High-quality seedlings are the basis of big cherry production. The quality of seedlings not only directly affects the growth speed, fruit and yield of trees, but also has a great influence on the adaptability and stress resistance of trees. Therefore, attention should be paid to cultivating high-quality and strong seedlings in production. The technical regulations of seedling breeding are introduced as follows.
First, select the appropriate rootstock.
There are many kinds of big cherry rootstocks. Among China cherries, Laiyang dwarf cherry, big leaf grass cherry (also called "big leaf"), maoba acid, Mahali, Kaoto and so on. Practice has proved that Prunus macrophylla has strong adaptability to soil and is most suitable for growing in sandy loam or gravel loam. Good resistance to root cancer; Strong grafting affinity with big cherry varieties, deep root distribution, many thick roots, strong growth of grafted big cherry, good land fixation, not easy to lodging and easy to yield. Therefore, it is suitable to choose the big leaf grass cherry as the rootstock for cultivating big cherry in production.
Second, the selection and arrangement of nursery land
1. It is best to choose neutral loam or sandy loam with sunny lee, fertile soil, no continuous cropping, no waterlogging and good drainage and irrigation conditions.
2. Nursery land should be cleaned, and base fertilizer of 5000-6000g/m2 should be applied before winter, and then it should be deeply ploughed. Before raising seedlings in the next spring, plough it again, rake it flat and thin, and make a border.
Third, the cultivation method of rootstock seedlings
1. It is easy to produce a large number of root seedlings around the rhizomes of Prunus macrophylla, and it is often used as the rootstock of Prunus macrophylla in production. The method is as follows: in spring and summer, the tiller seedlings growing around the root system are cultivated in the soil with a thickness of about 30 cm to make them take root; after autumn or before germination in the following spring, the rooted tillers are separated from the plants, and planted in a nursery for cultivation, so as to be used for grafting big cherries.
2. The methods of layering propagation of cherry rootstock seedlings in layering seedling production mainly include vertical layering and horizontal layering.
(1) Vertical layering: Planting cherry rootstock seedlings in the nursery in autumn or early spring. When planting, first dig a ditch with a depth of about 30 cm according to the row spacing of 1- 1.5 m, and then plant the rootstock seedlings in the ditch with a spacing of 50-60 cm, with the root neck lower than the ground. 5-6 buds are cut off before the rootstock seedlings germinate, and when the sprouted new buds grow to about 20 cm, 1 time soil culture is conducted, with a thickness of about 10 cm, and when the new buds grow to 40 cm 10 cm. Topdressing and irrigation should be carried out after each soil tillage. In the future, comprehensive management will be strengthened and the soil will be properly fertilized according to the situation. After the leaves fall in autumn, the soil can be removed and the plants can be divided.
⑵ Horizontal layering, also called buried layering, is a widely used method in cherry rootstock propagation. Ditching in early spring, with row spacing of 60-70cm, depth of 20cm and width of 20cm. Then, the excellent 1 year-old rootstock is obliquely inserted in the ditch along the ditch, the included angle between the rootstock and the ground is about 300, and the plant spacing is roughly equal to the seedling height. It should be practical after planting and watered with foot water. After the seedlings survive, the lateral buds germinate and grow new buds. When the new shoots grow to about 10 cm, press the rootstock horizontally into the bottom of the ditch, fix it with twigs, cover the trunk with about 2 cm of soil, and then water it. Later, with the growth of new buds, cover the soil several times until it is flush with the ground. In order to promote the growth of seedlings, 20 kg/mu of urea was applied in early and middle June. The seedlings with good growth can be grafted in the nursery from late June to early July, and those with poor growth can be grafted in September. When raising seedlings in autumn, cut the seedlings into independent rootstocks.
Fourthly, seedling grafting.
1, seedling grafting mostly adopts "T" bud grafting and plate bud grafting.
