QIAO Yanzhao , LIU Kai , LI Qinghua , HUANG Jianhao , WEI Hengxi , ZHANG Shouquan
2021, 42(2):1-8. DOI: 10.7671/j.issn.1001-411X.202002011
Abstract:Objective The Tet-on system was combined with the CRISPR/Cas9 system to establish a pig cell line with inducible Sohlh1 gene knockout.Method Porcine fetal fibroblast (PFF) was isolated and cultured for infection with lentiviral vector PCW-eSpCas9(1.1), screened by 1 μg/mL purinomycin and induced by doxycycline (Dox). The pLV-sgRNA vector was modified and transfected with 293FT cells for validation. The pLV-sgRNA-2A-GFP specific vector containing Sohlh1 gene target was constructed for lentivirus packaging detection. PCW-eSpCas9(1.1) PFF cell was transfected by package virus infection and screened by 3 μg/mL blasticidin, followed by Dox induction for expression analysis and knockout efficiency detection.Result PFF cell line, which was regulated by Dox to induce eSpCas9 (1.1) protein expression, was established. Without Dox addition, eSpCas9 (1.1) protein expression was not observed. Green fluorescence was expressed in 293FT cells, indicating the successful transformation of pLV-sgRNA-2A-GFP vector. The No. 3, 4 and 6 Sohlh1 gene targets had knockout activities. The pLV-sgRNA-2A-GFP specific vector was constructed with the two optimal targets, and the fluorescence expression showed that the vector lentivirus was successfully packaged. The PFF cell of stable PCW-eSpCas9(1.1) and pLV-sgRNA-2A-GFP transformation was constructed. After 72 hours of Dox induction, the knockout efficiency of Sohlh1 gene was 85%.Conclusion The pig cell line with inducible Sohlh1 gene knockout is successfully constructed using the Tet-on system and CRISPR/Cas9 system, which lays a foundation for studying the function of Sohlh1 gene and preparing the model pig with conditional Sohlh1 gene knockout to remove germ cells.
YU Yang , HUA Chengyun , XU Ying , FENG Yunyun , LIU Yu , HUANG Xianhui
2021, 42(2):9-16. DOI: 10.7671/j.issn.1001-411X.202005003
Abstract:Objective To prepare a doxycycline thermo-sensitive in situ gel uterine perfusate, evaluate its quality, and monitor drug concentration in sow uterus.Method Poloxamer 407 (P407) and poloxamer 188 (P188) were used as the main thermo-sensitive materials. The in situ gel was prepared by “cold” process. The prescription was screened and optimized by single factor analysis and orthogonal experiment. The in vitro dissolution and drug release of the preparation were measured by membrane free dissolution model. The stability of the developed thermo-sensitive gel was investigated under the conditions of high temperature, high humidity and strong light. Five binary hybrid sows were selected to monitor drug concentration in sow uterus.Result The final optimized prescription was doxycycline 1 g, P407 10 g, P188 2.5 g, magnesium chloride 2.3 g and sodium bisulfite 0.1 g in per 50 g preparation, pH was adjusted to 4.0±0.2 with ethanolamine, and the residue was ultrapure water. The in vitro dissolution and drug release time of the preparation lasted for 48 h, the cumulative dissolution rate and drug release rate were up to 100%. The preparation stability was complied with technical guidelines for the stability of veterinary chemical drugs. The drug concentration remained at 68.54 μg/mL after 96 h of the second administration.Conclusion The doxycycline thermo-sensitive in situ gel uterine perfusate is a simple preparation method and shows good stability. The local concentration of the drug in sow uterus maintains at a high level for a long time. The preparation has a sustained release effect and is expected to be an innovative way to treat sow endometritis.
