Rice varieties planted in Viet Nam

RICE VARIETIES PLANTED IN VIETNAM

Nguyễn Văn Ngưu

Rice varieties planted in Vietnam today are the result of long processes of collection, selection and improvement rice farmers and rice scientists. Planted rice varieties are either locally created or imported. The rice varieties that were imported from the International Rice Research Institute in Los Banos, Philippines in 1960 and 1970 decades has created the Green Revolution in rice production in Vietnam, In late 20th century and early 21st century, a number of hybrid rice varieties were imported from China for production. Recently rice biotechnology has also been applied in the improvement of rice varieties. The following pages briefly presented the rice varieties planted in the country during its long history.

I. TRADITIONAL RICE VARIETIES

The popular story about Bánh Chưng and Bánh Dày suggested that in early years of country’s history, glutinous rice varieties were widely planted. The rice grains found at Go Mun during the Dong Son Culture are short and round (Sakurai, 1987). Glutinous rice varieties belong to Oryza sativa L. var glutinousa and generally have short and round grains.

The cooked milled glutinous rice is call xôi in Vietnamese, which is elastic and easy to eat. Cook glutinous rice stays long in human stomach and it keeps people from feeling hungry for a long time, but glutinous rice grains do not swell much after being cooked. These characteristics of glutinous rice are suitable for people during the early years of history when the facilities and tools for cooking were simple. In the recent past, due to the difficult situation and conditions, people in the Northern Mountains and Midlands region still planted glutinous rice as main food crop (Nguyen Thi Quynh, 1988 cited by Nguyen Huu Nghia et al, 2001).

Vietnamese has a tradition of showing gratitude or be grateful to ancestors. The majority of Vietnamese today still have the tradition to set a table to worship their ancestors in their house and cooked glutinous rice or xôi is one of the five dishes that Vietnamese place on the worship table to offer to their ancestors. Vietnamese also has the tradition of having filialness/piety (or tính hiếu thảo in Vietnamese) to their parents. Vietnamese old people are usually being taken care by their children. Women having filialness/piety usually selected good grains of glutinous rice to cook for their old mothers.

Mẹ già ăn chuối Bà Hương

Ăn xôi nếp một ăn đường mía lau

Or

Old mother eats Bà Hương banana

She eats cooked glutinous rice and sugar from mía lau

Over the world, rice varieties of indica group are generally planted in areas of low elevation in tropical climate. The traditional tropical rice plant, an indica type, is tall (usually 160 to 200 cm) with long and drooping leaves. Indica rice grains are long to short, slender, somewhat flat, and the spikelets are awnless and shatter more easily. On the other hand, rice varieties of japonica group are generally planted in sub-tropical and temperate areas. The plants of japonica rice are short; their leaves are short, erect and deep green; and the grains of japonica rice are short and round (Matsuo et al., 1997).

With increased population and better tools and knowledge, Vietnamese selected new varieties of Oryza sativa L (or lúa tẻ in Vietnamese) to plant for higher yields for food security. Through the country’s southward expansion, Vietnamese also adopted/imported rice varieties of Cambodian and Champa people to plant. Nguyen Huu Nghia et al. (2001) grouped the traditional rice varieties planted in Vietnam into three groups: (a) Thai-Viet, (b) Viet and (c) Khmer-Viet. Rice varieties of Thai-Viet group were regularly found in the Northern Mountains and Midlands, while varieties of Viet group were frequently found in the Red River Delta and rice varieties of Khmer-Viet group were commonly found in Mekong River Delta (Table 1).

