9. Vietnam

Breeding New Rice Variety DT39 Quelamby Gamma RayBang. D. T. T. Nhung N. T. H., Duc N. M. and Hung N. P.
Institute of Agriculture Genetics

9.1 Introduction
In 2012, Vietnam rice export reached 7.7 millions of tons and overcomes Thailand and becomes thebiggest country for rice export in the world. However, price of Vietnamese rice in international
market is often lower than of Thailand’s because the quality is lower. Vietnam government conducts
many breeding projects for rice quality improvement. One of the most effective methods for ricequality improvement is mutation breeding by irradiation of Gamma rays 60Co source combined withselection process. Generally, mutation breeding by irradiation of Gamma rays has many advantages
compared to other breeding methods such as improvement of one or some characteristics while
maintaining the rest characteristics of variety. In Vietnam, rice variety Bacthom No.7 has very goodcooking quality, easily cultivated, relatively short growth duration, stable grain yield potential but
poor resistance to bacterial leaf blight. That’s why, Bacthom No.7 is not widely cultivated in manylocations, especially in summer season.
For the above reasons and also as a follow up on the sub-project on composition or quality in rice
under the FNCA, we carried out the project “Improvement of Bacthom No.7 by irradiation of dried
seeds with gamma rays of 60Co source”.
Aims of research: Creation of new rice variety with good cooking, high quality, easily cultivated,short growth duration, high and stable grain yield, and good resistance to bacterial leaf blight.

9.2 Materials and Methods
3,000 dry seed at 13% moisture content was used for irradiation by gamma ray 60Co source at therange doses of 150, 200 and 250Gy in the K hospital, Hanoi. The experiment was started in summer
season 2008.
9.3 Results and Discussion
9.3.1 Selection Process
9.3.1.1 M 1 generation: All main panicles in M1 generation were harvested to develop M2 population.
9.3.1.2 M2 generation: At the dose of 150Gy, there were no differences observed. However, from1,753 individual plants harvested from 200Gy, the frequency of variation observed was around 3%.
Mutants with changed characteristics consist of morphological traits, growth duration, tilleringability, hard stem, seed size and so on. From those variations observed, 112 mutant lines wereharvested individually for M3. At 250Gy, obtained variations included high sterility ratio and shortplant height. However, most of these variations were not useful for breeding, therefore all plantsfrom this dose were not included in the next experiment.
- 82 -9.3.1.3 M3 generation: Single plants were cultivated and evaluated separately, each plant is
considered as one family. Selection was continued to discard unfavorable lines for example less seed,less panicle, or sterile plants and so on. Elite individuals in M3 were selected to develop promising
rice lines in M4 generation. There were some elite individuals with better economic characteristics
compared to control variety namely BT15-1, BT15-2, BT15-3 BT20-1, BT20-2, and BT20-4 withlong seed, good cooking quality, high grain quality, and resistant to bacterial leaf blight. BT20-2 andBT20-2 have higher 1,000 seeds weight, 25.89g and 31.73g, respectively.
9.3.1.4 M4 - M6 generation: From 4 promising lines in M5, one outstanding lines M 6 -20.3 wasselected and showed no segregation, hard stem, long seed, stable grain yield potential, and good
resistant to bacterial leaf blight. Line M6 -20.3 was named DT39 Quelam and further evaluated in
narrow scale for agronomic and biological trait by author. Beside of that DT39 Quelam was officiallysent to the National Testing Center for Crop to test for Value of Cultivation and Use of crop (VCU)
from M6 - M 8 generation (during 2011- 2012).
9.3.2 Evaluation Process
9.3.2.1 Evaluation results of author
Evaluation experiment was carried out in order to compare yield performance and agronomic trait
with the control Bacthom 7 in both seasons. The result showed that the yield in spring season was
higher than summer season in both varieties, and DT39 Quelam had higher yield than Bacthom 7 inboth season.
Table 1: Evaluation agro-biological characters and yield of DT39 Quelam by author(Spring and summer 2010 in Tuliem, Hanoi)*

Variety

DT39QuelamBacthomControl

Growthduration(days)

