite markers were screened, their composition and characteristics were analyzed, and their polymorphisms were examined, which laid a foundation for the development of microsatellite markers in the plateau zokor. The results showed that among the 29 090 microsatellite markers obtained, the main repeat types were mononucleotide repeats A/T (54.31%), followed by the dinucleotide repeats CA/TG (10.46%), and other base repeat types only accounted for 16.79%. A total of 104 microsatellite loci were randomly selected for primer design, and 43 loci were successfully amplified. After 12 polymorphic loci were detected by capillary electrophoresis, we found that the number of alleles was 3~12, the observed heterozygosity (Ho) was 0.263~0.937, with an average value of 0.651, and the expected heterozygosity (He) was 0.285~0.844, with an average value of 0.600. After Bonferroni correction, two microsatellite loci deviated significantly from Hardy–Weinberg equilibrium (P < 0.01), and no significant linkage disequilibrium was observed in the 10 microsatellite loci (P > 0.01). The polymorphism information content (PIC) ranged from 0.251 to 0.816, all loci were moderately polymorphic (0.250 < PIC < 0.500), and seven microsatellite loci were highly polymorphic (PIC > 0.500). These microsatellite markers provided basic data for the identification of parental relationships and population genetics of the plateau zokor.
Effects of enzyme preparation on mixed silage from Myriophyllum elatinoides, corn flour, and rice straw powder
WU Kangle, CAO Xin, XIE Zhan, XIAO Runlin, ZHANG Zhifei
2021, 38(12): 2490-2496. doi: 10.11829/j.issn.1001-0629.2021-0272
[Abstract](1017) [FullText HTML] (441) [PDF 980KB](8)
The mixed silage materials of Myriophyllum elatinoides, corn flour, and rice straw were 70% ꞉ 15% ꞉ 15% for fresh ingredients. Cellulase, xylanase, or composite cellulase was added to the mixed silage but not in the control group. The effects of different enzyme preparations on fermentation quality, nutritional quality, and aerobic stability of mixed silage from M. elatinoides were studied. Compared with the control, the addition of enzyme preparation significantly reduced pH, ammonia nitrogen/total nitrogen (P < 0.05), and significantly increased soluble carbohydrate content (P < 0.05). The sensory score, V-score, pH, ammonia nitrogen/total nitrogen, and lactic acid content of the compound cellulase treatment group were the best. The xylanase treatment group had the best aerobic stability. The cellulase treatment group had the highest crude protein, neutral detergent fiber content, V-score, pH value, and ammonia nitrogen / total nitrogen; these fermentation-related indicators belong to the category of high-quality silage fermentation. Comprehensive fermentation quality, nutritional quality, and aerobic stability of the cellulase treatment group had the best effect.
Effects of additives and storage time on chemical composition and microbial population of native grass pellet
SUN Lin, NA na, FANG Yongyu, ZHAO Junli, WU Xiaoguang, XIAO Yanzi, WANG Chao, Wunier, Qilimoge, XUE Yanlin
2021, 38(12): 2497-2506. doi: 10.11829/j.issn.1001-0629.2021-0387
[Abstract](962) [FullText HTML] (464) [PDF 829KB](17)
The objective of this study was to investigate the effects of additives and storage time on the chemical composition and microbial population of native grass pellets. Scutellaria baicalensis and propionic acid were added to native grass, with a mass fraction of 1%, to make pellets. Samples were taken at 0, 30, 60, 90, 120, and 150 days of storage to determine the chemical composition and the number of microorganisms. The results showed that storage time had significant effects on dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) contents of native grass pellets (P < 0.05), and at the later stage of storage, the contents of NDF and ADF in native grass pellets decreased significantly (P < 0.05); but storage time had no significant effects on their crude protein (CP) and organic matter (OM) contents; the DM content of native grass pellets showed an increasing trend during storage, and tended to be stable at 120 d. At a later stage of storage, the content of NDF and ADF in native grass pellets decreased significantly (P < 0.05). Propionic acid significantly increased the contents of DM, NDF, and ADF in native grass pellets during storage (P < 0.05) and decreased the number of Escherichia coli and aerobic bacteria attached to the pellets ( P < 0.05). The addition of Scutellaria baicalensis significantly increased OM content (P < 0.05), decreased CP content (P < 0.05), and significantly inhibited the activities of yeast and aerobic bacteria on the surface of native grass pellets ( P < 0.05).
