What are the techniques for establishing a high-density, high-yield honeysuckle plantation?

Honeysuckle (Lonicera japonica) is a perennial semi-evergreen woody vine, also known as Erhua or Shuanghua, and is a traditional precious Chinese medicinal herb. The roots, stems, leaves and flowers of honeysuckle can all be used medicinally, but the main medicinal part is the dried flower buds, which have the effects of clearing heat and detoxifying, eliminating chronic inflammation and boosting human immunity.

In recent years, with the intensification of honeysuckle development and the broadening of its application fields, market demand has grown ever larger. Improving cultivation techniques to raise the early-stage yield of honeysuckle and maintain the duration of its full-production period has become a major problem urgently needing solution in production.

In recent years, based on the characteristics of honeysuckle cuttings - a short purely vegetative growth period and the simultaneous progression of vegetative and reproductive growth - we have adopted measures such as increasing the initial planting density and gradually thinning by roguing out alternate rows or plants after one year depending on growth conditions and available space. This has not only greatly increased the early-stage yield of honeysuckle, bringing it into full production 2 to 3 years earlier, but also left plant growth basically unaffected after entering the full-production period. Space utilization remains reasonably rational, making full use of land, space and climate resources and greatly improving overall benefits, while overcoming the shortcomings of pure high-density plantations (high early yield but declining later yield) and low-density plantations (late entry into full production and low early yield). The key technical points are introduced below.

I. Planting time

Honeysuckle can be planted in all four seasons. Planting from mid-September to mid-March of the following year gives a relatively high survival rate, and for areas south of North China autumn planting is preferable. Although air temperature drops noticeably during this period, soil temperature remains within the range suitable for root growth. Newly planted honeysuckle can heal wounded roots before the soil freezes and can produce large numbers of new roots, resulting in a high survival rate, vigorous growth the following spring, a short transplant-recovery period and high flower yield. Although honeysuckle planted after the New Year can survive, sprouting and root healing growth proceed simultaneously, creating a sharp conflict between the above-ground and below-ground parts for nutrients and water, with a long transplant-recovery period, poor early growth and low flower yield in the same year. In areas with severe winter cold, drought and water shortage, spring planting can be used to prevent desiccation injury.

II. Planting patterns

(1) Uniform row and plant spacing pattern

In this pattern, after entering the full-production period both row spacing and plant spacing are 1.5 to 2 m, with 167 to 296 plants per 667 sq m. The initial planting density (667 to 1,184 plants per 667 sq m) is 4 times the full-bloom density. After one year, thin by roguing out alternate rows, retaining 333 to 592 plants; after 2 to 3 years, thin by roguing out alternate plants, retaining 167 to 296 permanent plants. With this pattern, vegetables such as garlic, onion and spinach can be intercropped in the first year. The advantage of this pattern is that it ensures honeysuckle growth is unaffected by the intercrop, with high early yield: in the first year the yield per 667 sq m can reach 10 to 20 kg, in the second year 30 to 40 kg, and full production is reached in 3 to 4 years.

(2) Wide-row, dense-plant pattern

In this pattern, after entering the full-production period the row spacing is 1.8 to 2 m and the plant spacing is 1.6 to 2 m, with a density of 185 to 231 plants per 667 sq m. The initial planting density (740 to 924 plants per 667 sq m) is 4 times the full-bloom density. After one year, thin by roguing out alternate plants, retaining 370 to 462 plants per 667 sq m; after 2 to 3 years, carry out a second thinning by roguing out alternate plants, retaining the permanent plants. With this pattern, in the first year, besides intercropping vegetables between the rows, low-stalk crops such as @#@245@#@ and barley can also be intercropped, but the sowing width should not exceed 1 m so as not to affect honeysuckle growth. The advantage of this pattern is convenient field management, but honeysuckle growth is slightly affected by the intercrop.

(3) Direct-cutting plantation establishment pattern

Use vigorous branches with a diameter of more than 0.8 cm and a length of 35 to 40 cm as cuttings to establish the plantation in place of nursery stock. The planting density and thinning steps are the same as patterns 1 and 2. The burial depth of the branch is 1/2 to 2/3 of its length. After burying, firm the soil and water thoroughly. Water 2 to 3 times in total before overwintering, and before overwintering cover with soil to protect against freezing and conserve moisture. When establishing a plantation by this method, the issue of replanting gaps must be considered, so plants can be partially thickened within the row or two plants can be placed per hole. The advantage of this pattern is that it can solve the problem of insufficient nursery stock; the disadvantages are that it requires frequent watering, is poorly coordinated with intercrop management, and has a slightly lower survival rate than using nursery stock.

III. Main technical measures

(1) Variety selection

There are many honeysuckle varieties. The main superior varieties cultivated in production are Fengqiu Damaohua and Shandong Jizhuahua. Fengqiu Damaohua is a variety under national protection of origin. It has an upright tree habit and thick, sturdy branches, making shaping and pruning easy. The flower buds are 4 to 6 cm long, with a chlorogenic acid content of 5.6% to 6.7%, well-balanced medicinal components, resistance to pests and diseases, and strong adaptability. It can bear flowers in the same year after planting, and after entering the full-production period it can yield 100 to 150 kg per 667 sq m, making it the preferred variety in production.

(2) Plantation site selection

Honeysuckle is drought-tolerant, cold-tolerant, waterlogging-tolerant and barren-tolerant, and has no strict requirements for soil; it can grow and flower normally in both slightly acidic and slightly alkaline soils. However, to meet the requirements of high yield, high quality and pollution-free cultivation, the plantation site should be chosen as a plot with loose, fertile soil and convenient drainage and irrigation. It must also be far from cities, industrial and mining enterprises and major traffic routes, and the air, soil and irrigation water must be tested and meet national standards.

(3) Careful land preparation

Before planting a high-density honeysuckle plantation, the land must be levelled and sufficient base fertilizer applied. Apply per 667 sq m: 4 to 5 cubic meters of high-quality decomposed organic fertilizer, 50 kg of superphosphate, 50 kg of ammonium bicarbonate, 10 kg of potassium sulfate and 1 kg of zinc sulfate. To eliminate underground pests, 1 kg of phoxim per 667 sq m can be mixed with 20 kg of fine sandy soil and broadcast before ploughing for soil treatment. The ploughing depth is 25 cm. Harrow as you plough, then form beds with ridges 2 to 4 m wide.

(4) Use of strong seedlings

Strong seedlings are the foundation for raising the survival rate, advancing flower-bud formation and achieving early high yield. At present, the standard for strong seedlings used in Fengqiu honeysuckle production is: thick, sturdy stems, short internodes, small hollow core, seedling height above 50 cm, old stump diameter above 0.8 cm, old stump length above 15 cm, new shoot base diameter above 0.5 cm, new shoot length above 30 cm, and more than 3 lateral roots above 15 cm. Using strong seedlings allows abundant flower-bud formation in the same year and advances entry into the full-production period by 2 to 3 years.

(5) Scientific planting

First lay out the planting points according to the determined row and plant spacing, then dig planting holes 50 cm square at each planting point, placing raw soil and topsoil separately. Apply 5 to 10 kg of decomposed organic fertilizer and 0.3 to 0.5 kg of superphosphate per hole, mix the fertilizer evenly with the topsoil and fill it back into the hole. Plant 1 plant per hole, at a depth slightly deeper than the seedling was in the nursery. After planting, firm the soil and water thoroughly with the planting water. Once the water has dried, cover with soil slightly higher than ground level. To improve the survival rate and speed up recovery, generally water once more 2 to 3 weeks after planting, and thereafter water as conditions require.