Le Quang Quyen, Vu Xuan Long, et al.*
*Agronomy Department, Cotton Research Center, Nha Ho Village, Nink Son District, Ninh Thuan Province, Viet Nam.1. INTRODUCTION
In Viet Nam, grapevines can be seen everywhere. For a long time, the people in Hanoi Capital have grown grapevines around their houses for ornamental purposes and for shade; but these grapevine trellises have produced small berries and bunches with very sour taste and low food value. Grapes are now grown commercially only in the South. Their quality is not really ideal but is not inferior to other fruits (Vu Cong Hau, 1997).
In other parts of the world viticulture has existed for thousands of years, but in Viet Nam it has just begun to be developed in recent years. Since its economic value is superior to that of other crop plants, areas under grapes in Viet Nam have quickly increased since the early 1990s when only table grapes were the main article of commerce from grape cultivation.
The research work on grapes in Viet Nam has mainly been carried out by the Cotton Research Centre, which has a Food and Fruit Crops Department serving local agriculture. To understand more about the viticulture situation in Viet Nam and help the vine growers to solve production problems in varieties and techniques, since 1989 the Cotton Research Centre (an agricultural scientific research organization of the Government based in Ninh Thuan province) has carried out research on some urgent problems for the development of viticulture.
2. PRESENT STATUS OF GRAPE CULTIVATION
Major Vine Growing Regions
Growing grapes for commercial purposes began in the late 1970s in the North of former Thuan Hai province (including Ninh Thuan province and Tuy Phong District of Binh Thuan province). In Northern provinces such as Bac Giang, Ha Tay, Hai Duong, Quang Ninh and Vinh Phuc, vines have begun to be planted on a small scale for experimentation. Hence, the research work has only been carried out in the vine growing region of Ninh Thuan province.
Area Under Grapes
The statistical data on the areas under grapevines in Viet Nam are presented in Table 1.
Table 1. Areas under Grapevines in Viet Nam in Recent Years
Provinces
|
Areas under Grapevines (hectares) |
Notes
|
||||
1985 |
1990 |
1995 |
1999 |
|||
A. In the North: |
|
|
|
|
Both table |
|
|
1. Bac Giang |
0 |
0 |
23 |
3 |
grapes and |
|
2. Ha Tay |
0 |
0 |
16 |
10 |
grapes for |
|
3. Hai Duong |
0 |
0 |
17 |
0 |
processing |
|
4. Quang Ninh |
0 |
0 |
7 |
0 |
(wine and |
|
5. Vinh Phuc |
0 |
0 |
12 |
12 |
raisins) |
B. In the South: |
|
|
|
|
|
|
|
1. Binh Thuan |
0 |
0 |
100 |
250 |
Only table |
|
2. Ninh Thuan |
26 |
306 |
1952 |
2400 |
grapes |
Total (hectares) |
26 |
306 |
2127 |
2675 |
|
Up to now, statistical figures on the production of grapes in Viet Nam have not been given by the State Statistical Department because the area under grapes is very small in comparison to other crops.
Variety Information
In the middle of 1980s, the four grape varieties that were popular in former Thuan Hai province were Muscat blanc, Alden, Ribbier and Cardinal (Vu Xuan Long et al, 1992). In the 1990s, only the Cardinal variety became popular. This variety has some advantages such as high yield potential, difficult separation from pedicels, and short growing duration in comparison with Muscat blanc, Alden and Ribbier varieties. Duration of each cropping cycle is about 85-95 days from pruning to harvesting, with one month resting of vines before pruning again. Such a cycle needs about four months duration and three harvests per year can be possible.
Viet Nam did not introduce any new grape varieties for nearly 30 years. Hence, both producers and consumers have not been able to select other varieties at will and they have had to depend on the Cardinal variety to meet their urgent needs for local consumption.
Climatic Conditions in Grape Growing Regions
The rainfall in the Northern grape growing regions is much higher than that of Ninh Thuan. Annual rainfall in these provinces varies from 1,500 to 1,900 mm (Appendix 1). High rainfall is the main impediment that caused areas under grapes in the North not to increase but to be reduced, which was also based on experimental studies carried out for some years.
