How to Select Pomelo Varieties? A Detailed Guide to Seed Selection and Seedling Cultivation

Pomelo is a fruit with an extremely high vitamin C content and rich nutritional value. At present, it is cultivated in many regions of China, with the difference being the variety. So how exactly do you select pomelo varieties? What are the seedling cultivation methods?

1. How to select pomelo varieties?

1. Wendan pomelo

The fruit is oblate, slightly concave at the top, somewhat narrow at the base, with raised ridges at the stem end. The rind is thin and smooth, with small and densely packed oil cells, and the flesh flavor is slightly on the sour side. It is mainly produced in Fujian (the Zhangzhou area), and is also planted in Taiwan, China, Zhejiang and elsewhere.

2. Shatian pomelo

The fruit is pear-shaped or gourd-shaped, with a slightly flat top, obvious rings and radial grooves, and a narrow, elongated neck-like stem end. The flesh is crisp and refreshing with a strong sweet taste, but has relatively little juice and quite a lot of seeds. The fruiting period is after late October, making it a mid-season variety. It is mainly produced in Guangdong (Meizhou), Guangxi (Rongxian, Guilin, Liuzhou and other places). Rich in soluble solids and vitamin C, it is among the best of the pomelo types.

3. Juhong

Also known as Huazhou juhong or Huazhou xianju. The fruit is covered with soft hairs, and the rind is thicker than that of other pomelo varieties. The flesh is pale yellow-white, sour with a bitter taste, and not suitable for eating raw. The fruiting period is October to November. It is mainly produced in Guangdong (Huazhou, Maoming). It is also found in Guangxi (Bobai, Luchuan and others) and Hunan (Qianyang).

4. Red-fleshed honey pomelo

Red-fleshed honey pomelo, also known as red-fleshed honey pomelo, red heart pomelo, red-fleshed pomelo, or blood pomelo.

2. Pomelo seedling cultivation methods

1. Propagation method: Pomelos are usually propagated by grafting.

1.1 Selection of rootstock

The commonly used pomelo rootstocks are sour pomelo and trifoliate orange.

(1) Sour pomelo

Pomelo trees on sour pomelo rootstock have a well-developed root system, a strong taproot, strong compatibility, a high survival rate, vigorous growth, a tall canopy, and strong adaptability. They have high yields in the full fruiting period and good fruit quality. However, they come into production relatively late and are prone to gummosis.

(2) Trifoliate orange

Pomelo trees on trifoliate orange rootstock have fairly good compatibility, can dwarf the tree vigor, grow robustly, come into production and bear fruit early, and have good quality. However, they tend to age prematurely in the later stage and have low yields.

1.2 Cultivation of rootstock seedlings

The fruits used for seed collection (sour pomelo or trifoliate orange) are harvested when fully mature. Cut them open, take out the seeds and rinse them clean, then spread them in a ventilated, shady place and air-dry until the seed coat turns white.

Seeds sown immediately after collection have a relatively high germination rate. If not sowing right away, mix the seeds evenly with 3-4 times their volume of clean damp river sand (with a moisture level such that it forms a ball when squeezed by hand and breaks into a few pieces when spread out), pile it indoors in a cool, wind-sheltered place, with a pile height of 35-45 cm, a bottom layer and top layer of sand about 5 cm thick, cover with plastic film to retain moisture, and press the edges down with film to prevent rodent damage.

In February to March or September to October, choose a fertile plot with easy drainage and irrigation, prepare the land and sow. The sowing rate depends on the rootstock variety, sowing method and seed quality. For broadcast sowing, use 50-75 kg of sour pomelo seeds per mu, or 70-90 kg of trifoliate orange seeds. After sowing, press the bed surface lightly with a wooden board or similar so the seeds enter the soil, cover with river sand, burned soil or fine soil until the seeds are no longer visible, then cover with 3-4 cm of rice straw, fix the straw with straw rope and water thoroughly. After sowing, keep the soil moderately moist. After emergence, remove the straw in stages so the seedlings receive sunlight and to prevent bending. Fertilizer management at the seedling stage should follow the principle of frequent light applications. Before 3-4 true leaves appear, reduce watering and stop fertilizing. Seedlings are susceptible to damping-off, so attention should be paid to controlling damping-off, swallowtail butterflies, leafminers and other pests and diseases.

1.3 Transplanting of rootstock seedlings

When the seedlings have 10-14 true leaves and are more than 10 cm tall, they can be transplanted. If cultivating newly planted seedlings, transplant in May to June of the same year after sowing. Graft in winter or the following spring; the entire seedling cultivation period takes two years. If cultivating older planted seedlings, transplant in the autumn of the same year after sowing or in April to May of the following year after the spring shoots mature, and graft in the second winter or the third spring; the entire seedling cultivation period takes 3 years.

