Vol. 11 No. 7 (2013)

The cross between indica cultivar IR24 (Oryza sativa L.) and an accession of Oryza rufipogon Griff., was backcrossed to the recurrent parent (IR24) for four generations followed by repeated selfing and selection for short growth duration lines. A total of 19 backcross lines at BC4F5 generation were evaluated at spring crop seasons of 2011 in Ha Noi and 23 BC4F6 were further evaluated for agronomical traits in 2011 autumn cropping seasons in Hanoi, Thai Nguyen, and Lao Cai provinces. Among the introgression lines (IL), four lines (IL3-4-2-1-1, IL3-4-2-7-1, IL3-4-7-2 and IL19-4-3-8-2) showed shoter growth duration (10-12 days) than that of the recurrent parent IR24 and the control variety Khang dan 18 (10 -12 days), but grain yield was significantly higher than IR24 and Khang dan 18.

The experiment was conducted to identify suitable row distance for the hybrid maize cv. C.P. 333 on the infertile soil of Bac Giang province. The experiment was planted in two concecutive winter and spring crops of year 2010-2011 and applied with the following fertilizer rate:10tons manure+ 135 N + 90 P2O5 + 100 K2O per hectare. Results showed that the hybrid maize variety C.P.333 performed best when planted at row spacing of 50 cm with planting density of 70,000 plants per hectare. With this row spacing and population density, the hybrid maize showed highest LAI, low insect infestation, and higher yield in comparison with other planting densities in both cropping seasons.

The order Araneae deserves a special place in the study of ecology as it acts as a biological indicator. The objectives of the present study were to explore the guild composition and structure of spider families at Cu Lao Dung mangrove forest, Soc Trang Province. Efforts were made to evaluate the ecosystem status of Cu Lao Dung mangrove forest by surveying the diversity and species composition of spiders (class Arachnida, phylum Arthropoda). A total of 58 species of spiders belonging to 14 families were observed, Salticidae being the family with most species (23 scpecies)and accounting for39,7%. Based on classification byCardoso et al. (2006),six different guilds of spiderwere identified: orb web weavers and other hunters (29%), sheet web weavers and ground hunters (14%), space web weavers and ambush hunters (7%). This is the first report of the spider fauna from Cu Lao Dung mangrove forest.

The effects of flooding on growth and biomass accumulation of maize at the seedling stage was studiedin pot experiment in greenhouse conditions. Seedlings of eleven maize inbred lines were subjected to flood and control treatment for a period of one week. Growth in terms of root system, leaf area, leaf number, leaf chlorophyll content (SPAD), plant height, and dry matter of the plant were significantly reduced in flood stressed conditions. There was clear genetic variation inresponse to flooding stress among themaize inbred lines. Three inbred lines: CLT-T10, CLT- T83 and TB23 showed better tolerance to flooding condions. These inbred lines were recommended to use in further study at molecular level of response to flooding or to use in gerplasm improvement for flooding tolerance. The current study pointed out that there is a relationship between root development and flooding tolerance in maize. Root traits might be important to consider in maize improvement for flooding tolerance.

Studies of micropropagation of D. nobileLindl. were conducted in order to conserve and increase the genetic pool of this precious orchid species. The results showed that the suitable materials used for micropropagation were 5 month old seed capsules. The most suitable medium for germination and protocorm formation was MS+100ml coconut juice+10g saccharose+6.0g agar/liter. For in vitro propagation by traditional method, the optimal medium for propagation of protocorms was KC+100ml coconut juice+10g saccharose+6.0g agar/liter. The most appropriate medium for rapid in vitropropagation of shoots was MS+100ml coconut juice+10g saccharose+6.0g agar/liter. For in vitro propagation by improved method using liquid medium and cotton buttons combined with shaking or using liquid medium and ventilative buttons (cellulose acetate) combined with shaking had increased multiplication rate of protocorms (1.9 and 2.3 fold in comparing with the control). The propagation using solid medium with ventilation buttons reduced 25% of saccharose added to medium, and increased the multipliecation rate of protocorms up to 1.4 fold in comparison with propagation by the classical method. Similarly, rapid in vitro propagation using bioreactor redued the time of propagation by half. The most optimal medium used regenerating intact plants of D. nobilewas RE+10g saccharose +0.5g activated carbon+6.0g agar/liter combined with light intensity of 2300lux.

