What are the key points of high-yield cultivation techniques for fennel?

Fennel greens, also originally named small huixiang, also known as xiangsi vegetable, fennel, fennel seed, guxiang (Sichuan, Guizhou), hunxiang, the tender leaves are used as a vegetable, are the stem part of fennel, and are the dried mature fruit of the Umbelliferae plant fennel. It was first recorded in the Tang Materia Medica. Su Song said that northerners call it fennel, and the sound is close to huixiang. Tao Hongjing said: when boiling smelly meat, add a little, and there is no bad odor; smelly sauce also becomes fragrant when the powder is added, hence it is called fennel. Li Shizhen said that common people often hold it in their bosoms and chew it, so the name huixiang may perhaps come from this. The fruit (fennel) is used as a spice and also for medicinal purposes, and the roots, leaves, and whole plant can all be used as medicine.

Morphological characteristics of fennel

Perennial herb, 40-200 cm tall, the whole plant surface has a powdery bloom, hairless, with a strong aroma. Stem erect, smooth, grayish green or pale white[1], branched. Leaves are tripinnate to quadripinnate compound, the final leaflets linear, 4-40 mm long, about 0.5 mm wide; petiole about 14 cm long, base forming a sheath that clasps the stem. Compound umbel terminal; peduncle 4-25 cm long, involucre and involucel both absent; rays 8-20, unequal in length; flowers small, yellow; calyx teeth absent; petals 45, broadly ovate, upper part curled inward, slightly concave; stamens 5, longer than the petals; ovary inferior, 2-loculed, styles 2. Also, the schizocarp is oblong, with 5 raised ridges, flowering in June-July, fruiting in September-October.

Fennel is a long-day, semi-cold-resistant, drought-tolerant, cool-loving dicotyledonous spring crop, relatively drought-tolerant but not waterlogging-tolerant. After emergence, the growth period is 65-85 days. The growth process is fast; 35-45 days after emergence it enters the initial flowering stage, flowering in early to mid-May, fruiting from late May to early to mid-June, and the harvest period is mid-June. The conventional plant height is 30-55 cm, and the stem shows false dichotomous branching. Leaves alternate, the leaf blade is a ternately parted leaf, with a narrow lanceolate sheath. The umbel diameter is 1-2 cm, white or bluish white, with 5-7 single flowers, and the schizocarp is oblong-ovate, 5-8 mm long, 2-3 mm wide, containing two slightly yellow seeds.

How to cultivate fennel for high yield?

Fennel is a long-day, semi-cold-resistant, drought-tolerant, cool-loving dicotyledonous spring crop, relatively drought-tolerant but not waterlogging-tolerant. After emergence, the growth period is 65-85 days. The growth process is fast; 35-45 days after emergence it enters the initial flowering stage, flowering in early to mid-May, fruiting from late May to early to mid-June, and the harvest period is mid-June. The conventional plant height is 30-55 cm, and the stem shows false dichotomous branching. Leaves alternate, the leaf blade is a ternately parted leaf, with a narrow lanceolate sheath. The umbel diameter is 1-2 cm, white or bluish white, with 5-7 single flowers, and the schizocarp is oblong-ovate, 5-8 mm long, 2-3 mm wide, containing two slightly yellow seeds.

II. Cultivation techniques

1. Sowing methods

① Main sowing includes two methods: winter sowing (baodan) and spring sowing. For winter sowing, before winter of the previous year, sow the seeds into frozen farmland with suitable moisture after salt suppression (Kashgar reclamation area, November 25 to December 5, or using a 3 cm soil temperature below 5°C as the indicator), and harvest in the second year. Spring sowing is sowing, management, and harvesting in that spring (the degree of early spring sowing and the harvested fennel yield show a non-linear positive correlation).

② Intercropping takes advantage of fennel's short growth period and sows fennel in the wide rows after the spring sowing of wide-narrow row plastic film crops is completed. Intercropping is suitable before April 12 or when the 5 cm soil temperature is not higher than 15°C.