Table 1 Types of traditional rice varieties in Vietnam (Nguyen Huu Nghia et al, 2001)

Varietal type

Cultivated place and ecotype

Main characters

Thai-Viet

Mountainous in North Vietnam, mainly upland rice

Group of round seeds (japonica) and group of long seeds (javanica)

Viet

Red River Delta lowland rice of intensive tendency

Short seeds: group of winter rice, non-photoperiod-sensitive, vegetative cycle around 210 days and group of summer rice, photoperiod-sensitive, vegetative cycle of 110-180 days, plant height 100-170 cm

Khmer-Viet

Mekong River Delta lowland rice of intensive tendency

Slender seeds: vegetative cycle reaching 250 days, predominantly deep-water and floating rice, plant height reaching several metres, photoperiod-sensitive

Since the ancient times, Vietnamese people have distinguished two rice group: Tien and Canh, with different agro-morphological characters, corresponding to indica and japonica. Tien rice (indica) has higher plant height, paler leaf color, longer and slender seed size, and is less sticky on cooking. Brenier (1917) classified rice varieties that were planted in Vietnam during XIX century into the following 3 groups: (a) Glutinous rice (or Lua Nep in Vietnamese) or Oryza sativa L var glutinosa; (b) Paddy rice (or Lua Te in Vietnamese) or Oryza sativa L var dura and; (c) Upland rice (or Lua nuong, lua nui, lua ray in Vietnamese) or Oryza sativa L var montagna. Huard and Durand (1954) reported that about 3,000 rice varieties planted in Vietnam were catalogued in 19th century.

Luu Ngoc Trinh et al. (1995) concluded that 89% of rice varieties 85% of rice varieties in Vietnam belong to indica group, 9.5% belong to japonica group and 1.5% could not be classified. They also reported that Mr. Le Quy Don wrote the book “Phu bien tap luc” in the 18th century to describe the different rice varieties cultivated in the central coastal areas and the glutinous varieties Nep Ky Lan, Nep Suat, Nep Hat Cau, Nep Huong Bau, Nep Ong Lao and Nep Tran were included in the book. The following Ca Dao indicate that rice variety Tám xoan was famous in Northern Region or Bắc Bộ and Nghe An province, rice variety Gie An Cựu was famous in Thua Thien- Hue province, and rice varieties Gạo thơm Nàng Quốc and Ba Thắc were famous in Southern Region or Nam Bộ.

  • Northern Region: Gạo thơm cơm trắng chi bằng tám xoan Or Other white and smell good rice could not compete with tám xoan rice
  • Nghệ An Province: Gạo tám xoan, gan cá bống Or Tám xoan rice, liver of bống fish
  • Thua Thien-Hue Province: Tôm rằng lột vỏ bỏ đuôi, Gạo Gie An Cựu mà nuôi mẹ già Or Remove the skin and tail of shrimp (and), Cook the Gie An Cựu rice to feed old mother
  • Southern Region: Tôm rằng lột vỏ bỏ đuôi, Gạo thơm Nàng Quốc em nuôi mẹ già Or Remove the skin and tail of shrimp (and), Cook the aromatic Nàng Quốc rice to feed old mother
  • Southern Region: Gạo cơm Ba Thắc thơm ngon, Chan nước mắm Hòn ăn chẳng muốn thôi Or The delicious and aromatic Ba Thắc rice, Eating with Hòn fish sauce you could not resist

Table 2 show the amylose content in grains of 49 traditional rice varieties planted in Vietnam: the amylose content of three glutinous rice varieties Nép Dậu Hương, Nếp Hoa Cải Vàng and Nếp Lý rice varieties was about 3.5%; that of 20 other varieties ranged from 20 to 25%; and that in the remaining 26 varieties was greater than 25%. Data in table 2 also show that the 49 traditional rice varieties were grouped into groups such as Nep, Du, Di, Dau, Gie hay De, Loc, Tam and Thom.

Table 2 Amylose content of traditional rice varieties planted in Vietnam (Juliano and Villareal, 1993 and Nguyen Thanh Thuy and Nguyen Thi Huong Thuy, 1999).

