Fruit breeding program at Southern Horticultural Research Institute has been conducted and strongly developed from 2001 on some main fruit trees such as Pineapple, Orange, Pummelo, Mango, Dragon fruit and Longan.

Tran Thi Oanh Yen, Dao Thi Be Bay, Nguyen Ngoc Thi, Nguyen Nhat Truong, Nguyen Thi Ngoc Diem, Nguyen Thi Muoi, Bui Xuan Khoi and Nguyen Minh Chau.

Southern Horticultural Research Institute (SOFRI)

ABSTRACT

            Fruit breeding program at Southern Horticultural Research Institute has been conducted and strongly developed from 2001 on some main fruit trees such as Pineapple, Orange, Pummelo, Mango, Dragon fruit and Longan. By selection of elite individuals: one variety of seedless sweet orange, one individual of Da xanh pummelo variety, two individuals of Long Co co pummelo variety, four individuals of Queen Pineapple, one individual of Hoa Loc mango, and one individual of  cat Chu mango variety have been selected. Application of gamma rays to induce mutation have been conducted on King mandarin and Hoa Loc mango and Longan, results: one variety of seedless king mandarin LĐ6, and one variety of few seeds Duong la cam pummelo LĐ4 have been released in December, 2010. Traditional hybridization has been conducted on Dragon fruit, Mango, Longan, Citrus, Pineapple,.. So far, two varieties of  Dragon fruit: LD1 and LD5 dragon fruit with red and pink violet flesh have been released in December, 2005 and December 2010, respectively, and some  new varieties of Pineapple, Mango, Longan, Dragon fruit will be released in the near future.

I. INTRODUCTION

            Fruit breeding program at the Southern Horticultural Research Institute on some mainly crops such as pummelo, orange, mango, dragon fruit, longan, pineapple,... during 2006-2011. 

            Vietnamese fruits are diversity in kinds and rich in genetic resources, many kinds of fruits have been presented in the international markets such Dragon fruit, mango, pummelo, longan,...However, they still have many limits such as high number of seeds in citrus, thin peel in cat Hoa Loc mango, only white flesh Dragon fruit grown popularly, longan with thin flesh and big seed and fruit shape of queen pineapple is not suitable for processing,.. To improve these characteristics breeding progam on fruit trees at SOFRI has been conducted.

II. CONTENTS AND METHODS 

1. Research Contents

2.1. Breeding on pineapple for cylinder fruit shape and good quality

2.2. Breeding on citrus for seedless fruits

2.3. Breeding on cat Hoa Loc mango for thick fruit skin and good quality

2.4. Breeding on dragon fruit for different colours in peel and flesh

2.5. Breeding on longan for  bigger fruit size, smaller seed, thick flesh and sweet

2. Methodologies

2.1. Selection of elite individuals

            Investigation, observation and selection of elite individuals from farmers’ orchards. After that, they will be evaluated on the growth, yield, fruit quality, important pests and diseases during 3 continuous years. Selected individuals having high productivity, good quality will be multiplied for trials. The best individual will be certified by Department of Agriculture and Rural Development (DARD) of provinces as mother plants for mass propagation.

2.2. Using gamma rays to improve commercial varieties

            - Gamma ray was used to treat on buds and embryos of commercial varieties which need to improve one or some characteristics such as: number of seeds per fruit in King mandarin,  Duong la cam pummel, Da xanh pummelo,…; peel thickness of Hoa Loc mango; flesh thickness in longan; colours of peel and flesh in dragon fruit and queen pineapple with pillar fruit shape.

2.3. Breeding new fruit varieties by traditional hybridization method

            - Selection of local, commercial varieties or introduction varieties using as parents in crossing.

- Traditional hybridization, collection of seeds and sowing them in nursery

- Growing for fast evaluation on the field

- Screening of good individuals for further trials

- Value for Cultivation and Use (VCU) trials and Distinct Uniform and Stable (DUS) tests

- Collection, analysis of datas and writing the report

2.4. Analysis of datas:

            Data was collected, entered and analyzed on MS Excel with means, standard deviations and t-test; ANOVA analysis and comparison of means by IRRISTAT 3.1.

III. RESULTS AND DISCUSSIONS

1. Breeding on pineapple for cylinder fruit shape and high quality

            Four individuals of Queen pineapple were selected and certified for mass prodution by Tien Giang DARD in 2008. They were selected from farmers’orchards and evaluated on agronomic characteristics, yield and fruit quality through 3 continuous years.

            Breeding in pineapple by traditional hybridization method has been conducted from 2007. In 2010, fruits were evaluated on fruit shape and quality characteristics, three hybrids were selected for trials, they are: Cayenne TL 2 x III/1, Cayenne TL 2 x II/6 and Cayenne GU114 x II/6.

2. Breeding on orange, pummelo with seedless fruits

2.1. Selection of seedless orange and pummelo individuals: From 2005-2009, some  citrus varieties/individuals were selected, they are: seedless sweet orange variety in 2008, one individual of Da xanh pummelo in 2009, two individuals of Long Co co pummelo in 2008.

- Characteristics of seedless orange variety: Fruits have spherical shape, yellow green skin, and yellow flesh, sour sweet in taste with TSS 8%, high juice (40-42%), and seedless. Seedless sweet orange was certified by MARD for propagation in production from 2008.

- Characteristics of Da xanh pummelo (cetified individual): Fruits have spherical shape, green skin when mature, and pink red flesh, sweet in taste with TSS 11%, high edibe ratio (55-60%), and having a few seeds. Da xanh pummelo was certified by Ben Tre DARD in 2009 for propagation in production.