ZHANG Juan , HU Honghong , DENG Zhanzhao , MU Tong , GU Yaling , XIN Guosheng
2021, 42(2):17-25. DOI: 10.7671/j.issn.1001-411X.202006037
Abstract:Objective To explore the structure and function of protein encoded by AK1 gene screened by transcriptome sequencing of Ningxia local breed Jingyuan chicken, and construct its eukaryotic expression vector.Method According to the original chicken AK1 gene sequence published on GenBank, specific primers were designed for its CDS region, and the CDS region SNPs of AK1 gene were screened quickly by cloning and sequencing. The eukaryotic expression vector of AK1 gene was constructed. The bioinformatics function of the coding region was analyzed.Result The full length of AK1 gene coding region was 585 bp, which encoded 194 amino acids. AK1 protein had no transmembrane domain, and it had two CpG islands, 18 phosphorylation sites and 10 antigenic epitopes. AK1 protein was a stable water-soluble protein, and the spatial structure was mainly α-helix and irregular crimp. The results of subcellular localization showed that AK1 protein was mainly located in the cytoplasm, and GO enrichment analysis showed that AK1 gene was also enriched in the cytoplasm, which was consistent with the result of subcellular localization. Gene co-expression analysis of genes interacting with AK1 showed that AMPD1 and PKM2 coexpressed with AK1 gene, and the co-expression coefficients were 0.116 and 0.063, respectively. The AK1-pEGFP-N1 vector was successfully constructed.Conclusion The results of this study provide a scientific basis for further study of the function of AK1 protein and AK1 as an inosinic acid-related gene.
HE Mengchu , LI Siting , WANG Zhi , SHU Yingshuang , GUI Xueer , ZHU Jie , LI Jinchun , WU Jinjie
2021, 42(2):26-33. DOI: 10.7671/j.issn.1001-411X.202003020
Abstract:Objective To investigate the effects of probiotics on serum immunoglobulin and intestinal Toll-like receptor pathway in broilers.Method Ninety one-day-old white feather chicks were randomly divided into three groups including control group, low-dose probiotic group and high-dose probiotic group. The chicks in control group were fed basal diet, 109 cfu probiotics per kg basal diet were added in the low-dose probiotic group, and 2×109 cfu probiotics per kg basal diet were added in the high-dose probiotic group. On the 21st day, ten chicks in each group were sacrificed by bloodletting, and the samples were collected immediately for ELISA, immunohistochemistry, qPCR and Western blot.Result Compared with the control group on the 21st day, the feed conversion ratios of low- and high-dose probiotic groups decreased by 9% and 12% (P<0.05), the IgG levels in serum increased by 28% and 40% (P<0.01), and the IgM levels in serum increased by 44% and 58% (P<0.01) respectively. The protein and mRNA expression of TLR4 increased by 33% and 28% respectively in low-dose probiotic group (P<0.01), and the protein and mRNA expression of AP-1 increased by 106% and 67% respectively in low-dose probiotic group (P<0.01). The protein and mRNA expression of TLR4 increased by 106% and 69% respectively in high-dose probiotic group (P<0.01), and the protein and mRNA expression of AP-1 increased by 163% and 98% respectively in high-dose probiotic group (P<0.01).Conclusion Feeding probiotics can reduce the feed conversion ratio in broilers, increase the levels of IgG and IgM in serum, and enhance the immunity by regulating the expression of Toll-like receptor pathway proteins.
