High-quality and high-yield planting techniques of Wendan pomelo in Duwei Town, Xianyou County

Cultivation Techniques for High Quality and Yield of Pomelo in Duwei Town, Xianyou County

Duwei Wendan pomelo originated from Duwei Town, Xianyou County, Putian City, Fujian Province. It is a characteristic traditional famous fruit in Xianyou County. Its fruit quality is excellent, its smell is fragrant, its meat is tender and mellow, its sweet and sour is moderate, seedless, fresh and refreshing, and its flavor is unique [Jishan Huayao]. From 2002 to 2008,"Duwei" brand Wendan pomelo was recognized as "Green Food Class A Certificate" by China Green Food Development Center for three consecutive times; in 2010,"Duwei" brand Wendan pomelo was recognized as "Geographical Indication Product Protection" by China General Administration of Quality Supervision, Inspection and Quarantine. In recent years, Xianyou County has vigorously developed Duwei Wendan Pomelo and actively built Duwei Wendan Pomelo Industrial Park in Fujian Province. The output has increased year by year and the quality has been continuously improved. In order to achieve the goal of high yield and high quality, combined with the author's work practice, the high quality and high yield cultivation techniques of Duwei Wendan pomelo are summarized as follows.

1 Building a garden

1.1 climatic conditions

The annual average temperature is 19.9~20.2 ℃, the hottest month (July) is 28.3 ℃, the coldest month (January) is 11.0~11.2 ℃, the minimum temperature is above-1.0 ℃, the annual accumulated temperature is ≥10 ℃, the frost-free period is above 340~345 days, the annual sunshine hours are 1 500~2 100 hours, the annual rainfall is 1 500 ~2 200 mm, The relative humidity of air is 80%~85%.

1.2 soil conditions

The plots with fertile and loose soil, deep soil layer (more than 1 m) and organic matter content above 10 g/kg should be selected for planting pomelo. Plain planting should choose the low hill red soil with groundwater level below 0.8 m, strong flood control and drainage capacity and pH value between 5.5 and 6.5; mountain planting should choose barren hills and low hills with slope below 25° and elevation below 300 m. It is best to have convenient transportation, water source and no environmental pollution.

1.3 orchard planning

The main road runs through the whole orchard and is connected with the external road. The road surface is 3~4 m wide, the branch road is 2~3 m wide, and there is a return place; the small road surface is 1.0~1.5 m wide. The drainage system requires that the surface width of flood drainage ditch is 10 ~ 15 m, the bottom width of ditch is 0.8~1.0 m, and the depth of ditch is 10 ~ 15 m; the width of mountain table is 2.5~3.0 m, and the outer side of table is 10~15 cm higher than the inner side; the outer edge is built with water retaining ridge of 15 cm high and 20 cm wide, and the inner side is dug with bamboo joint drainage ditch of 40 cm wide and 25 cm deep, and the drainage ditch is connected with flood drainage ditch. A reservoir with water storage capacity of about 20 m3 was built every 1 hm2 garden plot.

2 Plantations

2.1 Soil preparation and basal fertilizer application

Before planting, dig planting holes with length, width and depth of 1 m according to the plan, dry the soil after digging, and then apply 50~100 kg green manure, 1~2 kg lime and 10~15 kg dried livestock manure to each hole. Apply 2~3 kg cake fertilizer and 1~2 kg phosphate fertilizer to each hole in the upper layer, and mix them with topsoil to make circular mounds with height of 30 cm and diameter of 80 cm.

2.2 nursery stock planting

Planting time is generally selected in September to October after autumn shoots mature or February to March before spring shoots sprout, but spring planting is appropriate. When seedlings are planted, the grafted seedlings with good healing interface, no diseases and insect pests and mechanical damage, developed root system and more fibrous roots are selected. Transplanted seedlings with soil ball can recover quickly after planting. At the same time, cross varieties are used as pollination trees, and the proportion of cross varieties is 1%~2%[3-7]. The row spacing is 5m × 4m in flat land and 4m × 4m in mountainous area, with 500~615 plants/hm2 planted; the row spacing is 4m ×4~ 5m in sloping land, with 615~700 plants/hm2 planted. When planting, dig holes in the center of mound for planting, so that the root system can naturally stretch, straighten the seedlings and gently lift and compact them at the filling side, so that the root system can be closely contacted with the soil. The planting depth is 10~ 15cm higher than the ground surface at the root neck of seedlings, and do not contact the bottom fertilizer. Then sprinkle enough root water, cover with thin soil again, and cover with grass to keep the soil moist until survival.

3 Scientific fertilization

3.1 Fertilization of young trees

Young trees should be fertilized mainly with water and fertilizer, and shoot attack and shoot protection should be done well. Adhere to the principle of thin fertilizer and frequent fertilization, apply shoot promotion fertilizer before each shoot, apply strong shoot fertilizer after shoot, apply urea and other nitrogen fertilizer 0.1~0.3 kg/plant, phosphorus fertilizer 0.10~0.15 kg/plant, human manure 25 kg/plant, dig circular ditch for irrigation. Application of quick-acting fertilizer before germination of spring shoots can promote early development and multiple spring shoots.