2. Pre-sowing land preparation

Choose sandy loam or loam with medium to high soil fertility and good water retention for planting. Apply sufficient base fertilizer, plow and level, irrigate enough pre-sowing water, and prepare the land finely. Apply about 30 tons of organic fertilizer, 150-225 kg of urea, 100-150 kg of diammonium phosphate, and 75-120 kg of potassium sulfate or compound fertilizer per hectare as base fertilizer. The plowing depth is 22-25 cm. Irrigate enough pre-sowing bottom moisture and suppress salt and wash away salt. Prepare the land at suitable moisture to reach the standards of moisture, levelness, looseness, fineness, and cleanliness. Before sowing, apply 2.25-2.7 kg of Shitianbu per hectare, mixed with 450 kg of water, for closed soil chemical weed control.

3. Variety selection

It is advisable to choose Shache fennel with strong branching ability, high yield, lodging resistance, and plump seeds that have been purified, rejuvenated, and screened.

4. Sowing requirements

Main sowing of fennel includes hole sowing and drill sowing. Winter sowing is mainly hole sowing (row spacing 20-30 cm, hole spacing 9-12 cm), and spring sowing is mainly drill sowing (30 cm equal row spacing, plant spacing 5-8 cm). Intercropping uses hole sowing. Sowing depth is 1.5-2.5 cm, and press the soil after sowing. The seeding rate is 22.5-30 kg per hectare (1,000-grain weight 1.3-1.8 g). Hole sowing has 300,000-500,000 holes per hectare, keeping 1.4-2 million seedlings, and drill sowing keeps 1.5-1.8 million seedlings.

5. Field management

① Early spring field management centers on increasing temperature and preserving moisture. For main-sown fennel, shallow harrowing and pressing should be carried out before emergence; if it rains before emergence, harrow the field in time to break the crust, so as to preserve moisture and promote early emergence and early growth. The shallow harrowing direction should be perpendicular to the sowing direction, the harrowing depth should not exceed 2 cm, and a soil-crushing press roller should be attached.

② Seedling-stage field management focuses on chemical regulation, supplemented by manual weeding and thinning and final singling. At the 2-4 leaf stage of fennel seedlings, spray foliar fertilizer once (1%-2% potassium dihydrogen phosphate + 0.5%-1% urea). At the 5-8 leaf stage of seedlings, spray 0.15%-0.3% mepiquat chloride locally on overly vigorous fields to increase the thickness of the basal internodes of vigorous seedlings, reduce plant height, and prevent later lodging.

③ Flowering and fruiting stage field management focuses on preventing waterlogging damage from accumulated rain, nourishing roots and preserving leaves, promoting grain filling, and increasing grain weight. Fennel is relatively drought-tolerant but not waterlogging-tolerant. If rainfall occurs in May-June and field water accumulation exceeds 8 hours, waterlogging damage will occur, causing plant death and even total crop failure. Therefore, in case of moderate to heavy rain, drain water in time. Although fennel has low water and fertilizer requirements during the flowering and fruiting stage, the overlapping period is relatively long. Abnormal climate and soil drought can adversely affect flowering, fertilization, and yield, so foliar spray 0.2%-0.4% boron and zinc micronutrient fertilizers to increase the seed-setting rate. In the middle and late growth stages of fennel, for patchy areas with fertilizer deficiency and premature aging (yellowing leaves), spray 1.5%-3% urea foliar fertilizer to improve the ability of roots and leaves to absorb nutrients and promote normal fruit ripening. For patchy areas with dark green leaves and a tendency to stay green and late ripening, spray 0.2%-0.4% potassium dihydrogen phosphate to increase 1,000-grain weight and achieve a consistent overall harvest period.

III. Timely harvest

Under the same production conditions, winter-sown fennel matures 7-12 days earlier than spring-sown fennel, and main sowing matures 3-7 days earlier than intercropping. The morphological standard for timely harvest: 70%-80% of fennel plants in the field have overall leaves turning orange-yellow and fruit skins slightly yellow. Harvesting too early results in insufficient maturity, while too late makes the fruit seeds easy to shatter and causes losses. Harvesting usually uses manual pulling, then centralized drying, mechanical impurity removal and cleaning after rolling, bagging, and storage, preventing moisture.