This study aimed at determining the growthof some vegetables using pots produced from organic or biodegradable materials(rice straw) as well as identifying the pottypessuitable for high yield and quality of vegetables. The following parameters were evaluated and identified: 1) degradation rate ofthe organic potswhen burrying in the soil,2) germination and seedling survival of some vegetables sown in the organic pots, and3) suitable potting mediafor celery (Apium gaveolens)and spinach (Spinacia oleracea)usingorganic pots. Results indicated that the organic pots decomposed after20 daysburying in soil. Among nine vegetablestested only four, i.e.squash, hybrid squash(Cacubita maxinta Duch. Ex Lam), yard long bean (Vigna sesquipedalis Fruwirth)and (Ipomoea aquaticL.)germinated and grew well in organic pots and the seedlings can be retained in pots for a longer period. Growing medium (GT1) composing of soil,rice dry leaf and stem,organic fertilizerand slow-release fertilizer appeared to be suitable for those vegetables. Similarly, celery and spinach seedshad higher germination rate when sown in organic pots compared with that in plastic or paper bags. Potting medium (GT2) composing of 40% soil, 25% rice draw, 25% soil moisture maintainer, 10% organic fertilizer and 2.5g/kg slow releasefertilizeris suitable for spinach. On the other hand GT1 was found appropriatefor celery.

This study aimed todetermine the applicability of Amblyseiussp. (Acarina: Phytosiidae) to control the red spider mite Panonychus citriKoch (Acarina: Tetranychidae). In orange trees,the density of red spider mite risesfrom the beginning of September and attainsthe pick inthe middle of October. The population of the predatory spider mite was harmony with the red spider mite. The occurenceand increaseof predatory spider mite were the factors leading the reduction of red spider mite population. Reproductive time of predatory mite lasted long (13-15 days in average), and the mean total eggsof one female was 21.86. The predation rate of Amblyseiussp. atdifferent stages showedthat mature femalesconsumed eggs significantly higher than other stages and mature males. However, the mature femaleshad significantly lower predation at adult stage of prey.

Experiments on the effects of broodstock size at 35-39g; 40-44g; 45-49g; 50-55g and 60g (experiment 1) and age ranging from 7; 8; 9; 10 and 11 months old (experiment 2) to reproductive performance of white leg shrimp (Litopenaeus vannamei) broodstocks free of pathogen were conducted in in-door composite tanks of 14m2(for broodstock intensive rearing) and 1m3(for spawning and larval rearing) under biosecurity conditionattemperature of 28-30oC, and salinity of 28-30‰. Shrimpswere fed 4 times per day with blood worm (50%) and fresh squid (50%).Water was renewed 100% daily. For breedinginduction, eye-stalk ablation was applied to the female shrimpsafter 30 days intensive rearing. Female shrimps of 45g or bigger showed significantly better reproductive performance than smaller ones (P<0.05), reaching mature rate of 89.0%, mating and spawning rate of 86.0%, fecundityof 175,200 eggs/dam/spawn, and nauplii production per spawn of 88,700 nauplii. On the other hand, shrimpsat age of 8 -12 months have considerably higher spawning performancecompared to age group of 7 months (P<0.05) with mature rate of 86.7%, mating and spawning rate of 84.1%, fecundity of 207,400 eggs/dam/spawn, production of nauplii per spawn of 127,500 nauplii.