            - Characteristics of Long Co Co pummelo (certified individuals): Fruits have spherical pyriform shape, green skin when mature with covering soft hairs, and pink red flesh, sweet in taste with TSS 10%, high edibe ratio (52-57%), and having a few seeds. Da xanh pummelo was certified by Tien Giang DARD in 2008 for propagation in production.     

2.2. Breeding on seedless citrus by gamma treatment on scions: gamma rays were applied for improving number of seeds per fruit on King mandarin and Duong la cam pummelo. Results indicated that: one seedless King mandarin individual- LĐ6 and one individual of few seeds Duong la cam LĐ4 were released in 2010.

- Characteristics of seedless King mandarin variety: Fruits have spherical shape, yellow green skin, and orange flesh, sweet and light sour in taste with TSS 7.5-8%, high juice (40-42%), and seedless. Seedless King mandarin was certified by MARD for propagation in production from 2010.

- Characteristics of few seeds Duong la cam pummelo LĐ4: Fruits have short pyriform shape, yellow skin when mature, and light yellow flesh, sweet in taste with TSS 12-13%, high edibe ratio (55-60%), and having a few seeds. Few seeds Duong la cam pummelo variety was certified by MARD for propagation in production in the Southeast provinces.

3.  Breeding for thick peel and high quality on cat Hoa Loc and cat chu mango

3.1. Selection of cat Hoa Loc and cat Chu mango individuals having thick peel and high quality: From 2002-2010, one individual of cat Hoa Loc mango (HL27) and one of cat Chu mango (C37) were selected, they were certified by Tien Giang DARD to propagation for production from 2010.

- Characteristics of Cat Hoa Loc mango HL27: strong growth, high fruitset ratio, fruit weight 418.5-456.0 g, thick fruit skin (1.3-1.4mm) and high flesh ratio (73.6-79.2%) as comparison to control individual (CT1).

- Characteristics of Cat Chu mango C37: strong growth, high fruit set ratio,  average fruit weight 386.2g, thick fruit skin (1.28± 0.13mm) and high flesh ratio (79.5%) as comparison to control individual (CD2).

3.2. Treatment of gamma rays on scions of Cat Hoa Loc mango variety: gamma rays were applied for increasing thickness of fruit peel in Cat Hoa Loc mango variety. Preliminary results of research: two individuals of mutation Cat Hoa Loc mango coded 4.5-15 and 4.5-23 were screened for trials. They have thickness of fruit peel: 1.72mm in 4.5-15 clone and 1,70 mm in 4.5-23 clone.

3.3. Traditional hybridization method: traditional hybridization progam in mango was conducted from 2001, Preliminary results, two hybrids XL-049 and XL-034 were selected for trials, they had good quality, fruit peel thickness  ≥1,5mm.

4. Breeding on dragon fruit having purple, pink or pale red in flesh

            Works conducted from 2005 was to develop a dragon fruit variety having pinkish purple flesh and good quality by traditional hybridization. For this, total of  1,855 hybrids were evaluated for fruit quality and 11 promising hybrids from H10 x white flesh BT and H14x CG had been selected for VCU and DUS tests in Tiengiang, LongAn and Baria-Vungtau from May 2009 to Oct. 2010. The results during twelve months observed for DUS trial on 51 characters (vegetative, flower and fruit ones) showed distinctness between them, and after fifteen months for VCU trials indicated that 11 hybrids having good growth, less to mild pests and diseases infectation/infection and  good bearing. Among them, T9 (coded name: H14 xCG-005) showed best advantageous characteristics such as good in fruit skin colour and bracts; firmness, medium juiciness and pinkish purple colour in fruit flesh as comparison to ‘Red flesh LĐ1’ variety. Beside of these, this hybrid also produced high in fruit yield and had been affected at low to mild pests and diseases, especially in anthracnose disease.           

5. Breeding on  longan: the purposes of breeding on longan are thick flesh, small seed, sweet in taste.

            - Selection of elite individuals, one individual of Xuong com rao longan and one of Xuong com vang longan were certified as mother plants for propagation by Ba Ria Vung Tau DARD.

-  Using gamma rays to yield mutations on embryos and buds: varieties used for irradiation as Xuong com vang longan and Tieu da bo longan. They have been evaluated on the field.

            - Traditional hybridization on longan was started from 2003: up to now, a lot of hybrids were made. Results showed that two good longan hybrids will be released in 2012.

IV. CONCLUSIONS AND SUGGESTIONS

          From 2006 to 2011, breeding progam on fruit trees at Southern Horticultural Research Institute, obtained such as:

          - Four individuals of Queen pineapple, 01 individual of Da xanh pummelo, 02 individuals of Long Co co pummelo, 01 individual of cat Hoa Loc mango, 01 individual of cat Chu mango, 01 individual of Xuong com vang longan, 01 individual of Xuong com rao longan were certified as mother individuals for propagation by Tien Giang, Ben Tre, and Baria Vung Tau DARD as well as 01 seedless sweet orange cultivar was certified by MARD.

          - Breeding by induced mutation and traditional hybridization: one individual of few seeds Duong la cam pummelo LĐ4 (5.45-6.62 seeds/fruit), 01 dragon fruit cultivar LĐ5 with pink purple colour in flesh, 01 individual of seedless king orange LĐ6 were certified by MARD for propagation in December 2010.

                       

Fig. Seedless sweet orange cultivar                           Fig. Few seed Duong la cam pummelo LĐ4

                     

Fig. Seedless king mandarin - LĐ6                         Fig. Pink purple flesh dragon fruit LĐ5