Factors affecting the Survival rate of Apple grafting and its overcoming measures

Factors affecting the Survival rate of Apple grafting and its overcoming measures

Apple grafting can not only rejuvenate the aging orchard through transformation, but also optimize and renew the aging varieties of young apple orchards, and make the apple seedling varieties pure and neat. Thus it can be seen that it is very important to do a good job of apple grafting. The factors affecting the survival rate of apple grafting and the overcoming measures should be considered from the following aspects.

1 rootstock and panicle combination

M26 is the most common dwarfing interstock of apple in China, with few tillers and good soil fixation, but the affinity and healing ability vary from variety to variety. On June 20, 2017, the apple orchard in Fengxiang County, Shaanxi Province suffered a sudden wind disaster. The grafting part of the orchard without pillars was blown apart by the strong wind, resulting in varying degrees of damage to the tree.

The results show that Fuji and M26 have strong affinity, good healing ability, no crack, no split and no break (figure 1). Asustek, honey crisp and other varieties have different degrees of splitting phenomenon, Gala varieties orchard damage is very serious (figure 2). Therefore, when building a new apple orchard in windy areas, suitable varieties should be selected and columns should be set up in time to bind the trees so as to reduce the economic losses caused by the storm.

Fig. 1 Fuji apple orchard was slightly damaged

Fig. 2 Gala apple orchard was seriously damaged

2 selection of scion

2.1 Source of scion

The quality of scion is an important prerequisite to ensure the survival of grafting. Scions should be collected from the mother garden of improved varieties or trees suitable for local production conditions, good variety characteristics and good fruiting characters, so as to ensure the purity and excellence of the varieties.

2.2 selection of scion

The scion chooses one-year-old branches with sunny, strong growth, full development, full bud, disease-free insect and mechanical damage.

2.3 Collection of scions

When bud grafting is carried out in the growing season, the scion had better be picked as it is used, and pay attention to fresh-keeping and moisturizing. Annual branches are generally used for branch grafting, which can be collected in combination with winter pruning.

2.4 Storage of scion

The temperature and humidity of storage environment also affect the quality of scion.

2.4.1 the suitable temperature is 0: 5 ℃. When the storage temperature is too low, the scion tissue is frozen, the bud becomes black, the vigor decreases and loses vitality; the storage environment temperature is too high, the scion bud expands or germinates, the cortex browns, can not form callus, and the grafting is not easy to survive.

2.4.2 the humidity should be about 90%, the storage humidity is too low, the scion is easy to dry and lose vitality; the humidity of the storage environment is too high, the scion is easy to mildew and lose vitality.

3 grafting operation

3.1 treatment of scion

3.1.1 the scion is 5-10 cm long, with more than two leaf buds.

3.1.2 the scion is cut with a knife on the non-budded side of the scion, a smooth long slope of about 2.5 cm, and then a short slope of about 1 cm on the budded side, so that the lower end of the scion is flat and wedge-shaped. When cutting the scion, the cutting surface should be smooth and smooth, preferably cut with one knife.

3.2 treatment of rootstocks

First cut (saw) the rootstock from 5cm to 10cm from the ground, and deal with it smoothly, and select the number of scions according to the thickness of the rootstock. If there are big trees in the old garden, 4-8 scions can be inserted at intervals (figure 3). If the thickness of the rootstock is not very large, 2-3 scions can be inserted (figure 4). If it is a young tree, just insert a scion.

3.3 grafting

The cutting surface of the rootstock and scion is smooth, the cambium is aligned with each other, and the upper end of the cutting surface of the scion should be exposed 0.2 cm, that is, "white", which is conducive to healing and growth.

3.4 binding

The interface is wrapped with plastic film for the purpose of heat preservation and moisturization. When binding, it should be firmly, airtight and tight, so as to improve the survival rate.

3.5 points for consideration

The scion incision has less exposure time in the air, the incision is not easy to oxidize, and the survival rate is high. Experienced fruit growers include scion incisions in the mouth to avoid oxidation and improve the survival rate.

4 Management in the later stage of grafting

About 10 days after grafting, it should be checked in time, and the unsurvived plants should be regrafted in time. In general, when the new tip grows to 15 to 20 centimeters, it should be untied in time, otherwise it is easy to form a ligature mark so that the part is too thin and weak, and seriously break from the ligature mark. While unbinding the plastic film, bind the bracket (figure 5).

Fig. 5 parallel connection and binding of stents after survival

After the grafting survived, the branches germinated from the rootstock were wiped out in time to concentrate nutrients to supply the bud growth of the variety and ensure the survival rate and growth rate.