Group

Rice varieties (Amylose content)

Nep

Nep Dau Huong (3.5%), Nep Ly (3.5%), Nep Hoa Cai Vang (3.5%)

Du

Du Huong (20.1%), Du Hai Duong (29.2%), Du Huong Hai Phong (29.1%), Du Thom Hai Duong (27.4%), Du Thom Thai Binh (24.4%), Du Vang Nam Dinh (24.1%)

Di

Di Do Hai Phong (29.0%), Di Huong (22.8%), Di Huong Hai Phong (29.1%), Di Son Tay (21.0%), Di Vang Hai Duong (28.0%)

Dau

Dau Den Ha Nam (29.2%), Dau Do Thai Binh (27.2%), Dau Hai Duong (29.2%), Dau Som Thai Binh (27.9%), Dau Trang Muon (28.3%)

Gie or De

Gie Hai Duong (25.8%), Gie Hien Nam Dinh (27.1%), Gie Thanh Hoa (29.2%), Gie Thom Hoa Binh (28.3%), Gie Xa Huong Hoa Binh (30.7%)

Loc

Loc Trang Son (28.5%), Loc Tron Ha Tinh (28.7%), Loc Tron Nghe An (24.5%), Loc Hien Thanh Hoa (27.6%), Loc Thai Binh (25.6%)

Tam

Tam Ap Be (22.5%), Tam Thom Hai Hau (22.2%), Tam Thom Thai Binh (23.1%), Tam Xoan Hai Duong (22.6%), Tam Xoan Thai Binh (23.2%)

Thom

Lua Thom (30.4%), Nang Thom (21.3%), Nang Thom Cho Sao (21.2%), Nang Thom Cho Dao (29.5%), Nang Thom Som (20.1%)

Others

Ba Le (27.7%), Chin Henh (28.6%), Mong Chim Roi (29.4%), Mong Chim Trang (21.6%), Nang Huong (22.7%), Tai Nguyen (21.1%), Tau Huong (22.4%), Tep Lai (24.9%)

At the beginning of the 20th century, rice research in northern part of Vietnam was carried out in Nghe An, Thanh Hoa, Phu Tho, Phu Lang Thuong, Thai Binh, Hai Hung, and Ha Noi (Brenier, 1917 and Dumont, 1995). Table 3 shows the growth duration of 4 groups of rice varieties planted from 1906 to 1910 at the Yen Dinh Research Center in Thanh Hoa Province: the growth duration of upland rice varieties was 130 days or less, while that of late maturing rice varieties planted on deeply flooded areas was 185 days or more. In 1931, Research Center at Vinh Yen released a number of rice varieties with high yields (2-3 tons/ha) and resistant to lodging such as Cut, Du, Hom and Nep (Dumont, 1995). The majority of rice varieties planted in north Vietnam before 1945 were late maturing varieties.

Table 3 Growth duration of rice varieties planted in experiments at Yen Dinh Research Center in Thanh Hoa Province during 1906-1910 (Brenier, 1917)

Seeding date

Transplanting date

Flowering date

Harvesting date

Growth duration (days)

Early Maturing Rice Varieties (Lua Chiem)

1906

24 May

22 July

10 Oct

16 Nov

177

1907

21 May

25 July

14 Sep

22 Oct

151

1908

14 Aug

20 Sep

22 Oct

1909

17 May

1 July

12 Sep

12 Oct

148

1910

12 June

10 July

20 Sep

30 Oct

141

Main or Medium Maturing Rice Varieties (Lua Mua)

