The Latest Pomelo Tree Cultivation Techniques: A Method Tutorial

Pomelo is also known as Wendan, Xiangluan, Zhuluan, Neizi, Tiao, Leiyou, Luyou, Hugan, Choucheng, Chouyou, Pao, Bao, Pao. Pomelo is the ripe fruit of the pomelo plant in the Rutaceae family, produced in southern regions of China such as Fujian, Jiangxi, Guangdong and Guangxi. Pomelo is fragrant, sweet and sour, cool and moistening, rich in nutrients, and has very high medicinal value. It is one of the fruits people love to eat, and is also recognized by the medical community as the fruit with the greatest dietary therapeutic effect. Pomelo tea and pomelo peel also have practical value.

Biological Characteristics

1. Variety classification

① Pomelo varieties whose pollen is fertile upon pollination bear fruit with many seeds, such as white sour pomelo and red sour pomelo.

② Pomelo varieties whose pollen is incompatible upon pollination have a very low fertilization rate and can bear a small number of fruits with fewer seeds; the fruit-setting rate is high only when pollinated with pollen from a different variety (strain), but the fruit has many seeds. Examples include Shatian Pomelo (white-fleshed line), Zaohe Pomelo, Sangma Pomelo, Jinlan Pomelo, Zhaipo Pomelo, Cuntou Pomelo, Caijia Pomelo, Shitou Pomelo, Jincun Pomelo, Changshou Shatian Pomelo Duanshi Pomelo, Gulaoqian Shatian Pomelo, and Sixian Pomelo.

③ Pomelo varieties whose pollen is sterile upon pollination have strong parthenocarpic ability and can bear seedless fruit, but the fruit-setting rate is relatively low and the fruit tends to split; pollination with pollen from a different variety significantly raises the fruit-setting rate and reduces fruit splitting, but the fruit has many seeds. Examples include Yuhuan flat-cone-round Wendan Pomelo, Guanxi Honey Pomelo, Dukou Pomelo, Duwei Wendan Pomelo, Liangping Pomelo, Yue Pomelo No. 5, and Xishi Pomelo.

④ Stamens are degenerated and pollen is lacking (male sterility), but parthenocarpic ability is relatively strong and seedless fruit can be borne; pollination with pollen from a different variety significantly raises the fruit-setting rate, but the fruit has many seeds. Examples include Maojuhong Pomelo.

2. Growth habits

Pomelo is an evergreen tree. Its leaves resemble those of mandarin and tangerine and are mostly long elliptic or long ovate, while the winged leaf is heart-shaped; the fruit is mostly gourd-shaped, pear-shaped or spherical, with the surface mostly yellow or orange, the rind glossy with sunken dots, generally with a pungent odor, and the peel relatively thick and peelable by hand. The fruit is larger than citrus, with a single weight often reaching more than 1 kg and a diameter of 15-25 cm. Between the peel and the flesh there is a white spongy layer. The flesh is red or yellowish-white, with white being more common, rich in juice and with a strong fragrance, tasting sweet or sweet-and-sour, sometimes with a bitter taste, which mainly comes from the bioflavonoids it contains. Pomelo can be stored in a natural environment for several months without spoiling. The segments number 12-15; in cultivation, bagging is often used to make the fruit seedless, while in the natural state a single fruit can have more than 100 seeds. Ordinary pomelos usually mature between October and November, while early-maturing varieties can reach the market in September and late-maturing varieties as late as January to February of the following year. The root system is relatively shallow, mostly concentrated at about 1 to 3 m.

① Root system. Root distribution: seedling trees have a tall crown and well-developed taproots; grafted trees have well-developed lateral roots. New root growth and new shoot growth proceed alternately, so there are several root-growth peaks in a year. The first root-growth peak comes after spring shoots stop growing and before summer shoots sprout, and is the largest root-growth period of the year; the upper limit temperature for root growth is 37°C. If the temperature is too high, root growth is inhibited.

② Branches and shoots. Young pomelo trees grow vigorously and can sprout 4 times a year in spring, summer, autumn and late autumn, with a large number of shoots and rapid crown expansion. Pomelo trees enter the fruiting stage at 4-5 years old, and the crown then has a large number of fruiting positions, which is an important reason for the high early yield of pomelo. After entering the full fruiting stage, generally only spring shoots are sprouted and summer shoots are not. New shoots sprouting from the beginning of spring to before the beginning of summer are called spring shoots. Spring shoots sprout neatly and in a concentrated way, in large numbers, with dense internodes, short, stout and full, 10-20 cm long, and are the main new shoots for fruiting that year and for creating and accumulating nutrients. Strong spring shoots can become the base branches for sprouting summer and autumn shoots; moderately growing ones can develop into the fruiting mother branches of the next year; spring shoots developed from mixed buds develop into the fruiting branches of that year. The number and quality of spring shoots depend on the nutritional status of the tree. If the tree accumulated sufficient nutrients the previous year, the spring shoots are numerous and of good quality, and the number and quality of spring shoots in turn determine the number and quality of fruiting branches that year and fruiting mother branches the following year. Cultivating spring shoots that are numerous and of good quality is the prerequisite for obtaining high and stable yields.

