What precautions need to be taken to ensure the survival rate when grafting?

What to pay attention to in grafting to ensure survival rate

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What to pay attention to in grafting to ensure survival rate

Grafting is a commonly used propagation method in plants such as fruit trees, solanaceous vegetables, melon vegetables, and flowers. The survival rate of grafting first depends on whether callus is produced, and whether it grows rapidly. The cambium layer is the main site for callus production, so in our grafting technique, we must always pay attention to aligning the cambium layers of the scion and rootstock.

Grafting is a commonly used propagation method in plants such as fruit trees, solanaceous vegetables, melon vegetables, and flowers.

It involves connecting the branches, buds, and other tissues of one plant to the appropriate parts of another plant's branches, trunk, or roots, which, after healing, form a new plant. The branches or buds used for grafting are called scions, and the branches, trunk, or roots of the grafted plant are called rootstock. Let's take fruit tree grafting as an example to discuss how to improve the survival rate of grafting.

Fruit tree grafting has many uses, such as propagating scions and seedlings, enhancing the adaptability and stress resistance of trees, updating varieties, saving aging or endangered fruit trees, improving pollination conditions, and promoting earlier fruiting.

In fruit tree grafting, some have high survival rates while others are low. Some people attribute this to the grafters' technique, saying they are not skilled enough. To be honest, this is indeed a reason, but it is not the only one. The survival rate of grafting is influenced by many factors.

Understanding the principles of graft healing and survival

After grafting, the cambium layers of the rootstock and scion produce callus due to injury, and both sides' callus heal into one and differentiate to produce new conductive tissue, thus connecting them, allowing the exchange of water and nutrients, and forming a new individual, indicating successful grafting.

Therefore, during the process of graft survival, the formation, growth, and differentiation of callus are very important for the survival rate of grafting, which is the main factor determining the survival rate.

Factors affecting the survival rate of grafting

The speed of callus formation and the speed of connection are not only related to the characteristics of the scion and rootstock, such as compatibility and nutrient content, but also to factors such as the thickness of the wrapping film, the smoothness of the cut surface, the tightness of the wrapping, temperature, humidity, and grafting technique.

Specifically:

1. Graft compatibility

Graft compatibility means that the closer the relationship between the scion and rootstock, the better, i.e., the strongest compatibility between the same species and varieties, resulting in a higher survival rate after grafting.

Compatibility between different species of the same genus varies depending on the type of fruit tree, while compatibility between different genera of the same family is weaker, and grafting between different families is basically not viable, with a survival rate close to zero.

Graft compatibility is a key factor and basic condition for the success or failure of grafting.

2. Environmental conditions such as temperature and humidity

Temperature is closely related to the success or failure of grafting. For example, grafting fruit trees in early spring has a low survival rate because the temperature is low in early spring, the cambium layer starts to activity slowly, and healing is slow. Too late, with the temperature rising, the scion buds germinate, which is also not conducive to healing and survival.

For example, apples are best grafted at around 22°C, which is conducive to apple callus formation, while walnuts are grafted at 22-27°C, and grapes at 24-27°C for higher survival rates.

Humidity affects graft survival mainly in three aspects:

- Callus growth requires a certain amount of humidity.

- The scion can only maintain vitality under certain humidity. Therefore, watering before and after grafting is necessary to keep the rootstock in a good water environment.

- In addition, measures such as wax dipping, plastic film wrapping, and wet sand covering should be taken to ensure that the scion does not lose water.

The grafting interface should be wrapped to maintain humidity, and the binding time should not be too early. Grafting with a plastic bag after grafting is beneficial for survival. In summer grafting, shading and cooling in nurseries can increase the survival rate of grafting, while low temperature, high humidity, drought, and rainy days are not conducive to graft survival.

3. Quality of rootstock and scion

Since the healing after grafting requires adequate nutrition, the quality of the scion and rootstock has a significant impact on the survival of the graft, especially the quality of the scion.

Therefore, when selecting scions, we should choose branches and buds that are full and vigorous, and select strong and robust rootstocks for grafting.

In addition, during the storage or transportation of scions, they should be kept at a certain humidity and temperature and should not lose vitality due to heat, frost, water loss, or rot.

4. Influence of substances such as bleeding and tree sap

Some fruit trees, such as grapes and walnuts, have bleeding from wounds on the above-ground parts after the activity of the root system in spring, and grafting during the bleeding period will affect the formation of callus and reduce the survival rate, so we need to avoid this period for grafting.

Some fruit trees, such as peaches and apricots, often have reduced survival rates due to sap flowing from wounds during grafting.

Some fruit trees contain some water-insoluble substances in their branches, such as persimmon trees, which can cause precipitation due to these substances on the cut surface of the branches, affecting healing and survival.

5. Grafting technique

No doubt, some people's grafting techniques are indeed not very good and can greatly affect survival.

Grafting requires flatness, accuracy, speed, and tightness, i.e., the cut surfaces of the rootstock and scion must be flat, the cambium layers of both sides must be aligned, the lower end of the scion should be connected to the upper end of the rootstock, the order should not be reversed, the grafting operation must be fast, and the binding must be tight and secure.

6. Timing of grafting

Although grafting can be done throughout the year, the most suitable period for bud grafting is from June to October, and the most suitable time for branch grafting is spring and autumn.

【Summary】

The survival rate of grafting first depends on whether callus is produced and whether it grows rapidly, and the cambium layer is the main site for callus production. Therefore, in our grafting technique, we must always pay attention to aligning the cambium layers of the scion and rootstock.

The detailed explanation of what to pay attention to in grafting to ensure the survival rate provided above is for reference and suggestion only!