Grafting technique of Pinus koraiensis by terminal bud split grafting

Pinus koraiensis (PinuskoraiensisSieb.etZucc.) is a tall tree of Pinus family with a straight trunk. The average height of the natural forest of Pinus koraiensis can reach 250m, the DBH can reach 40~80cm, and its life span can reach 30000years. In the place where the growth conditions are suitable, the height of the tree can reach 40m, the DBH can reach 200cm, and its life is about 500years; it has excellent material, straight texture, strong pressure resistance, rich resin, strong decay resistance, high technological value, good paint performance, easy to dry, and can be used as building, aviation, bridge, car and ship materials. Its wood planing, turning performance is good, easy to process, suitable for making all kinds of models, can also be used as plywood, musical instruments and sports equipment, etc., is an important precious timber tree species in our country.

Adult Korean pine is a kind of woody oil plant with high nutritional value because of its large seed setting, large seed and high oil content. Pine kernel is rich in vitamins An and E, as well as essential fatty acids, oleic acid, linoleic acid and linolenic acid, which are not found in other plants. It is a widely used natural green food. Also has a certain medicinal value, long-term food to strengthen the body and mind, moisturize the skin, prolong life, dispel disease and strengthen the body, but also has the role of cancer prevention, anti-cancer; it is also an excellent tree species for urban and rural landscaping, deeply loved by the masses.

Pinus koraiensis is not only the main component of natural forest in Northeast China, but also the main afforestation tree species. The climatic conditions in Northeast China are very suitable for the growth and development of Pinus koraiensis, which lays a good foundation for the development of Pinus koraiensis resources in Northeast China. Many areas in Northeast China regard the development of dual-purpose Korean pine forest as a very important forest model for economic development in forest areas. However, the growth of young Korean pine is slow, the fruiting is late and the growth cycle is long, so it is difficult to see economic benefits in the short term for the development of mixed-use Korean pine forest. However, the traditional grafting method has some disadvantages such as low survival rate, which greatly affects the enthusiasm of forest farmers to develop Korean pine fruit and wood forest.

After years of grafting experiments on Pinus koraiensis, some forest farmers with a certain knowledge base in the forest area have accumulated a great deal of experience in the grafting of Pinus koraiensis. After comparing and summarizing these methods, the author consults a large amount of data and makes a personal experiment. It is considered that split grafting of Korean pine is a good way to solve the above problems of Korean pine, which not only promotes the development of rural economy, but also provides a way for forest farmers to get rich. The split grafting techniques of Pinus koraiensis are summarized as follows:

1 rootstock cultivation

There are two kinds of rootstock cultivation methods, one is to cultivate rootstocks directly in the afforestation site, that is, rootstocks are planted according to the designed row spacing in the afforestation site, usually 3 rootstocks are planted in each hole, and the rootstocks to be planted are grafted when they can be grafted (about 5 years old). The other is to cultivate rootstocks in the nursery. The 2-year-old Korean pine seedlings were selected and put into a larger plastic container bag. The nutritious soil in the bag should have 1/3 organic fertilizer to meet the needs of seedling growth. Grafting was carried out when the container seedlings grew to about 5 years old. In forest areas, Korean pine seedlings planted under the forest sometimes need to be grafted, but it should be noted that before grafting, it must be "uncovered", and then cultivated for 1-2 years to restore the robust growth of Korean pine seedlings, and then grafted.

2 scion collection

2.1 selection of scion mother tree

20 fruiting trees were investigated in each of the 30-year-old plantations. The number of fruits and continuous fruiting (see fruit marks) of each tree were recorded and the average value was calculated. Those exceeding the average value in the standard land were excellent mother trees and marked to be harvested.

2.2 Collection of scions

Before the sap flow, on the pre-selected superior trees, take the upper branches of the crown as scions, and take three sheds of whorled branches when collecting to prevent drying up. Note that the top of the mother tree can not be collected, only 60% of the branches can be collected, so as not to affect the growth of the mother tree, and the scions will be bundled into bundles for frozen storage after collection.

2.3 Storage of scions

The cold storage cellar should be dug before the soil is frozen one year before ear harvesting. The cold storage cellar should be dug in the shade where there is no stagnant water. The cellar is 2m deep, 2m wide and long according to the amount of strips stored. Pour water into the cellar every night when freezing, so that the frozen layer at the bottom of the cellar can reach more than 50cm. In spring, the collected strips are placed on the ice layer in the cellar, cover the mouth of the cellar, keep the low temperature in the cellar, and prevent the spike from sprouting and drying up until grafting. Where there are conditions, empty vegetable cellar and empty fruit cellar can also be used. In the process of storage, we should pay attention to check that the temperature in the cellar is below 8 ℃ to ensure that the strip does not sprout, dry and mildew.

3 grafting

3.1 grafting period

The most exuberant period of sap flow is the best period from late April to early May.

3.2 cutting and stabilizing

The scion selected the full bud without disease and insect pests, which was equal to the thickness of the top of the main branch of the rootstock, cut off all the needles at the 3cm under the bud, and cut down into a double-sided wedge from the base 0.5~1cm of the bud with a single blade, and the cutting face length 2~2.5cm.

3.3 cut rootstocks

Cut off the top bud of the rootstock and split vertically from the middle pith. The cut length is 2.5~3cm or slightly longer than the scion section length.

3.4 engagement

Quickly insert the cut scion into the split of the rootstock, align the pith with the cambium, tie it tightly with plastic strips, and do not expose any gaps, but be careful not to tie the buds inside.

3.5 Technical points

In the process of operation, we should pay attention to the principle of "flat, accurate, clean, fast and tight". Flat means that the incision should be flat to ensure that the connecting layer of the cutting surface of the anvil and ear can be tangent to the maximum extent; it must be that the scion should be inserted accurately into the rootstock, once as far as possible, and do not move again; it means that the cutting surface should be clean and cannot bring sundries, and the blade should be disinfected with alcohol frequently; fast means to cut quickly, shorten the exposed time of the cut in the air, and prevent turpentine spillover and water consumption. Tight means to tie the rope tightly, buckle one ring, do not string, do not twist, reduce turpentine spillover, impermeable Rain Water, reduce external contamination and water distribution. As long as you master these, the Korean pine seedlings you grafted will basically survive.

4 conclusion

In the course of the experiment, through the comparison between the traditional coniferous species grafting method and the split method, it is found that the split method has obvious advantages in the following aspects:

4.1 the survival rate is high. The survival rate of the split method can reach an average of more than 95%, while the survival rate of the traditional pith cambium docking method is about 85%.

4.2 easy to operate. The operation process of the split method is simple and easy to learn, and the traditional pith cambium docking rule is relatively troublesome and difficult to master.

4.3 save scion. The split grafting method only uses the top bud, which is thick enough, and does not consider the ear length, so the suitable number of ears is greatly increased. The traditional pith cambium docking method needs to consider the appropriate length of the scion, which greatly reduces the number of ear strips suitable for ear picking.

4.4 the rapid growth after grafting can quickly form new trees. The average growth of Korean pine grafted by split grafting can reach more than 10cm in the same year, and the average growth in the second and third years can reach 24cm and 28cm respectively. The traditional pith cambium grafting method can not survive in the same year, and the lateral branches can still be grafted in the next year without damaging the rootstock.

4.5 the rootstock was grafted 2 ~ 3 years earlier than the pith cambium bonding method.