Vol. 15 No. 10 (2017)

In Vietnam, citrus is one of the major fruit commodities and citrus farming brings about economic benefit for farmers and creates employment opportunities. Chaetomium was used as biological control agents against several pathogens causing plant disease. The research was conducted to identify the local strains of Chaetomium species from citrus cultivated soil samples collected in nothern Vietnam. Chaetomium species were isolated by soil baiting technique. Based on morphological characteristics and molecular analysis of internal transcribed space gene, two species, Chaetomium cupreum and Chaetomium globosum were identified. Further research would formulate as biological fungicide and test in vitro conditions.

Prolonged postpartum vaginal discharge is believed to harmfully affect reproductive performance of sows. The present study investigated the factors affecting the duration of postpartum vaginal discharge in sows. Data were collected from 530 sows raised at 5 farms in 3 provinces, i.e, Hai Duong, Bac Ninh and Thai Nguyen. One way ANOVA tests were used to assess effects of parity and postpartum body temperature on the duration of postpartum vaginal discharge while student t-tests were employed to assess effects of assisted farrowing, stillbirth, accumulated duration of farrowing and of placental expulsion and presence of wound(s) on the duration of postpartum vaginal discharge. Results showed that incidence of wound, assisted farrowing and stillbirth was 13.47%, 35.20% and 39.35%, respectively. The accumulated duration of farrowing and of placental expulsion was 6.70 ± 2.95 h while the duration of postpartum vaginal discharge was 4.31 ± 1.08 days. The postpartum body temperature was 39.40 ± 0.450C. Assisted farrowing, stillbirth, accumulated duration of farrowing and of placental expulsion ≥ 5 h, parity > 5 and postpartum body temperature ≥ 39oC increased the duration of postpartum vaginal discharge. This study indicated that several factors affected the duration of postpartum vaginal discharge, therefore, there is a need to find out approach(es) to mininize the detrimental effects of those factors, and to consequently improve the reproductive performance of  sows.

The aim of the present study was to investigate the effects of different calcium contents in diet on the growth and survival rate of juvenile black apple snail (Pila polita). There were 3 replicates in each treatment and the snails were fed with graded calcium levels of 1% (Ca1), 3% (Ca3), 5% (Ca5), 7% (Ca7), 9% (Ca9) and 11% (Ca11). Newly hatched snails with initial body weight and shell height of 0.03g and 4.46 mm, respectively, were reared in the composite tanks (80×60 cm) with the density of 150 ind./tank. After 49 days of rearing period, the average weight and height of the snail reached the highest value in Ca7 (1.32 g; 18.3 mm) and Ca5 (1.23 g; 17.8 mm) and these were significantly different (p<0.05) compared to the remaining calcium contents (Ca1, Ca3, Ca9, Ca11). The highest survival rate of snails was obtained at Ca3 (91.8%), followed by Ca1 (90.9%) and the Ca11 (84.4%). The highest yield (365 g/m2) of snails was obtained at the Ca7 and differed significantly compared to the others Ca1 (231 g/m2), Ca3 (249 g/m2), Ca5 (305 g/m2), Ca9 (239 g/m2) and Ca11 (216 g/m2). The results of this study showed that the growth rate and yield of black apple snail were highest when feeding diet containing 7% calcium. The requirement of calcium content for the juvenile black apple snail growth was 6.57%.

This study was conducted by interviewing of 58 local households involved in Artemia farming in the salt field along the coastline of Soc Trang province. Three cooperatives, Vinh Phuoc, Vinh Tan and Lai Hoa were chosen for the survey from August to December 2015 to determine the current status, as well as to evaluate the effectiveness of various farming systems in the rainy season. The results showed that mono culture of tiger shrimp, mudskipper, mudcrabs, whiteleg shimp, seabass and integrated culture of mudcrabs with either shrimps or fish were practiced during rainy period, in which tiger shimp culture was the most popular. The culture started from Jun and ended in December and most farmers used the artificial seeds from hatcheries except the mudskipper. Stocking densities in major culture partterns were rather low leading to low profit. Among the farming, monoculture of mudskipper gave the highest profit (VND 247.4 million/ha/crop), following by tiger shrimp (VND 130.4 million/ha/crop) and the integrated mudcrabs-mullet offered the lowest profit (VND 20.4 million/ha/crop). The results suggested that mudskipper and black tiger shrimp should be the first choice for farming during rainy season in Artemia-salt field during rainy season because of high profit.

