The new technology of peach tree breeding can actually achieve annual grafting and high survival rate
Hu Fang et al
Funds: Special Fund for Modern Agricultural Industry Technology System [Hefei Comprehensive Experimental Station of National Peach Industry Technology System (CARS-30-Z-18)], Anhui Fruit Tree Industry Technology System (Anhui Nong Kehan [2021] No. 711), Huaibei Science and Technology Major Project "Huaibei Yellow Peach Series Variety Breeding and Cultivation Technology Research and Promotion Project" (HK2021017).
Peach tree seedlings are the basis of peach tree cultivation, and all peach cultivars sold in the market are grafted seedlings. Traditional grafting methods include T-shaped budding, intercalated budding, and grafting. In spring and summer, T-shaped budding is often used when the cortex of scion and rootstock is easy to peel, in autumn, when the rootstock and scion cortex are not easy to peel, and grafting is often used when the sap flow begins in spring and ends before bud germination. However, the final survival rate of peach seedlings grafted by various grafting methods is generally less than 90%, and some are even less than 60%, and the grafting time is still limited by the season.
The corresponding author of this paper has been working in the production line for more than 30 years, is committed to peach cultivation and production, and has accumulated rich production experience. The method is not only simple to operate, easy to master, high survival rate, and not limited by time, only divided into 2 time periods throughout the year, and each time period adopts a corresponding grafting method. In the T1 time period, one bud and one seedling are used for grafting, and the reproduction coefficient is high; in the T2 time period, the winter slack season can be used to stagger the peak period of labor demand, and the branches that will be discarded by winter pruning can be fully used to improve the reproduction rate, so as to multiply peach seedlings in a large-scale, standardized and rapid manner, and solve the problems of uneven quality of peach seedlings and the tight supply of excellent varieties. This technology is another innovation on the basis of the original more labor-saving, simpler operation, higher survival rate, annual grafting peach seedlings, and easier to promote and apply in a large area, which is reported as follows.
1 Grafting time
The grafting time of the whole year was divided into two time periods, T1 and T2, T1 was from the beginning of peach bud germination in early spring to the end of peach leaves in autumn, and T2 was from the beginning of peach leaves in autumn to the end of peach bud germination in early spring of the following year.
2 Grafting method
2.1 Grafting in the T1 period
These include scion shoot selection, grafting, and post-graft management, with the main steps as follows (Figure 1).
Figure 1 T1 Time Segment Grafting Steps
Note: a. scion, b. cut the bud (cut 1 knife at a downward slope of 30° at 1 cm above the scion bud, cut into the xylem), c. take the bud, d. cut the rootstock, e. remove the chipping block on the rootstock, f. embed the bud piece into the rootstock incision, g. binding, h. survival rate of more than 99%, industrial production site.
2.1.1 Scion branch and rootstock selection. Select the sturdy tree of the desired variety without diseases and insects and quarantine objects, and excellent lines as the mother plant, and then select the 1-year-old new shoots with full, full and robust buds on the mother plant, remove the leaves immediately after cutting to leave the petioles, tie the scion branches into 50 branches and 1 small bundle, tie the variety label, and wrap it in wet gauze for later use. If the scion shoots cannot be used immediately or cannot be grafted on the same day, the scion shoots should be stored in a cool place with the base facing down, erected in a container with 4.0 cm of deep water.
Preferably, rootstocks are selected from 1- or 2-year-old planned rootstock species of solid or vegetative rootstocks. The planned rootstock species include common peach, mountain peach, Gansu peach, Xinjiang peach and light walnut, among which common peach rootstock is a wild type or variety rootstock. The diameter of the rootstock measured at a distance of 3 cm from the ground surface should be ≥ 1.2 cm.
2.1.2 Cutting buds. At 0.8 cm below the scion bud, cut the xylem at a 45° oblique cut downward, and then cut 1 knife at a 30° oblique cut at 1.0 cm above the scion bud, and when the xylem is cut to a depth of 1~2 mm, continue to cut at 0°~15° downward until it is connected with the first cut.
2.1.3 Cutting rootstocks. For the smooth side of the rootstock at 20~30 cm from the ground, use the method of 2.1.2 to cut 1 knife 45° downward to cut into the xylem, and then 1.8~2.0 cm above the top of the first knife cut and then 30° oblique cut 1 knife downward, when the xylem is cut to a depth of 1~2 mm, continue to cut at 0°~15° downward until it is handed over with the first cut. The downward incision formed on the rootstock is 0.2~0.3 cm longer than the corresponding scion bud incision.