Plant
height(cm)No panicle/
plantPanicle
length(cm)Numberseed/panicleSeed setratio(%)

Yield(tons/ha)

Spring:132

102,2±0,30

5,5±0,2830,2±0,24

162,3±6,1389,5±0,32

6,3±0,31

Summer:105

112,2±0,22

5,0±0,30

28,5±0,27

147,3±6,05

88,2±0,25

5,9±0,30

Spring:134

98,6±0,27

5,2±0,22

22,3±0,30

152,5±5,76

87,5±0,31

5,6±0,26

Summer:
106

107
±0,32

5,2±0,30

20,6±0,23

140,2±6,20

82,3±0,28

5,0±0,31*Transplanting 1 seedling per hill, 45 hills per square meter.

The results in the above table showed that mutant line DT39 Quelam and Bacthom 7 have the same
growth duration. Panicle length of DT39 Quelam is longer than Bacthom 7 and number of seeds wasalso higher. The resulting grain yield of DT39 Quelam was higher than that of Bacthom 7.
- 83 -Table 2 shows the main characteristics of DT39 Quelam and Bacthom 7.
Table 2: Some main characteristics of mutant DT39 Quelamand control Bacthom 7Bacthom 7(control variety)DT39 Quelam(mutant variety)- Spring

130-135

130-135- Summer

105-108

104-106

2Plant height (cm)

106

110

3Tilerring abilityMedium

Medium4

Leaf colour in harvest

Ligh yellow

yellow

5

Flag Leaf type

short, narrow, incline

short, narrow, arrect

7

Stem hardness

HardHarder

8

Flowering duration (days)

55

9

No. of panicle/hills

5.4

5.5

10

Panicle length (cm)

25.2

28.2

12

No. of seeds/panicle

140

155

13

Abort grain ratio (%)

12-15

12-17

14

Awn

AbsentShort and partly

15

Weight of 1000 seeds (gram)

19.2

23.8

16

Seed type

Small, short (2.0-7.2 mm)

Small, length (2.2-9.3 mm)

17Husk color

Light brown

Dark brown

Characteristics
1Growth duration (days)

The data in table 2 showed that mutant variety DT39 Quelam7 was not so much different fromBachom 7 in 17 phenotype characters. In some main characters such as length of panicle, grain
weight of 1,000 seeds, number of seeds per panicle DT39 Quelam was higher than Bacthom 7. DT39
Quelam had harder stem, darker husk color than Bacthom 7.
9.3.2.2 Evaluation results of The National Testing Center for Crop (NTCC)The National Testing Center for Crops (NTCC) is the unique office that is responsible forindependently evaluating and testing new varieties in Vietnam before release.
DT39 Quelam had been sent to NTCC for testing and evaluation in three continuous seasons(summer season 2011, spring and summer season 2012).

- 84 -Table3: Assessment for agronomic traits of DT39 Quelam variety by NTCC (Source: NTCC)*

Seasons

Variety
BT7Summer(control)

2011

DT39
QuelamBT7Spring(control)

2012

DT39Quelam
BT7Summer(control)2012

DT39Quelam

Seedling
vigor(points)

Flowering
duration(points)

Plant
hardness(points)

Plantheight (cm)Growthduration(days)

553112.8

106551120105

551101139151106

140551108.5

107551112.8

104*points: from 1 to 9 means best to worst

The result of NTCC for Crop for three continuous seasons (Table 3) showed that generally, DT39Quelam and Bacthom 7 (BT7) have the approriate growth duration for rice production in many
locations in spring season and shorter in summer season, 104-105 days (DT39 Quelam), 106-107
days (Bacthom 7). In spring season 2012, seedling vigor of DT39 Quelam was point 1 (cold tolerant)better than Bacthom 7, point 5. Plant height of DT39 Quelam was higher than Bacthom 7, flowering
duration was similar in both varieties.
Table 4 induced that grain weight of DT39 Quelam was higher than Bacthom 7 in three tests. But thedata also showed the disadvantage of DT39 Quelam. The abort ratio in three test was higher thanBacthom 7 and the purity (point 1, 5 and 3 for each season) was lower than Bacthom 7 (point 1) inthree tests. However, field puritication index of variety could be improved by selection proccess.
Evaluation of 1,000 grain weight of DT39 Quelam and Bacthom 7 (table 5) showed clearly differentbetween two varieties. 1,000 grain weight of origin variety, Bacthom 7 was from 18.5g to 19.2g
meanwhile that of DT39 Quelam was from 23.2g to 25.2g in three seasons. It may result that theyielding performance of DT39 Quelam is often higher than Bacthom 7 (table5).

