Detailed Explanation of Key Points for Early-Maturing Cultivation Techniques of Edamame in Greenhouses

Edamame is also known as soybean. Soybean was called "shu" in ancient times. Soybean is the general term for soybeans of various colors including yellow, green, black, brown and bicolor. It has a cultivation history of about 5,000 years and originated in China. About ninety percent of the soybeans grown in China are yellow soybeans. Edamame is simply fresh soybeans in their pods; after being sun-dried, they are also called soybeans. Seeds are classified into six sizes by size: extra-large: 100-seed weight above 30 grams; super-large: 100-seed weight 24.1-30 grams; large: 100-seed weight 18.1-24 grams; medium: 100-seed weight 12.1-18 grams; small: 100-seed weight 6.1-12 grams; extra-small: 100-seed weight below 6 grams.

Using greenhouses to cultivate edamame can advance the edamame's entry into the maturity stage. So how should greenhouses be used for cultivation to achieve early maturity of edamame? Below we introduce the early-maturing greenhouse cultivation techniques for edamame.

1. Land preparation and fertilization. Edamame prefers warmth and is a short-day plant. It is best suited to neutral, well-drained soil that is deep, rich in calcium and organic matter. When sowing early in greenhouses, soil moisture should not be too high; otherwise, seeds are prone to rotting under low temperatures. Generally, apply about 1,000 kg of decomposed chicken manure and 15 kg of imported ternary compound fertilizer per mu as base fertilizer, applied 1 month before sowing. Practice has shown that heavy application of base fertilizer can improve the cold resistance and yield of edamame. After fertilizing, make flat beds, with a bed width of 2.1 m, a bed ditch width of 0.3 m, and a ditch depth of 0.2 m.

2. Timely sowing

1. Variety selection. Local edamame varieties used for early-maturing cultivation include Tezao No. 4, Tezaoshu Edamame, and Hefeng 35, but Tezao No. 4 is the most ideal.

2. Sowing. It is best to sow from the end of January to the beginning of February, choosing weather without the influence of strong cold air. Use 5-6 kg of seed per mu. Sow by the dibbling method, with a plant spacing and row spacing of 25 cm × 25 cm, and a sowing depth of 3-5 cm. The depth should be consistent to facilitate uniform emergence. Generally, when the temperature inside the greenhouse is 10-25°C (outside temperature 8-15°C), full emergence occurs in about 10 days.

3. Chemical weeding. After sowing and covering with soil, use 80-100 ml of 5% acetochlor emulsifiable concentrate per mu, diluted with 30-40 kg of water, and spray evenly on the bed surface for weed control.

3. Greenhouse management

1. Temperature management. In the early stage, the main focus is freeze protection and warmth retention; in the later stage, strengthen ventilation and air exchange. It is required to cover the greenhouse 1 week before direct sowing, and immediately cover with plastic film or add arched greenhouse film after sowing. After emergence, pay attention to choosing sunny days to promptly break the film and release seedlings. Before emergence, the suitable temperature inside the greenhouse is 15-25°C; during the growth period, the suitable temperature is 20-25°C; during the flowering period, the suitable temperature is 20-28°C. Therefore, according to the growth characteristics of each period, close the greenhouse in time for warmth or ventilate for air exchange.

2. Fertilizer and water management. Generally, fertilization is not suitable at the seedling stage. If leaves wrinkle due to low temperature, use 50 g of Huangyedi micro-fertilizer per mu diluted with 30-45 kg of water and spray once at noon on a sunny day. During the flowering period, use a 0.5% potassium dihydrogen phosphate aqueous solution for foliar topdressing. Spray before 10 a.m. or after 4 p.m., preferably on cloudy days. Spray again after 7-10 days; if rain occurs after spraying, spray once more. In addition, during the pod-setting stage after flowering, apply 10 kg of urea per mu diluted with water.

In terms of water management, do not water after sowing before seedlings emerge; if the seedling stage is excessively dry, water moderately to promote root development. For water management during the dry-flower and pod-setting stage, adopt the principle of "dry flowers, wet pods."

3. Pest and disease control. Because greenhouse edamame experiences low temperature and high humidity at the seedling stage, combined with the application of undecomposed farmyard manure, it is very prone to damping-off and seedling death. Therefore, at the seedling stage in the greenhouse, 200 g of chlorothalonil smoke agent per mu can be selected for chemical control, and water-based agents should be used as little as possible. When edamame has 4 leaves, it can be sprayed with agents such as chlorothalonil and carbendazim for control. Spray once every week for a total of 2 sprays.

4. Timely harvest. Generally, greenhouse edamame enters the harvest period in late April to early May. Early-maturing edamame values the word "early," so pods should be picked in batches at the right time and brought to market early to obtain better returns.

Two methods for increasing edamame yield

Artificial topping or spraying foliar fertilizer can increase edamame yield by about 10%. Interested friends may want to give it a try.

For artificial topping, remove the terminal bud by 2-3 cm at the full flowering stage, which can prevent the bean plants from excessive vegetative growth and lodging, and can also concentrate the nutrients produced by photosynthesis for transport to the pods and seeds, increasing pod weight and seed weight and raising yield. For spraying foliar fertilizer, in the middle and late growth stages of edamame, use 150-200 g of potassium dihydrogen phosphate and 25 g of ammonium molybdate per mu, diluted with 75 kg of water, and spray on the foliage, which can increase the pod-setting rate and seed weight. In the late flowering stage, use 75-100 kg per mu of 60-100 ppm ammonium bisulfite solution and spray 2-3 times, which can inhibit photorespiration, reduce non-productive nutrient consumption of edamame, and increase edamame yield.