2.1.4 Embedding. Remove the rootstock slices, remove the scion bud slices, quickly embed the bud slices into the rootstock incision, and make sure that at least one side of the cambium layer of the scion and the rootstock is aligned, and the lower end is tightly combined.
2.1.5 Lashing. Tie tightly with a plastic strip for grafting.
2.1.6 Post-graft management. The xylem of the rootstock was broken at 2~3 cm above the scion bud within 7~10 days of grafting, and at least 1/3 of the cortex was left at the broken part; when the new shoots from the scion buds grew to more than 15 cm and 5~7 new leaves grew, the rootstock was cut at 1.5~2.0 cm above the scion buds; after the second cutting of the rootstock, the conventional technology was used to manage the rootstock.
2.2 Grafting in T2 periods
These include scion shoot selection, grafting, and post-graft management, with the main steps as follows (Figure 2).
Figure 2 T2 time period grafting steps
Note: a. cut the scion section, b. cut the scion, c. cut the scion, d. cut the rootstock, e. embed the scion into the rootstock incision, f. tie it, g. study the survival rate.
2.2.1 Scion branch and rootstock selection. Select the sturdy trees of the desired variety that are free of diseases and insects and quarantine objects, and excellent lines as the mother plant, and then select the 1-year-old mediocre branches with full buds and full buds on the mother tree, and tie the scion branches into 50 branches and 1 small bundle after cutting, tie the variety label, and wrap it in wet gauze for later use. If the scion cannot be used immediately or cannot be grafted on the same day, the scion shoots should be placed in a container with 4 cm of water facing down, and stored in a cool place, or in a cellar with wet sand.
The rootstock selection is the same as in 2.1.1.
2.2.2 Cutting the scion. The scion shoots were cut into 4.0~5.0 cm/segment scion, each segment was ensured with 1 full and full bud, the morphological upper bud was sealed with wax, cut vertically at 2.0 cm above the bud, cut 1 knife at 45° downward oblique 1 knife from the bottom 1.0 cm, cut into the xylem until the bottom, and then cut 1 knife at 30° oblique at 2.5 cm from the lowest end, and then 0°~15° when cutting into the xylem to a depth of 1~2mmCut downwards until the bottom, and finally cut 20°~30° diagonally at 2.8 cm from the bottom of the cutting surface on the opposite side of the above-mentioned cutting surface, and cut into the xylem until the bottom.
2.2.3 Cutting rootstocks. For the smooth side of the rootstock at 20.0~30.0 cm from the ground, the rootstock is cut at a 30° oblique angle with the method of 2.2.2, and when the xylem is cut to a depth of 1~2 mm, it is cut downward at 0°~15°, and the downward incision formed on the rootstock is 0.2~0.3 cm longer than the corresponding scion incision.
2.2.4 Insertion. Quickly insert the scion cut end into the rootstock incision, and make sure that the cambium layer of the scion and the rootstock is aligned on at least one side and the lower end is tightly bonded.
2.2.5 Lashing. Quickly tie tightly with a plastic strip for grafting.
2.2.6 Post-graft management. Do not water within 1 week after grafting; cut off the above part of the rootstock flush with the upper end of the scion before the peach buds germinate in early spring; wait for the buds to grow new shoots after germination, check once every 10 days, remove all the sprouts or new shoots on the rootstock in time, only select 1 strong new shoot on the scion, and erase the rest in time; other management is the same as conventional management.
3. Grafted seedling management
3.1 Unbinding and cutting anvils
3.1.1 Cultivating sprouts. Check the survival 10 days after grafting, if the petiole on the scion falls at the touch and the bud remains fresh, it means that the grafting is alive and untied after 8~10 days.
3.1.2 Cultivate 1-year-old fast-growing seedlings. The rootstock should be folded 1 cm above the bud to slow down the growth of the rootstock seedlings, promote them to supply nutrients and water to the bud, and accelerate the germination. When 6~7 true leaves have grown in the bud, the rootstock is cut at 0.5~1 cm above the bud joint. The base retains 6~8 old leaves to provide nutrients and water. In the future, it will be untied according to the situation, so as not to hinder the thickening of the rootstock.
3.1.3 Cultivation of 2-year-old seedlings. The sprouts and seedlings left in the nursery in the previous year are cut before the sap flows in the spring. The rootstock seedlings of the previous year are grafted in the next spring, and after the scion is alive and germinated, one vigorous new shoot is left, and the rest of the branches and buds are erased, and the interface is completely healed and untied.
