Methods and Technical Key Points for Raising Black Locust Seedlings from Seed
Black locust is a pioneer tree species for afforestation on barren hills, with characteristics such as tolerance to poor soil, tolerance to drought, fast growth, and wide uses.
1. Nursery site selection and land preparation The seedling-raising site should be selected as level ground with good drainage, deep and fertile neutral sandy loam soil, and irrigation conditions. Vegetable plots must absolutely not be chosen, and continuous cropping is even less suitable. After the seedling-raising site is selected, plow it in autumn to a depth of about 30 cm. In early spring, harrow it fine and level, and apply 5000 kg of decomposed barnyard manure per mu. During land preparation, poisonous soil made from phoxim emulsifiable concentrate should be applied to control underground pests.
2. Seed treatment The seed coat of black locust is thick and hard, and the outer coat contains pectin, making it difficult for water to be absorbed. 10 days before sowing, put the seeds into a vat, pour in 90°C hot water, stirring while pouring, until it is no longer too hot to touch. After soaking for 24 hours, remove the floating material and bad seeds, then use a fine-mesh sieve to separate the swollen seeds from the unswollen seeds. The unswollen seeds can be treated again with 90°C hot water 1 to 2 more times. Pour the water-absorbed and swollen seeds into a basket, cover with a wet gunny sack, and place in a warm place to promote germination. To prevent the seeds from becoming sticky and spoiling, rinse them with clean water 1 to 2 times a day. After about 1 week, when 1/3 of the seeds have split open and exposed the root tip, sowing can begin.
3. Sowing Sowing is carried out around mid-April, when the temperature reaches 16°C. The target seedling output per mu is about 10,000 plants, with a seed rate of 5 kg. Ridge sowing is generally used, with a ridge spacing of 70 cm and double-row drilling. If the soil is relatively dry, the water-seated sowing method should be used. When sowing, the seeds should be evenly scattered into the furrow, covered with soil to a thickness of 1 to 1.5 cm, and then lightly pressed once with a roller so that the seeds make close contact with the soil.
4. Seedling-stage tending and management When the seedlings grow to 3 to 4 cm, thin out the diseased and weak seedlings and separate the overly dense seedlings. When the seedlings grow to 10 to 15 cm, carry out final thinning. Leave about 10 seedlings per linear meter, and when thinning in double rows, they must be staggered. Leave about 12,000 seedlings per mu.
After the seedlings emerge completely, irrigate timely and appropriately according to soil moisture, with 2 to 3 irrigations throughout the year. If the seedlings are not lifted in autumn, irrigate once with antifreeze water before overwintering. In early June, apply urea once as a top dressing, 10 kg per mu. After fertilizing, irrigate once.
For control of damping-off at the seedling stage, spray 0.5% to 1% equal-amount Bordeaux mixture or 1% to 2% ferrous sulfate, once every 10 days. For aphid control, use 40% dimethoate 800-fold solution. To make the seedlings grow evenly, cut the tops of the saplings once at the end of July. Cut more from large seedlings and less from small seedlings, and after cutting, the height should not be lower than 80 cm.
5. Lifting seedlings from the nursery Before lifting seedlings, cut the stem at 15 to 20 cm above the ground surface, then use a "U"-shaped seedling-lifting plow to lift the seedlings. The lifting depth should be such that the main root of the seedling is not less than 18 to 20 cm. Seedlings should be lifted, picked up, and selected as they go, and seedlings that cannot be planted the same day should be heeled in promptly.