Ninh Thuan is a dry region with a mean temperature of 24-28o C, a low relative humidity of 72-85 percent, high sunshine hours per month ranging between 130-287 hours, an annual average rainfall of 750-900 mm, and a lesser number of rainy days per year (Appendix 2). These climatic conditions are fairly favourable for the growth and development of grapes.
Soil Conditions in Ninh Thuan Grape Region
The results from a survey on the nutrition status in the soil of 800 hectares in Ninh Thuan showed that the soil conditions were very suitable for the growth and development of grapes, which included neutral to low acidity, high availability of phosphorous and potassium, and medium level humus content.
3. PRODUCTION OF PLANTING MATERIAL
Many years ago, there were no Government or private nurseries producing planting material of grapes in Viet Nam. Hence, farmers had to produce planting material of grapes for themselves by using cuttings and a few by layering.
Today, there are three organizations that have been tasked to produce planting material of grapes for farmers, namely the Cotton Research Centre, Ninh Thuan Domestic Animal and Crop Breeding Centre and Binh Thuan Socio-Economic Development Centre. All of them are researching on rootstocks to identify suitable planting materials for different soil and climatic conditions of the various grape growing regions. Besides, the Cotton Research Centre is conducting studies to propagate grapes by the in vitro method.
4. ESTABLISHMENT OF VINEYARDS
Land Preparation
Some operations that need to be carried out before planting include deep plowing and harrowing to improve good porosity and aeration of the soil. The land is then divided into plots following the general gradient of the land to facilitate appropriate irrigation and drainage layout. This is followed by fine leveling of the surface of each plot, digging holes, and filling with a mixture of topsoil, phosphate fertilizer and lime (if necessary) before commencement of planting.
Planting Season
In Ninh Thuan and Binh Thuan provinces, the farmers usually plant grapes at the end of the rainy season and at the beginning of the dry season. The most suitable planting time is in December and January.
Spacing
Grapes are planted at a spacing of 2.5 x 2.0 m, which gives a density of about 2,000 plants per hectare. In Ninh Thuan and Binh Thuan grape growing regions, the farmers have only used the overhead arbor system for training vines. The height of the trellis depends on the convenience of the worker.
5. CARE AND MANAGEMENT OF VINEYARDS
5.1 Training and Pruning of Plants
Training
In Viet Nam, vine branches are trained into a cobweb-like design. When vines climb to the top of the trellis (about 2-3 months after planting), the tops of main stems are cut in order to promote 2-3 main arms or branches. After 1-1.5 months, the tops of these arms are pruned back to induce 2-3 secondary branches, and canes are spaced at convenient distances along the secondary branches to achieve the required network. Ninh Thuan farmers have a habit of pruning bearing canes for the first harvest after allowing vines to grow for about 8-10 months.
It is necessary to tie branches to the trellis and pluck unwanted axillary buds in time before the blooming period. Vine branches are usually tied along the horizontal plane on the surface of the trellis for better flowering. Plucking axillary buds is regularly done in order to create good conditions for growth and development of the main branches.
Pruning
Vines in Ninh Thuan can be induced to produce at any time of the year (2.5-3 harvests a year), so grape pruning time is possible all the year round. A grape season lasts about 4 months, and 25-30 days after each harvest vines are pruned again for the next crop. The 8-month old branches are usually pruned in winter-spring for the first crop and every 4 months thereafter. Pruning positions on the canes are from the eighth to the twelfth nodes for the strong branches, and from the fourth to the sixth nodes for the weak canes.
5.2 Application of fertilizers
The results from a survey on fertilizer use are presented in Table 2.
Table 2. Fertilizer Doses for Grapes in Ninh Thuan (Cotton Research Centre, 1992)
Kinds of Fertilizers
|
Total (kg/ hectare/crop)
|
Percentages of Weights on Different Stages (%) |
||
Before Pruning |
Pruning-Flowering |
Flowering- Ripening |
||
1. Humus |
25.300 ± 7.850 |
100 |
- |
- |
2. N |
539 ± 68 |
54.76 |
26.19 |
19.05 |
3. P2O5 |
339 ± 56 |
65.30 |
10.20 |
24.68 |
4. K2O |
288 ± 73 |
45.25 |
11.21 |
43.53 |
Almost all phosphorous fertilizer was given before pruning, the rest was applied at the bud, flower and berry enlarging stages in the form of mixed fertilizers. However, it was observed that fertilizing nearly 25 percent of the total amount of phosphorous fertilizer in the berry growing stage was rather high.
