The fruit of the climbing or creeping herbaceous plant, Luffa acutangula, of the Cucurbitaceae family, is called Yuegua in Chinese. It has the effects of promoting digestion, relieving thirst, diuretic, relieving heat and toxicity, and expelling hot air. It can be eaten raw, pickled, or stir-fried. It is cultivated in various regions of China. The fruit is harvested when it is immature in summer and autumn.
【Sowing and Seedling Raising】
1. Direct sowing:
In northern regions, hole sowing is commonly used. Direct sowing requires less labor. When hole sowing, dig small holes about 3-4 cm deep, put in 4-5 dried or moist seeds, and cover with 1-2 cm of soil. If sowing seedlings, water should be poured into the hole, and seeds should be sown after the water seeps down. 2-3 seeds should be sown in each hole. The seed quantity per hectare is about 1.5 kg, and the seedling quantity per hectare is 30,000-37,500 plants (row spacing 1.0 m, plant spacing 0.3 m). Mulching with plastic film should be done if conditions permit.
After emergence, weeding should be strengthened to promote deep rooting. Generally, loosen the soil 3-4 times. When using plastic mulching cultivation, intertillage is not necessary. Thinning and final selection of seedlings should be done in a timely manner during the seedling stage. Thinning should be conducted in three stages: the first thinning is done when the cotyledons are spread out and the true leaves are exposed, leaving 3 seedlings; the second thinning is done when there are two true leaves, leaving 2 seedlings; the third thinning is done at the stage of cluster planting, leaving the best 1 seedling.
2. Seedling raising:
In recent years, seedling raising and transplanting have been widely used in Luffa acutangula production areas. This method can avoid frost damage, prolong the growth period, and ensure that the fruit development period is in the high temperature period. It also allows the flowering and pollination period to avoid the rainy season, ensuring safe production, early market entry, and higher yield and quality. The seedbed should be located in a place with good wind direction, high and dry terrain, flat ground, and convenient watering and management. The seedling bed is generally a plastic film small arch shed or a windbreak and sunny slope.
Luffa acutangula has weak root regeneration ability. Therefore, when raising seedlings, nutrient soil in nutrient bowls should be used to reduce root damage and improve the survival rate after transplanting. Commonly used containers include plastic bowls, paper cups, small pots, and grass bowls.
For seedling raising in northern China, a seedling age of 30 days is required, and sowing should be done 30 days before the last frost. Generally, it is sown in mid-to-late March in a plastic small arch shed.
Soak the seeds in warm water before germination. The water temperature should be 50℃, and stir for 3 minutes. Then, soak the seeds in 30℃ warm water for 4-6 hours. After soaking, rinse and remove the floating seeds. Alternatively, the seeds can be soaked in a 100-fold formalin solution for 30-60 minutes for disinfection, then rinsed and soaked for germination. After soaking, take out the seeds and drain them, wrap them in gauze, and germinate them at a temperature of 30℃. Generally, they will germinate in about 30 hours.
Before sowing, water should be thoroughly poured into the nutrient bowl, and a small hole about 2 cm deep should be made in the middle of the bowl. The germinated seeds should be sown into the hole with the sprout facing down, and then covered with 1 cm of soil.
After sowing, the plastic film on the seedbed should be tightly covered to maintain the temperature and humidity in the bed. Before emergence, the temperature should be kept at 25-35℃. After emergence, the temperature should be kept at 25-28℃ during the day and 20-22℃ at night, with a minimum temperature not lower than 15℃. After all the seedlings have emerged, ventilation should be gradually increased during the day to prevent excessive temperature and humidity causing elongation of the seedlings.
During the seedling stage, the covering material for insulation should be uncovered and extended light exposure time. If it is dry, a small amount of water can be sprinkled. As long as the base fertilizer on the bed is sufficient, additional fertilization is not necessary.
7-10 days before transplanting, ventilation should be opened at night or the cover should be removed. During the day, the ventilation should be gradually increased until the plastic film is completely removed to expose the seedlings to low temperatures and improve their adaptability.
Transplanting: The transplanting period is determined by the stability of the soil temperature above 15℃ and the end of the local last frost. In northern China, it is generally in mid-to-late April. Care should be taken to minimize root damage when transplanting seedlings. The plant spacing is (60-70) cm x (30-50) cm, and the seedling quantity per hectare is 27,000-39,000 plants. Mulching with plastic film should be done if conditions permit. After transplanting, water should be immediately applied.