1.4 Grafting

(1) Collection of scions

Scions should be collected from healthy mother trees that are high-yielding, stable-yielding, high-quality and free of quarantine pests and diseases, or from young trees directly propagated from these excellent mother trees or from nursery stock in a scion orchard. Choose autumn shoots or spring shoots from the middle and upper parts of the outer canopy that are plump, have full buds, moderate thickness, and complete, glossy leaves as scions. Scions should be collected on windless sunny days in the morning after the dew has dried and in the afternoon when sunlight is weaker; it should not be done on rainy days. Remove the leaves immediately after cutting the scions.

(2) Storage

Grafting scions as soon as they are collected gives a relatively high survival rate. If the quantity is large or they must be transported over long distances and therefore must be stored, layer them with clean damp river sand (with a moisture level such that when a hand is inserted into the sand, sand sticks to the hand but not to the fingernails). During storage, check frequently, adjust the moisture of the sand, and remove rotting branches and scions to prevent spread. In the lower-temperature seasons of winter and spring, they can be stored for 50-60 days.

(3) Grafting methods

In spring, cut grafting is the main method; in autumn, side grafting is the main method.

① Single-bud cut grafting method

Cutting the scion: Hold the scion with the angular side facing up and the flat side facing down against the index finger. About 1 cm below the bud, make a forward diagonal cut at a 45° angle; then turn the flat side of the scion upward and, starting near the bud, cut forward through the bark layer, requiring a smooth cut surface that just reaches the cambium and slightly exposes the white part of the wood; then turn the scion sideways with the bud facing up; cut it off about 0.2 cm above the bud and place it in a basin of clean water.

Cutting the rootstock: At 6-8 cm above the ground on the rootstock, choose a smooth side and make a diagonal cut to remove the upper part of the rootstock, with the cut surface at a 45° angle. Then, below the diagonal surface, make a vertical cut along the junction of the bark and wood, with the cut surface preferably just showing the white wood. The length of the cut surface depends on the length of the scion.

Inserting the bud and wrapping: Choose a bud as close as possible in size and length to the rootstock cut surface, insert it into the rootstock cut surface so that the base of the bud fits tightly against the bottom of the rootstock cut, and the cambium of the rootstock and the scion cut surface are in close contact; if the rootstock is thicker than the scion, align one side of the cambium, which makes it easier to achieve successful grafting. Finally, wrap with plastic film tape and seal with wax.

② Small-bud side grafting method

Cutting the scion: With the bud of the scion facing up, about 1 cm below the bud, make a diagonal cut at a 45° angle, then about 0.5 cm above the bud, cut forward horizontally to remove the bud with a little wood attached, and place it in a basin of clean water. The bud piece of a long small bud is relatively thin, 1.2-1.5 cm long, longer than the small buds of ordinary budding.

Cutting the rootstock: Do not cut off the upper part of the rootstock. At 10-20 cm above the ground on the smooth side of the trunk, cut through the bark layer, requiring a smooth cut surface with a depth that just reaches the cambium, and a cut surface length sufficient to hold the scion bud; then cut away 1/3 of the removed bark to facilitate wrapping and bud sprouting.

Inserting the bud and wrapping: Insert the cut bud piece into the rootstock cut, so that the bases of the rootstock and scion fit tightly and the cut surfaces align, and wrap with plastic film tape, leaving the bud eye exposed.

③ Single-bud side grafting method

Cutting the scion is the same as the single-bud cut grafting method.

Cutting the rootstock, inserting the bud and wrapping are the same as the small-bud side grafting method.

(4) Management of grafted seedlings

① Checking survival and re-grafting

If, 15 days after budding, the bud is fresh and the leaf stalk falls off at a touch, it indicates survival. Rootstock seedlings that have not survived should be re-grafted in good time; if too late, the rootstock bark will not slip, affecting survival.

② Cutting the rootstock and re-grafting

If the grafted bud has survived, except for cut grafting, side grafting requires cutting the rootstock: before sprouting, cut off the part of the rootstock above the grafted bud to concentrate nutrients for the growth of the grafted bud. But the rootstock should not be cut too early, to avoid the cut drying out in the wind and being damaged by frost. For rootstocks that did not survive after overwintering, branch grafting can be used for re-grafting in spring.

③ Removing sprouts

After cutting the rootstock, a large number of sprouts are likely to emerge from the base of the rootstock and must be removed in good time, to avoid the cut drying out in the wind and being damaged by frost.

④ Trunk training and shaping

For pomelo seedlings, cut the top around the Beginning of Autumn, leaving a trunk height of 30-40 cm; generally it is most suitable to cut the top at the 2nd-3rd node from the top of the first summer shoot. Cultivate seedlings about 50 cm tall with 2-3 robust shoots evenly distributed.

⑤ Fertilizer and water management

The principle of fertilizing is frequent light applications. In drought, water once every 3-4 days. In rainy summers, do a good job of drainage.

⑥ Pest and disease control

Control anthracnose, canker, and damage from leafminers, red spider mites, yellow spider mites, aphids, swallowtail butterfly larvae and others in good time.

In summary, everyone can refer to this for study. If you also want to learn the cultivation and management techniques for different pomelo varieties, you can continue learning at Nongxun Network.

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