Eastern Black Walnut is one of the best hardwood species recognized in the world. It is the most economical and fruity tree species. It can withstand a low temperature of -43 °C and can also be used in semi-arid areas with an average annual precipitation of 3 000 mm. Growth, because of its adaptability, rapid growth, easy management, drought tolerance and salt and alkali, it has become a high quality walnut rootstock species. Today, Xiaobian will briefly talk about the technical points of cultivation and grafting of American black walnut rootstocks in Guanzhong area, as follows.
1 real fertility
1.1 Seed harvesting, treatment and sand germination
1.1.1 Seed collection time
In the first ten days of each year, collect a large, full-bodied, pest-free green-skinned walnut, remove it from the green skin and store it in a dry and ventilated place.
1.1.2 Sandland selection and bunker specifications
The collected seeds were layered in the middle of December. The bunker selects a sunny place with a flat terrain and good drainage. The depth of the pit is 60-80 cm and the width is 60-100 cm. The length depends on the number of seeds.
1.1.3 Sand method
Shovel the bottom of the pit, pad a layer of 10cm thick river sand at the bottom of the pit, and then a layer of wet sand (3 ~ 5cm) a layer of seeds (3 ~ 5cm), followed by filling up to 20cm from the ground, every 1.5 m From the bottom of the pit to the top of the pit, a grass is used to ventilate the air, and finally the wet sand is leveled with the pit, covered with a straw curtain, and a drainage ditch is left.
1.2 Selection of nursery land and land preparation
Choose a land with a flat terrain, deep soil, loose soil and good irrigation and drainage as a nursery land. Deeply ploughing more than 40cm in autumn and winter, about 30.0t · hm -2 of fertilized farmyard manure, about 750kg · hm-2 of compound fertilizer, then 耙The bed is flat, the bed is 1.4-1.6m wide, the length depends on the terrain, and the ground irrigation is in the form of sprinkler irrigation.
1.3 Sowing
Wide and narrow row seeding, wide row spacing 60cm, narrow row spacing 40cm, plant spacing 15 ~ 20cm, autumn sowing deep sowing, spring sowing shallow sowing.
1.3.1 Autumn broadcast
The autumn sowing is carried out before the soil is thawed. The method of ditching and sloughing is used to broadcast the fully mature green-skinned walnuts. The seeding amount is 3.0-4.5t · hm -2 , the thickness of the soil after sowing is 7-10cm, and then the film is covered and moisturized. To promote the early germination of seeds, and when the buds are exposed to the ground, the mulch is cut, which is beneficial to the growth of the seedlings.
1.3.2 Spring sowing
From mid-March to early April, the seeds of the winter sand are soaked in water and then planted. The method is the same as that in autumn, and the seeding amount is 1.5-2.3t · hm-2.
1.4 Seedling management
After about 20 days of planting, it began to be unearthed, and it was released around 40 days. It is necessary to do a good job in seedling management.
1.4.1 æ¾è‰é”„è‰
During the growth period of the seedlings, 4 to 6 times of loose soil, the grass is kept loose.
1.4.2 Fertilization and irrigation
After the seedlings are out (from mid-June to the end of June), timely application of quick-acting nitrogen fertilizer, application of urea 150kg · hm -2; second time in the late growth stage of seedlings (late July to mid-August), adding a compound fertilizer The amount of fertilizer applied is 150kg · hm-2, and it should be filled after fertilization. The number of sprinklers depends on the drought.
1.4.3 Pest Control
The main pests and diseases of walnut seedlings are chafers, anthracnose, etc., which can be sprayed with 2.5% cyhalothrin 1,500 to 2,000 times solution, and the disease is controlled by spraying 70% methyl thiophanate 600-8 000 times.
2 grafted seedling cultivation
Excellent walnut varieties with strong affinity to black walnut and high grafting survival rate are: Liao nuclear series, Xiangling, Qingxiang, Shannu 5, etc.
2.1 Black walnut rootstock selection
Seedlings with a thickness of 1 to 2 cm, strong growth, no pests and diseases, and damage are selected as rootstocks.
2.2 Scion
In the late autumn and early winter, the branches and the shoots of the current year are collected more than 50cm long and 1~1.5cm thick. It is required to develop vigorously, with less medulla, no pests and diseases, and from the fine seed collection or fine varieties of mother trees and excellent singles. Collected on the plant. The buds are attached to the ear and the scion is collected to remove the leaves and pay attention to moisturizing.
2.3 Grafting method
2.3.1 Branching
20 to 25 days before the germination of the spring seedlings, the seedlings were used as rootstocks, cut from the roots 4 to 5 cm, cut into 3 to 4 cm slopes, and cut at a distance of 1 / 3 at the slant surface, the depth was 1-2 cm, and then The tongue faces of the rootstock are inserted into each other's slits so that the tails are aligned, the white tails are not exposed, and the gaps are not leaked. The new high-strength plastic strips are about 1.5 to 2 cm wide, and the double-layered layers are mixed from bottom to top. Pressure, tied tightly.
2.3.2 Bud connection
From late May to late June, take a block of buds. The scion collects the healthy and vigorous branches of the year, and cuts the middle and lower leaf buds to the leaves, leaving a 1 cm long petiole. The rootstock is selected from 1 to 2a, and the thickness is 1.2cm. When the bud is connected, the bud is used to cut the knife to the xylem at the upper and lower sides of the bud, then cut a knife on both sides of the bud, and then remove the bud in the same way on the grafted part of the rootstock. The rootstock bark, which is about the size of the root, is quickly attached to the bud, and the upper and lower layers are aligned to reveal the buds and petioles. When the buds grow to 10 cm, the ligature is released. After grafting, remove the sprout, bud, fertilize, water, and prevent pests and diseases in time to ensure the normal growth of seedlings.
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