FRUIT BREEDING AND IMPROVEMENT AT SOFRI docx

Vietnam has not only many promissing fruit trees but also some particular fruit varieties having big potential for export such as Ri-6 durian, Hoa Loc mango, and Nam roi pummelo, Mangost

FRUIT BREEDING AND IMPROVEMENT AT SOFRI

Nguyen Minh Chau Southern Fruit Research Institute (SOFRI)

1 PRESENT STATUS OF FRUIT TREES IN VIETNAM

Fruit area and production in Vietnam were estimated about 574.000 ha and 5,090250 tons in 2000, respectively In the North, fruit area and production were 235.000

ha and 990.250 tons while in the South those were 339.000 ha and 4.1 million tons, respectively The important fruit trees of Vietnam are citrus group, banana, pineapple, longan, mango,

Vietnam has not only many promissing fruit trees but also some particular fruit varieties having big potential for export such as Ri-6 durian, Hoa Loc mango, and Nam roi pummelo, Mangosteen, dragon fruit, rambutan, Xuong com vang longan, Lo ren star apple, Pineapple, etc The available export markets are Hongkong, Singapore, Taiwan, and China, The South of Vietnam has many superior tropical fruits attractive to the world market The fruit trees have been developed in adapted ecology regions such as Rambutan, Durian in Dong Nai, Ben Tre, Vinh Long provinces; Jackfruit and Mangosteen in Binh Duong province; Star apple in Vinh Kim of Tiengiang; Hoa Loc mango in Tiengiang; Nam roi pummelo in Binh Minh, Vinh Long; and dragon fruit in Binh Thuan and Long An province

However, some constrains were defined They are as follows:

- Most of fruit areas in the Mekong delta of Vietnam based on small orchards are hard for mechanization

- In production, many cultivars exist, although this showed a rich fruit germplasm,

it is the main problem that limit the development of exportation and processing An example is mango, we have Cat Hoa loc, Cat chu, Xiem num, Thanh ca, Buoi,

- The activities related to the study on fruit markets and marketing for export or even for local consumption are still lacking

- Fruit processing starts at some enterprises in Tiengiang, Dong Nai, Ho Chi Minh city, Kien Giang and some private enterprises in Dong Nai, Bimh Duong,

Table 1: Distribution of fruit area and production in the major fruit trees in Vietnam (Sources from RIFAV & SOFRI, 2001)

Fruit kinds

The North The South The North The South

2.COLLECTION, EVALUATION AND CONSERVATION FRUIT GERMPLASM

From 1994 up to July 2001, Southern Fruit Research Institute has collected and conserved 42 fruit kinds with 653 varieties, including 317 local varieties and 336 foreign varieties They are conserved in the net houses and orchard of SOFRI, farmer ‘s orchards, and in our sub-station, i.e, South East Fruit Research Center, Baria-Vung Tau They include 238 citrus varieties, 102 mango varieties, 54 banana varieties, 28 longan varieties,

23 guava varieties, 21 wax apple varieties, 22 pineapple varieties, 23 avocado varieties,

26 dragon fruit varieties and some varieties of other fruit kinds

Most of them have been tested in different ecological regions in Vietnam Varieties were evaluated as having good potential development are belong to the follows:

• Good quality local fruit varieties:

1 Citrus varieties: nam roi, da xanh, duong la cam and Phuc Trach pummelo; sweet orange, soan orange; sugar mandarin, tieu son mandarin, king mandarin

2 Rambutan varieties: nhan and java

3 Banana varieties: gia Ben Tre, gia Da Lat, cau trang, xiem trang

4 Wax apple varieties: Hong dao da, da xanh, trang sua Cho Lach

5 Longan varieties: xuong com vang, tieu da bo, super, Long Hung Yen

6 Durian varieties: Ri-6, seedless-milk (BenTre), seedless (Dong nai)

7 Dragon fruit variety: Binh Thuan

8 Guava varieties: xa ly nghe, xa ly gion, ruot do da lang

9 Mango varieties: cat Hoa Loc, cat chu, canh nong

10 Star apple variety: Lo ren

• Introduced fruit varieties that found suited to local conditions:

Nakon pummelo (USA); Tangelo orlando SRA 21 (France); Rong rieng rambutan (Thailand); Mongthong durian (Thailand); Red flesh dragon fruit (Colombia) and Khieu

sa voi mango (Thailand), Edor longan (Thailand)

Table 2: Some promissing local and foreign varieties in the South Vietnam,

(SOFRI, 2001)

1 Pummelo Nam Roi, Da xanh, Duong la cam, Phuc

Trach

Nakon (Florida, USA)

