Why do dragon fruit plants need lights during cultivation?

SummaryBecause growing dragon fruit requires hand pollination, and the flowering period of dragon fruit is very short - the flowers generally begin to open one and a half hours before sunset, and by the time dawn breaks the corolla begins to close gradually, so workers must use lights before dawn to hand-pollinate the dragon fruit to ensure the fruit sets and increase the yield.

The flowers of dragon fruit begin to open 1.5 hours before sunset, are fully open at sunset, and after dawn the corolla gradually closes; after the sun rises they wither. To ensure the yield of dragon fruit, during the flowering period workers must use lights at night to hand-pollinate the dragon fruit.

Generally workers begin pollinating after dinner. To hand-pollinate dragon fruit, cross-pollination must be used: the male pollen is collected with a brush and then applied to the stigma of the female flower to complete the process.

Propagation methods for dragon fruit

1. Cuttings

It is best to do this in spring. Choose well-grown stem segments as cuttings, cut them into 375px pieces, and after the wounds have air-dried, insert them into a sand bed or plant them directly under the support frame or beside the concrete post.

After planting the cuttings, keep the soil dry; no watering is needed. Start watering 10 days after planting the cuttings. They generally take root in about 15-30 days, and when the roots have grown to 3-100px they can be transplanted to the seedbed.

2. Grafting

Choose a “Liangtianchi” (dragon fruit rootstock) in good growing condition, with plump stem flesh and no pests or diseases, as the rootstock, and carry out the grafting on a sunny day.

Cut a flat surface on the dragon fruit stem with a knife, then insert the scion, align the cambium, and tie them firmly with cotton thread. Generally at a temperature of 28-30 degrees C it takes only 4-5 days for a large amount of callus tissue to form on the wound's joining surface. When the colour of the scion is similar to that of the rootstock, it means the vascular bundles of the two have healed and the grafting has succeeded; they can then be moved to a false-planting seedbed to continue growing.

1. Selection of rootstock and scion

Choose a suitable rootstock according to the flesh type. For red-fleshed dragon fruit, white-fleshed dragon fruit can be chosen as the rootstock; for yellow-fleshed dragon fruit, wild triangular cactus can be chosen as the rootstock. It is best to choose 1-2 year old triangular cactus, cut them off from the parent plant at the stem joint, and plant them in loose soil with a fairly high sand content. Set up a shade shed above, water them, and they can then serve as rootstock. They generally root in about 15 days, after which grafting can be carried out. For the scion, it is best to choose branches of the current year that are in good growing condition.

2. Grafting time

Apart from winter when the temperature is colder, grafting can be done at any other time. The cold, damp period in winter and spring lasts a long time, the wound heals with difficulty during grafting, and the wound also easily enlarges, affecting the plant, so it is best to graft dragon fruit from March to October, giving the plant sufficient time to heal and promoting fruit set.

3. Chemical treatment before grafting

Use alcohol or white liquor to disinfect the knife used for grafting to avoid bacterial infection. If conditions allow, the base of the scion can be dipped in sodium naphthalene acetate solution, which can promote callus formation and also raise the survival rate of the plant.

4. Grafting methods

Flat grafting: First make a horizontal cut at a suitable height on the three-ribbed stem of the night-blooming cereus, then cut the three rib peaks, then take a cactus spine, disinfect it, and pierce it into the vascular bundle in the middle of the rootstock. Connect the flat-cut scion to the other end of the spine, then join the scion and rootstock together with the spine, keeping the rootstock and scion as close as possible. This avoids bacterial infection. Finally add a spine on each side to secure it, then wrap and tie the base tightly with fine thread.

Wedge grafting: After disinfecting the knife, make a vertical slit at the top of the rootstock; take care that the slit is not too deep. Then cut the scion part into a duck-bill shape, and immediately insert them into the slit of the rootstock, then fix them with plastic adhesive tape. At this point a plastic bag can be put over them to maintain air humidity and promote their survival. After half a month, check the growth of the graft; if it is still fresh and green, it means the graft has survived, and after one month they can leave the nursery.