- 85 -

Table4: Variety purity and other traits

Seasons

Variety(Source: NTCC)*

Purity(points)

No.panicle
per hill

No. Seeds
per panicle

Abort ratio(%)

Grain Weight of
1,000 seeds (g)SummerBT715.2

141

17.6

18.5

2011DT39 Quelam

15.0

147

22.0

23.2

SpringBT71

5.2

152

13.0

18.6

2012

DT39 Quelam

54.9

148

16.6

24.8

SummerBT7

1

5.6

139

11.9

19.2

2012

DT39 Quelam

35.6

145

22.5

25.2

*points: higher means better.

Table5: Yield performance evaluation in rice production trials (Source: NTCC)Unit: tons/hectare
Location
Season Variety

Thái

Thanh

Vĩnh

HòaHàHải

Yên DươngAnBình

Hoá

Phúc

Bình

TĩnhPhòng Quang Giang Biên

5.47

5.18-

3.79

4.28

5.07-

4.81

6.24

4.99-

-

4.98

5.67

5.39-

3.83

4.13

5.59

-

5.15

6.60

5.59-

-

5.23

Spring2012

BT75.23

3.87

6.00

3.56

4.81

5.10

5.73

4.76

-

---

4.88

DT39Quelam

5.47

4.24

5.57

3.41

5.67

6.13

5.63

5.23

-

---

5.17

5.79

5.74

-

3.90

4.83

3.47

4.97

-

--

5.77

5.37

4.98

6.06

6.00

-

5.03

5.44

4.60

4.67

-

--

6.73

6.20

5.59

BT7Summer
2012
DT39Quelam

Hải

Tuyên

Bắc

Điện

Aver.

Nghệ

BT7Summer
2011
DT39QuelamHưngIn three continuous seasons of the test for value of cultivation and use, the mutant variety gavehigher yield compare to Bacthom 7. In summer 2011, DT39 Quelam gained 5% compare to Bacthom
7. Especially at 6/8 location trail test in summer 2012, the yield of DT39 Quelam reached average
5.59 t/ha higher by 12.24% while that of Bacthom 7 was 4.98 t/ha.
For the rice production in northern part of Vietnam, Bacthom 7 variety is mainly grown in spring
season, because this variety often gives high yield, good quality and moreover but it is very sensitive
to bacterial leaf blight in summer season. Therefore, the cultivation area is significant decreased eventhe quality is accepted for consumption. The result from the NTCC indicated that new mutant variety
DT39 Quelam could be used for summer season.

- 86 -Table6: Resistant ability for pests and diseases (Source: NTCC)

Seasons

Summer2011

BT7
DT39Quelam

Spring2012

BT7
DT39Quelam

Summer2012

Blast

SheathBacterial

Brown

Stem

Leaf

Brown

In leaf In panicle

blightLeaf blightblightborer

rollerhopperVariety

BT7
DT39
Quelam

--

0-1

3-5

-

1-3

0-1

0-1

--

0-1

1-3

-

0-1

1-3

1-3

0-1

-

1-3

0-1

0-1

0-1

0-1

0-1

0-2

-

1-3

0-1

0-1

0-1

0-1

1-3

1-3

0-1

1-3

1-31-3

1-3

1-3

1-3

1-2

0-1

1-3

1-3

0-1

0-1

1-3

1-3

*points: smaller means better.