1906

21 May

22 July

20 Oct

18 Nov

182

1907

21 May

27 July

8 Oct

9 Nov

173

1908

20 June

1 Oct

9 Nov

1909

28 May

1 July

7 Oct

1 Nov

158

1010

28 May

27 July

17 Oct

16 Nov

173

Late Maturing Rice Varieties (Lua Muon or Thong)*

1906

9 May

1 Nov

3 Dec

190

1907

20 April

14 Oct

17 Nov

212

1909

11 May

17 Oct

23 Nov

197

1910

27 May

25 Oct

27 Nov

185

Upland Rice Varieties (Lua Loc, Lua Can, Lua Nui)*

1906

18 June

20 Sep

27 Oct

131

1907

17 June

14 Aug

10 Sep

80

1910

18 June

1 Aug

12 Sep

80

*Direct seeding

In South Vietnam, the Institute of Agricultural Science for Southern Vietnam (IAS) was established in 1909 with a Rice Section. The research site of the Rice Section was established in Can Tho in 1913 and during the next 6 years, the Rice Section created other sites in the Mekong River Delta. In 1915, the Rice Section of IAS imported about 800 varieties and evaluated them in 2017 (Tran Van Dat, 2002). According to Brenier (1917), the 519 local rice varieties planted in South Vietnam at the beginning of 20th century included:

  • 198 medium maturing rice varieties,
  • 87 late maturing rice varieties,
  • 52 early maturing rice varieties with growth duration of 3 to 4 months, and
  • 16 floating rice varieties.

Table 4 shows the major characteristics of rice varieties planted in Mekong River Delta from 1900 to 1910. The floating rice varieties planted in Chau Doc Province in 1906 were: Song Lon, Tham Dung, Lua Say, Va Vai, Nang Dai, Nang Phuoc, Nang Rung, Nang Guot and Nam Luong. The Nang Phuoc and Tham Dung rice varieties were rarely more 3 metres tall, while Song Lon and Lua Say rice varieties could grow up to 5 metres or taller. The Rice Section’s research site in Can Tho selected the following rice varieties: Ba Trang, Bong Dua.

Table 4. Characteristics of rice varieties planted in Mekong River Delta during 1900-1910 (Brenier, 1917)

Variety name

Planting location

Yield (kg/ha)

1000 grain weight (g)

Spikelet

Milled rice grain

Bong buoi

Soc Trang

2,420

60.5

awnless

White, long

Giong Bac Lieu

Soc Trang

2,856

59.5

awnless

White, long

Giong Tra Vinh

Soc Trang

2,600

65

White, long

Thom

Soc Trang

2,250

62.5

awnless

White long

Ca Tien

Soc Trang

>2,304

64

awnless

White long

Nang Tay

Soc Trang

2,412

60.3

awn

White long

Nang Xiem

Soc Trang

2,156

59.9

awnless

White round

So Sat

Soc Trang

2,838

59

White long

Ra Chum

Soc Trang

2,869

65.2

awn

White long

Tam Ruot Trang

Soc Trang

>2,329

64.7

awnless

White long

Bong do

Chau Doc

1,200

White, long

Con Nhut

Chau Doc

1,200

Song Lon

Chau Doc

1,500

White round

Bong Dua

Chau Doc

1,800

White long

Nang Ton

Chau Doc

1,200

White long

Bong Dua

Rach Gia

>2,600

66.5

White, round

Ca dung

Rach Gia

>2,600

65

White, round

Mong Tay

Tan An

1,842

65.8

awnless

White round

Ca dung

Tan An

1,392

58

awnless

White, round

Dan

Sa Dec

2,100

White, long

Bong Dua

Sa Dec

3,273

68.2

White, round

Thang Be

Sa Dec

3,168

White round

Thang Chet Nho

Can Tho

>2,100

52.5

White long

The rice experiment site in Can Tho had selected the following rice varieties: Ba Trang, Bong Dua,, Bong Dau, Ca Dung, Ca Dung Da, Ca Dung Nga, Lua Hon, Mong Tay, Nang Gong, Nang Gong Trang, Nang Be, Nang Ngoc Chum, Ra May, Ra Nieu, Ra Chum, Tau Chen, Trang Lon and Trang Nho. Brenier (1917) reported that rice varieties Lua Thom, Lua Ca, Lua Bat Ngoat, Lua Lot, Lua Dong Doi Lien, Lua Song Doi Thau, Lua Nep Doc, Lua Nep Sap, and Lua Nhon were tested at one site in Hue City in 1906.