This study was undertaken to determine apparent digestibility of four protein feed ingredients (full fat soybean meal, shrimp by-product meal, soya cake meal and peanut cake meal) for rabbit fish. Five groups of rabbit fish were set up in glass tanks according to Latin square design (5 treatments x 5 replications). They werefed with test diets and reference dietwhichcontained 0.5% chromic oxide as an inert marker. Results showed that, apparent digestibility of rabbit fish in terms ofnutrients, energy and essential amino acids was significantlydifferent among treatments (P <0.05). The apparent digestibility of crude protein, crude lipid and crude fiber infull fat soybean meal was significantly higher than that of other tested ingredients (P<0.05). There was no significant difference in apparent digestibility of essential amino acids between full fat soybean meal and peanut cake meal (P>0.05) but significantly higher than that on shrimp by-product meal (P<0.05). Results from this study indicated that it is possible to use those high protein ingredients as substitute forfish mealin rabbit fish farming.

Rainbow trout (Oncorhynchus mykiss) is an economical and nutritional fish cultured in cold water areas in Vietnam. The fish meat quality is assessed not only by nutrition values (such as protein, lipid, amino acids) but also by pigmentation of fish muscle. The wildlife rainbow trout muscle pigmentation variesfrom pink to red colour. The pigmentation supplementationsuch as astaxanthin and canthaxanthin with different proportion were usually added in pellet feed to enhance thecolour of fish muscle. The objective of this study wasto assess the effect of different carotenoid sources on pigmentation of rainbow trout fillet. The fish (initial body weight of 309,20 ± 22,36g) were fed with three dietscontaining 80mg kg-1astaxanthin (CTTA 1), 60mg kg-1astaxanthin + 20mg kg-1canthaxanthin (CTTA 2) and 40mg kg-1astaxanthin + 40mg kg-1canthaxanthin (CTTA 3). There was no significant difference among experiment groups in the average weights and survey rates at the end of the experiment. After 60 daysof experiment, the pigmentation levels of trout fillet was analysed usingSalmoFan Linealpigmentation chart. The pigmentation level of fillet in fish fed with diet containing mixture of 40mg kg-1astaxanthin + 40mg kg-1canthaxanthin (29.25 ± 0.92)washigher than that of fish fed with diet containing 80mg kg-1astaxanthin (25.36 ± 1.16) or mixture of 60mg kg-1astaxanthin + 20mg kg-1canthaxanthin (26.73 ± 0.95) (P<0,5).

Hard clam farming in coastal provinces of North and Northern Central Vietnam has notably developed since last decade and this activity generates high income source for farmers, improving socio-economic development of many local communities. However, many farms are facing with difficulties due to frequent occurrence of massive death of cultured clam, lack of capital and unstable market for clam product. This study, therefore, investigated status of hard clam farming in some coastal provinces of North and Northern Central Vietnam in order to provide basic information for building technical and management solutions, contributing to stable development of hard clam farming in Vietnam. The results showed that Thai Binh province has the highest hard clam farming areas as well as clam production (1,984 ha, 30,130 tons), followed by Nam Dinh (1,271 ha, 5,123 tons), Thanh Hoa (960 ha, 7,700 tons), Quang Ninh (1,271 ha, 5,123 tons), and Ha Tinh (200 ha, 2,800 tons). About 84.1% surveyed farmers reported that their farms had at least one time of massive death of cultured clam and only 15.9% surveyed farms did not suffer with massive hard clam death. Even though the massive death of cultured clam may happen at any time, it usually occurs from February to May each year. Most of surveyed farmers supposed that changes in temperature, salinity and the decline of water quality were the main reasons for massive hard clam death in recent years. Lack of capital and unstable market are main constraints that most farms encounter with and require support from the government.