Potassium fertilizer used for grapes before pruning was 45 percent and 44 percent for the berry enlargement and colour break stages.
5.3 Weeding
Average vineyard size of each household is very small, usually about 0.1-0.4 hectares. Hence, controlling weeds is only carried out by hand. In recent years, roundup herbicide has begun to be used. At present, the Cotton Research Centre has been carrying out some research on polyethylene film mulching as a measure for control of weeds in grapes.
The results from the survey on farming techniques showed that 70 percent of vine growing households turned up the soil at least once per crop and others did it once per year. Turning up the soil is often carried out after the last harvest together with the incorporation of organic and inorganic fertilizers before the next pruning.
5.4 Supplementary Irrigation
According to Ninh Thuan farmers, irrigation and fertilization are the main inputs for ensuring high grape productivity and quality. Irrigation is only necessary in the dry season but not important in the wet season. Farmers have often used the flooding method of irrigation on the surface of grape beds. The quantity of water and the irrigation frequency together with inorganic fertilizer application are the most important practices of all the field operations. Vineyards are usually irrigated according to a 10-15 day schedule, but in sandy soils it is shorter, usually about 5-7 day intervals.
5.5 Insects and Diseases
Insects
Vines are attacked by some destructive insects such as mealy bug (Ferrisiana virgata), thrips (Thrips sp.), red spider mites (Eotraniclus carpini), and yellow spider mites etc. These pests usually exist on vines and cause great damage in dry seasons.
The main kind of chewing pest is the army worm (Spodoptera exigua). It bites young leaves, buds and flowers. It occurs and causes serious damage in dry seasons.
Diseases
Grapes are infected by several diseases that are economically important.
Downy mildew disease caused by Plasmopara viticola fungus infects mostly young and fully grown leaves. The population dynamics and damage caused by this pest indicate that the disease is persistent in vineyards and causes damage all the year round, especially in the rainy season (May to November).
Bunch rot disease caused by Diplodia natalensis fungus infects the peduncles of bunches at flowering and young berry stages. Hence, it is very difficult to control this disease when vines are infected which causes serious losses to grape yields. Population dynamics and nature of damage indicate that this disease seems to occur nearly all the year round, especially in the rainy season (May to November).
Powdery mildew disease caused by Uncinula necator fungus infects berries and old branches. Population dynamics and damage show that this disease exists in vineyards and develops and causes damage all the year round, especially in dry seasons (December to April).
Rust disease is caused by Kuehneola vitis fungus, which infects fully grown leaves. This disease often develops and debilitates vines only in the rainy seasons (June to November).
Table 3. Some kinds of Pests and Diseases Recorded on Grapevines in Viet Nam
Common Name |
Scientific Name |
Infected Part |
|
Diseases: |
|
|
|
|
Downy mildew |
Plasmopara viticola |
Young and full leaves |
|
Bunch rot |
Diplodia natalensis |
Peduncles of bunches |
|
Powdery mildew |
Uncinula necator |
Berries and old branches |
|
Rust |
Kuehneola vitis |
Full and old leaves |
Pests: |
|
|
|
|
Army worm |
Spodoptera exigua |
Leaves, squares and flowers |
|
Mealy bug |
Ferrisiana virgata |
Branches |
|
Thrips |
Thrips sp. |
Leaves, Berries, Branches |
Spider mites: |
|
|
|
|
Red spider mites |
Eotraniclus carpini |
Leaves |
|
Yellow spider mites |
Unknown |
Leaves |
Nematodes: |
Unknown |
Roots |
As mentioned above, the Cardinal variety in Ninh Thuan has degenerated and possesses weak pest resistance. Moreover, haphazard pruning at any time of the year without any organized cropping system always causes conditions favourable for pests and diseases to develop and cause damage. Hence, controlling them becomes one of the important factors that affect the yield and economic effectiveness in viticulture programmes.