6 Banana Gia Ben Tre, Gia Da Lat, Cau trang, Xiem

trang, Bom

-

7 Wax apple Hong Dao da, Da xanh, Trang sua Cho

Lach,

- 2 varieties: green and red from Thailand

21

10 Durian Com vang hat lep (Seedless), Ri6,

Milk-seedless (Ben Tre), Dong Nai Milk-seedless durian

Mongthon (Thailand)

13 Mango Cat Hoa Loc, Cat chu, Canh nong Khieu sa voi, Nang

lang wan

• Varieties that could be used as rootstock as parents

+ Ta A mandarin: vigour, high yield, tolerant to Phytophthora sp

+ Sanh variety (citrus group): vigour, tolerant to flooding, and Phytophthora sp + Tuong lemon: strong vigour, tolerant to flooding and Phytophthora sp

+ Muong sweet orange: tolerant to dried and acidic soil

+ Tieu la bau longan: vigour, easily flowering and setting fruit, it is used for root stock, flood-tolerant

+ Giong longan: tolerant to sandy land + Tu quy durian: very vigour, high yield, tree could flower 3 times/year, tolerant

to Phytophthora palmivora

+ La queo durian: tolerant to flooding and Phytophthora palmivora

+ Ta rambutan: vigour, high yield, tolerant to flooding, used for root stock

+ Chau hang vo and thanh ca mango: very vigour, high yield, tolerant to flooding + Canh nong mango: high yield, tolerant to sandy land

3 CLONAL SELECTION:

To meet urgent farmers’ need, SOFRI conducted clonal selection, and the Fruit Tree Contests from 1996 up to now on the important fruit trees such as Mango, Durian, Rambutan, Longan, Mandarin and Pummelo in the provinces of South As a result, 13 fruit clones of some fruit types have been released by Ministry of Agriculture and Rural Development (MARD) in December, 1997 They are the following clones such as:

è Mango: Two clones of Cat Hoa Loc mango: CT1 and CT6, and one clone of

cat chu mango (CD2)

* Cat Hoa Loc mango is grown commonly in Tien Giang, Dong Thap, Can Tho,

Vinh Long, and Ben Tre provinces Harvesting time is from March to May

+ Original of CT1 clone: Can Tho city, and of CT6 clone: Hoa Loc, Hoa Hung, Cai Be, Tien Giang

+ Fruit: Oblong elongate shape with round base Average fruit weight: 500-600g, when ripe the skin is bright yellow with fine, firm flesh and very sweet, Brix 20-22, strong flavor, none fibre, % edible portion 80-84%, thin skin, and covered with bloom, when fruit is going to ripe Yield: 150-250kg/tree/year (at >20years)

* Cat chu mango clone (CD2): Original is in Cao Lanh, Dong Thap, grown

commonly in Dong thap, Tien Giang, and Can Tho province Harvesting time is from February to April, round fruit shape with average weight 300-350g Fruit flesh is dark yellow at ripen, firm, fine, non fibre, Acidic sweet taste, Brix 18-19% Edible portion: 80% Thin skin with lots of brown small spot Yield average is 400-600kg/tree/year (>25 years in orchard)

è Durian: Two of durian are SDNO 1L clone and Dong Nai seedless durian

S11DL clone

* Clone SDNO 1L: This clone is original in Long Thanh, Dong Nai and grown

commonly in Long Thanh, Dong Nai, having harvesting time from June to August Round fruit shape, flesh is yellow with average fruit weigh from 1.5-2.0 kg Flesh is dry, fine, firm, none fibre, sweet, creamy, and attractive aroma High aborted seed and edible portion are 50% and 27%, respectively Yield: 80-90 fruits/tree/year

* Dong Nai seedless durian clone (S11DL): Original is in Long Khanh, Dong

Nai They are commonly grown in Dong Nai, harvesting time is from April to June Yield obtains 80-100 fruits/tree/year Fruit shape is elliptical with average weight is 1,5-1,8kg Flesh is yellow, firm, fine, dry and non fibre with sweet, creamy taste and attractive aroma High edible portion is 29,6%

è Pummelo: Two clones of pummelo are Duong la cam clone (BC12) and nam

roi clone (BNR25)

* Duong la cam clone (BC12): Original is in Vinh Cuu, Dong Nai Harvesting time: is from August to January Fruit shape is low piriform, yellow green peel when ripen Fruit average weight is 1300 g, flesh is separated from mesocarp easily, light yellow, Brix 10.6% Juice is much, with good, sweet taste, many seeds per fruit

* Nam roi pummelo clone (BNR25): This clone has originated in Binh Minh,

Vinh Long and grown commonly in Vinh Long, Can Tho Time harvesting is from September to February Fruit shape is piriform, green yellow skin when ripe with average fruit weight about 1800g Fruit flesh is separated from mesocarp easily, light yellow, Brix 8-9% Juice is much, good and sweet taste, strong flavour Many seeds per fruit Yield could obtain 300 fruits/tree/year