Vietnam is tropical country, where pests and diseases appear every year. So, resistance to pests anddiseases in rice is a very important criterial standard for commercial production. The data from table
6 indicated that the resistance to pests and diseases in the field condition for blast, bacterial leaf
blight, brown blight, and stem borer of DT39 Quelam was similar to Bacthom 7. Especially, insummer season 2011, DT39 Quelam showed resistance to bacteria leaf blight at 1-3 point while
Bacthom 7 showed it at 3-5 point.
Table7: Grain quality evaluation of DT39 Quelam (Source: NTCC, 2012)

Variety

DT39Quelam
BT7

Milled riceHusked
AmyloseRice ratio ofratio
rice length
Content (%)
length/width
(%)
(mm)

Protein
CollagenicGelcontenttemp.
Durability(%)

71.25

17.82

6.47

3.09

(70 – 74 oC)

medium

9.10

69.40

15.65

5.59

2.83

(70 – 74 oC)

soft

8.21

Evaluation for the quality according to phenotype of milled and cooked rice indicated that DT39Quelam had some advantage characters (table 7), and amylose content (17.82%) was higher thanBacthom 7 (15.8%). In this case, the higher amylose content leads to the better quality because low
amylose content results in sticky cooked quality. In this experiment, after mutation induction protein
content was increased from 8.21% of Bacthom 7 to 9.10% in DT39 Quelam. The most importantcharacter of new mutant variety DT39 Quelam is that the cooked rice is soft, not so sticky, highprotein and with light aroma.
- 87 -

Table8: Testing for cooking quality of DT39 Quelam (Source: NTCC, 2012)

VarietyAroma

Softness

Stickness

Whiteness

PolishAttractive

DT39 Quelam

144533

Huongthom 1234532

Bacthom 7244533*points:- Aroma: bigger means better; - Softness: smaller means harder- Stickiness: bigger means sticker ; - Attractive: bigger means better cooking

Test for cooking quality of DT39 Quelam was carried out by committee consisted of 7 persons whoworked independent evaluation. The result showed that in most indexes, DT39 Quelam was similar toBacthom 7 except for aroma which was lower in DT39 Quelam. Due to irradiation treatment, aroma
character of Bacthom 7 was decreased in DT39 Quelam.

Bacthom 7

DT 39 Quelam

Photos of DT39 Quelam in experiment and exhibition field

9.4 Conclusion
1) New rice variety DT39 Quelam was created by gamma ray irradiation of cobalt source at the doseof 200Gy from Bacthom 7.
2) Main characteristics of DT39 Quelam: Grow duration in spring season: 130-135 days, summer
season: 104-105 days; good tolerance to main pest and disease. Good cooking quality, high yield,
hard stem, high protein, better resistance to bacteria leaf blight and better cold tolerance comparedto the original variety.
- 88 -3) DT39 Quelam has been planting in some provinces in northern part of Vietnam in more than 87 ha.
In most location of trial field, the mutant variety gave higher yield around 5-14% from the originalvariety.

9.5 Acknowledgement
The authors wish to express sincerely thank to the IAEA and FNCA for its long time supports on ourrice mutation breeding programs and my attendance at the annually FNCA work shop 2009-2013. I
also wish to thank Dr. Atsushi Tanaka, Dr. Hirokazu Nakai and Ms. Aki Koike for their kindhospitality and help me during the meeting.
9.6References

Bang Dao ThiThanh et al., 2008, new rice variety, DT38 selected sucessfully by gamma rayirradiation, poster at International Symposium on Induced Mutation in Plant organized by
FAO/IAEA 12-15 August, 2008-Vienna, Austria.
Bang Dao ThiThanh et al. 18-19 August 2011, Primary results of application of carbon ion beam andgamma ray for rice beeding improvement. The IX National symposium on Nuclear Scienceand Technology, Phanrang-Vietnam
ProccedingInternational Symposium on Induced Mutation in Plant, FAO/IAEA 12-15 August,2008-Vienna, Austria
Recently progress of rice mutation breeding and germplasm in China. Plant breeding report, Vol.1
No.1; 2006 pag 4
THINH DO KHAC et al., 2008. Socio-Economic impacts of mutant rice varieties in SouthernVietnam, reported at International Symposium on Induced Mutation in Plant organized byFAO/IAEA 12-15 August, 2008-Vienna, Austria.
Yu Zengliang, Introduction to ion beam Biotechnology, 2006, P 183-199- 89 -