Ghana journal of agricultural science最新文献_第3页

Effect of temperature and pH variation on anaerobic digestion for biogas production 温度和pH变化对厌氧消化生产沼气的影响

Ghana journal of agricultural science Pub Date : 2021-12-31 DOI: 10.4314/gjas.v56i2.1

M. N. Zainudeen, M. Kwarteng, A. Nyamful, L. Mohammed, M. Mutala

{"title":"Effect of temperature and pH variation on anaerobic digestion for biogas production","authors":"M. N. Zainudeen, M. Kwarteng, A. Nyamful, L. Mohammed, M. Mutala","doi":"10.4314/gjas.v56i2.1","DOIUrl":"https://doi.org/10.4314/gjas.v56i2.1","url":null,"abstract":"A comparative analysis study of pH and temperature effects on the anaerobic digestion process of different agricultural wastes was carried out during the production of biogas. The investigation was in two phases. Phase one involved the use of a single substrate of cow dung, cassava peels, yam peels and pineapple peels while the second involved co-digestion of the substrates with cow dung. The composition of gas produced by a single substrate and a mixture of these substrates were determined. The feedstock for each experiment was a 1:1 mixture of the substrates with water. For the co-digestion, one part of the substrate and one part of cow dung were used with two parts of water, making the ratio 1:1:2. Routine measurements of pH and temperature of the feedstock were taken and the composition of the produced biogas was determined. It was deduced that cow dung co-digested with cassava peels gave a higher yield with methane content of 65.3% followed by cow dung only, co-digestion of cow dung and yam peels, cassava peels only, yam peels only and pineapple peels with 63.4%, 51.4%, 46.2%, 42.3% and 0.0%, respectively. Therefore co-digestion, with cow dung and cassava peels is most efficient for biogas production.","PeriodicalId":174273,"journal":{"name":"Ghana journal of agricultural science","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114753700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Incidence and severity of major fungal diseases on tomato in three districts within the forest and forest-savannah agro-ecological zones of Ghana 加纳森林和森林-草原农业生态区三个地区番茄主要真菌病的发病率和严重程度

Ghana journal of agricultural science Pub Date : 2021-12-31 DOI: 10.4314/gjas.v56i2.5

B. Opoku, C. Kwoseh, E. Gyasi, E. Moses

{"title":"Incidence and severity of major fungal diseases on tomato in three districts within the forest and forest-savannah agro-ecological zones of Ghana","authors":"B. Opoku, C. Kwoseh, E. Gyasi, E. Moses","doi":"10.4314/gjas.v56i2.5","DOIUrl":"https://doi.org/10.4314/gjas.v56i2.5","url":null,"abstract":"This study was initiated to determine the incidence and severity of fungal diseases of tomatoes and document farmers’ knowledge of these diseases and their control measures in Offinso North, Techiman North and Asante Akim North Districts within the forest and forest-savannah agro-ecological zones of Ghana. A survey was conducted in three selected communities in each district to document the incidence and severity of fungal diseases of tomato and also farmers’ knowledge of fungal diseases of tomato and control practices adopted on their farms using a well-structured questionnaire. Early blight, Septoria leaf spot, Fusarium wilt, Crown rot and Sclerotium rot were the major fungal diseases identified in the study. The mean incidence of diseases recorded for the districts was low with the exception of early blight with an incidence of 63.9% at Asante Akim North District. Though the mean fungal disease severities in the three districts were also low, the highest score was recorded by early blight and fusarium wilt in the Asante Akim North District and fusarium wilt and sclerotium rot in the Offinso North District. In general, farmers had perceived knowledge of the tomato diseases because of losses that these diseases caused, but their knowledge on control was poor.","PeriodicalId":174273,"journal":{"name":"Ghana journal of agricultural science","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131101318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Contribution of fish farming to the socio-economic status of fish farmers in Oyo State, Nigeria 鱼类养殖对尼日利亚奥约州养鱼户社会经济地位的贡献

Ghana journal of agricultural science Pub Date : 2021-12-31 DOI: 10.4314/gjas.v56i2.7

