What are the key points of high-yield management techniques for loofah in greenhouses?
Loofah (scientific name: Luffa cylindrica); in the Pearl River Delta, loofah specifically refers to the eight-angled gourd. It is a cucurbitaceous plant native to India, also known as vegetable gourd, and is widely cultivated in East Asia. It is a climbing herbaceous plant of the Cucurbitaceae family, and loofah has a strong root system. The stem is vine-like, five-angled and green; both the main vine and side vines grow vigorously, and the stem nodes bear branching tendrils and readily produce adventitious roots. It is distributed and cultivated both in China and abroad.
Growing environment of loofah
Light: Loofah is a short-day crop, prefers relatively strong sunlight, and is also fairly tolerant of weak light. During the seedling stage, treatment with short days and a large temperature difference favors female flower bud differentiation and can lead to earlier fruiting and high yield. During the whole growth period, relatively short sunshine and higher temperatures are favorable for stem and leaf growth and development, can maintain robust vegetative growth, and are conducive to flowering, fruit setting, young gourd development and increased yield.
Temperature: Loofah is a temperature-loving, heat-tolerant crop. The suitable temperature for loofah growth and development is 20-30°C, the suitable temperature for loofah seed germination is 28-30°C, and germination is rapid at 30-35°C.
Water: Loofah likes moisture and is afraid of drought. It grows well when soil moisture is relatively high and the water content is above 70%, and grows slowly when it is below 50%. Air humidity should not be less than 60%. At 75%-85%, growth is fast and many gourds are set; when air humidity reaches saturation for a short time, it can still grow and develop normally.
Soil: Loofah is a vegetable crop with strong adaptability and is not strict about soil requirements; it can be cultivated in all types of soil. However, in order to obtain high yields, it is best to choose loam or sandy loam with a thick soil layer, high organic matter content, good air permeability, and strong water and fertilizer retention capacity.
How to manage loofah in greenhouses for high yield?
Variety selection
For greenhouse loofah, it is advisable to choose varieties with vigorous plant growth, cold tolerance and strong adaptability, such as cylindrical loofah.
Land preparation and fertilization
Before sowing, in conjunction with plowing, apply more than 5000 kg of high-quality barnyard manure per mu. After leveling and harrowing evenly, open furrows along the planting rows, and apply another 50 kg of superphosphate and 25 kg of potassium sulfate per mu, or 100 kg of decomposed cake fertilizer; then close the furrows and raise ridges, ready for planting.
Sowing time and cultivation method
Greenhouse loofah can be directly sown in mid-October, or raised as seedlings and transplanted. The cultivation method generally adopts ridge planting with large and small spacings: large row spacing 70 cm, small row spacing 60 cm, plant spacing 30 cm, 3400 plants per mu.
Sowing and seedling raising
Before sowing, soak the seeds in warm water at 50-60°C for 10 minutes, then soak for 24 hours after cooling. Take them out, wrap them well in mixed cloth and place them at 28-32°C for germination, rinsing once a day with clean water. When most seeds have sprouted, they can be sown. Before sowing, first water thoroughly; after sowing, cover with 1.5 cm of soil. In direct-sown fields, furrows can be opened and seeds sown on both sides of the ridge back; seedlings emerge in 3-4 days. When the seedlings grow to 1-2 true leaves, thinning can be carried out in direct-sown fields, and transplanting can be carried out in fields to be planted, leaving only one strong seedling per hole.
Management in the greenhouse
1. Adjust temperature and light well. Loofah requires relatively high temperatures throughout the growth period. The optimum temperature for growth is 20-24°C, and the optimum temperature for fruit development is 24-28°C; growth is slow at around 15°C, and growth is inhibited below 10°C. During management, keep the temperature inside the greenhouse at 25-30°C during the day and around 18°C at night. Before loofah begins to vine, straw mats can be used to properly control the sunshine duration to promote stem and leaf growth and female flower differentiation. During the flowering and fruiting period, the straw mats should be opened in good time to make full use of sunlight to raise the temperature.
2. Water and topdress in good time. Loofah has little water demand at the seedling stage, so small amounts of water can be applied 1-2 times according to soil moisture. When the vine grows to about 5 cm, in conjunction with hilling again, apply 30 kg of potassium dihydrogen phosphate per mu and water heavily once. After flowering and fruiting, generally water once every 7-8 days, and at the same time topdress 5 kg of urea per mu.
3. Build trellises, tie vines, and adjust the plants. Loofah vines can reach up to 7-8 m long. When the vine grows to about 25 cm, trellises need to be built. To reduce the space occupied by trellis poles and shading, generally wire or nylon rope is tied directly to the greenhouse frame to form a single-row vertical trellis, with no crossing at the top, and vines are guided vertically upward according to the original planting row spacing and density. After the vines are on the trellis, tie them once every 4-5 leaves, and an “S”-shaped tying method can be used.
4. Preserve flowers and fruits. Applying 2.4-D to flowers can reduce flower drop and significantly increase the fruit-setting rate. When the temperature is high, the concentration is 20×10-6; when low, use 30×10-6. Either use a brush dipped in the solution to apply it to the stigma of female flowers and the base of the corolla, or directly dip the flowers in the solution. The application time should be around 8 a.m.
5. Pest and disease control. The main diseases of loofah include anthracnose, phytophthora blight and gray mold, which can be controlled with pesticides such as carbendazim, chlorothalonil and dimethomorph. The main insect pests include melon aphids and whiteflies, which can be controlled with derris extract, saoshiling, and the like.