Fennel bulb is a variety of fennel in the Apiaceae family. It is native to southern Italy, mainly distributed along the Mediterranean coast and West Asia, and was introduced and cultivated in my country. Fennel is a crisp and tender "bulb" formed from the layers at the base of the leaf sheath, which can be used for stir-frying and cold mixing. The young leaves can be used as fillings, sauces and plate decorations. Fennel stems and leaves contain a special spicy flavor that can increase appetite. It has the health-care effects of warming the liver and stomach, warming stomach qi and dispersing cold. It is also rich in amino acids, vitamins and minerals.

Characteristics of bulb fennel

Bull fennel is a shallow-rooted vegetable with more fibrous roots and is darker than leaf fennel. The root system is distributed in the soil 7 to 10 cm from the surface, with a lateral distribution range of only about 20 cm and a small absorption area; the stem is shortened into a "bulb", about 10 cm high and wide, and about 6 cm thick; the leaves are 2-4 pinnate, with filamentous lobes. Smooth; compound umbels of golden yellow flowers. The fruit is double-petaled, oblong, off-white, and weighs about 3 grams per thousand grains. Bulb fennel has strong adaptability, resistance to cold and heat, fast growth, late bolting and high yield. The yield per mu is 8,000 kilograms, and the growth period is about 50 days. Solar greenhouse cultivation in autumn and winter does not have strict requirements on temperature and light. It is the first choice for rural greenhouse cultivation of cash crops and has the characteristics of low risk and high profit.

Types and variety selection of bulb fennel

1. Oblate type: the leaves are green, the plant grows vigorously, the base of the leaf sheath is enlarged and oblate, light green, the outer leaf sheath is upright and shortened left and right. , the stem is obvious, the outer leaf sheath is not close to the ground, the bulb is small, and the single bulb weighs 300-500g. Two varieties introduced from the Netherlands and Italy belong to this type, with strong disease resistance, early maturity, and suitable for dense planting. Can be grown in a greenhouse or in the open field.

2. Spherical shape: There is little difference in plant height, leaf color, and oblate spherical shape. The bulb is compact, white, fist-shaped, the leaf sheath is short, and the stem is tightly held. It extends not only to the left and right sides, but also forward and backward. The outer leaf sheath is closer to the ground and sclerotinia is prone to occur at low temperatures. The weight of a single ball is 500-1000g, which is suitable for greenhouse cultivation, and the density should not be too high. The F1 type imported from France belongs to this type.

Variety selection: For planting fennel bulbs in solar greenhouses, varieties with beautiful appearance, low temperature resistance, and low light tolerance should be selected, such as some early-maturing varieties in the Netherlands.

Sowing and planting

1. Preparation before sowing: A place with flat ground, higher terrain, and good drainage and irrigation should be selected as the border. Apply 3,000 kilograms of decomposed and screened organic fertilizer and 30 kilograms of ternary compound fertilizer per acre, and mix well with the subsoil. After the edge surface is flat, it should be stepped on once, then the bottom water should be poured in, and after the water has seeped out, a layer of sieved fine soil should be sprinkled. Generally, the nursery area per mu is 25-30 square meters, and the seeds are about 100 grams.

2. Sowing: Autumn and winter stubble cultivation in solar greenhouses should be carried out in mid-July. Seeds should be soaked in cold water one day before sowing and then placed in a relatively cool place to promote germination. After 5-6 days, spread the sprouts evenly on the seedbed, cover them with 1 cm thick sieved soil, and cover them with a sunshade net.

3. Seedling management: The seedlings will fully grow one week after sowing. After emergence, pour a small amount of water at a time to delay the growth of the seedlings. The shade net will be removed and covered with a thin layer of soil approximately 0.5 cm thick. When 1-2 true leaves appear, the seedlings should be thinned and covered with a shading net to prevent high temperatures. At the same time, pay attention to prevent rain erosion. When 3-4 true leaves appear, the second thinning should be carried out according to 6cm square, and attention should be paid to cooling and ventilation. Using plug trays to raise seedlings can avoid thinning out seedlings, save seeds, cultivate healthy and strong seedlings at one time, and grow quickly after sowing.

4. Planting: The seedbed should be watered once a day before planting so that seedlings can be dug the next day. When digging seedlings, take soil blocks that will cause less damage to the root system. In mid-August, combined with land reclamation before planting, apply 1,000 kilograms of compost per acre, and plant in the afternoon on a sunny day or on a cloudy day. Since the root system of fennel is not developed, it is advisable to plow the dry land flat, plow it 15 to 20cm shallowly, and rake it flat; when sowing, first take out two centimeters of topsoil from the furrow surface and pile it on both ends of the furrow. After leveling, spread evenly and cover with topsoil. If the soil is dry, water before sowing and sow after water has soaked. After sowing, we must suppress and maintain soil moisture.

Generally, the planting density per acre is 5000-6000 plants, and the spacing between plants is 25×50 cm. Water the seedlings promptly after planting. Greenhouse planting should not be too dense, otherwise the bulbs will easily rot.

On-site management

1. Fennel seedlings can emerge 7-10 days after sowing. Fennel seedlings grow slowly and should be weeded in time to prevent grass shortages.

2. The optimal fermentation temperature of fennel is 20℃-28℃ before and after emergence, and at least 10℃-15℃. If the temperature is lower than this temperature, it will be easily frozen. If the temperature is higher than 25°C, it will not grow well. When the temperature is lower than 15℃, ventilation should be strengthened and ventilation should be stopped.

3. After watering the planting water, watering needs to be done 1-2 times depending on the growth conditions. In order to promote the growth and expansion of the bulbs, the water should be properly controlled before the bulbs expand, and the water should be replenished after the bulbs expand.

4. 7-10 days after planting, when the seedling height is about 30 cm (7-8 leaves), the first top dressing should be carried out, and 10 kg of biological compound fertilizer should be applied per acre. When the bulbs begin to swell, the second topdressing is increased by 30% compared to the first. The third top dressing is carried out during the rapid expansion period of the bulbs, and the amount of top dressing is the same as the first time.

Harvest

When the fennel bulbs grow to more than 250 grams, they can be harvested. The availability of bulb fennel can be adjusted according to market demand. Properly lowering the temperature of the solar greenhouse can delay the market launch of bulb fennel by 15-30 days. After harvesting fennel bulbs, cut off the root disk, remove the yellow leaves, leave the petiole about 5 cm long at the top of the bulb, and cut off the rest.