MU Tong , HU Honghong , FENG Xiaofang , GU Yaling , TIAN Jia , WEN Wan , ZHANG Juan , WANG Ying
2021, 42(2):34-43. DOI: 10.7671/j.issn.1001-411X.202005023
Abstract:Objective To clarify the effects of non-genetic factors on the raw milk composition and related traits of Holstein in Ningxia region.Method Based on the DHI data of Holstein in Ningxia region, the effects of parity, lactation stage and calving season on nine lactation traits were analyzed by GLM process of SAS 9.2 software, and the variation characteristics of lactation traits in different somatic cell scores were explored.Result Parity, lactation stage, calving season, lactation stage×calving season had significant effects (P<0.05) on nine lactation traits. Comparison of different parities showed that milk fat percentage and milk solid content decreased significantly after the second parity (P<0.05), milk protein percentage and peak milk yield decreased significantly after the third parity (P<0.05), daily milk yield decreased slightly after the fourth parity, milk lactose percentage decreased first and then increased, reaching the lowest level of 4.84% in the third parity (P<0.05), somatic cell score increased gradually with the increase of parity, and the day of peak milk yield was the latest in the first parity(94.07 d) and the earliest in the fourth parity (67.33 d). Comparison of different lactation stages showed that daily milk yield and milk lactose percentage gradually decreased with the prolongation of lactation in the second and third parities (P<0.05), while milk protein percentage, milk solid content, somatic cell score and milk fat percentage showed an increasing trend (P<0.05). Comparison of different calving seasons showed that from spring to winter, milk fat percentage of the first parity to third parity and milk solid content of the first parity gradually decreased, while daily milk yield and milk lactose percentage showed an increasing trend for the first parity and were at the lowest level in summer for the second parity and third parity. Milk protein percentage, somatic cell score, the day of peak milk yield and peak milk yield showed a trend of increasing first and then decreasing from the first parity to third parity, and the highest levels of all these traits for different parities were found in summer. With the increase of somatic cell score, milk lactose percentage, daily milk yield and peak milk yield decreased gradually, while milk fat percentage and milk protein percentage increased slowly. Milk solid content and the day of peak milk yield reached the highest level when somatic cell score was 4 and 5, respectively.Conclusion The results of this study provide a theoretical basis for improving the lactation performance and fresh milk quality of Holstein in Ningxia.
WANG Chaohuan , SONG Bowen , YU Sijia , XIAO Wuming , HUANG Ming
2021, 42(2):44-50. DOI: 10.7671/j.issn.1001-411X.202006039
Abstract:Objective The indica cultivar ‘MDS’ and ‘R315’ were used as parents to construct a high-density genetic map, explore the important agronomic traits related genes of rice (Oryza sativa L.) and accelerate the breeding of rice cultivars.Method Whole genome sequencing of parents and their 192 recombinant inbred lines (RILs ) were performed to screen high-quality single nucleotide polymorphisms (SNPs) and construct bin markers. The bin markers were sorted using JoinMap4.0 for each linkage group, and perl SVG was used to draw the linkage map. Collinearity analysis was conducted according to the position of the markers on the genome and genetic map.Result A total of 221 494 high-quality SNPs were screened between the two parents. The constructed high-density genetic map contained 1 612 bin markers. The total map distance was 1 327.82 cM, and the average genetic map distance between adjacent markers was 0.82 cM. The collinearity analysis showed that the order of most markers on each linkage group was consistent with that on the genome. The collinearity was good and the map was of high quality.Conclusion The constructed high-density genetic map is of high quality, providing a preliminary basis for the subsequent identification of functional genes.