è Mandarin: Two clones of mandarin are King mandarin clone (CS8) and Tieu

mandarin clone (QT12)

* King mandarin (CS8): The clone has originated in Mo Cay, Ben Tre and

grown commonly in Vinh Long, Ben Tre, Can Tho Harvesting time from August to October and from December to January Fruit shape is spheroid, green skin at ripen with average fruit weight 300-350g, much juice, Brix: 9.2% strong flavour and very good, sweet in taste of juice Number of seeds/fruit are 21 Yield could obtained 170kg/tree/year

* Tieu mandarin clone (QT12): Original is in Lai Vung, Dong Thap Common

growing areas is Dong Thap, Can Tho Harvesting time from December to January Fruit shape is oblate with orang red peel when ripe Average fruit weight around 190-195g, lots

of juice, Brix 10.3% Taste is very good, sweet and wild flavour, number seeds/ fruit are

15 Yield could obtain 150kg/tree/year

è Longan: Two clones of longan are xuong com vang clone (VT0XCV) and tieu

la bau clone (Bt9TLBa)

* Xuong com vang (VT0XCV): The clone has originated in Baria, Vung Tau

Common growing areas are Vung Tau, Tien Giang, Vinh Long Harvesting time: from June to August Fruit shape is oblate spheroid, light brown peel when ripe with average fruit weight 18g Flesh is dry, firm, thick with light yellow, Brix: 21.5% Taste is very sweet and good Yield could obtained 300kg/tree/year This variety is also popular now

in some Asian Southeast countries

* Tieu la bau (Bt9TLBa): Original is in Cho Lach, Ben Tre and grown

commonly in Ben Tre, Tien Giang, Vinh Long Harvesting time is from March to May and from June to August Fruit shape is round with dark brown yellow fruit skin when

ripe with fruit weight average 10.2g Flesh is dry, firm and thick with Brix 24.5%, very sweet and good in taste

è Rambutan: Two clones of rambutan are java clone: (CDN9J) and nhan

rambutan clone(CDN13N)

* Java rambutan clone (CDN9J): Original is in Dong Nai, grown commonly in

most of provinces in the South Vietnam they have harvesting time from Aril to August Fruit skin is dark red at ripen, average fruit weight is 36g The aril is firm, dry, acidic sweet and peels well, Brix: 20.5%, yield could obtain 800kg/tree/year

* Nhan rambutan clone: (CDN13N): The clone has originated in Long Khanh,

Dong Nai Common growing areas is Dong Nai, Tien Giang, Ben Tre, Vinh Long Harvesting time from Aril to August Fruit skin is red yellow with average fruit weight 22g The aril is firm, dry, acidic sweet and peels well, Brix 22% Yield could obtain 400kg/tree/year

In addition to 13 above registered clones to MARD, some other promissing clones

of above fruit kinds have been surveyed They are tieu da bo longan, da xanh pummelo, sweet orang, sugar mandarin, etc Besides, clonal selection in some other fruit kinds such

as Jack fruit, star apple, pineapple, banana have been also conducting Some preliminary results:

è Jack fruit: collected and evaluated 32 varieties, 10 of them are selected for

trying in some other regions They belong to Nghe variety and To nu variety

è Star apple: Star apple is a specific fruit of the South Vietnam and it is still

new to world markets Five lo ren star apple clones were selected for trial in some other ecological regions

è Pineapple: In the Mekong delta pineapple has been grown at Tien Giang,

Long An, and Kien Giang provinces with two cultivars Queen and Cayenne Demand for fresh fruit to export is not very high However, the demand of concentrated juice and canned products are high Pineapple varieties were colleted, evaluated and selected these promissing clones that will be multipled The demand for Cayenne planting materials is very high in whole country now

è Bananna: In the South of Vietnam, three cultivars have potential for export

namely Gia, Cau, and Bom Gia variety has big potential but it is not grown in large

scale, and varies clones At present, the cau cultivar could be exported with fresh compsumtion and bom cultivar could be exported dried Collection, selection banana clones for micropropagation and production disease-free banana have been conducting

4 FRUIT BREEDING AND IMPROVEMENT AT SOFRI:

? Hybridization:

4.1 Papaya:

Papaya in South Vietnam is grown commonly with 2 groups: yellow and red flesh

* Red flesh group is popularly grown with two varieties: Dai Loan tim and Ma Lai tim and common growing areas are Dong Thap, Tien Giang, Can Tho, Soc Trang provinces Flesh of these varieties is red, firm, sweet, Brix: 13% However, fruit skin these varieties is thin This group is only grown in the Mekong Delta of Vietnam