In recent years, coffee mono-cropping area is shifting toward intercrop system. To provide the basis for recommending land use types (LUT) for coffee in Cu M'gar district, the research was conducted to assess the economic, social and environmental  efficiency of four LUTs for coffee. The results showed that coffee mono-cropping was of  low efficiency while other types of intercropping were moderately to  highly efficient. The disparity in the efficiency resulted from land quality and production conditions. In the sub-area 1, the most efficient ones were coffee intercropped with avocado and durian; in the sub-area 2, the most efficient one was coffee intercropped with avocado; and  in the sub-area 3, the most efficient ones were coffee intercropped with pepper and avocado. Based on the results, the land use for coffee  intercrop system in Cu M'gar district is recommended as follows: in the  sub-area 1, the priority order is coffee intercropped with avocado, durian, and pepper; in the  sub-area 2, the priority order is coffee intercropped with avocado, durian, and pepper; and in the  sub-area 3, the priority order is coffee intercropped with avocado, pepper, and durian.

Land use is one of the most important factors that affects soil erosion because land use types impact changes in soil surface, land cover, and soil nutrition. This study of agricultural land use types (coffee, pepper, and forest) intercropped with Macadamia on basalt soil in Tuy Duc district, Dak Nong province showed that these land use types clearly affected soil erosion, leaching, and soil nutrition depletion. Four treatments (Tr) were planted on a 6 - 7o slope including 1 treatment of 3 - year old Macadamia trees planted as a monoculture and 3 treatments of 3 - year old Macadamia trees intercropped with coffee, pepper, or forest trees, and 2 treatments were planted on a 12 - 13o slope including 6 - year old Macadamia trees planted as a monoculture and Macadamia intercropped with forest tress. The results of the 6 treatments showed that at the slope of 6 - 7o, treatment 2 (Tr.2; Macadamia and coffee) had the highest coverage (72.09%) and the Macadamia monoculture (Tr.1) had the lowest coverage (6.96%). Surface runoff varied from 153 to 195 mm, and the amount of soil erosion was from 10.8 to 26.4 tons/ha/year. At the slope of 12 - 13o, surface runoff was from 188 to 285 mm and soil erosion amount was from 15.6 to 33.7 tons/ha. The above results also depended on land use types. On the land use type of Macadamia monoculture planted on a slope of 12 - 13o, soil loss was 33.7 tons/ha. On land use type of Macadamia intercropped with forest trees, soil loss was only 25.3 tons/ha. Total N, P2O5 and K2O were lost more than those in available form. For example, in treatment 1 (only Macadamia), total N loss was 100.23 kg, of which, available N loss was only 25.08 kg/ha.

The study aimed at assessing the status of complaints and lawsuits on issuance of land use right certificates (CLILURCs) and their settlement and proposed solutions to improve the settlement of CLILURCs in Yen Dinh district, Thanh Hoa province. Secondary data related to addressing the issue of CLILURCs in Yen Dinh district  for the period 2012-2016 were collected at agencies and units in Thanh Hoa province and from survey of 76 households and individuals having CLILURCs, wherein 35 people involved in resolving CLILURCs. The results of the study showed that 49/76 CLILURCs have been resolved, the remaining cases were mainly in the settlement and handling of the court. In addition, there existed some shortcomings such as the qualifications and expertise of  staff and civil servants involved in resolving CLILURCs and limited coordination between functional sectors. Some solutions included improving the quality of  staff and civil servants, strengthening the responsibility of agencies and organizations, and completing  preparation and management of cadastral records.

The purpose of this study was to determine the suitable temperature and type of hydroxypropyl methylcellulose-based  wraping membranes for preserving purple passion fruits. The parameters measured included nutritional quality attributes, weight loss  and respiratory rate of the fruits. The experimental design consisted of 9 runs with two factors: temperature (50C ± 1, 100C ± 1, 150C±1, control experiment at room temperature) and membranes (HPMC 3%,HPMC 3%-Carnauba 3%, HPMC 3% - Carnauba 6%, HPMC 3% - Carnauba 9%, control experiment at 50C ± 1). The combination of HPMC and carnauba membrane created a good quality membrane appropriate for preserving and maintaining natural aroma of passion fruits. The results showed that the suitable storage temperature was 50C ± 1 at relative humidty 75-80% and the combination of HPMC 3% and Carnauba 6% was most suitable membrane. Highest quality of samples were found at 28 days of storage with acid content of 3.63%, vitamin C content of 43.22 mg / 100g, TSS 19.10Bx, and weight loss of 19.7%.

Bacterial rice leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo)  is the most devastating in terms of annual yield losses to rice. This research aimed to examine the extraction efficiency for Clerodendron fragrans Vent. (C. fragrans) and Excoecaria cochinchinensis Lour. (E. cochinchinensis) by six solvents with different polarities (distilled water,  ethanol, chloroform, n-hexane, acetone and acetonitrile) and  to evaluate antibacterial effect of the extracts on Xoo under both in vitro and in vivo conditions. In comparison to the dry input materials, the extraction efficiency for C. fragrans Vent stem and root varied from 8.3% to 29.1%, while the figure for E. cochinchinensis leaf varied from 7.2% to 20.3%, depending on solvents.  C. fragrans extracted  by ethanol at 100 mg/ml showed the best anti-bacterial effect in terms of inhibition zone. The minimum inhibiting concentration (MIC) of C. fragrans extract was 1.56 mg/ml and of E. cochinchinensis extract was 3.13 mg/ml. These MICs reduced to 0.39 mg/ml and 0.78 mg/ml, respectively, when the extracts were mixed with nanosilver solution at 3.13 ppm. The in vivo test demonstrated that C. fragrans extract 3.13 mg/ml, and the mixture of nanosilver solution 3.13 ppm with C. fragrans or E. cochinchinensis extract at 3.13 mg/ml could intrigue resistance of IR24 rice to BLB.