ZHANG Lidan , LIU Qinghu , LIU Fang , SUN Shaolong , FAN Xiaolin
2021, 42(2):51-57. DOI: 10.7671/j.issn.1001-411X.202005018
Abstract:Objective To explore the necessity and importance of phosphorus fertilization in phosphorus-rich soil, clarify the effects of phosphorus application rate in controlled release formula fertilizer on banana yield, phosphorus accumulation and use efficiency of phosphorus fertilizer, and provide a theoretical basis for determining fertilizer formula and rational application of phosphorus fertilizer in phosphorus-rich soil.Method The field experiment of phosphorus gradient was carried out to study the effects of phosphorus application rate in the controlled release formula fertilizer on banana shooting and harvest time, yield, phosphorus accumulation and phosphorus fertilizer use efficiency.Result In phosphorus-rich soil with Bray-P of 158 mg·kg-1, the supply levels of nitrogen (200 g N per plant) and potassium (400 g K2O per plant) were fixed. When the phosphorus application rate was 80 g P2O5 per plant, the effect of promoting bud emerging and harvest time of banana was most obvious, and the harvest rate at the same period increased by 5.3 to 31.1 percentage points than other treatments. The banana yield and phosphorus fertilizer use efficiency both increased first and then decreased with the increase of the phosphorus application rate. When the phosphorus application rate was 80 g P2O5 per plant, the banana yield and apparent P recovery efficiency in the current season were the highest reaching 27.7 kg·plant-1 and 16.0%, respectively.Conclusion In phosphorus-rich soil, phosphorus application can increase the banana yield and economic benefit. The ratio of nitrogen (N), phosphorus (P2O5), and potassium (K2O) in the controlled release formula fertilizer was recommended to be 1.0∶0.4∶2.0, and the recommended fertilization application rates were 200 g N, 80 g P2O5 and 400 g K2O per banana plant, of which controlled release N accounted for 20% of total nitrogen.
LIN Tingrui , SUN Zheng , LU Rihui , LIU Kexing , XU Hanhong
2021, 42(2):58-64. DOI: 10.7671/j.issn.1001-411X.202004032
Abstract:Objective To study the effects of new organic fertilizers with botanical pesticide components (tobacco residue organic fertilizer and tea saponin organic fertilizer) on rice growth and pest control efficiency, and promote the double reduction of chemical fertilizers and pesticides in rice cultivation.Method Three treatments were designed as following: Conventional fertilization (control), tobacco residue organic fertilizer plus 80% conventional fertilization, tea saponin organic fertilizer plus 80% conventional fertilization. The rice yields were recorded. Nutrient uptake of rice and straw and soil available nutrients content were analyzed after rice harvest. The control effects of new organic fertilizers on rice leaf roller (Cnaphalocrocis medinalis) and white-backed planthopper (Sogatella furcifera) were evaluated at rice tillering stage.Result Compared with conventional fertilization, the partial substitution application of tobacco residue organic fertilizer and tea saponin organic fertilizer increased rice yield by 22.29% and 18.58% respectively, and the N and P uptake of rice grain and K uptake of straw increased significantly. But there were no significant difference in the soil available nutrient contents after rice harvest. The control efficiencies of tobacco residue organic fertilizer and tea saponin organic fertilizer on rice leaf roller and white-backed planthopper were obvious. The rice leaf roller control effects were 81.27% and 51.09% respectively, and the decline rate of white-backed planthopper were 55.74% and 37.70% respectively.Conclusion The application of botanical organic fertilizers with botanical pesticide components can partially replace chemical fertilizers and reduce the application of chemical pesticides, which is important for increasing yield, reducing rice pests, and promoting sustainable agricultural production.
LIN Huijiao , MOU Guiping , TENG Shaona , ZHANG Haipeng , ZHOU Erxun
2021, 42(2):65-70. DOI: 10.7671/j.issn.1001-411X.202004031
Abstract:Objective To establish a real-time fluorescent PCR assay for detecting Botryosphaeria stevensii, which is the causal agent of Diplodia canker on apple and is presently subjected to phytosanitary legislation in China.Method A pair of specific primers and a TaqMan MGB probe were designed based on the conserved sequences of β-tubulin genes of B. stevensii and related species. The specificity and sensitivity of the probe were evaluated using DNAs of B. stevensii strains and recombinant plasmid of β-tubulin gene sequence as positive standard, respectively.Result The probe of BsP267 displayed specificity to B. stevensii strains with positive amplification, while there was no crossing reaction with related species and other common fruit rot pathogens. The PCR amplification efficiency was 105.858% and the detection sensitivity of DNA reached 1 fg/μL.Conclusion The real-time PCR method developed in this study can detect B. stevensii from apple with strong specificity and high sensitivity, thus can be used for the prevention, control, detection and quarantine of this disease.