* Yellow flesh group is popularly grown with three varieties: Hong Kong da bong, Da bong lun and Long Khanh yellow papaya Fruit skin is thick, it is adaptable to transport Growing common area are the South-northeasteen and Cai Be,Tien Giang and Cao Lanh, Dong Thap This group is used as fresh and processing (juice)

We introduced some varieties from USA, Thailand, Malaysia, etc introduced varieties have evaluated at SOFRI’s orchard on some major characteristics such as morphology, fruit quality, yield, and reaction to major pest to select parents for crossing

A crossing has been doing, the selected varieties as parents are Sunrise solo (USA), Dai Loan tim and Hong Kong da bong Before crossing, they are maintained for the purity through 6 generations and reciprocal hybridizations between selected parents in 2000 At present, we are evaluating introduction cultivars and hybrids at the SOFRI’s orchard and maintaining the purity of selected papaya cultivars for using as parental trees and crossing in some other hybridizations (Yen,1998)

SOFRI would like to test the performmances of Papaya Ringspot Virus resistance varieties developed by Hawaii, etc under the Mekong delta of Vietnam, as the disease is very severe here

2 Dragon Fruit: In Vietnam, dragon fruit is commonly grown in the South (Binh

Thuan, Long An, Tien Giang) with the same cultivar Fruit characteristics are red peel,

white flesh, Brix 14%, acidic, sweet taste We introduced dragon fruit varieties from Colombia and Taiwan, and evaluated for development and their quality in SOFRI’s orchard from 1995 to 1999 Red flesh dragon fruit from Colombia was selected and released by MARD and being used as parent in crossing with Binh Thuan clone because red flesh dragon fruit grows up fast, many flowers and fruit flesh is very sweet, dark red However, if the flower is pollinated naturely, fruit is small, average fruit weight is only about 100-150g, fruit peel is usually attacked by fungi and aunt Therefore, to improve fruit quality for export market We used Binh Thuan (local) to cross reciprocal with Red flesh (Colombia) dragon fruit with wishes to have fruit peel and shape, big fruit (>300g)

(Yen et al, 2001)

4.3 Mango: In the South though there are many mango cultivars only 3 varieties,

i.e., Hoa Loc, Thom and Tuong (green eaten) can be exported as fresh fruit (Man, 1998) Out of them, Cat hoa Loc mango is known well due to good fruit quality, fruits have been exported to France, Germany and Suisse, and some Asian countries such as Singapore, and North America such as Canada,

Its fruit skin is thin so it is difficult to transport and yield is low To Improve this cultivar, we have made hybridizations such as Irwin x cat Hoa Loc, Tommy attkin x cat Hoa Loc, Cat chu x cat Hoa Loc, Kent x cat Hoa Loc, Keitt x cat Hoa Loc After

polination 45-60 days, young fruits will be cultured in-vitro to rescue the embryo (Hang

et al, 2000)

Mutation Breeding:

4.4 Mango: To improve thin skin character of Cat Hoa loc variety, scions of

selected cat Hoa Loc clones have been treated by gamma radiation and grafted on root

stock mango trees (Hang et al, 2001)

2 Mandarin: Tieu and King mandarin have good fruit shape and quality, fruits,

however, contain a lots of seeds To improve this character, mutagenesis and polyploid techniques have been applied Mutagenesis by gamma radiation in buds and calli of tieu

mandarin, King mandarin cultured in vitro We are studying to produce triploid trees in these mandarin cultivars (Nhan et al, 2001)

5 BIOTECHNOLOGY

5 1 Development technology of production disease-free citrus samplings:

- Shoot tip grafting technique and indexing some severe diseases (Greening by PCR technology, Tristeza by ELISA) in citrus to produce disease-free citrus was

completed in 1999 (Hong et al, 1999) and this technology has been transferred to

different provinces Disease-free planting materials have been also supplied by SOFRI (50,000-60,000 plants/year) to Seed company of different provinces, Universities in the South for further multiplication

- Indexing virus diseases in banana such as Banana Bunchy top virus, banana streak virus, banana mosaic virus, banana bract mosaic by PCR, RT-PCR, ELISA, and

DIBA methods to select virus-free clones (Hong et al, 2001)

2 Tissue culture:

- Studies on micropropagation for citrus root stock cultivars have been conducted

on Volkameriana, nam roi pummelo, etc (Nhan et al, 2001)

- Micropropagation and conservation in- vitro for virus-free banana clones

3 Embryo rescue: started in mango that come from distance hybridization

(Hang et al, 2000)

4.Genetic markers:

- Isozymes have been used for analysis of genetic variability in citrus group

(Nhan et al, 2000)

- Isozymes have been also used for identify nucellar and zygotic seedlings in

citrus (Nhan et al, 2001)