A. A. Ayeloja, G. L. Adebisi, L. Oyebode

{"title":"Contribution of fish farming to the socio-economic status of fish farmers in Oyo State, Nigeria","authors":"A. A. Ayeloja, G. L. Adebisi, L. Oyebode","doi":"10.4314/gjas.v56i2.7","DOIUrl":"https://doi.org/10.4314/gjas.v56i2.7","url":null,"abstract":"This study determined the contribution of fish farming to the socio-economic status of fish farmers in Oyo State. A multistage sampling procedure was used to select the respondents resulting in a total number of 120 fish farmers used for this study. The primary data for this study was collected using an interview schedule which was analyzed using descriptive and inferential statistics. Results revealed that the major constraint to fish farming was lack of access to credit facilities and the contribution of fish farming to the socio-economic status of fish farmers was high. At 0.05 level of significance, significant relationships exist between the respondents age (r=0.389, p=0.004), household size (r=0.286, p=0.002), years of experience (r=0.298, p=0.001), benefits (r=0.279, p=0.002) and their socio-economic status. Chi-square analysis of the result shows that there was significant relationship between marital status (χ2=5.835, p=0.023) and socio-economic status. Based on these findings, the study recommended that credit facilities should be made available to fish farmers and conventional feeds should be available to users at a reduced rate.","PeriodicalId":174273,"journal":{"name":"Ghana journal of agricultural science","volume":"1031 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131475357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effects of dried cashew (Anacardium occidentale L.) apple meal (DCAM) on the growth performance and internal organs of albino rats 干腰果苹果粉对白化大鼠生长性能及内脏器官的影响

Ghana journal of agricultural science Pub Date : 2021-12-31 DOI: 10.4314/gjas.v56i2.2

M. Boateng, K. Amoah, P. Y. Atuahene, Y. Frimpong, D. Okai, G. Osei

{"title":"Effects of dried cashew (Anacardium occidentale L.) apple meal (DCAM) on the growth performance and internal organs of albino rats","authors":"M. Boateng, K. Amoah, P. Y. Atuahene, Y. Frimpong, D. Okai, G. Osei","doi":"10.4314/gjas.v56i2.2","DOIUrl":"https://doi.org/10.4314/gjas.v56i2.2","url":null,"abstract":"An experiment was conducted to ascertain the nutrient composition of dried cashew apple meal (DCAM) and the effect of diets containing varying levels of the DCAM on the growth performance, economics of production and the internal organs of albino rats. Sixteen rats with a mean initial weight of 64.7 g were randomly allotted to four isoproteic and isocaloric diets in a Randomized Complete Block Design based on their weight and sex. The diets were: T0 (0% DCAM), T1 (5% DCAM), T2 (10% DCAM) and T3 (15% DCAM). Each treatment had four replicates. Feed and water were provided ad libitum. Data collected were analysed using ANOVA of GenStat Discovery Edition 4. No differences occurred between diets for daily feed intake, daily weight gain and FCR. It cost $0.009, $0.016 and $0.002 more for rats on T1, T2 and T3 respectively to gain 100 g of weight. No differences occurred between treatments for internal organs except for the relative weight of the empty GIT where rats on T3 had higher weight (P < 0.05). It was deduced that the DCAM could be useful in monogastric livestock feeding and could be added to a rate up to 15% of the diet.","PeriodicalId":174273,"journal":{"name":"Ghana journal of agricultural science","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129161514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Energy consumption and thermal properties of drying banana (musa ssp) under varied relative humidity 不同相对湿度下干燥香蕉的能量消耗和热性能

Ghana journal of agricultural science Pub Date : 2021-12-31 DOI: 10.4314/gjas.v56i2.3

F. Sarpong, M. T. Rashid, J. Owusu-Kwarteng, C. Zhou

{"title":"Energy consumption and thermal properties of drying banana (musa ssp) under varied relative humidity","authors":"F. Sarpong, M. T. Rashid, J. Owusu-Kwarteng, C. Zhou","doi":"10.4314/gjas.v56i2.3","DOIUrl":"https://doi.org/10.4314/gjas.v56i2.3","url":null,"abstract":"The drying of banana slices was investigated under different relative humidity (RH) in a convective hot-air dryer. The experiments were conducted using 10, 20, 30 and 40% RH, 75oC and 2.0 m/s air velocity drying conditions. Drying kinetics, energy consumption and thermal properties were investigated. Eight mathematical models describing thin layer drying were employed and results were compared to their goodness of fit in terms of coefficient of correlation (R2), the root mean square error (RMSE) and the reduced chi square (χ2). The Midilli–Kucuk model could satisfactorily describe RH-convective drying of banana slices with R2, RMSE and χ2 in the ranges of 0.99947-0.99986, 0.00002-0.00008, and 0.0142-0.01618 respectively. For energy consumption, RH condition increased the energy consumption such that at every 10% increase in RH, a range of 17.9-41.0% increase in energy consumption was observed. In the case of thermal properties, endothermic peak revealed precise composition, fine particle size, and dispersion in a matrix of banana slices thus altering the transition in solid state. In effect, RH drying present new drying concept with prospecting thermodynamics absorbing properties. However, energy consumption issue needs to be addressed in further research.","PeriodicalId":174273,"journal":{"name":"Ghana journal of agricultural science","volume":"154 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127341876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Assessment of perceived effects of climate change on rice production among farmers in North-west zone, Nigeria 评估气候变化对尼日利亚西北地区农民水稻生产的影响