LI Xianjia , WU Jiyingzi , DAI Xiuchun , WANG Yongqing , WANG Ruifei , ZHANG Zhixiang , XU Hanhong
2021, 42(2):71-79. DOI: 10.7671/j.issn.1001-411X.202006031
Abstract:Objective To investigate the damage of Spodoptera frugiperda to ears of 22 maize cultivars widely planted in Guangdong Province.Method The damage of corn ear was investigated by “Z” shaped five-point sampling method. The damage of the upper and lower corn ears of each plant, including the numbers of 1st to 3rd instar larvae, 4th to 6th instar larvae, live insects, live pupae and the damage position drilled by larvae were recorded.Result Twenty-two maize cultivars were all damaged seriously by S. frugiperda and the ratios of damaged plants were higher than 25% for all cultivars, while there were significant differences in damage degree among different cultivars. The sweet corns suffered the most serious damage compared to other cultivars, especially the ratio of damaged plants of ‘Yuetian 16’ was up to 99.67%. There was no significant difference in damage between the upper and lower corn ears for each cultivar except ‘Yuenong 19’ and ‘Guangcainuo 19’. Majority of corn ears had S. frugiperda larvae and the ratio of corn ear containing 1 and 2 larvae was 26% − 85%, the ratio of corn ear containing 3 larvae was 2% − 17%, while no corn ear was found to have more than 3 larvae. The number of 4th to 6th instar larvae was higher than that of 1st to 3rd instar larvae for each cultivar except ‘Guangnuo 9’ and ‘Guangnuo 2005’. Ranging from 38% to 71% S. frugiperda larvae entered into corn ear from corn silk and pupated, and the average number of pupae per 100 plants were 9−32.Conclusion S. frugiperda prefer to eat sweet corn and waxy corn and pupate in their ears, while the damage to feed corn is relatively light. The 1st-3rd and 4th-6th instar larvae of S. frugiperda have the same feeding behavior during the milky stage of corn and they prefer to enter into corn ear from corn silk and damage corn. The results can provide references for breeding resistant corn cultivars and precise control of S. frugiperda.
YAN Shu , WANG Runhui , DENG Houyin , ZHENG Huiquan , HU Dehuo , WEI Ruping
2021, 42(2):80-89. DOI: 10.7671/j.issn.1001-411X.202005022
Abstract:Objective To explore the dominant ecological environment factors and stand control factors for the formation of large-diameter wood of Cunninghamia lanceolata in Nanling Mountains, investigate their influence rule and provide a theoretical guidance for cultivation and management of large-diameter wood stands of C. lanceolata in Guangdong Province.Method Based on the investigation of the existing large-diameter wood stands of C. lanceolata in Nanling Mountains, the site index (SI), soil integrated fertility index (I), micro-topography index (M) and geographical index (G) were extracted and the index evaluation system was established. The relationships of large-diameter wood volume (Vl), output (Ol), proportion (ND≥26), outturn percentage (Yl) with each index were analyzed.Result There were significant positive correlations of each index of large-diameter wood with SI, M (P<0.01), the correlation coefficients were 0.37-0.44 and 0.22-0.33 respectively. Vl、Ol and ND≥26 had significant positive correlations with I (P<0.05), the correlation coefficients were 0.24-0.39. Vl and Ol showed a gentle quadratic curve trend of slowly increasing first and then slowly decreasing with the increase of reserved density (D), the correlations were significant (P<0.05). There were no significant correlations of G, stand age (A) with each index of large-diameter wood. The large-diameter wood output at the age of 20-30 was predicted by a quantitative model: Ol=${{\rm{e}}^{{\rm{5}}{\rm{.781 + 0}}{\rm{.004}}\;{\rm{SI + 5}}{\rm{.004}}{A^{{\rm{ - 1}}}}{\rm{ + 0}}{\rm{.261}}\ln D{\rm{ - 45}}{\rm{.151S}}{{\rm{I}}^{{\rm{ - 1}}}}}}$(R=0.62, P<0.01).Conclusion SI, I, M and D are the dominant impact factors for growth of large-diameter wood in Nanling Mountains. It is benefitial for large-diameter wood formation when SI is above 18, the soil has higher porosity, moisture and nutrient contents, the micro-topography condition is a shady and concave slope below 35° in the lower part, and the reserved density is 1 100-1 300 plants·hm-2.