This study was carried out in Tam Diep pig research stationofThuy Phuong National Pig Research from 2009 to 2013 to evaluate growth performance, carcass characteristics and meat quality of VCN03 boars between two generations (initialgeneration and first selection (G1)). Growth performance was measured on 205 boars (G0: 114, G1: 91). Carcass characteristics were conducted on 40 boars (G0: 20, G1: 20), meat quality was determined on 36 longissimus dorsimuscle samples (G0: 17, G1: 19). Average daily gain and lean meat percentage of selected boars were higher than those of G0(P<0.05). Average daily gain, backfat thickness, longissimus dorsimuscle thickness and lean meat percentage of G0and G1were 769.51 and 829.60g/day, 10.27 and 9.38mm, 46.84 and 48.80mm, 59.74 and 61.14% respectively. Killing out percentage and carcass yield werenot significantly different between two generations (P>0.05). Killing out percentage and carcass yield of G0and G1were 80.68 and 81.26%, 72.01 and 72.30% respectively. The pH of logissimus dorsimuscle at 45 minutes (6.01 and 6.28 for G0and G1respectively), pH (5.57 and 5.45) and L* (54.39 and 53.76) were in the range corresponding to the normal meat. Average daily gain and lean meat percentage of VCN03 boars after selection were improved without affecting carcass characteristics and meat quality.

Dactylogyrus sp., a common external parasite frequently occurs with high percentage and intensity of infection in fresh water fish. The infection of this prasite causes great influence on the growth and production of many freshwater fish, especially grasscarp (Ctenopharyngodon idella) at fry and fingerling stage. The study was carried out on 180 fry grasscarp, 363 mature Dactylogyrus sp. and 1813 eggs of Monogenea to investigate major features of the reproductive biology of this parasite. The results showed that the maturation time of the eggs from being laid to hatching to oncommiracidia was 4.65 ±0.27days. This parasite reaches sexual maturity and completes their life cycle in 11.4 ± 0.24 days. Egg production increased gradually over time, rising from 2.75 ± 0.17 to 8.08± 0.53 eggs/h from day 1 to day 5.. At night time, the rate of laying and egg production was 1.7 to 2 and 1.6 to 2.1 times, respectively, higher than those at day time. This study is the first instance that the reproductive biology of Dactylogyrus sp. infecting grasscarp was examined in Vietnam.

Diatoms are the important primary creature of the food chains in aquatic ecosystem. High diversity of diatom species is an essential element to increase biomass productivity of the food chain in aquatic ecosystem. High number of species and diatom valves help to stabilize the sediment overtime. This study aimed to compare diversity of benthic diatoms in sediment at Cu Lao Dung mangrove forest between four forest habitats and two seasons (dry and rainy) by using Margalef’s species richnessindex, Shannon-Weiner index, Simpson index, Pielou’s evenness and Rarefaction index. Results showed that not only diatom valve density but also diversity indices were significantly differentbetween four habitats and two seasons. The Margalef's species richness index and the Shannon-Weiner index were significantlydifferent between both habitats and two seasons whilethe Simpson index and Rarefaction index were only significantlydifferentbetween habitatsandPielou's evenness differed significantly just between two seasons. Diversity indices of the habitat of Sonneratia spp. forest and the mixed habitat of Sonneratiaspp. and Nypa fruticansforests were higher than those of the mud and the mud-seedling.

Assessment of practicesof land consolidation work and its impacttothe agricultural and rural development inPhuVangdistrict, ThuaThienHueprovincewas carried out throughfield study and analysis of 10 years-long aggregated data,. The agricultural landfragmentation with small avarage of 3.91 plots per householdpresent major obstacle to large-scale agricultural production andincreasesthe productioncost ofindividual householdsand the whole communityas well. The land consolidation to2.26 plots per household with 747.51square meterseach is meaningful andhas broughtabout thepractical efficiencyandincreasedbenefitsforhouseholdsandcommunities. Especially, post-consolidationof land has created much support fortheagrcultural and rual development. However, theland consolidationstill revealsmany limitationssuch asthelag in land use planning, delayedland use right certificates, inadequate infrastructureandincompleteproductiverelocation. The findingsalsosuggestedsome sets ofspecific solutionsto improvetheland consolidationandactivelysupportnewruraldevelopment of local community.