In the past, lime-sulphur, copper sulphate and bordeaux mixture were mainly used to control diseases of grapes. These chemicals were cheap but had to be sprayed many times per crop. When new foreign-made chemical fungicides and pesticides were used to control diseases and insects of grapes, some remarkable results were obtained including fewer spraying times, long-lasting effect from each spraying, and lower labor costs. Since 1989, the Cotton Research Centre has screened many fungicides and recommended some of them to farmers, including Rovral, Rozin, Ridomil MZ, Ridomil combi, Score, Topas, Anvil, Antracol, Copperhydroxide, Tilt, Baycor, Curzate, and Bayfidan, etc.
For army worm (Spodoptera exigua), it has been found that it is very difficult to control this kind of pest with chemical insecticides. However, researchers found it easy to control army worm with a biological product, Nuclear Polyhedrosis Virus (NPVSe) made at the Cotton Research Centre.
Nematodes, such as the vine-damaging nematode, were mentioned by scientists of the Cotton Research Centre some years ago. However, this problem has not yet been studied due to lack of budget resources.
6. HARVESTING AND YIELDS
Grape yields are shown in Table 4.
Table 4. Grape Yield (t/ha) Based on Different Age of Vines and Crops (By Vu Xuan Long, et al. 1992)
Plant age (year) |
1992 Spring-Summer Crop (Pruning in April and in
May) |
1992 Autumn-Winter Crop (Pruning in Sep. and in
Oct.) |
1992-1993 Winter-Spring Crop (Pruning in Dec. and in
Jan.) |
Total of 3 crops/year |
1 |
- |
- |
8.00 |
8.00 |
2 |
10.55 (4.75 |
2.67 (3.46 |
18.67 (4.71 |
31.89 (10.90 |
3 |
20.00 (11.32 |
8.10 (7.19 |
20.61 (5.87 |
40.71 (22.20 |
4 |
15.56 (4.45 |
8.70 (5.85 |
16.73 (3.29 |
41.33 (9.82 |
5 |
14.90 (4.70 |
10.24 (6.61 |
16.30 (2.98 |
41.44 (13.06 |
6 |
9.38 (3.74 |
6.13 (2.93 |
10.62 (4.08 |
26.12 (5.35 |
7 |
22.50 |
5.00 |
5.75 |
33.25 |
12 |
5.33 |
7.33 |
- |
12.66 |
Average grape yield (metric tonnes/hectare/year) |
29.43 |
· Grapes in Ninh Thuan age fast and become senescent due to severe exploitation of vines. Normally, the vine growers have to get rid of old vines for replanting after they are cropped for about 10 years. This seems to be a bad way of forcing culture (pruning and harvesting 2.5-3 times per year) and the vines consequently degenerate fast.The results from a random investigation of 50 vineyards of different plant ages in 1995 and 1996 showed that mean grape productivity in Ninh Thuan was over 30 tonnes per hectare/year. Planting grapes could bring a profit of over VND 100 million per hectare/year. Grape yield is high and stable in Winter to Spring or Spring to Summer seasons but low and unstable in Autumn to Winter (Appendix 3).· The grape yield of the Autumn-Winter season is the lowest in a year, which is only about 50 percent in comparison with other seasons. The main reason for low productivity is that, in the pruning period of this season (in September and October), heavy and continuous rains often appear, which cause root rot and disadvantages for the blossoming process.
7. MARKETING
Up to now, most grapes produced in Ninh Thuan and Binh Thuan provinces have been consumed in the form of table grapes, and a small quantity of grapes with very poor quality are processed into local juice and wine. Grapes are transported everywhere in Viet Nam by dealers and middlemen.
At present, Viet Nam is importing 2 kinds of table grapes from abroad. Consumers are aware that they are produced in the United States, Australia or Thailand. Table grape prices are shown in Table 5.