LIU Xiaojin , XU Daping , ZHANG Ningnan , YANG Zengjiang
2021, 42(2):90-95. DOI: 10.7671/j.issn.1001-411X.202005027
Abstract:Objective To investigate the rules of mineral nutrient concentrations in heartwood and sapwood of sandal (Santalum album L.) plantation, and provide references for further study of heartwood formation process.Method Variations of mineral nutrient contents of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) at different positions (pith, middle heartwood, outer heartwood, sapwood) and directions (east, south, west, north) in 21-year old sandal plantation in Jianfeng Mountain, Hainan Island were investigated. Result The distribution patterns of mineral nutrients between heartwood and sapwood in 21-year old sandal plantation in Jianfeng Mountain were element-specific. The contents of P, K and Ca decreased in turn from outside to the central pith, the P contents in sapwood, outer heartwood, middle heartwood and pith were 0.153, 0.032, 0.020 and 0.020 g·kg-1 respectively, the K contents were 1.883, 0.529, 0.190 and 0.182 g·kg-1 respectively, and the Ca contents were 2.414, 1.417, 1.321 and 1.281 g·kg-1 respectively. The contents of P, K and Ca in sapwood were statistically higher than those in heartwood (P<0.01), while N content got a complete opposite distribution pattern, meaning that N content in heartwood was statistically higher than that in sapwood (P<0.01). However, there was no significant difference of Mg content across radius (P=0.132). No significant difference of all above mineral nutrient contents between heartwood and sapwood was observed among four azimuths including east, south, west and north (P>0.05).Conclusion P, K and Ca are recycled from heartwood to sapwood during heartwood formation in sandal, which can improve nutrient use efficiency. N keeps a higher content in heartwood than that in sapwood, indicating that sandal can acquire enough N from its hosts or soil.
ZHOU Xinhua , LI Junshao , WEN Changwu , WU Xichang , YANG Wu , ZENG Pingsheng , WU Xiaoyu
2021, 42(2):96-101. DOI: 10.7671/j.issn.1001-411X.202006053
Abstract:Objective To explore the quality differences of wild Prunella vulgaris L. from different geographical provenances, reveal the main environmental factors that affect the medicinal ingredient contents of P. vulgaris, and provide a theoretical support for the rational development and effective protection of P. vulgaris germplasm resources.Method Taking ten geographical provenances of P. vulgaris distributed in different regions as the research object, the differences of polysaccharide and flavonoid contents were compared and analyzed, and the correlations of polysaccharide and flavonoid contents with environmental factors were studied by Pearson correlation analysis. The cluster analysis and membership function evaluation method were used to select high-quality geographical provenance.Result The polysaccharide and flavonoid contents of P. vulgaris from different geographical provenances were significantly different. The polysaccharide content ranged from 70.45 to 120.39 mg·g-1, and the flavonoid content ranged from 34.40 to 59.04 mg·g-1. The polysaccharide content of the provenance in Yichang of Hubei and the flavonoid content of the provenance in Guilin of Guangxi were the highest, with the content reaching 120.39 and 59.04 mg·g-1, respectively. The polysaccharide content in P. vulgaris showed a highly significant negative correlation with the flavonoid content. The main environmental factors affecting the polysaccharide content of P. vulgaris were latitude, longitude and altitude; And the main environmental factors affecting the flavonoid content were longitude, altitude, annual average air temperature, annual sunshine hour and annual precipitation. The clustering results divided the ten geographical provenances into three categories. The provenance in Guilin of Guangxi had the largest average membership function value and the best comprehensive quality among all the provenances.Conclusion There were significant differences in the contents of medicinal ingredients in P. vulgaris from different geographical provenances. Different environmental factors have inconsistent effects on the major medicinal ingredients. The better-quality geographical provenances and ranking of different geographical provenances can provide a basis for the selection, development and utilization of P. vulgaris germplasm resources.
