Seedling emergence, grading and Storage of Walnut seedlings

In the cold areas of    in winter, the seedlings are put out of the nursery before freezing after falling leaves. The emergence of seedlings from the nursery is an important part of raising seedlings. The drawing plan should be worked out according to the needs, and the nursery should be sent out in batches according to the variety and planting needs and the situation of sale, so as to avoid the mixing of varieties in the process of coming out, storage, transportation and so on. In the areas where there is no striping phenomenon in winter, they can come out of the nursery after thawing in the following spring and before bud germination, and plant along with digging, which has the advantages of high survival rate, fast slow seedling and convenient operation.

   seedling standard

   standard for walnut grafted seedlings is currently implemented according to the national standard GB7907-87. Generally, seedlings sold should reach grade 2 or above, and the interface of grafted seedlings should be well healed, fully lignified, free of diseases and insect pests and mechanical damage. It should be noted that the seedling height generally refers to the height above the grafting interface in production. This standard was established in 1987, when walnut grafting propagation technology did not pass, and the quality of seedlings was generally not high. Now higher quality seedlings can be bred by grafting from the end of May to the beginning of June, and the height of the seedlings can reach more than 1 meter or even higher. Combined with the production practice, it is suggested that the standard of first-grade walnut seedlings can be raised to 1. 5%. 2 meters, easy to dry after planting.

Seedling initiation, grading and storage of   

   1. Seedlings should be raised, planted, transported or centrally stored after defoliation in early winter and before soil freezing. Walnut is a deep-rooted tree species, and the healing ability of the root system is poor after damage, so the root system should be protected as far as possible. Water should be irrigated once a week before leaving the nursery to increase soil moisture and prevent root damage during seedling emergence due to soil dryness. Less or no watering can be done in case of rain. Generally dig out the seedlings with a shovel, pay attention to less damage to the root system. There are also mechanical seedlings, the speed is fast, the efficiency is high, but we should pay attention to the seedling depth of more than 25cm to 30cm to prevent excessive cutting off the root system. After the seedling comes out, the seedlings should be pruned properly, mainly to cut off the split and broken roots and retain the small roots as much as possible. It is necessary to prepare mud when raising seedlings, and dip them in mud while raising seedlings to reduce the time when the roots are exposed in the air, so as to protect the roots. Mud to be sticky, dipped in the root system should be stained with a thicker layer of mud, too thin mud effect is not good.

   2. The seedlings sold by grades should be graded, and at the same time, the seedlings should be divided into first-class seedlings, second-class seedlings and equal seedlings according to the national standard GB7907-87, and the seedlings without grafting should be excluded at the same time. Qualified seedlings are bundled into a bundle of 20 or 30 trees, hung with labels, and pseudo-planted, transported or planted as soon as possible. The seedlings can be returned to the nursery for another year, and then out of the nursery the next year. Seedlings can also be replanted together to be regrafted the following year.

   3. The seedlings that can not be planted immediately after storage should be pseudo-planted. Short-term fake planting is a temporary fake planting that cannot be transported in time after the seedlings are raised, or when the purchased seedlings are about to be planted, generally no more than 10 days, open a ditch about 3cm deep in a cool place, bury the roots of the seedlings with wet soil, sprinkle and moisturize at the same time, and cover the sunshade net to reduce the transpiration loss of seedlings. Long-term false planting refers to the false planting of seedlings overwintering for a long time, the seedlings lose much water, and the requirements of false planting are higher.

When    pseudo-planting, choose the place with high terrain, shady back, little wind and convenient transportation to dig false planting ditch. First dig a ditch with a width of about 50 cm, a depth of 50 cm and a length of 3 cm. The soil dug out is piled on the south side of the false planting ditch to form a soil ridge. The bundled seedlings are opened and tilted into an angle of 30 °~ 45 °, and then discharged into the ditch in turn. The soil of the second row of trenches is used to fill the first row of seedlings, and no gaps are left. When the soil is sticky and heavy, it can be mixed with sand, preferably with pure sand, which is easy to adjust humidity and operation, and can better fill the gap of the root system. After the second row of trenches are dug, the seedlings are placed, and the soil from the third row of trenches is used to fill the seedlings of the second row, and so on, until all the seedlings are pseudo-planted. At the same time, dig drainage ditches around the fake planting site to prevent stagnant water. After the fake planting of the whole seedling, it is necessary to spray water once to increase the soil moisture and prevent the seedling from draining, similar to pouring frozen water. It can be covered with waste grass curtains when it is cold in winter. Check in time after the temperature rises in spring to prevent the seedlings from mildew and rot and plant as soon as possible. Pseudo-planting soil should be kept soft, try not to trample on, in order to facilitate ventilation. In the cold climate area, the shoots of the seedlings are all buried in the soil and are easy to dry when exposed.

In order to store seedlings better,    can use fruit cellar or air-conditioned storage to store seedlings where possible. The temperature in the cellar is low, which can delay germination and prolong the planting time of seedlings in spring. A small amount of seedlings can also be placed in the vegetables, and the roots can be covered with wet sand.