Key Technical Points for Greenhouse Cultivation and Management of Dragon Fruit
Dragon fruit, also known as red dragon fruit, green dragon fruit, immortal honey fruit, etc. Currently cultivated varieties mainly include white dragon fruit, red dragon fruit, and yellow dragon fruit. Dragon fruit is very nutritious, mainly containing vitamins, cellulose, glucose, carotene, fat, amino acids, and minerals such as phosphorus and iron needed by the human body. It has effects such as detoxification, nourishing the intestines and stomach, purifying the blood, lowering blood pressure, lowering cholesterol, preventing vascular sclerosis, constipation, anemia, angular stomatitis, and colds. It also has beautifying, skin-nourishing, and anti-aging effects. Dragon fruit is not only a treasure among fruits, but because of its large, pure white flowers and bright red fruit, it is also a rare top-grade ornamental flower. Its key greenhouse cultivation technical points are as follows.
(1) Construction of the greenhouse
The greenhouse can use the "Langfang 40-type solar greenhouse", which has the characteristics of high light transmittance, strong heat preservation, and low construction cost.
This greenhouse occupies 80 m east-west and 18 m north-south. The greenhouse faces south, deviating 5-100 degrees to the west, which is favorable for light collection. The back wall of the greenhouse is 2.8 m high, 4.5 m wide at the bottom, 2 m wide at the top, 0.7 m at the lower base, and the highest point of the east and west gable walls is 3.5 m. The wall thickness is 2-3 m, and the inner span of the greenhouse is 7.25 m. The construction of the greenhouse wall can be carried out with mechanical operations. For every 40-50 cm of soil padded, roll 6-8 times, for about 4-5 layers of soil, then carry out manual trimming so that the inner wall is straight and level, the outer wall slope is gentle, and it is solid and firm. Place 1 iron arch beam every 1.5 m. The arch beam is mainly supported by the central column and front and rear fixed stakes. The rear roof projection is 0.8 m, and the inclination angle is 45 degrees. Dig 1.2 m deep anchor trenches on the east and west sides of the greenhouse, with 23 anchors on each side. Use 23 strands of No. 8 galvanized iron wire on the front and rear slopes to form piano-string-style tension lines, of which 16 strands are on the front slope and 7 strands are on the rear slope. Lay 30 cm thick corn stalks on the rear slope, and cover the corn stalks with 30 cm of soil. On the piano-string-style tension lines of the front slope, fix 7 m bamboo poles as arch rods, then cover with polyvinyl chloride non-drip film, then press tightly with film-pressing lines. In early winter, cover with 4 cm thick straw mats, with a coverage rate of 150%. In January-February, add 4 layers of kraft paper, with a coverage rate of 110%. On snowy days, add 1 layer of old film on top of the straw mats to prevent the straw mats from becoming too wet and affecting heat preservation.
(2) Seedling planting
Dragon fruit is a vine-like cactus family plant. During artificial cultivation, trellises must be set up for it to climb and grow. First, in the greenhouse, bury 305 cement posts 1.3 m high at a plant spacing of 1.2 m and a row spacing of 1.5 m. Plant 2 dragon fruit seedlings at each cement post. Before planting, apply 12 cubic meters of coarse manure and 50 kg of diammonium phosphate per greenhouse as base fertilizer, and water thoroughly after planting.
(3) Cultivation management
① Watering. Dragon fruit is a drought-tolerant plant. Generally, when the relative soil moisture content reaches 70%-80%, it can grow normally, but its waterlogging tolerance is poor. If water accumulates at the roots for a long time, it will cause root rot, leading to reduced yield or death. When watering, grasp the principle of not watering if not dry, and watering thoroughly when watering. In addition, during the growth process, do not water before the fruit has set. Wait until the fruit grows to the size of an egg before watering. Under normal circumstances, watering once every 15-20 days is appropriate.
② Fertilization. Because dragon fruit grows vigorously and bears fruit year-round, it requires more fertilizer. To ensure fruit quality and yield, the principle of mainly using organic fertilizer and supplementing with chemical fertilizer must be adhered to when fertilizing.
Under the condition of applying sufficient base fertilizer, after entering the fruiting period, topdress once every 15-20 days. Note that organic fertilizer and chemical fertilizer should be applied alternately. Pay attention to balanced fertilization, ensure complete nutrients, and fully meet the plant's needs for various nutrients. There are many topdressing methods, such as ring-shaped topdressing, radial topdressing, irrigation-type topdressing, and foliar topdressing. The root system of dragon fruit is different from other fruit trees. It does not have a strong taproot, but a fibrous root system, and the root system is very shallow, basically distributed in the surface layer of the soil. Therefore, when topdressing, special attention should be paid not to damage the root system.
③ Pruning. After the dragon fruit seedlings are planted, they can sprout and grow rapidly in about 15-20 days. During the growth process, many buds will multiply, forming disorderly lateral branches. If not pruned in time, they will affect the normal growth of the plant. When pruning dragon fruit, keep only 1 main trunk and cut off all other lateral branches to ensure the normal growth of the main trunk. When the main trunk reaches 1.3-1.5 m high (when cultivated as a potted flower, the main trunk height should be about 1 m), top it to force it to produce lateral branches. These lateral branches are the fruiting branches. According to the plant's growth status and environmental conditions, about 20 fruiting branches can be retained per plant, and it is appropriate to retain 3 fruits per fruiting branch. If the fruit-setting distance is less than 15 cm, one weak fruit can be removed to ensure the normal growth of the other fruits. After entering the full fruiting period, all branches that have borne fruit should be cut off to reduce nutrient consumption.
(4) Pest and disease control
Dragon fruit is in a wild state in its place of origin and has strong resistance to pests and diseases. After being introduced and cultivated in China, no serious pests or diseases have been found, but snails and slugs often gnaw on its tender branches, affecting the growth of dragon fruit. Generally, spreading lime can be used for control. If the pest density is high, poisoned bait can also be used for trapping and killing.
When the fruit matures, fruit flies often lay eggs inside the fruit skin, causing fruit cracking and rotting. The control method is to hang sticky fly paper on the branches and trunks to trap and kill adult flies, or spray with the biological pesticide "Qianchongke" at 800 times dilution, which also has a relatively ideal effect.
(5) Harvesting and storage
Dragon fruit generally takes 30-40 days from flowering to maturity. When the fruit skin turns red and has luster, it can be harvested.
When harvesting, use fruit shears to cut off the fruit stalk close to the branch. It is best to retain a section of the fruit stalk to reduce nutrient consumption of the fruit during storage and transportation. After harvesting, place it gently in a fruit basket to minimize mechanical damage.
Dragon fruit is storage-tolerant. Generally, after harvest, it can be stored at room temperature for more than 15 days. If stored in a fresh-keeping warehouse at 10-15 degrees Celsius, the time can be extended to more than 2 months.