Ghana journal of agricultural science Pub Date : 2021-06-30 DOI: 10.4314/gjas.v56i1.4

D. Yakubu, J. Akpoko, M. O. Akinola, Z. Abdulsalam

{"title":"Assessment of perceived effects of climate change on rice production among farmers in North-west zone, Nigeria","authors":"D. Yakubu, J. Akpoko, M. O. Akinola, Z. Abdulsalam","doi":"10.4314/gjas.v56i1.4","DOIUrl":"https://doi.org/10.4314/gjas.v56i1.4","url":null,"abstract":"Rice farming is highly dependent on environmental factors such as rainfall and temperature. Rice yield is affected by changes in these climatic elements. Rice farmers’ perceptions of the changes in climate are important determinants of the management practices they use in reducing the effects on rice production. This study assessed the perceived effects of climate change on rice production among farmers. A multistage sampling procedure was used to obtain a sample of 522 farmers. Data were obtained with the aid of structured questionnaire. The data were analyzed using both descriptive and inferential statistics. Findings revealed that majority (94%) of the respondents were males. They were married (88%) and had farming as a major occupation (89%). They perceived that climate change was posing risks to rice production (X = 2.16), would lower rice production (X = 2.07) and would continue to affect storage of rice (X = 2.01). The study determined a significant relationship (p<0.01) between farmers’ perceived effects of climate change and rice yield. It was concluded that positive perception can lead to high adoption of climate change adaptation practices. The climate change knowledge-base of the farmers needs to be improved through more sensitization on climate smart agriculture.","PeriodicalId":174273,"journal":{"name":"Ghana journal of agricultural science","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125884584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Time of introducing component crop influences productivity of intercropping system 组份作物的引进时间影响间作系统的生产力

Ghana journal of agricultural science Pub Date : 2020-12-24 DOI: 10.4314/GJAS.V55I2.2

M. Iwuagwu, D. Okpara, C. Muoneke

{"title":"Time of introducing component crop influences productivity of intercropping system","authors":"M. Iwuagwu, D. Okpara, C. Muoneke","doi":"10.4314/GJAS.V55I2.2","DOIUrl":"https://doi.org/10.4314/GJAS.V55I2.2","url":null,"abstract":"Field experiment was conducted at National Horticultural Research Institute (NIHORT), Mbato Sub-station, Okigwe, Imo State, South-eastern Nigeria in the 2012 and 2013 cropping seasons to establish the most appropriate time to introduce component crops in cocoyam/cowpea mixture. Five different planting schemes (two and four weeks before, two and four weeks after and same day) and two cowpea genotypes (climbing Akidienu and erect IT97K-499-35) were used. The component crops were grown in monocultures to assess the productivity of the systems. The experimental design used was a completely randomized design with three replicates. Growth and yield of cocoyam and the cowpea genotypes increased significantly (P<0.05) when either of the component crops was planted earlier than the other. Intercropping reduced significantly (P<0.05) cocoyam yield by 0.7 − 74% in IT97K-499-35 and 22 − 80% in Akidienu. Sowing the cowpea genotypes the same day or before cocoyam resulted in over-yielding of cowpea, whereas sowing Akidienu and IT97K-499-35 after cocoyam caused pod yield reductions of 64% − 73% and 32% − 59% on average, respectively. Cocoyam planted two weeks before IT97K-499-35 produced more satisfactory yields of the intercrops than the other planting schedules with LER, LEC and ATER of 2.15, 1.03 and 1.57, respectively.","PeriodicalId":174273,"journal":{"name":"Ghana journal of agricultural science","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129394367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Compatibility of Mancozeb 75 WP with some plant extracts in the integrated management of Cercospora leaf spot disease of okra (Abelmoschus esculentus (L.) Moench) Mancozeb 75wp与部分植物提取物的配合性在秋葵斑叶病综合治理中的应用Moench)

Ghana journal of agricultural science Pub Date : 2020-12-24 DOI: 10.4314/GJAS.V55I2.3