Table 5. The Prices of some Kinds of Grapes at the Free Markets in Viet Nam (April 2000)
Kind of Table Grapes |
Place of Production |
Wholesale Price(VND/kg) |
Retail Price (VND/kg) |
A kind of table grape with very big berries, red colour, few
seeds |
Abroad |
Unknown |
90,000-110,000 |
A kind of table grape with big berries, green-yellow colour,
seedless |
Abroad |
Unknown |
60,000-80,000 |
Cardinal |
Viet Nam |
5,000-10,000 |
10,000-15,000 |
Note: Exchange Rate VND 14,000/USD8. POTENTIAL FOR GRAPE PRODUCTION DEVELOPMENT
The potential for grape production development in Viet Nam, especially in Ninh Thuan and Binh Thuan provinces, is very good because of some salient factors that are linked to high demand for grapes. These are as follows:
- Consumer needs for grapes keep increasing.9. CONSTRAINTS IN GRAPE PRODUCTION DEVELOPMENT- Market potential for grapes in Viet Nam is still very large for fresh grapes and processed products.
- The vine growing region of Ninh Thuan and Binh Thuan have relatively dry conditions with the lowest rainfall in the country.
- There is considerable wasteland on the hills and near the low mountains that can be utilized for expanding viticulture.
- The vine growers have a lot of experience on intensive cultivation of grapes.
- Both Government and local authorities are interested in the development of the grape industry.
In 1998 and 1999, like other provinces in the centre of Viet Nam, Ninh Thuan was affected by natural disasters (storms and floods) that caused serious damage to viticulture. The total area under destroyed vineyards by storms and floods was 1,487 hectares (occupying more than 50 percent of areas under grapes at the beginning of 1998). Storms and floods weakened the crop that survived and it may take a long time for them to recover.
Due to the economic advantages of viticulture, some farmers have diversified from other crops to grow grapes, even in double-cropped rice fields or in the sandy soils near the coast. Hence, there were some vineyards established in unsuitable soils such as in sunken terrain which floods frequently, soils with high acid content, as well as in very infertile soils. In order to get reasonable harvests from such soils, farmers had to invest more in comparison to other areas.
Heavy rains often occurred at the end of the year (August to November) together with high temperature, when some diseases develop very quickly. Large quantities of fungicides have to be used in this period.
Up to now, cultivation techniques for grapes have not been properly studied. Farmers have had to toil in their vineyards in order to gain experience for themselves. As a result, the harvests are unstable, uses of fertilizers are excessive and consequently, production tends to suffer.
10. GOVERNMENT POLICIES FOR VITICULTURE DEVELOPMENT
The Government of Viet Nam has issued several general policy directives for development of fruit crops all over the country, including grapes. These policies include encouraging farmers to change crop planting composition to diversify agriculture and farm products, providing loans to farmers at low interest rates, and constructing new water reservoirs as well as main channel systems for agricultural production. In recent years, Viet Nam Agriculture and Rural Development Ministry has made initial investments for research and agriculture extension including surveys on grape cultivation techniques for farmers, forming agro-extension models for planting new varieties, as well as IPM programmes. These investments are, however, too small in comparison with the grape growers needs, especially on production techniques.
Since Ninh Thuan province was re-established in 1992, the provincial authorities have affirmed that the development of viticulture is one of the key tasks in its socio-economic programme. Hence, they have begun to show their concern for the development of viticulture by investing more for research on variety collections, surveying the suitable areas for grapes, and building wineries for processing, etc. However, these investments are still insufficient in comparison with production needs.
Research Work on Grapes in Viet Nam
Research on Vine Collections
There are four organizations in Viet Nam maintaining and researching on vine collections. These are the Cotton Research Centre, Hanoi Vegetable and Fruit Research Institute, Ninh Thuan Domestic Animal and Crops Breeding Centre and Binh Thuan Social and Economic Development Centre.
At the Cotton Research Centre these varietal studies carried out from 1994 to 2000 have included the collection and introduction of 61 accessions. Among them there are 12 domestically collected accessions and 49 accessions introduced from abroad (France, United States, Australia, India, Thailand, China and Germany) including 34 table grape accessions, 25 wine grape accessions and 3 rootstock varieties. Through the results of research on this collection, some specific promising accessions were identified and presented for further research. Table grape accessions selected are NH-01-08, NH-01-48 and NH-01-60; wine grape accessions selected are NH-02-04, NH-02-10 and NH-02-17 and the raisin grape accession is NH-01-11.
