Seed collection and seed storage of nursery land

   1. The selection of nursery land generally needs to consider the land with deep soil layer, high soil organic matter content, low groundwater level, low saline-alkali content, leeward and sunny land, which is suitable for sandy loam or light clay. Nursery land should be irrigated so that it can be irrigated early and waterlogged. At the same time, pay attention to the previous crop can not be walnut trees or walnut nursery, need to plant other crops for 5 to 8 years before they can be used to raise walnut seedlings.

The    nursery land is ploughed 20 ~ 25 cm in autumn, and before deep ploughing, the base fertilizer is mainly organic fertilizer, 4000kg farm manure is applied in the south, and 50kg of mixed superphosphate is applied. After deep ploughing, there is no need to rake flat, in order to make use of the winter sun, rain and snow for "frozen construction" to promote soil ripening. Shallow ploughing again before sowing in spring, rake flat, make beds, and prepare for sowing.

   2. The mother tree is first selected for seed collection, which requires a mature tree with strong growth, no diseases and insect pests, full kernels, uniform fruit and stable yield in successive years. The seeds of senescent trees should not be used as rootstock seeds.

Walnuts with    as seeds should be harvested properly to enrich the kernels. Generally speaking, after White Dew, it is better to exceed the mature period for 5-7 days. At this time, the walnut kernel harvested is full, fully developed, and the green skin is easy to take off. The embryo development of walnut harvested early is not complete, the seed kernel is not full, the germination rate is low, and the seedling growth is weak. There are two methods of seed collection: picking method and falling method. The former is that the fruit falls naturally during the fruit ripening period and is picked up once every 3-5 days. The fruit quality obtained by this method is the best. The latter is artificially knocked down and harvested at one time when there is a green degree of walnut fruit with 1 stroke and 3 on the tree. Remove the green skin in time after the fruit is harvested. For the fruit that is not easy to remove, you can use the method of stacking and retting. Pile the green skin in a cool place for 3 days and then remove the green skin. Pay attention to prevent the heat in the process of stacking and burning the seeds. Avoid using plastic sheeting to cover or pile the thickness is too large, generally the heap height is about 50 cm.

Walnuts for    sowing should not be exposed on cement, stone or iron slabs, so as not to reduce the seed vitality due to high temperature. the best way is to dry in the shade and air-dry on the ventilated and shaded soil. Special attention should be paid to the fact that walnuts used as seeds can not be bleached, and the germination rate of walnuts after bleaching is greatly reduced.

In order to save the cost of raising seedlings,    often advocated the selection of smaller walnuts as seeds. The production practice has proved that the effect of sowing and raising seedlings with large seeds is better. Although the amount of seed used per unit area increased, the emergence rate was high, the seedling growth was exuberant, and the proportion of grafting coarseness in the second year was greatly increased, thus reducing the production cost. The seedling growth potential of small walnut is weak in the future, so it is necessary to increase fertilizer and water management.

   in most cases, walnuts for seeds are purchased in the market. When choosing and buying walnuts, you should knock some more to observe whether the kernels are full or not. The cross-sectional color of the seeds is required to be milky white. Be careful not to use the old walnut of the next year to sow. The old walnut in summer is prone to oil deterioration and the germination rate is greatly reduced. Generally speaking, walnuts with exposed kernels are not used as seeds. Walnut kernels with exposed kernels are easy to suffer during storage. The insect is resident or moldy, which reduces the germination rate. The fresh walnut kernels are milky white and colorful, while the old walnut kernels are yellow and oil-soaked.

   3. If the walnut seeds are directly sown after harvest in autumn, the seeds may not be treated. Seeds sown in spring need to be stored and treated before sowing. Seed storage methods are generally divided into sand storage and dry storage.

   (1) there is no post-ripening stage of dried walnut, and the seeds can germinate normally without post-ripening. Generally, dried walnuts are packed in gunny bags and placed in a ventilated, overcast, dry room or basement. Regular inspection should be conducted to prevent rodent damage during storage. Where possible, it can be stored in an air-conditioned storage or cold storage of 0 ℃, and a small amount of seeds can also be stored in the freezer.

   (2) sand reservoir is also called wet reservoir and stratification treatment. Choose high terrain, no stagnant water, back shade shelter, dig a ditch 1 meter deep and 1 meter wide before freezing, and the length depends on the total amount of walnuts to be stored. Choose clean river sand with 0. 5%. After the treatment of 1% potassium permanganate or 50% carbendazim wettable powder 600 to 800 times, the water content is about 60%. The experience is that if the soil in the ditch is dry, the water content of the sand can also be appropriately higher or sprinkled in the ditch. When storing walnuts, spread 5 cm of wet sand at the bottom of the ditch, then spread a layer of walnut, sprinkle a layer of wet sand until 10 cm above the ground, and then spread about 10 cm of wet sand on top. Then use the soil on the top to form a ridge shape for drainage, the thickness of the soil should be greater than the thickness of the local permafrost, generally at least 20 cm. When the ditch is longer, it is necessary to erect a corn stalk bundle with a diameter of 20 cm at an interval of 1 to 2 meters in the ditch as a vent, and then build a drainage ditch around to prevent stagnant water. For a small amount of walnut seeds hidden in sand, you can also put them in a suitable flowerpot. The sand is 5 to 7 times the size of the walnut and can be buried in the shade. After warming up in early spring, you should pay attention to check the seeds in the pit to prevent mildew and rot. If you find signs of mildew, you should dig up, clean and wash the seeds as soon as possible, and then save the seeds in a cool home and sow them as soon as possible.