ZHANG Long , SONG Shuran , SUN Daozong , XUE Xiuyun , DAI Qiufang , LI Zhen
2021, 42(2):102-109. DOI: 10.7671/j.issn.1001-411X.202006012
Abstract:Objective To study the effect of different viscosities of pesticides on the atomization characteristics of spray nozzles, and provide a theoretical reference for agricultural pesticide spray technology.Method Different mass fractions of glycerol solution were configured to replace pesticide reagents for research. The spray area of the spray nozzle was gridded, and the phase Doppler anemometry was used to measure droplet parameters at different positions in the spray area. The statistical law of droplet size in the axial direction and radial direction was analyzed using SPSS.Result In the axis direction of the spray area of the nozzle, arithmetic mean diameter, volume mean diameter, and Sauter mean diameter showed the law of first becoming smaller and then gradually increasing. The disturbance of the external air resistance made a certain pattern of surface waves on the surface of the ejected liquid. As the distance increased, the amplitude of the waves became larger, and the wave crests were torn off and broken into small droplets. Then under the action of gravity, the droplets collided and aggregated, and the droplet size gradually increased. In the radial direction of the spray area of the nozzle, the droplets were approximately symmetrically distributed, and the size of the droplets was small in the middle and large on the two sides. With the increase of the radial distance, the size of the droplets gradually increased. SPSS analysis showed that in the axial direction of the spray area the correlation coefficients of axial distance, liquid viscosity with droplet size were 0.531 and 0.795 respectively. In the radial direction the correlation coefficients of radial distance, liquid viscosity with droplet size were 0.932 and 0.328 respectively.Conclusion To a certain extent, liquids with greater viscosity have a certain effect of preventing drift. The changes in liquid viscosity have a significant effect on the droplet size in the axial direction. In the axial direction of the nozzle, changes in distance have a significant effect on the droplet size.
YANG Yanshan , DING Qishuo , ZHAO Yaping , SUN Cuihua , WANG Feng
2021, 42(2):110-115. DOI: 10.7671/j.issn.1001-411X.202007020
Abstract:Objective To optimize the design of the rotary tiller tool for wheat strip-till planter, and improve the operation quality.Method Three typical rotary tillage tools (C-type blade, straight blade and deep tillage blade) and one optimized rotary tillage tool (combination of straight blade and deep tillage blade) were applied. The field in-situ cultivation was performed under the condition of centralized surface straw treatment with the rotation speed of the blade shaft at 180, 280, 380 and 510 r/min.Result The C-type blade could create continuous and intact seedbed, but most soil fragments were thrown out seedbed during the cultivation process, and the backfill effect was the worst. The deep tillage blade had good performance in soil tillage and breaking, it created continuous and intact seedbed but the boundary was irregular, and it could not effectively control the soil disturbance range in the process of tillage. The straight blade had advantage in its control of seedbed boundary, but it could not make continuous seedbed when the rotation speed of blade shaft was 180 and 510 r/min, and the soil fragments formed by tillage was too large (mean weight diameter > 40 mm) when the rotation speed of the blade shaft was 280 or 380 r/min. The combination blades benefited from the organic combination of straight blade and deep tillage blade, therefore it had outstanding advantages in shape formation of seedbed, soil fragmentation degree and backfill effect and energy consumption.Conclusion Under the condition of centralized treatment of surface straw, the combination blades are recommended as the tillage tool of wheat strip-till planter for clay soil.