【Field Management】
1. Seedling filling:
1 day after transplanting, check the field and fill in any missing seedlings.
2. Pruning and topping:
Pruning and topping are key management techniques. In northern regions, common methods include three-vine or four-vine pruning.
Three-vine pruning: Top the plant when it has 4-5 leaves to promote the growth of secondary vines. Leave 3 effective secondary vines on each plant to achieve the goal of 3 fruits per plant.
Four-vine pruning: When the seedling has 6 true leaves, top it at 4 leaves to promote the growth of 4 secondary vines. Let the secondary vines grow naturally without topping. Alternatively, after fruit set, remove 3-4 leaves from the upper part of the vine and remove other useless branches.
3. Water and fertilizer management:
From transplanting to the first female flower blooming, the soil should be kept moist but not waterlogged. Generally, water should be applied every 7-10 days. Excessive watering can cause excessive elongation of the plants and delay fruiting. After each watering, the soil should be immediately loosened to retain moisture and increase soil temperature. During the flowering period, no watering should be done to prevent excessive water causing flower and fruit drop. After fruit set, watering should be increased appropriately. During this period, the weather is hot and the soil evaporation is high, so water should be applied every 5-7 days to keep the soil moist but not waterlogged.
The first additional fertilizer application should be done during the seedling stage, with 150 kg of urea and 225 kg of calcium superphosphate per hectare. The second additional fertilizer application should be done at fruit set, with 750-1500 kg of cake fertilizer and about 150 kg of potassium sulfate per hectare. Each additional fertilizer application should be placed in pits between plants, with a depth of 10 cm, and then covered with soil.
4. Early spring cultivation techniques
Early spring cultivation is a cultivation method in which seedlings are raised in winter or early spring and transplanted in protective facilities, and harvesting and market entry begin in late spring or early summer. This method has high yield, good quality, early market entry, and high economic benefits, and it has a certain production area in northern China.
Cultivation time: The cultivation time varies depending on the region and the facilities used. In the northern region, when using sun-heated greenhouses with good thermal insulation, sowing is done in mid-January, and transplanting is done in mid-to-late February. The products can be on the market in mid-April. When using plastic medium and small greenhouses with a grass cover on top as thermal insulation, sowing is done in early February, and transplanting is done in early to mid-March. The products can be on the market in early May. When using plastic greenhouses, sowing is done in mid-to-late February, and transplanting is done in late March. The products can be harvested in mid-to-late May. The general requirement is that after transplanting, the soil temperature in the protective facility should be stable above 12℃, and the minimum temperature should be above 10℃. There should be no frost. Seedling raising facilities are generally located in sunny plots or sun-heated greenhouses.
Seedling raising: In early spring cultivation, the earlier the sowing, the earlier the products can be on the market, and the higher the economic benefits. Therefore, as long as the temperature conditions permit, sowing should be done as early as possible in the selected protective facility. The sowing method is the same as in open field seedling raising. After sowing, the seedbed should be kept at 30℃ to promote emergence. After emergence, remove the plastic film immediately, ventilate and cool appropriately to prevent excessive elongation of the seedlings. The temperature should be kept at 25-28℃ during the day and 15-18℃ at night. The soil moisture should be controlled appropriately during the seedling stage, and watering should be minimized to prevent excessive water from reducing the soil temperature and causing seedling stiffness or slow growth. If the soil is dry, a small amount of water can be sprinkled once. 7-10 days before transplanting, the temperature of the seedbed should be reduced, with 20-25℃ during the day and 12-15℃ at night, to conduct low-temperature hardening of the seedlings and improve their adaptability to ensure the survival rate after transplanting. The seedlings can be transplanted when they have 3 leaves and 1 heart and are 30-35 days old. Other matters can refer to the open field cultivation section.
Transplanting: Before transplanting, apply 45,000-50,000 kg of high-quality manure, 750 kg of calcium superphosphate, and 450 kg of potassium sulfate per hectare. After fertilization, deep plowing and harrowing should be done, and small ridges should be built with a row spacing of 70-100 cm and a height of 15 cm. 15-20 days before transplanting, the plastic film of the protective facility should be tightly covered, and a grass cover should be added at night to increase the ground temperature as much as possible. Transplanting should be done on sunny mornings, and healthy seedlings with 3 leaves and 1 heart should be lifted with soil clumps and planted with a spacing of 30-50 cm. Water the holes thoroughly after planting. Immediately cover the plastic film of the protective facility, and add a grass cover at night to increase the temperature inside the facility and promote the seedling's recovery and growth.