II. HIGH YIELDING RICE VARIETIES

Up to 1960, most of traditional rice varieties planted in Vietnam have the following characteristics:

  • Low yield, less than 5 tons/ha
  • Tall plant and easily lodge
  • Long and drooping leaves
  • Photoperiod sensitive

In the 1950 decade, the International Rice Commission of the Food and Agriculture Organization of the United Nations (FAO) cooperated with its member countries in conducting series of crossing between indica rice varieties with japonica rice varieties, which resulted into a number of high yielding rice varieties such as ADT in Tamil, India and Malinga and Mashuri in Malaysia. Similarly, rice research in the Philippines released high yielding variety BPI-76 and rice research in Sri Lanka released high yielding varieties H-4 and H-5. Scientists at the International Rice Research Institute (IRRI) in Los Banos, Philippines made crosses between rice variety Dee-geo-woo-gen and rice variety Peta. One of the lines resulted from these crosses was selected and named IR8 in 1966. Rice variety IR8 has the following characteristics (FAO, 2000):

  • Short and strong stem: 90 to 100 cm
  • Resistant to lodging
  • Short, erect and medium size leaves
  • High tillering capacity
  • High milling ratio
  • Non-photoperiod sensitivity

Rice variety IR8 and other rice varieties, which were created following the IR8 model, were called High Yielding Varieties (HYV). In 1966, the rice research station in Long Dinh received the seeds of IR8, planted them on a 2000 square metres and the crop yield 4 tons/ha, while traditional rice varieties yielded only 2 tons/ha or less (Tran Van Dat, 2002). The results of this experiment started the campaign to import HYV for the Green Revolution in Vietnam. The area planted to HYV increased from about 500 hectares in 1967-68 to about 900,000 hectares in 1974-1975. The high yielding rice varieties imported by South Vietnam from 1967 to 1975 included IR8, IR5, IR20, IR22, RD1 and IR26 (Table 5).

Table 5 List of high yielding rice varieties imported from 1968 to 1975 and the imported quantity of their seeds (Darymple, 1986)

Rice variety

Quantity of imported seeds (tons)

1967-68

IR8

4.5

1968-69

IR8

2,000

IR5

5

1969-70

IR20

0.1

1970-71

IR20

0.1

IR22

1

1971-72

IR20

5

RD1

1

1973-74

IR26

2.0

In 1977, brown plant hopper destroyed thousands of hectares of rice in South Vietnam and Vietnam government imported 250 tons of seeds of rice variety IR36 from the International Rice Research Institute in 1978 (Darymple, 1986 and Khush et al, 1995). In 1981, seeds of rice variety IR42 were imported for planting to salted soils. Table 6 shows the high yielding rice varieties imported by South Vietnam from the International Rice Research Institute from 1978 to 1983.

Table 6 Names of high yielding rice varieties imported from IRRI from 1978 to 1983 (Darymple, 1986)

Year

IRRI Name

Vietnam Name

1978

IR36

NN3A

IR2070-734-3

NN4A

IR2071-179-3

NN5A

1980

IR2307-247-2-2-3

NN6A

IR9129-192-2-3-5

NN7A

IR2823-309-5-6

NN2B

IR2797-115-3

NN3B

1981

IR2070-199-2-6-6

NN8A

IR42

NN4B

IR48

NN5B

1983

IR9224-73-2-2-2-3

OM33

After 1980, the creation of high yielding rice varieties was strengthened. Vietnamese rice breeders crossed local rice varieties with good capacity to resist insects and diseases and good eating quality with imported high yielding rice varieties. Up to 1995, about 104 new varieties, 64 imported varieties and 41 varieties created in Vietnam, were released for cultivation by farmers in the whole country (Nguyen Huu Nghia, 1996). Since then several hundred high yielding rice varieties have been created by different research institutes in Vietnam and released for farmers’ cultivation.

