How to grow durian? A detailed tutorial on the latest technical methods

Durian is one of the famous tropical fruits and a fruit of great economic value. Some countries in Southeast Asia grow it in relatively large quantities, with Thailand growing the most; among Thailand's fresh fruit exports, durian ranks first, and in 1987 durian exports reached 10 million US dollars. Hainan, China has a small number of durian trees, and some durian varieties have also been introduced from abroad. With the opening up to the outside world, foreign durian has entered the Chinese market and is well received. Due to a lack of understanding of durian's appeal, China has not attached great importance to durian cultivation, and there has been very little research on durian. According to the phenological characteristics of durian, it can be grown in areas with an average daily temperature above 22°C and no frost, and parts of Hainan Province and Yunnan Province in China can develop it.

Durian requires a year-round high-temperature climate to grow and bear fruit. Even in equatorial regions, at highlands above 600 m in altitude, because temperatures drop, durian cannot be grown or cannot bear fruit. The market season is from September to December each year, and it is also produced in other months.

For a long time, people have commonly used seeds to propagate durian, but durian has great genetic variability. If one durian has ten seeds, each seed may grow into ten kinds of fruit of different quality, and the good and the poor are uneven; inferior durian can produce very excellent varieties. Likewise, good durian can also produce inferior varieties, and some seedling-grown durian never bears fruit in its lifetime. In order to cultivate excellent varieties, ensure variety purity, and achieve early fruiting and high yield, people today increasingly use grafting propagation to cultivate durian. The 6 propagation methods for durian (excluding seed propagation) are briefly described as follows:

1. Bud grafting

Except for monocotyledons and some plants with irregular cambium, almost all dicotyledonous woody plants can be propagated by bud grafting. The rootstock should be about the size of a pencil. At 10 cm above the soil on the rootstock stem, cut two slits from top to bottom, 0.7 cm wide and 3 to 4 cm long. Make a horizontal cut at the top of the two slits, lift the bark, and match the length to the bud piece. Leave a small amount of the already lifted bark at the lower end of the cut to support the bud piece. The process of obtaining the bud piece is the same as the method of slitting and lifting the bark on the rootstock. After fitting them together, bind tightly with a 1 cm wide plastic film strip. The graft union should preferably not come into contact with rainwater within two days.

Note that in the bud grafting method for other fruit trees, the bud body can be completely wrapped, but durian is the exception, because the bud body on the bud piece easily falls off. After two weeks, it will be known whether it has survived. After survival, cut off the upper part of the rootstock about 30 cm from the grafted bud to stimulate rapid growth of the bud eye. Later, the rootstock will grow many rootstock branches. These rootstock branches must not be completely removed; one or two branches must be bent down to help the grafted bud absorb nutrients, but the retained rootstock branches must not be allowed to grow too vigorously, and they need to be pruned frequently so as not to hinder the growth of the grafted bud.

2. Cleft grafting

Seedlings whose seeds have germinated but have not yet opened leaves, or that have not yet become woody, are most suitable as rootstocks. Cut the rootstock flat at 6 to 7 cm above the ground, and make a vertical cut about 1 cm deep down the middle of the flat rootstock stump to form a “V” shape; obtain a shoot with two or three buds and a diameter comparable to the rootstock stump as the scion, about 8 to 10 cm long, cut off 3/4 of the leaves, whittle the lower end of the scion into a wedge shape, insert it into the cut in the rootstock stump, and bind tightly with a plastic film strip. Afterwards, cover the entire seedling with a transparent plastic bag to prevent water in the scion from evaporating away, and place it in a cool place. After about two or three weeks, if the leaves of the scion do not fall off, it is considered successful.

3. Approach grafting

It is only suitable for small-scale propagation. Seedlings planted in plastic bags about six or seven months old can be used as rootstocks. The size of the relevant scion shoot should be equal to that of the rootstock, and the most ideal is an upright vegetative shoot.

4. Cutting

Use a shoot about 15 cm long, with a diameter about the size of a chopstick, and with several leaves and buds. Two-thirds of each leaf needs to be cut off to prevent water evaporation. Cut the lower end of the shoot obliquely or make a 1 cm cross-cut from bottom to top, apply a layer of hormone rooting agent, insert it into a cup of moist sand, place it in a greenhouse with weak light, water it, and after seven or eight weeks, if the leaves do not fall off and young roots grow, it can be transplanted into a plastic bag.

5. Shoot side grafting

The rootstock can be of any size, as long as it has become woody and its bark can be easily peeled open; the height of the insertion point can be chosen freely, and the cutting process is similar to bud grafting. Select a vigorous young shoot 10 cm long that has not yet opened leaves and has not yet become woody as the scion. The oblique cut on the scion should be slightly shorter than the rootstock cut, insert it into the rootstock cut, bind it with plastic tape, then wrap it tightly with transparent plastic paper, and place it in a cool place. After two weeks, cut open the plastic paper, but the tape must not be removed until the shoot has grown.

6. Air layering

There is no seasonality in air layering. Choose a branch a little larger than a pencil, and from the tail end, at about 40 cm, make a ring cut about 3 cm long. After peeling the bark, use the back of a knife to scrape off the cambium at the cut, otherwise the bark at the cut will regenerate and no roots will grow. Wrap a ball of moist soil around the cut, about the size of a duck egg. Wrap it with three layers of plastic paper, tie both ends tightly, and after about three months when new roots have grown, it can be cut off from the mother plant. Cut open the plastic paper, plant it in a black fruit seedling plastic bag, place it in a cool place, and after about one or two months it can be transplanted. Because the survival rate is low, it is rarely used when propagating durian.