V. Dania, N. Sam

{"title":"Compatibility of Mancozeb 75 WP with some plant extracts in the integrated management of Cercospora leaf spot disease of okra (Abelmoschus esculentus (L.) Moench)","authors":"V. Dania, N. Sam","doi":"10.4314/GJAS.V55I2.3","DOIUrl":"https://doi.org/10.4314/GJAS.V55I2.3","url":null,"abstract":"The use of synthetic mancozeb fungicide has not been effective in the control of okra leaf spot (Pseudocercospora abelmoschi) disease amidst critical issues of environmental concerns. Therefore, this study evaluated the compatibility of mancozeb 75 WP with some botanicals in the integrated management of the disease. Laboratory assay was a 3×4×2 factorial laid out in a completely randomized design with three replications, while the field experiment was a randomized complete block design with 14 treatments. Four extract concentrations, 15, 30, 45 and 50% w/v and 0.5 g/l Mancozeb 75 WP were evaluated. The application of Syzygium aromaticum extract at 50% w/v concentration had the highest mycelial growth reduction of 71.89% of the pathogen. The soil textural class was sandy loam and treatments effect on okra growth indices did not differ significantly (p>0.05). The highest pod yield of 15.48 t/ha-1 was obtained in treatment inoculated with P. abelmoschi. but treated with a combination of S. aromaticum and Mancozeb. The same treatment had the lowest disease incidence of 4.01%, while combined application of C. papaya, S. aromaticum and Mancozeb recorded significantly (p<0.05) lower disease severity among inoculated plants. Therefore, this combination is recommended as foliar spray on okra in place of Mancozeb.","PeriodicalId":174273,"journal":{"name":"Ghana journal of agricultural science","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114881673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effects of ensiling cassava peels on some fermentation characteristics and growth performance of sheep on-farm 青贮木薯皮对农场绵羊发酵特性和生长性能的影响

Ghana journal of agricultural science Pub Date : 2020-12-24 DOI: 10.4314/GJAS.V55I2.9

R. Niayale, W. Addah, A. Ayantunde

{"title":"Effects of ensiling cassava peels on some fermentation characteristics and growth performance of sheep on-farm","authors":"R. Niayale, W. Addah, A. Ayantunde","doi":"10.4314/GJAS.V55I2.9","DOIUrl":"https://doi.org/10.4314/GJAS.V55I2.9","url":null,"abstract":"This study determined the effect of drying or ensiling cassava peels on some conservation characteristics and growth performance of sheep. Fresh peels were either sun-dried to a DM of 904 g/kg or ensiled for 45 days for determination of some chemical and microbial characteristics, and growth performance of sheep. 45 Djallonké sheep were randomly assigned to three supplementary dietary treatments (Control and dried or ensiled) and fed for 70 days. Ensiling reduced the pH from 5.65 in the fresh peel to 4.15 compared to 6.15 in the dried peel. Crude protein (CP) increased from 45±0.44 g/kg DM in the fresh peel to 46±0.48 and 52±0.88 g/kg DM in the dried and ensiled peel, respectively. Reduction in neutral detergent fibre concentration was greater by ensiling than by drying. However, a greater (P = 0.001) reduction in HCN concentration was achieved by drying than by ensiling. Moulds were greater (P = 0.011) in the ensiled than dry peels. Average daily weight gain was higher (P = 0.031) for sheep offered the ensiled than the dried or Control diet. In conclusion, sun-drying was more effective at reducing HCN concentration whereas ensiling improved the CP content of cassava peels and growth performance of sheep.","PeriodicalId":174273,"journal":{"name":"Ghana journal of agricultural science","volume":" 18","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120971509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Awareness and adoption levels of improved smoking oven among fish processors in Lagos Lagoon, Nigeria 尼日利亚拉各斯泻湖的鱼类加工商对改进的烟熏炉的认识和采用程度

Ghana journal of agricultural science Pub Date : 2020-12-24 DOI: 10.4314/GJAS.V55I2.4

O. Alabi, O. J. Olaoye, F. George, A. Adeola, J. Alabi, W. G. Ojebiyi

{"title":"Awareness and adoption levels of improved smoking oven among fish processors in Lagos Lagoon, Nigeria","authors":"O. Alabi, O. J. Olaoye, F. George, A. Adeola, J. Alabi, W. G. Ojebiyi","doi":"10.4314/GJAS.V55I2.4","DOIUrl":"https://doi.org/10.4314/GJAS.V55I2.4","url":null,"abstract":"This paper investigated awareness and adoption levels of improved smoking oven among fish processors in four fishing communities along Lagos Lagoon, Nigeria. Multi-stage sampling procedure was used to select 153 respondents who were engaged in fish smoking. Data collected using structured interview guides were subjected to descriptive and inferential analyses. Results revealed that majority of the respondents were young, married women with average fish smoking experience of 22.6 years. Majority (90.8%) of them were solely engaged in fish smoking while 9.2% combined fish smoking with other income-generating activities. All the processors used traditional smoking oven (drum, box and mud ovens). More than 66.0% of the fish processors were not aware of improved fish smoking equipment. Lack of awareness, inadequate access to the technologies, low relative advantage and lack of maintenance services and high cost of procurement were responsible for low adoption levels of improved smoking oven. Irregular visits of extension agents to the study area had negative impact on the adoption of improved traditional smoking ovens. Proper dissemination of innovations developed on improved fish processing equipment to the active fish processors in Lagos State using available communication channels is hereby advocated.","PeriodicalId":174273,"journal":{"name":"Ghana journal of agricultural science","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126734901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2