Key Techniques for High-Yield Cultivation of Honeysuckle (Lonicera japonica) in Saline-Alkali Soil

The Yellow River Delta is located in a warm temperate semi-humid region with a continental monsoon climate, and the climatic conditions are suitable for the growth of honeysuckle. In recent years, the honeysuckle planting area has gradually expanded, but due to the high degree of soil salinization and insufficient cultivation experience, honeysuckle production has been characterized by small scale, low yield, delayed returns, and severe pests and diseases. Through research on large-scale high-yield cultivation techniques for honeysuckle in saline-alkali soil, the results show that the goals of raising seedlings in the same year, transplanting in the same year, and harvesting flowers the following year can be fully achieved. After 3 years, the yield of dried flowers per mu (667 sq m, the same below) can reach as high as over 150 kg, with considerable economic benefits. The high-yield cultivation techniques for honeysuckle in saline-alkali soil are described as follows:

1 Saline-Alkali Soil Improvement

The soil parent material in the Yellow River Delta region is Yellow River alluvial deposits. Among the salinizing ions, chloride is absolutely dominant, making it coastal salinized fluvo-aquic soil. The soil texture is sticky and tight with poor aeration. The natural cultivated layer soil salinity is about 2.6%, at which crops cannot grow. The cultivated layer soil salinity of already developed low-yield fields is also 0.4%-0.8%. Therefore, soil improvement must be carried out first before planting honeysuckle.

1.1 Digging Ponds and Building Platforms to Control Alkalinity and Accelerate Soil Desalinization

Digging ponds and building platforms to control alkalinity means using excavation machinery to dig water storage ponds on site and piling the soil into platform fields to control alkalinity, thereby reducing soil salinity and meeting crop growth and development requirements. The specific implementation plan is: ① Platform top width 29 m, bottom width 32 m, height 1.8 m, slope ratio 1:1; ② Water storage pond top width 24 m, bottom width 12 m, depth 3 m; ③ diversion ditch top width 11 m, bottom width 2 m, depth 3 m, slope ratio 1:1.5; ④ Drainage ditch bottom width 2 m, top width 14 m, depth 3 m, slope ratio 1:2; ⑤ Production road top width 6 m, height 0.5 m, slope ratio 1:1. This is the "farming on top, fishing below" 442 planting model (for every 1 mu of farmland, dig 4 fen of water storage pond, 4 fen of platform field, and 2 fen of ditch and road surface).

1.2 Irrigation and Salt Washing

When soil salinity is high, fresh water can be used for washing; excess soluble harmful salts in the soil are leached out and flow away through drainage ditches, thereby desalinizing the soil. Early spring and late autumn are the seasons of salt return, and it is advisable to irrigate 2-3 times. When irrigating, an appropriate irrigation amount must be controlled so that water is distributed evenly within the border. The water flow should not be too slow, otherwise the alkalinity control effect will be poor; but if the water flow is too fast, it is easy to wash away the border ridges and cause water loss. Borders close to the channel and far from the drainage ditch should be irrigated first.

1.3 Deep Plowing and Sun-Drying for Salt, Increasing Application of Organic Fertilizer

Deep plowing and sun-drying for salt is a physical tillage method. Carrying out deep plowing and sun-drying of the field in late autumn of the year before planting can not only accelerate salt differentiation but also kill field pests and diseases. Increasing the application of organic fertilizer is an indispensable measure in improving saline soil. Applying more organic fertilizer can make saline-alkali compacted soil loose, with large porosity and low bulk density, and the soil moisture and physical properties are improved.

2 Seedling Raising

2.1 Sowing Period, Seedbed Preparation Before Sowing, and Sowing Methods

Salt return in spring soil affects the survival rate of seedlings. To improve the survival rate, protected seedling raising methods should be adopted. In early March, select loam or sandy loam with loose texture, fertile soil, and good aeration, deep plow more than 30 cm, apply 6000-7500 kg of base fertilizer and 40-50 kg of ammonium bicarbonate per mu, mix evenly with the soil, and blend into culture soil rich in organic matter, then level and make borders, with border length 10 m and width 12 m, rake the border surface level, and prepare for sowing. To control underground pests, broadcast 1.5-2 kg of Jiadi powder or 0.15-0.25 kg of phoxim emulsion per mu, and appropriately apply some zinc sulfate or ferrous sulfate to prevent seedling-stage diseases. Before sowing, germination must be promoted first. Rinse honeysuckle seeds with clean water first to wash away blighted seeds and insect-damaged seeds, then soak them in 40°C warm water for 24 hours. After removing them, stratify them with 3 times the amount of wet sand to promote germination. When 50% of the seeds have cracked and shown white, the seeds can be screened out for drilling. Water thoroughly, and when the surface soil is slightly dry, level the border surface, open horizontal furrows on the border surface at a row spacing of 20 cm, with furrow depth 3-5 cm and sowing width 10 cm. Evenly scatter the germinated seeds into the furrows, cover with fine soil 1 cm thick and press firmly, then cover with plastic film. The sowing rate per mu is 1-1.5 kg.

2.2 Management After Sowing

Water management after sowing is very important and directly affects the emergence rate. Honeysuckle seeds are small. Before seedlings emerge, strictly prevent soil from crusting and cracking. Check daily, and for plots lacking water, lift the film and spray water. When about 30% of seedlings have emerged, remove the plastic film. After seedlings emerge completely, irrigate frequently to keep the soil moist. During the seedling growth period, frequently weed, loosen the soil, and water. Depending on seedling condition, nitrogen fertilizer can be applied as a top dressing at 7-10 kg per mu.

When seedlings are 15-20 cm tall, pinch off the growing tips to wait for new branches to develop. Carry this out continuously 2-3 times afterward. By July, each plant can have 4-8 branches, and in autumn they can be lifted from the nursery for planting.

3 Transplanting

3.1 Site Selection and Land Preparation For field transplanting, fertile soil close to a water source should be selected. Apply sufficient base fertilizer: 50 kg of diammonium phosphate and 3000-4000 kg of decomposed barnyard manure per mu, and deep plow 30-40 cm. The soil is required to have good bottom moisture, with a water content of about 40%, forming a ball when squeezed by hand. Level the land and harrow it fine, and make high ridges running north-south.

3.2 Transplanting

Transplanting should be carried out in early spring before new buds sprout or during the autumn-winter dormant period. On the prepared planting site, dig holes at a row spacing of 150 cm and plant spacing of 120 cm, with width and depth of 30-40 cm each. Apply 5 kg of farmyard manure into each hole and mix evenly with the subsoil, then plant 1 strong seedling, fill with fine soil, press firmly, tread solid, and water thoroughly to settle the roots. After the water seeps away, seal tightly with soil again.

3.3 Field Management