At Hanoi Vegetable and Fruit Research Institute, 5 accession wine grape collections introduced from France have been studied since 1995. As a result, Vilard noir accession has been identified as a variety having the highest productivity and the best quality (By Nguyen Quoc Hung, Tran The Tuc, Vu Manh Hai and Stephen Desmazieres, 1999). Besides, this Institute has just introduced some additional vine accessions. There are 28 accessions in the collection here at present, including 16 table grape and 12 wine grape accessions.
At Ninh Thuan Domestic Animal and Crop Breeding Centre, the grape collection mainly contained wine grape accessions introduced from Australia from 1995. In 1996, the Germans supplemented some table grape and rootstock accessions to this collection. Now, there are 33 accessions in the collection including 17 table grape accessions, 13 wine grape accessions and 3 rootstocks. From the result of the research on the vine collection, Black Queen table grape variety has been released for screening on an experimental and pilot production scale.
At Binh Thuan Social and Economic Development Centre (established by the Germans together with local authorities in Binh Thuan province) one of its tasks was to research on vine varieties for farmers in Tuy Phong district. Hence, up to now a 42 accession vine collection has been established here. Among them there are 32 table grape accessions, 5 wine grape accessions and 5 rootstocks. Today, this Centre has also released the Black Queen table grape variety for screening and pilot production on a small scale.
Research on Some Promising Table Grape Varieties
Initial results of studies on grape yield and quality in preliminary investigations showed that NH-01-48 table grape accession has more advantages than the Cardinal variety. Hence, this accession was selected for testing on a large scale. From these demonstrations carried out over several seasons, the following results were obtained:
The growth duration of NH-01-48 grape variety (from pruning to the last harvest) was about 25-30 days longer than that of the Cardinal variety. The NH-01-48 variety could resist downy mildew, bunch rot and powdery mildew better than Cardinal variety. Finally, the yield of this new variety was higher than that of the Cardinal check variety.
NH-01-48 grape variety had better quality characteristics compared with Cardinal, which included higher sugar content, fewer seeds, and sweeter taste and aroma.
Research on Micro-element Mixtures
The Cotton Research Centre succeeded in studying several kinds of mixed foliar fertilizers from macro, semi-macro and micro fertilizers, called Duong nho. Spraying Duong nho on grapes increased yield and sugar content. It also increased farmers profit from VND 3 to 5.76 million per hectare (Nguyen Huu Binh, Le Quang Quyen, Vu Xuan Long, et al. 1997). This product was recognized as a technical achievement and was released for trial on a large scale by the Scientific Commission of the Agriculture and Rural Development Ministry.
Research on Growth Regulators
Based on research on the effectiveness of some growth regulators for grapes, a yield-increasing product called LH1 was found for grapes. This product contained a-Naphtyl acetic acid, gibberellic acid and some micro-elements. Berry weight, bunch weight, number of the berries per bunch and yield increased when LH1 0.1 percent was used, which especially brought profit for farmers exceeding over VND 7 million per hectare (Vu Xuan Long, Nguyen Quang Thach, 1997).
Research on Cultivation Techniques for Grapes
Currently, the Cotton Research Centre has been carrying out some research on cultivation techniques for grapes which included research on polythene film mulching, vine planting using a ditch and dyke system of land reclamation in low-lying areas, grape bunch covering techniques, use of rootstock and grafting techniques, use of economical irrigation methods, and research on some methods of agricultural extension.
11. CONCLUSIONS
· In Viet Nam, grapes have mainly been grown in Ninh Thuan and Binh Thuan provinces. Today, the areas under grapevines are some 2,400 hectares in Ninh Thuan (occupying 90 percent) and 250 hectares in Binh Thuan (occupying 9 percent of the total areas under grapes in the country). In the North of Viet Nam, grapes are being planted on a small scale for experimentation.REFERENCES· The climatic and soil conditions of Ninh Thuan province are very suitable for the growth and development of vines. It is in this region that grapevines can be pruned at any time of the year giving 2.5-3 harvests a year.