DUAN Jieli , YI Wenfeng , WANG Hongjun , ZHAO Lei , WANG Yu , YANG Zhou
2021, 42(2):116-123. DOI: 10.7671/j.issn.1001-411X.202009025
Abstract:Objective Banana harvesters are equipped to carry large loads of bunches. We propose a nail holding mechanism for bananas which posses high strength and reliable clamping force while ensuring flexible and effective operation.Method An inner palm holding mechanism with nails for picking bananas was designed, the clamping effects of different combination factors affecting the gripping force were tested, and the clamping test platform was built. The three main factors of cylinder pressure, the number and arrangement of nails affecting the clamping effect were selected, and the single factor experiment and response surface method were used to test the clamping force.Result In the cylinder pressure test, when the cylinder pressure was 0.4 MPa, the corresponding tension was about 500 N closest to the maximum static friction force between the banana handle and the palm, and banana could be clamped stably. In the test of nail arrangement, the friction that the rectangle could withstand was the maximum with a value of 800 N, which was greater than the maximum static friction force between the banana handle and the palm, and the stable clamping effect could be obtained. In the test of nail number, when the numbers of nails were eight and ten, their pulls closed to. The reason may be that the banana handle is not a regular cylindrical shape, so that the nails on the round holding palm may not be all inserted into the banana handle. When the number of nails was eight or ten, only six nails plunged into banana handle and effectively clamped. When the number of nails exceeded ten, the tension dropped instead of rising. The reason for this phenomenon may be that the more nails there are, the more serious the mutual interference occurs, and the number of effective nails decreases instead of rising.Conclusion The factors influencing the clamping force effect of clamping mechanism are cylinder pressure > nail arrangement > number of nails. The optimal parameter combination is 0.4 MPa cylinder pressure, ten nails and rectangular arrangement. This paper provides a theoretical reference for the design of clamping mechanism of key components of banana harvester equipment in flat banana plantation.
SHEN Guanghui , LI Zhihong , ZHAO Qingfeng , ZENG Yuhong , ZHAO Xinyue , ZOU Han , LIU Meiting , ZHANG Zhiqing , CHEN Anjun
2021, 42(2):124-132. DOI: 10.7671/j.issn.1001-411X.202006028
Abstract:Objective Potato juice of freeze-thaw process is the liquid by-product derived from the production of purple potato flour by solid-liquid separation method, and it is rich in carbohydrates and anthocyanins. In order to increase the utilization value of the liquid by-product, the enzymolysis juice was added as supplementary ingredient into wort to prepare dark beer by fermentation.Method Single factor test combining orthogonal experiment was performed to optimize the fermentation conditions. The contents and activities of antioxidant components in the dark beer were evaluated.Result The optimum fermentation conditions for dark beer preparation with addition of purple potato enzymolysis liquid were as follows: Content of potato enzymolysis liquid was 25% (φ), initial pH was 6.5, inoculation of 2% (φ) M21 beer starter, and fermentation for 10 d under the temperature of 15 ℃. The prepared beer was amber color and crystal clear, had harmonious flavor and mellow taste. Its sensory score was 86.9, alcohol content was 5.84%, total acid content was 15.6 mL/L beer, total reducing sugar content was 18.69 mg/mL, chroma was 37.71 EBC, total phenol content was 360.2 mg/L, chlorogenic acid content was 685.7 mg/L, and anthocyanin content was 208.4 mg/L. The total reduction capacity of 10-fold diluent beer was equivalent to that of 0.150 mg/mL vitamin C, the scavenging rate of DPPH radical was 49.9%, which was equivalent to that of 0.043 mg/mL vitamin C, and the scavenging rate of ABTS+ was 83.9%.Conclusion Addition of purple potato juice of freeze-thaw process can partially replace wort for brewing of dark beer with high antioxidant activities.
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