Over the past time, the Southern Fruit Research Institute has researched and put into production many scientific and technical advances on durian trees.
Breeding 3 new durian lines: fat, edible, and low seeds
According to the Department of Crop Production, in 2021, the durian area of some key provinces will reach 84,800 hectares, the average yield will be 15.7 tons/ha, the total output is about 694 thousand tons. In the Central Highlands, Dak Lak province has 14.9 thousand hectares. Lam Dong has 14,000 hectares. In the Southeast, Dong Nai province has 9.2 thousand hectares. Binh Phuoc has 3.4 thousand hectares. In the Mekong Delta, Tien Giang province has 15.2 thousand hectares. Vinh Long has 3.5 thousand hectares. Ben Tre has 2.5 thousand hectares. Can Tho has 2.4 thousand hectares.
In 2021, the area of durian in key areas is more than 84,800 hectares. Photo: Minh Dam.
According to the Southern Fruit Research Institute, up to now, durian trees have 83 known varieties/lineages. In which, 19 varieties/lines were selected and put into production. Some typical local durian varieties have been put into production such as Ri6, Golden Rice with Chin Hoa Pear Seeds, Dong Nai Pear Seeds, Tien Giang Flat Seeds, Ku Qua Xanh, La Queo, Chuong Bo, Sau Huu. Popular imported varieties such as Monthong, Chanee, Kanyao, D6, D195, D175, Musang king... The highest percentage of varieties produced by people is Monthong (41.5%). Next is Ri6 (25.5%). Chin Hoa yellow rice with flat-seeded rice is 21.8%.
Since 2008, in order to contribute to the development of durian varieties with high yield and quality, adapted to the local climate, the Eastern Fruit Research Center under the Southern Fruit Research Institute has selected created 3 excellent hybrids from the cross between the father Ri6 durian and the mother Monthong. Three new hybrids were placed: RM20, RM22 and RM60 respectively.
Information on some common characteristics of these three hybrids, Ms. Pham Thi Muoi, working at the Department of Breeding and Biotechnology, Center for Fruit Tree Research in the Southeast of the Institute of Plant Research Southern fruit says:
“The canopy is tower-shaped. Average branch density. Regular natural flowering is concentrated in February every year. Flower buds grow in clusters, average flower density. Average fruiting rate. Time from flower bloom - harvest: 105-110 days. The main harvest season in early June is similar to Chin Hoa's yellow rice and 1-2 weeks earlier than Monthong".
The durian line RM22 was bred by the Southern Fruit Institute. Photo: TL.
Durian hybrid line RM20, high meat percentage, average 32.9%. The percentage of flat seeds is quite high 35.8%. The flesh is light yellow (similar to Monthong), drained, very smooth, sweet, fatty, not fibrous, not mushy, very aromatic, not bitter aftertaste under normal conditions. High brix level 26.5%. Not infected with dangerous pests and diseases.
The hybrid durian line RM22 has a high percentage of meat, averaging 34.9%. In particular, the percentage of flat seeds was very high, the highest among the three lines, reaching 85.3%. The flesh is medium yellow, drained, very smooth, sweet and fatty, not fibrous, not mushy, very fragrant, the aftertaste is not bitter under normal conditions. High brix, reaching 25.7%. Not infected with dangerous pests and diseases.
The RM60 hybrid durian line has a high percentage of 32.4% flesh. The percentage of flat seeds is very high 65.5%. The flesh is dark yellow, drained, very smooth, sweet, fatty, not fibrous, not mushy, sweet, very fragrant, not bitter aftertaste under normal conditions. High brix degree 24.7%. Not infected with dangerous pests and diseases.
“We have only recently evaluated the characteristics of the hybrid durian lines, finding them to have similar characteristics compared to their parents. In particular, there are some outstanding characteristics such as fat, high percentage of fruit pulp, high percentage of flat seeds. The percentage of flat seeds is one of the factors that determine the high edible rate or not. In the near future, we will take steps to get the new variety recognized and popularized into production”, Ms. Pham Thi Muoi shared more about the newly bred durian lines.
In addition, the Center also successfully restored 22 excellent individuals of the Ri6 durian variety and 4 excellent individuals of Chin Hoa's golden rice with milky seed, contributing to preserving and maintaining quality varieties for production.