Optimization of extraction conditions and qualitative and quantitative analysis of volatile components of alfalfa
YUAN Ning, Terigele, SUN Lin, JIA Yushan, Gegentu, WANG Zhijun, LU Qiang, LI Yuyu, LI Junfeng, SUN Pengbo
2021, 38(12): 2507-2523. doi: 10.11829/j.issn.1001-0629.2021-0217
[Abstract](872) [FullText HTML] (427) [PDF 1171KB](15)
Volatile components are the basic sensory indicators of the quality of alfalfa hay, which is subject to environmental changes and microbial effects during storage, resulting in significant changes in the volatile components, directly affecting the palatability of alfalfa hay. At present, there is a lack of analytical methods to identify the volatile components of alfalfa hay in China’s forage industry. So, this experiment used headspace solid phase microextraction–gas chromatography–mass spectrometry (HS–SPME–GC–MS) to analyze the volatile components of alfalfa (Medicago sativa), combined with areas of peak. Normalization method determines the relative content of each compound. The results showed that an extraction temperature of 90 ℃, extraction time of 80 min, desorption temperature of 250 ℃, and desorption time of 3 min are the best extraction conditions. A total of 52 compounds were detected in alfalfa under these extraction conditions, including 9 ketones, accounting for 37.55% of the total volatiles, 12 alcohols, accounting for 21.74% of the total volatiles, and 15 aldehydes, accounting for 19.31% of the total volatile matter, 6 kinds of ester compounds, accounting for 9.41% of the total volatile matter. The content of β-ionone can reach about 20% of the total volatiles, phenethyl alcohol, trans-2-hexenal, 2-phenylacetaldehyde, nonanal, decanal, 6-methyl-5-heptene-2-ketones, 3, 5, 5-trimethylcyclohex-2-enone, menthone, etc. contribute significantly to the volatile components of alfalfa.
The impact of multi-household rangeland operation on non-agricultural employment and household income in the Qinghai-Tibet Plateau: An empirical analysis based on Qinghai and Gansu survey data
ZHOU Xue, DONG Ruitong, QIN Changsheng, TANG Zeng, WANG Lijia, ZHANG Yan
2021, 38(12): 2524-2535. doi: 10.11829/j.issn.1001-0629.2021-0166
[Abstract](1071) [FullText HTML] (433) [PDF 961KB](22)
The multiple household operations of rangeland is common in the pastoral area of the Qinghai-Tibet Plateau, and it is widely believed that this operation can save management labor. However, little is known about whether the released labor is laid aside or transferred to non-farm employment leading to increase in household income. None of the previous studies have explored this issue in the Qinghai-Tibet Plateau. Based on survey data of 357 herders collected from the pastoral areas of Qinghai and Gansu provinces, this study analyzed the impact of multiple household operations on non-agricultural employment and household income using the endogenous switching probit (ESP) regression and treatment effect model (TEM). The empirical results show that multiple household operations can effectively promote non-agricultural employment and significantly increase household income (P < 0.01). But as a spontaneous organization exists, the management of many families has strong instability. Our results suggest the necessity to strengthen and optimize the behavior of herders’ cooperative organizations and formalize herders’ cooperative organizations to achieve economies of scale. Promoting the development of non-agricultural industries and increasing suitable non-agricultural employment positions are also very important to pastoral areas.
2021, 38(12): 2536-2536.
[Abstract](158) [FullText HTML] (66) [PDF 0KB](1)