Soft rot disease caused by Erwinia carotovora is commonly encountered in many crops. In this study, 41 different diseased plant samples from Ha Noi, Bac Ninh, Hung Yen, Bac Giang, and Ninh Binh provinces were collected. By preliminary screening 29 bacterial strains were isolated. Based on physiological and biochemical characteristics, four strains, M12-2, M17-4, M21-4 and M12ydc showing similarities with Erwinia carotovora subsp. carotovora ATCC15713 strain were identified. These strains were capable of causing soft rot in potato, cabbage and tomato by artificial inoculation in the laboratory. PCR analysis using specific primers of Ec001 indicated that these strains carried virulent gene like Erwinia carotovora subsp. carotovora ATCC15713.

Bài báo trình bày lời giải giải tích và mô hình phần tử hữu hạn trên cơ sở lý thuyết vỏ bậc nhất (5 ẩn số chuyển vị) cho bài toán phân tích dao động riêng vỏ thoải hai độ cong có cơ tính biến thiên và có xét đến ảnh hưởng của nhiệt độ. Trường nhiệt độ được xét đến là phân bố đều trên các bề mặt vỏ và chỉ biến thiên theo phương chiều dày vỏ. Các cơ tính của vật liệu FGM được giả thiết phụ thuộc vào nhiệt độ và thay đổi dọc theo phương chiều dày với quy luật của hàm lũy thừa. Các đối tượng vỏ được khảo sát với điều kiện biên tựa khớp trên tất cả các cạnh. Kết quả số đã được kiểm chứng với kết quả của các tác giả khác cho thấy sự tương đồng cũng như độ tin cậy của hai lời giải đề xuất trong nghiên cứu này. Mặt khác, ảnh hưởng của tỉ số kích thước cạnh/chiều dày vỏ (a/h), trường nhiệt độ (Tc) và chỉ số tỉ lệ thể tích vật liệu (p) đến giá trị tần số dao động riêng của vỏ thoải hai độ cong cũng đã được khảo sát thông qua các ví dụ số.

 The application of machine vision in automation of the pesticide spray machine will  contribute to promotin of  automatic applications in plant protection mechanization, improve productivity and efficiency of pesticide, minimize negative impacts of chemicals in pesticide, and protect environment. The article reported theoretical and experimental results of machine vision to determine the distance and location through image processing and image zone and to record image processing program received from one and more cameras. These parameters were used as a basis for the calculation, designing and manufacturing pesticide spraying machine vision applying automatic machine vision and controlling operating conditions of spraying systems.

The corn dryer powered by gasification from burning agricultural residues SN-1.0 has been designed and manufactured at the Department of Food engineering, Vietnam National University of Agriculture. It was designed according to new principle using screw that placed vertically in drying bin to allow cyclic motion of drying materials inside the drying bin. Experiment was conducted to determine effects of temperature and flow of drying airflow, velocity of screw to the dryness, drying time and fuel cost. Experimental result showed that material dryness increased thanks to continuous stirring of materials during drying process, allowing moisture from center of corn seed to easily diffuse to the surface and vaporize. The capability of removal moisture was increased contributing to shorten drying time as well as fuel cost.

This study was conducted to analyze socio-economic factors influencing the decision of farm households in leasing farm-land under the contract between farm household and enterprise in the Northern delta. The data were gathered from 304 farm households at representative sites in Ha Nam, Thai Binh and Vinh Phuc provinces. Probit model was employed to measure the factors influencing the decision of farm households to lease farm-land. It was found that the revenue disparity between farm-land lease and farm-land productive performance, size of farm-land, the state guarantee for farm-land leasing contract, possibility of shifting to non-agricultural purpose and irrigation accessibility of agricultural land had significant positive impact on the decision of farm households. In contrast, the educational level of the household heads, number of family labor and time of farm-land lease significantly exhibted negative effects on the decision of farm households. To promote land accumulation for concentrated agricultural production in the northern delta, relevant policy implications were suggested.

The fourth industrial revolution in agriculture has been widely adopting in many countries and has just started  in Vietnam. This paper discusses nature and interrelated components of the Agriculture 4.0 and tendencies in technology innovation and development in agricultural economics, natural resources and environmental management, crop, animal and aquaculture production, food storage and processing, marketing and agricultural extension. The paper also points out some benefits and challenges of the Agriculture 4.0 and provides policy recommendation for sustainable development of Vietnam’s Agriculture 4.0.