· At present, Cardinal is an unique variety popularly grown in Viet Nam. This variety has a high yield potential but not excellent berry quality and is especially weak in pest and disease resistance. Vines are mainly propagated by cuttings.
· Ninh Thuan and Binh Thuan farmers have only used the overhead trellis system for vines. Grape planting time is mainly carried out in December and January every year. Popularly used plant density is some 2000 plants per hectare. The system of vine training is similar to a cobweb-like design. Pruning is done at any time of the year and irrigation is given usually every 10-15 days. Inter-cultivation is mainly done once per season together with the application of organic and inorganic fertilizers. Fertilizer doses used are rather high, most of which are given before the pruning stage.
· Vines in Ninh Thuan are infected by four kinds of diseases: downy mildew, bunch rot, powdery mildew, and rust. Among them, downy mildew, bunch rot and rust diseases often develop and cause serious damage in the wet season, but powdery mildew occurs in dry weather. In addition, vines are attacked by army worm, thrips, mealy bug and spider mites. These insects and spider mites mainly cause damage in the dry season.
· Vines in Ninh Thuan age soon because of intensive exploitation. Normally, vine growers have to get rid of old vines for replanting after about 10 years. Average grape yield in Ninh Thuan was estimated at about 30 tonnes per hectare a year. High grape yield is focused on Winter-Spring and Spring-Summer seasons but it is low and unstable in Autumn to Winter.
· There are four organizations maintaining and researching on grape collections, which are the Cotton Research Centre, Hanoi Vegetable and Fruit Research Institute, Ninh Thuan Domestic Animal and Crops Breeding Centre, and Binh Thuan Socio-Economic Development Centre. The quantities of accessions in these collections are 61, 26, 33 and 42 respectively.
· NH-01-48 table grape variety has more advantages than Cardinal variety in characters such as easy blossoming after pruning, high yield, high sugar content, delicious taste and good disease resistance.
· Because Viet Nam is a poor country, the Government has not yet been able to invest much capital for the development of viticulture. Although leaders at all levels have begun to show their concerns for viticulture development and invested on grape research, these investments are too small in comparison with the grape growers needs in the domains of basic and applied research techniques.
Duong Phu, 1979. Result of research on vine collection. Annual studying results of Southern Central Agricultural Technical Centre, 1979; (Vietnamese).
Le Quang Quyen, Le Cong Nong, Bui Tat Vu et al. 1999. Result of research on some promising table grape varieties. Presented at the Scientific Conference of Agriculture and Rural Development Ministry in 1999 (Vietnamese).
Le Quang Quyen et al. 2000. Results of collecting, introducing and maintaining on vine collection. Annual studying results of Cotton Research Centre, 2000 (Vietnamese).
Nguyen Thi Thanh Binh et al. 1995. Screening on effectiveness of some kinds of chemical fungicides controlling downy mildew and bunch rot diseases on vine. Annual studying results of Cotton Research Centre, 1995 (Vietnamese).
Nguyen Huu Binh, Vu Xuan Long, 1996. Real viticulture situation and productive capability clean grapes in Ninh Thuan. Presented at the Special Workshop on Clean vegetable and fruit in Hanoi, 1996 (Vietnamese).
Nguyen Huu Binh, Vu Xuan Long, Le Cong Nong, 1996. Result from the survey on the nutrition states in vine growing soil of Ninh Thuan Province. Presented at the Agricultural science meeting of Ninh Thuan Province, 1996 (Vietnamese).
Nguyen Huu Binh, Le Quang Quyen, Vu Xuan Long et al. 1997. VCC, Duong nho foliar fertilizers and their effectiveness on some crops. Presented at the Scientific Conference of Agriculture and Rural Development Ministry in 1997 (Vietnamese).
Nguyen Huu Binh, Le Quang Quyen et al. 1999. Result of collecting, introducing and investigating on vine collection. Presented at the Agricultural Science meeting of Ninh Thuan Province, 1999 (Vietnamese).
Ninh Thuan Statistical Year-book, 1998. Ninh Thuan Statistical Branch.