Water enough for durian in the dry season. Photo: Minh Dam.
Cultivation of durian trees: before - during - after drought and salinity
Information with farmers about some cultivation techniques on durian trees, Dr. Tran Thi My Hanh, Deputy Head of Plant Protection Department, Southern Fruit Research Institute said: “Some techniques people need to pay attention to now are pruning to create canopy; solutions to prepare before, during and after salinity drought; identification of some pests and diseases and how to manage them”.
For the technique of pruning to create a canopy, on a 5-year-old Ri6 durian tree with a diameter of 7m, farmers cut the top and control it at a height of 4.5 m. After cutting the tops, pruning is carried out ineffectively such as: level 1 branches with a diameter of less than 4cm, hidden branches, toothpick branches, vertical pruning, and diseased branches.
The Mekong Delta is often affected by the saline intrusion, so people need to prepare well for their durian gardens to overcome the drought-salt season.
Before the salinity drought, it is necessary to harvest completely from the 10-11 solar calendar. Complete 1 bet on 12 solar calendars. Next, people improve the soil by applying organic fertilizers, acid humus and restoring the roots. In the process of tree care, people should pay attention to pruning branches and leaves (to limit transpiration), do not create young buds, do not handle flowering and trim off fruits (if any). To reduce water evaporation, people need to cover the soil and keep the garden grass. In addition, people need to dredge garden ditches to store fresh water for watering plants.
The right durian is the canopy and the left is not yet canopy. Photo: TL.
In saline drought, when providing fertilizers for plants, people should water soluble fertilizers such as nitrogen, potassium, and phosphorus (through the drip irrigation system, spraying through leaves). Along with that, spraying supports foliar fertilizers with compounds containing Cobalt, Mo, Bo, Zn, and Silicon. When providing water for plants, people need to apply drip irrigation, and ditch irrigation, to increase water use efficiency. At the same time, it is possible to apply partial, fixed, or alternating irrigation to increase the efficiency of water use for plants in dry conditions. At the same time, reduce water evaporation by soil mulching.
After the drought, farmers took 5 steps to restore durian trees. Step 1, clean the field and wash the soil with salt. Step 2, Restore the roots and leaves. Step 3, support the leaf set to grow. Step 4, support the roots and complete the set of leaves. Step 5, enhances nutrient absorption and photosynthesis. To better understand the technique of restoring durian trees after being affected by drought and salinity, people should read the article: Solutions to restore durian gardens affected by drought and salinity in the dry season 2019 -2020 by Dr. Vo Huu Thoai on the website of the Southern Fruit Institute.
People carry fresh water to water durian trees in the dry season of 2019-2020. Photo: TL.
Pest identification and management
With regard to pest identification and management, Dr. Tran Thi My Hanh said some main pests on durian trees such as jumping hoppers, green planthoppers, fruit borers, thrips, red spiders, hair clippers, and weevils. Disease problems on durian trees often appear as anthracnose, stem pus, pink fungus, root rot, leaf burn, flower rot, fruit rot, and seaweed spot.
For treatment, mechanical, biological, and herbal extracts can be used. Simultaneously, select some durian varieties that are resistant to stem pus and root rot such as Chanee and Que la as rootstocks.
With mechanical measures, people can use light traps to repel and attract the larvae of pests such as fruit borers and hair clippers. Biological measures can use natural enemies to catch prey such as: ladybugs, web beetles, pincer-tail beetles, and bait-eating spiders to destroy the larvae of harmful objects: mealybugs, spiders, eggs and insects. borer larvae. People should spray a little sugar water (help predators develop well).
In addition, use parasitic fungi such as purple fungus (Paecilomyces) and green fungus (Metarhizium) to parasitize and destroy pests such as mealybugs, thrips, spiders. People water parasitic fungi around the root to kill thrips pupae, stem borers in the soil (50 gr/10 liters of water).
Along with that, people can also use antagonistic fungi (Trichoderma) to treat diseases caused by fungi. At the same time, combine with decayed organic fertilizer (2-4 kg/ton of manure). When using, water the inoculant around the root (50g/10 liters of water/plant).
People can also spray a solution of soaking garlic + onions in combination with 5% alcohol or 5% neem extract to treat thrips, planthoppers, and spiders.
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