【Cultivation Management】
1. Temperature management:
Within 7 days after transplanting, the temperature in the greenhouse should be maintained at 28-30℃ during the day and 18-20℃ at night, with a soil temperature of 27℃, to promote seedling recovery. After the seedlings have recovered, gradually increase ventilation and lower the temperature. During the vegetative growth period, the temperature should be kept at 25-30℃ during the day, not lower than 15℃ at night, and the soil temperature should be 23-25℃. During the flowering period, the temperature should be 27-30℃ during the day, 15-18℃ at night, and the soil temperature should be 23-25℃. After fruit set, the temperature should be moderately increased, with 28-32℃ during the day and 15℃ at night.
In early spring cultivation, the external temperature is relatively low during the early growth stage, so ventilation should be reduced to ensure thermal insulation. In the later growth stage, the external temperature gradually increases, so attention should be paid to increasing ventilation and reducing temperature to prevent sunburn caused by high temperatures. When the nighttime temperature outside stabilizes above 15℃, the grass cover can be gradually removed, and the plastic film can be removed to switch to open field cultivation.
2. Water and fertilizer management:
After transplanting, water the seedlings once to promote seedling recovery. From transplanting to fruit set, water should be minimized to avoid reducing the soil temperature and affecting plant growth and development. If the soil is dry, a small amount of water can be applied once or twice to promote root and vine growth. During the flowering period, watering should be avoided to prevent flower drop. After the fruit is set, watering should be increased appropriately. Each time, 150 kg of compound fertilizer containing nitrogen, phosphorus, and potassium should be applied per hectare to promote fruit enlargement. Watering should be increased appropriately to keep the soil moist but not waterlogged, generally watering once every 7-10 days.
3. Light management:
Luffa acutangula requires strong light during the growth period. Therefore, under the condition of guaranteed temperature, the grass cover should be removed early and covered late to extend the exposure time to light. The plastic film should be cleaned frequently to increase light transmission.
4. Pruning and vine suspension:
Pruning methods can refer to open field cultivation. Each plant should bear 4-6 fruits. To increase the utilization rate of protective facilities, vine suspension is generally used. Plastic strips are installed in the facility, with 1-4 strips per plant and 1 strip per vine. During the growth period, when the vine grows by 30 cm, it should be manually tied. This can improve the light conditions and increase the number of plants.
5. Artificial pollination and 2,4-D dipping:
In early spring cultivation, there are no insect pollinators in the facility, and the fruit is not easy to set. Therefore, artificial pollination is necessary. During the flowering period, take the male flowers that opened on the day, remove the corolla to expose the anthers, and gently rub them on the stigma of the female flowers a few times. Alternatively, dip the flowers in a 20 x 106 concentration of 2,4-D to prevent flower and fruit drop.
Harvesting:
Luffa acutangula is a fresh fruit that is consumed by people. It requires sufficient maturity, and maturity is closely related to the quality of the fruit. If harvested too early, the fruit will have low sugar content, insufficient aroma, and a bitter taste. If harvested too late, the fruit flesh will become gelatinous, and the cell tissue will become soft, resulting in poor taste and reduced edible value. Therefore, harvesting should be done at the right time. Under certain temperature conditions, the number of days from flowering to fruit maturity is fixed for each variety. For example, early-maturing small fruit varieties take about 24 days, mid-maturing varieties take 25-27 days, and late-maturing varieties take about 30 days. Luffa acutangula has a colorful skin, and the color of the fruit skin changes significantly when it is ripe. The young fruit is green, and when ripe, it changes to milky white or light green (at the stem end). The skin of Luffa acutangula is thin and easily damaged. The fruit contains a lot of water and is large, so it is prone to hollowing. It is not suitable for storage and transportation. Attention should be paid to handle it gently during harvesting and sales. Use scissors for harvesting, preferably in the field after the morning dew has dried to avoid direct exposure to intense sunlight. The products should be sold within 1-2 days to maintain freshness and quality.