3.2 Remove cuteness
If the bud germinated by the rootstock itself grows stronger than the bud, it is necessary to remove the germination in time to ensure the normal growth of the seedling.
3.3 Medium tillage weeding
Cultivating and weeding can keep the soil loose, reduce water evaporation, increase ground temperature, prevent weeds from competing with seedlings for fertilizer, and promote the development of grafted seedlings.
3.4 Fertilizer and water management
In order to cultivate high-quality seedlings, fertilize water frequently, and fertilize once every 20~30 days depending on the seedling condition. In the early stage, nitrogen fertilizer is mainly used to promote the rapid growth of seedlings, and in the later stage, phosphorus and potassium fertilizers are appropriately combined to make the seedlings robust. The amount of fertilizer per application is 225~300 kg/hm 2. If the soil is dry, it should be irrigated in time, preferably by soaking or dripping, to prevent soil compaction.
3.5 Pest and disease control
To control aphids, red spiders, pear heartworms and moths, 10% imidacloprid EC 2 000 times solution, 1.8% phytodicarin EC 3 000 times solution, 40% chlorpyrifos EC 1 200 times solution, etc. For disease control, 50% carbendazim WP 600 times solution and 80% mancozeb WP 800~1 000 times solution can be used.
4 Seedling Fields
4.1 Seedling standards
In order to standardize the production of peach seedlings and make the survival rate and robust growth of peach seedlings after planting, the Ministry of Agriculture and Rural Affairs has issued technical regulations for pollution-free peach production, which stipulates the quality requirements and grading standards for peach seedlings (GB19175 peach seedlings). It is hoped that seedling producers and seedling buyers will strictly control the standards to promote the development of the peach industry.
4.2 Seedling
Seedlings can be raised from late autumn (subject to more than 80% of the natural leaf loss of the whole tree) to spring before budding. The seedling time is best connected with the planting time, and the planting time is followed by planting, which not only eliminates the false planting link, but also has a high survival rate and robust growth of seedlings after planting. If the nursery needs to be cleared in autumn, the seedlings can also be raised at one time, and the seedlings can be planted falsely to wait for cultivation or sales.
The seedlings should be raised with as little damage as possible to the roots, and the branches and shoots should be protected. If the soil in the nursery is too dry, it needs to be irrigated and infiltrated, and if it is too wet and sticky, it will be dried and then seedlings will be raised, which will save labor and reduce damage to the root system. After the seedlings are raised, the seedlings with root cancer and root-knot nematode disease are removed, and then they are bundled according to the quality standards and varieties, each bundle of 50 or 100 plants, or packed according to the quantity required by the user. Each packaging unit should be labeled to indicate the variety, grade and quantity. After the seedlings are arranged, they are disinfected with 5% bacterial poison AS 100 times to prevent the spread of germs.
4.3 False planting and transportation
Seedlings that are waiting to be planted and sold after seedling formation should be falsely planted. Dig a trench with a depth of 60~80 cm and a width of 2~3 m in the nursery, and the length depends on the number of seedlings. The seedlings are placed obliquely in rows, and the seedlings in one row are covered with one layer of wet soil or fine sand, covering a depth of 50~60 cm, so as not to expose the roots and not hurt the seedlings. After the seedlings are discharged, they should be filled with sufficient water, and covered with straw curtains or plastic sheets in winter to prevent dry seedlings and frozen seedlings. Seedlings of different varieties are planted separately and marked in detail, and it is strictly forbidden to mix.
When transporting, it should go to the local forestry department for inspection and quarantine, and issue a quarantine certificate after determining that there is no quarantine object. Before loading, the roots of the seedlings are stained with mud and wrapped with wet straw bags or plastic sheets to prevent the root system from losing water and ensure the survival rate of seedling planting.
5 Conclusion
The annual grafting of this set of technology is divided into only 2 time periods, and only 1 grafting method is used in each time period, which is not only simple to operate, has a high survival rate, and is not limited by time. Among them, in the T1 time period, 1 bud and 1 seedling are adopted, not only saving scion, but also easy to operate, fast grafting speed, skilled workers can graft 2 500 plants in 1 day, up to 3 000 plants, and a large number of grafted seedlings can be obtained; Standardized propagation of peach seedlings to solve the problems of uneven quality of peach seedlings and tight supply of excellent varieties.