⑴ "T" type bud grafting in Yantai cherry producing area, and the suitable time for "T" type bud grafting is divided into early stage and late stage. The prophase is in the first half of June 15-20 days; The later period is from the end of July to August, and sometimes it can last until mid-September, lasting about 50 days. Grafting is too early (May), the scion is tender, the cortex is thin, and the bud development is not full. Grafting is too late (after mid-September), most branches have stopped growing, and grafted buds are not easy to fall off. In the first half of July, it is rainy season, so it is easy to flow glue after connection, and the interface is difficult to heal. Mastering the budding time is one of the keys to improve the survival rate.
When grafting at different time, the choice of scion and bud should be different. In the early stage of budding (the first half of June), 5-6 full buds in the middle of strong branches should be selected as budding. In the late stage (July-August), in addition to the basal buds and autumn shoot buds, strong scions can be selected as scions. In September, bud grafting should be carried out, and full buds should be selected from the branches that grow too vigorously in the crown.
When grafting, cut a knife 0.5 cm above the scion bud, then cut into the xylem from shallow to deep at 1.5 cm below the bud, gently tilt it upward, and then pinch one side of the bud by hand to take off the shield-shaped bud with the size of 2 cm. Then, select the smooth shaded part at the base of the rootstock about 10 cm, and cut a T-shaped knife with a bud grafting knife to reach the xylem. Then gently peel off the left and right cortex from top to bottom with a knife tip, then insert the cut bud into the incision of the rootstock so that the upper end of the bud is aligned with the transverse incision of the rootstock, and then tie it tightly with a plastic strip.
(2) Flat bud grafting can be used all year round. The thickness of the rootstock for grafting should be above 0.7 cm, and the scion should collect 1 year branches, and select full buds as scion. When grafting, select the smooth part of the rootstock base about 10 cm from the ground, and gently cut it into an oblong shape with a length of about 2.5 cm and a depth of about 2 mm along the vertical direction. When cutting the scion, cut the knife under the scion 1.5 cm, gently cut off the bud from the scion, cut it into long oval bud with a length of 2.5 cm and a thickness of about 2 mm, and then stick the bud tightly on the cutting surface of the rootstock and wrap it tightly with plastic film tape.
V. Post-event management
1, unbind in time. Check whether the grafted buds survive about half a month after grafting. If the grafted bud is fresh and swollen, it means it has survived. Those that do not survive should be replanted in time, and the surviving buds can be untied in about 25 days, so as not to affect the germination of the buds.
2. Cut the anvil and take out the bud. After grafting survives or before budding in spring, cut the stock at 1 cm above budding. When the rootstock buds germinate, the buds on the rootstock should be erased in time to promote the germination and growth of grafted buds. It will be removed 3-4 times in a row. When the new shoots grow to more than 20 cm, a post should be inserted next to the seedlings, and the new shoots should be tied and fixed on the post with hemp rope or plastic film tape to prevent the new shoots from being broken by the wind.
3. Fertilizer and water management. In order to promote the growth of seedlings, it is necessary to strengthen fertilizer and water management. Water topdressing in time according to drought and seedling growth. Nitrogen fertilizer is the main fertilizer in the early stage and phosphorus and potassium fertilizer is the main fertilizer in the later stage. Water every time after topdressing, and weed regularly in intertillage. Topdressing outside the roots can be carried out 2-3 times in the whole growing season. In order to improve the cold resistance of seedlings in winter and prevent seedlings from drying up, water and fertilizer should be properly controlled in the later stage to avoid seedlings being greedy for green and incomplete organization.
4. Pest control. During the growth of seedlings, it is necessary to do a good job in pest control. After germination, it is necessary to guard against the small gray elephant, which can be captured manually or made into poisonous bait with 80% crystal trichlorfon. From June to July, 50% chlorfenapyr EC 1000 times or 2.5% deltamethrin EC 2500 times can be used to control pear fruit borer. In July and August, spray 1-2 times 500 times of 65% zineb wettable powder, or 600-800 times of 40% manganese zinc, or zinc sulfate lime solution (1 part zinc sulfate, 4 parts hydrated lime, 240 parts water, fully mixed) to prevent bacterial perforation and early defoliation. It can be sprayed with 25% diflubenzuron No.3 2000 times solution or 50% dichlorvos EC 1000- 1500 times solution to prevent and control pests such as leaf roller moth and stickleback moth.