III. HYBRID RICE VARIETIES

The utilization of hybrid vigor of F1 seeds for rice production on large scale was started in 1976 in China. In the 1960th decade, the research group of Professor Yuan Long Ping in China found among the wild rice varieties two following lines: (1) rice line with cytoplasmic sterile male and (2) rice line, which has similar basic characteristics as line 1 but with cytoplasmic fertile. In 1974, this research group created some hybrid rice varieties/lines using the following rice lines:

  • Line A: rice line with cytoplasmic sterile or CMS
  • Line B: rice line, which is similar to line A but with cytoplasmic fertile or maintainer
  • Line R: rice line, which is used to cross with line A to produce F1 seeds or restorer

In 1975, the first generation of newly created hybrid rice varieties were tested on 250 hectares and it was found that yields of hybrid rice varieties were at least about 20% higher than yields of high yielding rice varieties (HYV) in China (Yuan Longping 1999 and 2002). Subsequently, China implemented the program to adopt hybrid rice varieties for popular production and the area planted to hybrid rice increased rapidly to reach 15 million hectares in 1990. Thanks to hybrid rice, China obtain security for popular consumption, while reducing country’s rice planted area.

In Vietnam, a program for hybrid rice creation was started in 1983 at the Cuu Long Delta (or Mekong River Delta) Rice Research and Development Institute (CLRRI) and this program released 2 hybrid rice varieties namely UTL1 and UTL2. However, these two varieties did not produce good result and they were not adopted by rice farmers in Mekong River Delta. In recognition of the potential role of hybrid rice in providing food security and reducing poverty of farmers, FAO created a program on hybrid rice to assist its member countries (Ton That Trinh and Tran Van Dat, 1989 and Ton That Trinh, 1993). In 1991, Vietnam imported some hybrid rice varieties from China for planting in a trial on 100 hectares in Northern Region. The results of this trial showed that yields of Chinese hybrid rice varieties Shanyou 93, Boyou 64, and Shanyou Gui 99 were about 20% or 1 tons/ha more than yields of currently best high yielding rice varieties in Vietnam (Nguyen Cong Tan, 1994).

With technical assistance from FAO, the hybrid rice in Vietnam start to grow rapidly in 1992 and area planted to hybrid rice increased to 11,300 hectares in 1992 and then 102,800 hectares in 1996 (Quach Ngoc An, 1998). In addition, the Hybrid Rice Research Center was established in 1994 at Van Dien, Thanh Tri, Ha Noi. The hybrid rice varieties planted in Vietnam before 2000, however, have lower grain’s amylose content and longer growth duration than high yielding varieties IR64 – the popular HYV at this time (Bui Chi Buu, 1994).

The worldwide programs on creation hybrid rice had continued to grow rapidly and after obtaining rice varieties with male cytoplasmic sterile by effects of day length (PGMS) and/or temperature (TGMS), two-line hybrid rice varieties were created. Yields of two-line hybrid rice varieties were generally about 5 to 10% higher than those of 3-line hybrid rice varieties (Tran Van Dat and Nguyen Van Nguu, 1998). Table 7 shows the hybrid rice varieties that were created and released for production in Vietnam.

Table 7 Hybrid rice varieties that were created and released for planting in Vietnam (Nguyen Tri Hoan, 2004)

Year

Hybrid rice variety

Planting season

Yield (tons/ha)

1999

HR1 (3-lines)

Winter-spring

6-8

2000

HYT57 (3-lines)

Mua (or Main season)

6-8

2001

TM4 (3-lines)

Winter-spring

7-8

2002

VL20 (2-lines)

Summer-Autumn and Winter-spring

6-8

2003

HYT83 (3-lines)

Summer-Autumn and Winter-spring

7-9

2003

TH33 (3-lines)

Summer-Autumn and Winter-spring

6-8

2004

HYT92 (3-lines)

Winter-spring

7-8

2004

HYT100 (3-lines)

Winter-spring

8

IV. OTHER RICE VARIETIES

In 1990 decade, the International Rice Research Institute (IRRI) has a program to create Super Rice varieties with yield potential up to 12 to 13 tons/ha. Recently, efforts to created transgenic and genetically modified or GM rice varieties have also been carried out and IRRI and some rice research centers in some countries have been trying to create the C4 rice varieties. In Vietnam, CLRRI has been using biotechnology in creation of new rice varieties (Bui Chi Buu, 2004).