Vu Xuan Long, Nguyen Thi Thanh Binh et al. 1992. The results of researches on vine in Ninh Thuan. Presented at the Scientific Conference of Agriculture and Rural Development Ministry in 1992 (Vietnamese).
Vu Cong Hau, 1997. Vine; Agricultural Publishing House, 1997 (Vietnamese).
Vu Xuan Long, Nguyen Quang Thach et al. 1997. Effectiveness of LB1 and LH1 growth regulator products for grapes. Presented at the Agricultural Science meeting of Ninh Thuan Province, 1997 (Vietnamese).
APPENDICES
Appendix 1. Average Annual Rainfall in some Vine growing Regions in Viet Nam
Stations (Prov., City)
|
Months |
Total (mm)
|
|||||||||||
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
||
1. Lang (Hanoi) |
18.6 |
26.2 |
43.8 |
90.1 |
188.5 |
239.9 |
288.2 |
318.0 |
265.4 |
130.7 |
43.4 |
23.4 |
1676.2 |
2. Moc Chau (Son La) |
14.8 |
21.2 |
34.0 |
98.7 |
165.5 |
220.8 |
266.3 |
331.4 |
257.2 |
106.4 |
31.8 |
11.8 |
1559.9 |
3. Vinh Yen (Vinh Phuc) |
19.4 |
24.1 |
30.4 |
106.5 |
174.1 |
240.2 |
262.8 |
333.4 |
221.0 |
127.2 |
48.2 |
16.2 |
1603.5 |
4. My Duc (Ha Tay) |
30.4 |
17.2 |
33.0 |
129.8 |
208.5 |
263.5 |
238.7 |
372.9 |
329.1 |
201.8 |
70.3 |
20.0 |
1915.2 |
5. Nha Ho (Ninh Thuan) |
7.7 |
2.4 |
7.8 |
12.1 |
77.1 |
66.4 |
74.7 |
149.1 |
169.8 |
150.4 |
140.1 |
55.0 |
912.6 |
Month
|
Temperature (oC) |
Relative humidity (%)
|
Sunshine hours/ month
|
Rainfall (mm)
|
Rainy days/ month
|
||
Mean |
Max. |
Min. |
|||||
1 |
24.4 |
33.5 |
16.3 |
72 |
213.6 |
7.7 |
1 |
2 |
24.8 |
35.2 |
17.3 |
72 |
225.6 |
2.4 |
1 |
3 |
26.1 |
36.5 |
18.0 |
75 |
286.6 |
7.8 |
1 |
4 |
27.7 |
36.8 |
20.4 |
76 |
236.9 |
12.1 |
2 |
5 |
28.2 |
39.0 |
19.9 |
79 |
198.4 |
77.1 |
10 |
6 |
28.4 |
40.5 |
22.2 |
79 |
218.9 |
66.4 |
11 |
7 |
28.2 |
39.6 |
21.9 |
76 |
183.2 |
74.7 |
9 |
8 |
28.2 |
39.5 |
21.2 |
78 |
205.9 |
149.1 |
10 |
9 |
27.0 |
37.7 |
20.8 |
82 |
141.4 |
169.8 |
14 |
10 |
26.6 |
34.5 |
19.3 |
84 |
169.5 |
150.4 |
15 |
11 |
26.0 |
34.5 |
17.7 |
84 |
136.4 |
140.1 |
15 |
12 |
24.9 |
34.0 |
16.4 |
80 |
129.5 |
55.0 |
8 |
Crops
|
Yield (kg/ha)
|
Total income (1000 VND/ha)
|
Expenditure (1000 VND/ha) |
Profit (1000 VND/ha)
|
|
Materials |
Labour |
||||
1. Spring-Summer 1995 |
12293.6 |
63184.17 |
16844.24 |
6900.07 |
43258.13 |
2. Autumn-Winter 1995 |
7735.6 |
42885.78 |
16840.33 |
7021.20 |
19024.25 |
3. Winter-Spring 1995-1996 |
12677.8 |
70063.95 |
16477.02 |
6852.29 |
46734.67 |
Total/year |
32707.0 |
176133.90 |
50161.59 |
20773.56 |
109017.05 |