Acute dead seedlings and key points of seedling raising in greenhouse of cucumber

Cucumber, cucumber genus of Cucurbitaceae. Also known as cucumber and cucumber. The color of the fruit is oil green or emerald green, with soft spines on the surface. It is widely cultivated in all parts of China and is now widely cultivated in temperate and tropical regions. Cucumber likes warmth and is not resistant to cold, so it is one of the main greenhouse products.

Morphological characteristics of Cucumber

1. Root: the root system is underdeveloped, and the main root groups are distributed in the root layer of 25cm. Good gas, weak absorptive capacity, requires loose and fertile soil, sufficient water. The ability of regeneration is poor, so root protection measures should be taken and seedling age should be strictly controlled.

2. Stem: trailing, quadrangular or pentagonal, hollow, with bristles on top, infinite growth type, easy to break, short internodes at seedling stage, erect, 5 Mel 6 true leaves begin to elongate, showing trailing nature. Leaf axils bear tendrils, lateral branches and male and female flowers. The stem length and branching ability depend on the variety and cultivation conditions. The early-maturing varieties had shorter stems and fewer lateral branches, while the middle and late-maturing varieties had longer stems and more lateral branches.

3. Leaves: cotyledons long-oval, opposite. True leaves palmately lobed, simple leaves alternate, both sides have spiny hairs, leaves are large and thin, transpiration is large, and water is needed.

4. Flowers: mostly unisexual flowers, monoecious, axillary. Male flowers appear earlier than female flowers, often in clusters, female flowers are more solitary, ovary inferior, with unisexual fruiting characteristics. Insect-pollinated flowers, cross-pollination. Artificial pollination can increase yield in overcast and rainy season or protected cultivation.

5. Fruit: bottle gourd, tube-shaped to long stick-shaped, usually reaching commercial maturity 18 days after flowering. The tender fruit is green or dark green, a few are yellowish or white, and the fruit surface is smooth or angled, verrucous or prickly. It takes 35 mi 45 days from flowering to physiological maturity, the fruit is yellowish white or brown, and some fruit faces appear cracks.

6. Seeds: flat, long oval, yellow and white. There are 300 seeds per melon, and the weight of 1000 seeds is 20-40g. The life span of seeds is 4-5 years, and the seeds of 1-2 years should be used in production.

Key points of Acute Seedling death and Seedling raising in Cucumber greenhouse

In the process of out-of-season cucumber cultivation covered with plastic film, when the cucumber enters the flowering and fruiting stage, there are often cucumbers which are growing well in the previous period, and the acute death of seedlings suddenly occurs within a few days. This acute atrophy of cucumber occurs rapidly and is difficult to prevent and cure.

The reasons for its formation: weather problems, continuous rain or steep sunshine after snow, temperature inversion leading to rapid death of seedlings; wind problems, cucumbers enter the flowering and melon period, sunny days with high temperature, large air volume, rapid leaf transpiration, some plants with poor roots begin to atrophy, and those with severe water loss wither; the film surface of the greenhouse is partially damaged by cold injury or freezing injury, and the wilting seedlings are caused by cold wind. The problem of excessive concentration of fertilizer, especially the application of chemical fertilizer near the base of cucumber stem, is very easy to burn dead seedlings.

Using greenhouse heat preservation cultivation places, cucumber acute atrophy occurs to varying degrees every year, in order to prevent it as soon as possible, the following measures should be taken.

1. The seedlings should be properly watered at the right time.

The root system of cucumber is relatively developed, but it is mostly concentrated on the surface of the soil to produce new roots. It is necessary to avoid watering mistakes and restrain the growth of root populations, and pay attention to watering seedlings in time.

Irrigate less fixed planting water, drink back to the seedling water. The temperature is low, the soil moisture is high, or encounter continuous rainy weather, less or no return seedling water. Enter the peak period of melon, combined with topdressing, water with fertilizer, irrigated every 10 days or so, strictly prevent excessive fertilization to burn melon seedlings. It is appropriate to water in the morning on a sunny day, and avoid watering in the afternoon and evening. It is not suitable to water the whole shed on cloudy and rainy days. Small water should be watered frequently, not flooding.

2. Control the temperature in the shed reasonably.

At the initial stage of planting, it was generally not ventilated, keeping 25 ℃-30 ℃ in the greenhouse during the day and 12 ℃-15 ℃ at night, no less than 10 ℃. With the growth of melon seedlings, it is necessary to regulate gas and control temperature in time, and its functions are: preventing diseases, avoiding plant aging, and replenishing carbon dioxide. However, the regulation of temperature must be beneficial to the growth of cucumber. It is generally ventilated when the temperature rises to 30 ℃ in the daytime and closes the greenhouse film when it drops to 28 ℃ in the afternoon. The temperature during the melon setting period should not be lower than 12 ℃.

Often dredge the ditches around the cucumbers planted in the shed to ensure smooth flow, so as to drain and irrigate in time and filter water quickly. Every day to check whether the greenhouse film is damaged or leaking cover, we should pay attention to repair, so as to keep warm and warm. Cover the grass and lock the rope before the strong wind cools down to prevent the cold wind from invading and injuring the melon seedlings.

Five key points of raising cucumber seedlings in greenhouse

First, strengthen seedling management and cultivate strong seedlings to prevent and control diseases and insect pests in a timely manner.

The second is to strengthen greenhouse warmth and warming work, pay attention to heat preservation when the cold current comes, and pay attention to not watering, so as not to reduce the soil temperature.

The third is to apply less quick-acting chemical fertilizer, more rotten organic fertilizer and extra-root topdressing, which can be sprayed with foliar fertilizer such as high-efficiency phytin and compound potassium dihydrogen phosphate.

Fourth, when the weather is fine after snow, the shed should uncover the grass, uncover the cover, and spray about 20 ℃ of warm water on the leaf surface to remove the old leaves in time and reduce transpiration. After the seedlings return to normal growth, they can all be pulled up during the day, even on cloudy days, so that the seedlings can see more scattered light, but they should still be covered with two layers of protective film at night to do a good job of heat preservation and strictly prevent the seedlings from being frozen the second time.

Fifth, watering in time after the weather clears up. The soil moisture of cucumber was fully watered 15-20 days before planting. If the living soil layer is too deep, the border should be leveled again after watering, so that the soil can reach the standard of deep, transparent, fine, flat and solid. Note: drip irrigation is suitable for watering to avoid flooding and maintain good soil permeability.