3. Flowering and fruiting habits

Seedling pomelo trees generally begin to bear fruit at 8-10 years, grafted trees at 4-5 years, and enter the full fruiting stage 1-2 years after first fruiting. Grafted trees on trifoliate orange rootstock at 5-7 years old yield 15-50 kg per tree, and at 8-10 years can reach 50-100 kg.

① Fruiting mother branch. The spring shoots of pomelo are the main fruiting mother branches. Each leaf axil on a fruiting mother branch can differentiate flower buds and sprout fruiting branches, with more fruiting branches sprouting from the top few nodes. According to surveys, fruiting branches sprouting from the 1st node account for 23.7%, and those sprouting from nodes 1-4 account for 72.7%. Fruiting branches sprouting from the top few nodes have large flower bud numbers and a relatively high fruit-setting rate. Therefore the fruit is mostly concentrated on the fruiting branches sprouting from the top few nodes of the fruiting mother branch, and pruning should avoid cutting back the fruiting mother branch. A survey of the fruiting ability of fruiting mother branches of different lengths showed that fruiting mother branches 10-20 cm long have the strongest fruiting ability, and the fruit they bear accounts for 56.9% of the total.

② Fruiting branch. Pomelo flower buds are mixed buds, which sprout and then bloom in spring. Fruiting branches can be divided into four types by form: inflorescence branches, leafless inflorescence branches, leafy single-flower branches, and leafless single-flower branches. The leafy single-flower branch, that is, a fruiting branch with one flower bud borne at the tip of a leafy spring shoot, blooms slightly later, has a high fruit-setting rate and good fruit quality, but is relatively few in number. Leafy fruiting branches have a higher fruit-setting rate than leafless fruiting branches. Leafless fruiting branches are numerous and have a low fruit-setting rate. When tree vigor is strong, there are more leafy inflorescence branches and leafy flowering branches; when tree vigor is weak, there are more leafless inflorescence branches. Therefore, cultivating strong tree vigor and good fruiting mother branches and striving to sprout more leafy fruiting branches, especially more leafy single-flower branches, reducing the number of flower buds and nutrient consumption and raising the fruit-setting rate, is of great significance for achieving high and stable yields. Pomelo branches in the inner canopy have strong fruiting ability, and inner-canopy branches with relatively weak light intensity can differentiate and develop normal flower buds and bloom and bear fruit. This is also one of the important factors in the good high-yielding performance of pomelo.

③ Flowering and fruiting. Pomelo flowers are solitary or in racemes. Flowering begins in late April and reaches full bloom in early May. After pollination and fertilization of normally developed stamens and pistils, fruit with seeds is produced; pomelo also has parthenocarpic ability, and an ovary that has not been pollinated or fertilized can also swell and develop into seedless fruit. Physiological fruit drop: physiological fruit drop of pomelo basically ends from mid-May to the end of June. Fruit drop in mid-May accounts for 17.8% of the total fruit drop, and in late May accounts for 40.6%, which is the peak period of physiological fruit drop; fruit drop from mid-May to mid-June accounts for about 90% of the total flowers and fruit, and by early July physiological fruit drop has basically ended. Pomelo fruit matures around the Beginning of Winter.

3. Growing conditions

① Climatic conditions. In the place of origin, the annual average temperature is 17.5°C, the extreme maximum temperature is 40.5°C, the extreme minimum temperature is -9.2°C, the frost-free period is 238 days, the annual precipitation is 1725.3 mm, and the annual sunshine is 1898.6 hours. Pomelo has a stronger tolerance for low temperatures than sweet orange, Ponkan and Wenzhou mandarin.

② Terrain and topography. Pomelo has no strict requirements for terrain; plains, sand beaches, hills and low mountains below 500 m in altitude and with a slope of no more than 25 degrees can all be planted.

③ Pomelo has no strict requirements for soil, and the soil pH value is preferably 5.5-6.5. Alluvial soil, red-yellow soil, purple sandy soil and vegetable garden soil can all be planted as long as the soil layer is deep and drainage is good. Sandy loam soil is the best.