Computer vision is an inter-discipline research field, which has many real life applications. One of the important tasks is to identify and classify objects from their digital images. Computer vision has been applied successfully in many fields of agriculture such as agricultural automation, precision agriculture, classification of agricultural products and identification (trees, weeds, fruits etc). This paper presents the application of the computer vision technique to leaf image classification by using Support Vector Machine (SVM). The experimental results with classification accuracy of 98% showed the success of using SVM to classify leaf images. This also showed that the approach can be employed for other practical applications effectively.

The aim of the study was to build a recipe and procedure for cookies making with cashew supplement in order to produce a tasty, nutritive and convenient fast food to market. The best proportion of cashew added to flour is 10% of the total powder weight. The procedure suggested includes the following steps. Firstly, shortening and butter is l mixed for 3-5 minutes before adding powder milk, sugar, salt and vanilla, then mixing is continued until homogeneous dough is obtained. Secondly, flour and cashew are added and blended in 12-15 minutes afterward. The dough temperature is in range from 19 to 25oC and the moisture is between 16 and 20%. Thirdly, the dough is shaped in to small pieces with 4-5cm in diameter and 3-4mm in thickness. Baking step is carried out at 160oC for 5 minutes followed by 240oC for 3 minutes. The new “cashew cookies” has better nutrient components, higher calories as well as specific characteristics.

Profile of amino acid and volatile compounds of four commercial fish sauces in Viet Nam were investigated. Four fish sauces included Nha Trang (NTFS), 584 (584FS), Khai Hoan (KHFS) and Chinsu (CSFS). Results showed that all of fish sauces contained essential amino acids with a range from 1.14 to 3.69 mg/g. Based on essential amino acid contents, four fish sauces can be ranked in the following descending order: 584FS > NTFS > KHFS > CSFS. A total of 56 volatile compounds were detected in four fish sauces investigated and their amount in CSFS, 584FS, KHFS and NTFS was 22, 22, 19 and 16, respectively. Generally, amino acid content and amino acid profile as well as volatile compounds in these fish sauces are very complicated and they vary depending on fish sauce type.

This paper presents a method for establishing a general model which enables to simulate tractor’s turning process and calculate its main characters in considering basic characteristics of engine, transmission system andinteraction between tyre wheels and flexible base pavement. The mathematical model which describes approximatively working characters of the farm tractor, can display general image for the ralation of kinetic and dynamic parameters when a farm tractor moves on the deformation ground. The boundary condition and the input parameters of the model can be defined from experimental studies.The built model has been applied in order to investigate qualitatively and quantitatively by digital computer the effects of some structure parameters and working condition on turning capacity of several popular farm tractors in Vietnam.

This paper compares profitability of rice production between contract and non-contract farmers in An Giang province of the Mekong delta in order to measure the role of contract farming in economic performance of rice growers. The present paper also analyzes households’ characteristics associated with participation in rice contract farming and explores constraints to contract farming practice by farmers’ perspective. The findings showedthat contract farmers are likely to get significantly higher net returnthan non-contract farmers but their production costs are also much higher; particularly, labor cost is remarkably higher. We also found not a few evidences that there is a sharp association of joining farmer’s organizations with participation in rice contract farming, large farmers and farmers residing in favorable location are more likely to be selected for contract participation, implying that small farmers will be marginalized in the contract scheme.

Urbanization is an inevitable process in socio-economic development. In Vietnam, urbanization has been happening with bigger scale and higher speed. Urbanization has impacted on peri-urban livelihood strategies both positively and negatively. However, negative influences, particularly the reduction of farmland, unemployment and food insecurity, have been more concerned by researchers and policy-makers. According to several researchers, maintenance and development of peri-urban agriculture is one of the solutions to reduce negative impacts. Based on a combination of quantitative and qualitative research methods, this study shows that agriculture plays important roles in socio-economic lives of households in Trau Quy town. For economic aspect, agriculture contributes to households’ income, food security and safety, and generates job opportunities for family labours, especially for those who could not find new off-farm jobs in labour market. With regard to social roles, farmland property, livelihood security, and maintenance of traditional community relationship are considered as significant roles of suburb agriculture.