The latest course of grapefruit grafting techniques

Grapefruit is a tree of the citrus genus of Rutaceae, also known as pomelo, Wendan, fragrance, Zhu Zi, and so on. Grapefruit is mainly raised by grafting methods. It usually takes 5 to 8 years for grapefruit seedlings to bear fruit. Grafted seedlings will bear grapefruit as long as the mother plant was originally fruited. If it can be restored for a year by freezing injury, let's take a look at grapefruit grafting techniques.

Selection of grapefruit rootstocks

1. Sour pomelo: the grapefruit tree with sour pomelo rootstock has developed root system, strong main root, strong affinity, high survival rate, vigorous growth, high crown, strong adaptability, high yield in full fruit stage and good fruit quality. However, it is easy to be infected with gum disease because it is put into production late.

2. Fructus Aurantii: the grapefruit of Fructus Aurantii rootstock has good affinity, dwarfing tree potential, strong growth, early production and good quality. But in the later stage, it is easy to senescence early and the yield is low.

Cultivation of grapefruit rootstock

1. Seed collection: the fruit used by rootstock seedlings (sour pomelo or Fructus Aurantii) is harvested when it is fully ripe, cut open and rinse the seeds, then spread them in a cool and ventilated place and dry until the seed coat turns white.

2. Sowing: the seed is sown immediately after harvest and its germination rate is relatively high. if you do not sow immediately, you can use 3-4 times of clean wet river sand (humidity pinched by hand, which can be dispersed into several pieces) and seeds, stacked in a cool leeward place indoors, 35-45 cm high, the bottom two layers of sand are about 5 cm thick, the upper cover is covered with plastic film to moisturize, and the periphery is pressed with film to prevent rodent damage.

3. Management: after sowing the seeds, gently press the border surface such as wood to make the seeds into the soil, cover the river sand, burn the soil or fine soil until the seeds are not seen, then cover the straw 3cm, fix the straw with a straw rope and fully water it. After sowing, keep the soil moderately moist, remove the straw after emergence, make the seedlings accept the sun and prevent bending. The principle of applying thin fertilizer frequently should be grasped in the management of fertilization at seedling stage, watering should be reduced and fertilization should be stopped before the occurrence of 3-4 true leaves, seedlings are prone to bacterial blight, and attention should be paid to the prevention and control of diseases and insect pests such as blight, butterfly, leaf moth and so on.

4. Transplant: when the seedling has 10-14 true leaves and the height is more than 10 cm, it can be transplanted. For example, the newly planted seedlings will be transplanted from May to June of the same year after sowing. Grafting in winter or the following spring will take two years for the whole seedling period. If the old seedlings are cultivated, the spring shoots are transplanted in the autumn of the same year or April to May of the following year after sowing, and then grafted in the winter of the second year or in the spring of the third year. The whole seedling raising period takes 3 years.

Scion collection of grapefruit tree

1. Scion collection: scions should be collected from strong mother trees with high yield, stable yield, high quality and no quarantine STD pests, or from young trees or seedlings in ear nurseries directly propagated by these excellent mother trees. Choose autumn or spring shoots with full growth, full bud eyes, moderate thickness, complete leaves and glossy autumn or spring shoots as scions. Scions should be picked on windless sunny days after dew drying in the morning and weak sunshine in the afternoon, but not in rainy days. Remove the leaves immediately after the scion is cut off.

2. Storage and transportation: the survival rate of grafting with picking is relatively high. If the scion must be stored in large quantity or long-distance transportation, it can be stacked in layers with clean wet river sand (inserted into the sand by hand, hands stick to sand and nails are not). During storage, the humidity of sand should be checked and adjusted frequently, and rotten branches and ears should be removed to prevent spread. It can be stored for 50 to 60 days in winter and spring.

Grafting technique of pomelo

1. Single bud splicing method

① cutting scion: the prismatic side of the scion is upward, the flat side is pressed down against the index finger, and an oblique knife is cut forward about 1 cm below the bud point, with an angle of 45 °. Then turn the flat side of the scion upward and peel the skin forward from near the bud point, requiring the cutting surface to be smooth, just to the cambium, and it is appropriate to expose the white part of the xylem. Then turn the scion to the side and the bud point up. Cut off about 0.2 cm above the bud point and put it in a basin filled with water.

② cutting rootstock: at the place where the rootstock is 6cm away from the ground, choose the smooth side and obliquely cut off the upper part of the rootstock at an angle of 45 °. Then at the bottom of the slope, cut longitudinally along the junction of the cortex and xylem, preferably the white xylem you just saw. The section length depends on the scion length.

③ embedded bud bandaging: select buds similar to the size and length of the cutting surface of the rootstock as far as possible, and insert them into the cutting surface of the rootstock, so that the base of the bud is close to the bottom of the cut of the rootstock, and the cambium of the cutting surface of the rootstock and the scion are closely joined. If the rootstock is thicker than the scion, it should be aligned with one side of the cambium, which is easier to take over. Finally, it is wrapped with plastic film tape and sealed with wax.

2. Abdominal grafting of small buds

① cutting scion: the bud point of the scion is upward, cut obliquely at an angle of 45 °at about 1 cm below the bud, then cut forward at about 0.5cm above the bud, cut off the bud slightly with xylem and put it into a basin filled with water. The buds of long buds are thinner, 1.2 cm long and 1.5 cm long, which are longer than those of common buds.

② cutting rootstock: the upper part of the rootstock is not cut off, and the smooth side of the trunk is cut on the smooth side of the ground, requiring that the cutting surface is smooth, the depth is just to the cambium, and the cutting surface length is to be able to put down the buds, and then cut off the cut layer 1 to 3, in order to facilitate bandaging and bud germination.

③ embedded bud bandaging: insert the cut bud into the incision of the rootstock, close the base of the rootstock and ear, align the cutting surface, and bandage with plastic film to expose the bud eye.

3. Single bud ventral grafting method: cutting scion with single bud cutting method, cutting rootstock, embedded bud, bandaging with small bud ventral grafting method.

4. Management of grafted seedlings

① replacement: where the bud is fresh and the petiole falls immediately after 15 days of grafting, it indicates that it has survived. The rootstock that did not survive should be repaired in time, and the rootstock could not be removed from the skin too late, which would affect the survival.

② cutting stock: if the grafted buds have survived, in addition to cutting, the ventral grafted rootstocks should be cut off before germination in order to concentrate nutrients for budding and growth. However, the cutting anvil should not be too early, so as not to be easily air-dried and frozen. The rootstocks that did not survive after overwintering can be repaired by grafting in spring.

③ de-sprouting: grafted pomelo seedlings are easy to sprout from the base of the rootstock after cutting rootstocks, which should be removed in time to avoid easy air-drying and freezing.

④ fixed dry: pomelo seedlings the Beginning of Autumn before and after cutting the top, leaving a dry height of 30cm to 40cm, generally in the first summer shoot top 2-3 internodes are the most suitable. The height of the cultivated seedlings is about 50 cm, and there are 2-3 strong seedlings with uniform distribution of branches and tips.

⑤ fertilization: the principle of fertilization for grafted grapefruit seedlings is to apply thin fertilizer frequently, drench water once every 3-4 days in case of drought, and it is rainy in summer, so drainage should be done well.

⑥ disease prevention: grafted pomelo seedlings timely control anthracnose, canker and leaf moths, red spiders, yellow spiders, aphids, butterfly larvae and so on.