When walnut seedlings are grown, they should be selected for growing walnuts. The walnut seed is selected for soaking treatment 7 to 10 days before sowing. When processing, the selected walnut seeds are soaked in cold water, changed water every day, soaked for 2 to 3 days, then removed, exposed to sunlight for 1 to 2 hours, and then soaked. After 7 to 10 days, the seeds can all be split and can be sowed at this time.
2. Soil treatment
Walnut is a deep-rooted tree species and should be ploughed deep into the soil before sowing to create loose soil conditions and lay a good foundation for the healthy growth of seedlings. Generally, the depth should be between 30 and 40 cm. In combination with deep plowing, the Mushi soil mixed fertilizer 4000 ~ 5000 kg, urea 15 kg, at the same time exhausted stones, grass roots and other debris that affects the growth of walnuts, and finally leveling into a seedbed, generally for the convenience of operation, the seedbed should be made into concrete, wide 1 to 1.5 meters long and 10 to 12 meters long.
3. Suitable for sowing
Walnut seeds can be sowed in autumn, but they can also be planted in spring. Autumn sowing seeds do not need to be treated. Generally, sowing is appropriate from late October to early November. Before soil freezing, sowing is better as soon as possible; spring sowing should be delayed after soil thawing. Sowing, late sowing temperature, rapid germination, generally planted in early April in eastern Yunnan is appropriate.
4. Seeding method
Walnut seeds are larger, usually by the open-deep seeding method, generally the groove distance is kept at 30-50 cm, the depth of the ditch is 5-8 cm, and 1 seed is sowed every 12-15 cm. It is better to use sutures and the ground perpendicularly when sowing, which is beneficial to emergence.
5. Cover soil
After sowing, 5 ~ 7 cm soil is appropriate, too thin soil easy to dry, affect the emergence, too thick walnut perishable, unfavorable emergence.
6. Management of seedlings
After the walnut seedlings are unearthed, measures should be taken to promote the post-control and strengthen the field management so as to cultivate strong seedlings and facilitate grafting. Specific should grasp the following management:
(1) Timely weeding: The growth of weeds in the field is easy to compete with the walnut seedlings to compete for water to compete for space conflicts. In the production, we should promptly carry out cultivating and weed control to reduce the consumption of soil moisture and nutrients by weeds and ensure the robust growth of walnut seedlings.
(2) Top-dressing watering: After the emergence of walnuts to August, the management should be promoted mainly, multiple top-dressing watering, to ensure the growth of walnut seedlings, pay attention to the principle of a small number of times in the top dressing watering . Due to the weak absorption capacity of walnut seedlings, the amount of fertilizer should not be too large, and the amount of fertilizer should be gradually increased with the growth of seedlings. It is advisable to apply 5 kg of urea per acre for the first time dressing, and the maximum amount of fertilizer should be controlled within 10 kg per mu. It is best to apply water or water after application.
Walnut is a wet tree species, and the field should be kept moist during the seedling period. The soil moisture content should be between 60% and 70% of the maximum water holding capacity in the field. Watering should be done in time when drought occurs.
(3) Topping: When the seedling height is about 30 centimeters, it is necessary to pick up the heart in time to limit the lengthened growth, promote the long thick, and create conditions for grafting.
(4) Water control and nitrogen control in the late growth stage: After August, it is necessary to pay attention to controlling the supply of nitrogenous fertilizer and water to increase tree material accumulation and improve tree resistance so as to facilitate safe wintering.
7. Grafting
When the walnut seedlings are propagated, they are mainly “branches and budsâ€. Because the walnut tree contains tannins, the tannins are easily oxidized and black, which affects the survival of grafting. When the walnuts show wounds, there will be a large amount of sap flowing from the wounds, which will affect the callus. Produce, so walnut grafting technology requirements are more stringent, more difficult, production should pay attention to the following points to improve the survival rate.
(1) Strictly grasp the grafting time: When buds are planted in the north of the country, it is advisable to use it in the middle or late June in northern China. At this time, the rootstock sticks have been lignified, and the budding is close to maturity. The rainy season has not yet arrived, the grafting and bleeding are small, and then survive. The rate is high.
(2) scion fresh: Scion grafting, preferably with picking, external transfer scion, transfer faster, in the transfer process to do a good job of moisturizing, prevent scion dehydration, affect survival.
(3) Take buds to be all: The growing point of walnut buds grows more firmly, it is not easy to take down when taking buds, which affects survival. Therefore, it is necessary to take buds carefully, and it is necessary to ensure that the bud buds have growth points.
(4) Grafting speed is faster: grafting speed can effectively prevent tannins from being oxidized, which can improve the survival rate, and thus the speed of operation is faster.
(5) Pay attention to the release of water: After grafting, pull a knife under the interface to discharge water, strictly control the moisture content of the joint of the scion and root, and promote survival.
(6) The ligatures should be kept in prison: After grafting, the grafted parts should be tightly packed with plastic, and only the petiole should be exposed to prevent air leakage from the interface and oxidize to black, affecting the survival rate.
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