V. REFERENCES

  • Brenier M.H., 1917 Catalogue des produits de l’Indochine Tome 1: Produits alimentaires. Gouvernment generale de l’ Indochine.
  • Bui Chi Buu, 1994 Rice breeding at CLRRI. PP 100-104 in Proc of Training course on rice-based farming systems and vegetable cultivation; Hochiminh City 1-18 November 1994.
  • Bui Chi Buu, 2004 Current status of molecular rice breeding in Vietnam. Asian Biotech Rev 7(1): 97-107
  • Darymple, D.C., 1986 Development and spread of high yielding rice varieties in developing countries. USAID, Washington DC, USA
  • Dumont, R. 1995 La riziculture en Tonkin. Printing house. Bangkok, Thailand
  • FAO, 2000 FAO Rice Information Vol I
  • Huard, P. and Durand, M., 1954 Connaissance du Vietnam. Imperie nationale – Ecole francaise d’ extreme-orient. Ha Noi, 1954
  • Juliano, B.O. and Villareal, C.P., 1993 Grain quality evaluation of world rice. IRRI, Los Banos, Philippines
  • Khush, G.S., Vo Tong Xuan, Nguyen Van Luat, Bui Chi Buu, Dao The Tuan, and Vu Tien Hoang, 1995. Vietnam-IRRI collaboration in rice varietal improvement. PP 55-60 in Proc.of Conference on Partnership in Rice Research, ed. By Vo Tong Xuan and G.L. Denning. Ha Noi
  • Nguyen Huu Nghia, 1996 Rice production in Vietnam: Present status and major issues on improving productivity through multilateral cooperation. Paper presented at FAO-Japan workshop on major issues on improving rice productivity through multilateral cooperation. 20-23 February 1996, Tokyo, Japan
  • Nguyen Huu Nghia, Bui Chi Buu, Luu Ngoc Trinh and Le Vinh Thao 2001 Breeding, production and marketing. PP 175-191 in Rice Speciality, FAO, Rome, Italy 2001
  • Nguyen Tri Hoan, 2004 Vietnam Progress Report. Paper presented at the concluding workshop of IRRI-Asian Bank Development funded project on Sustaining Food Security in Asia through development of Hybrid rice Technology. 7-9 December 2004 IRRI, Los Banos, Philippines
  • Nguyen Cong Tan, 1994 Progress in hybrid rice program in Vietnam. IRC Newsletter 43:23-28
  • Quach Ngoc An, 1998 Experience in the development of hybrid rice production in Vietnam. PP 39-46 in Proc Regional workshop on progress in development and use of hybrid rice outside China. Ed. By Nguyen Van Nguu, Tran Van Dat and Quach Ngoc An. MARD and FAO Hanoi, 1998
  • Ton That Trinh, 1993 Les nouveaux developpements du riz hybride. IRC Newsletter 42:28-34
  • Ton That Trinh and Tran Van Dat, 1989 Prospect for a new generation of high yielding rice vatieties. IRC Newletters Vol 47: 16-28
  • Tran Van Dat, 2002 Tien trinh phat trien san xuat lua gao tai Viet Nam. Nha Xuat Ban Nong Nghiep, TP Hochiminh
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  • Yuan Longping 1999 Hybrid rice development and use: Innovative approach and challenges. PP 77-85 Proc of 19th Session of the International Rice Commission. FAO Rome 1999
  • Yuan Longping 2002 Recent progress in the development of hybrid rice in China. PP 65-68 in Adoption of hybrid rice in Asia. Policy Support, FAO Rome, 2002