3.2 Fertilization of adult trees

Fertilization of adult trees is mainly organic fertilizer, supplemented by chemical fertilizer, combined with extra-root fertilization. The proportion of N, P, K, Ca and Mg should be controlled at 1.00∶0.50∶0.90∶1.00∶0.28. Fertilization 4 times a year, namely good winter fertilizer, pre-flowering fertilizer, stable fruit fertilizer, strong fruit fertilizer. Fertilization amount should be determined according to soil fertility, age, tree vigor and fruit yield. For fruit trees with a yield of 75 kg, urea 2 kg/plant, manure 50 kg/plant, potassium sulfate 1 kg/plant, peanut cake 8 kg/plant and calcium superphosphate 2 kg/plant should be applied. The emphasis is on applying fruit-picking fertilizer in combination with deep ploughing and hole enlargement in winter, which accounts for 40%~60% of the annual fertilizer application. Fertilization is done by digging trenches under the canopy drip line and applying fertilizer.

4 Soil improvement

4.1 interplanting green manure

Generally, green manure is interplanted in the whole garden before closing, and green manure crops such as peanuts, soybeans and mung beans can be selected. According to the soil condition, the soil was improved by interplanting green manure, and the time was from October to December. The ditch with length of 1.5 m, width of 0.6 m and depth of 0.8 m was opened on both sides of the planting hole, and green manure 50 kg/plant, calcium superphosphate 2~3 kg/plant and lime 1~2 kg/plant were applied in layers to improve the physical and chemical properties of the soil and ensure that the soil was loose, moist and nutritious.

4.2 field mulch

Covering crop straw or weeds in summer and autumn dry season keeps soil loose and moisture; covering soil in winter can improve soil temperature and enhance cold resistance of trees.

5. Shaping and pruning

5.1 young tree pruning

Young tree pruning mainly adopts the principle of "removing early and keeping neat, removing less and keeping more" to wipe buds and control shoots. In the first year after planting, 3~4 branches with uniform distribution and strong branches are selected from the trunk 40~60 cm away from the ground as the basic main branches. When the main branches grow to 20~25 cm, the second top is cut to promote multiple shooting and lignification. Each main branch is selected and 2~3 branches are reserved as auxiliary main branches. In the second year, there are 2 main branches with a distance of 30~40 cm from the main branch of the first layer, and each main branch naturally extends to the terminal bud to self-shear. The adjustment of branch angle and position is realized by supporting, pulling and hanging, so as to realize the control of growth potential.

5.2 pruning at full fruiting stage

In full fruiting period, the weak branches and the mother branches that have borne fruit in the current year shall be appropriately cut off. For the trees with serious crown closure and excessive backbone branches, the erect backbone branches and large branches in the middle shall be sawed off, and the "skylight" shall be opened to introduce light into the bore, so as to control the tree height below 3 m. The pruning of adult trees is generally divided into summer pruning and winter pruning. The summer pruning time is generally 15~20 days before autumn shoot. A small number of cross branches, fallen flowers and fruit branches, overdense strong branches and so on are mainly cut off from the middle and upper parts of the crown. The vegetative branches of summer and autumn shoots that are sprouted in the current year are adjusted by cutting or thinning. Winter pruning time is generally 15~20 days after fruit picking to before spring bud germination, mainly cutting dead branches, diseased branches, thinning cross branches affecting tree shape, strong branches in the middle and upper parts of crown periphery, over-dense shade branches, etc.

6 Flower Management

6.1 ring cutting

Circumcision can inhibit vegetative growth and promote flower bud differentiation and flowering. Circumcision was performed on the smooth and flat part of the basal trunk, reaching deep to xylem, with a circumcision width of 0.2~0.3 cm, from bottom to top year by year. The trees with strong vigor should be girdled 2 times, the trees with medium vigor should be girdled 1 time, the lateral branches should not be girdled, and the trees with weak growth potential should not be girdled. The time of girdling is generally controlled from late November to early December.

6.2 flower and fruit protection

It was proved that the fruit weight was negatively correlated with fruit size, and the fruit granulation rate was positively correlated with fruit size. Spray 0.1% borax +0.2% urea +0.2% potassium dinitrate for 1~2 times at bud stage to keep flowers and fruits. At the same time, in order to adjust the number of fruits per plant, we can thinning inflorescences first and then buds, remove heads and pinches tail to keep middle, thinning weak flowers to keep 2~3 strong flowers, thinning about 60% of total buds. Spraying 0.2% potassium dihydrogen phosphate +0.2% urea or special fruit-preserving agent for pomelo at young fruit stage, thinning fruit when young fruit diameter is about 3 cm, thinning over-large fruit, over-small fruit, abnormal fruit, combined fruit and disease and insect fruit, determining fruit yield according to tree vigor, and evenly distributing the remaining fruit.

6.3 fruit bagging

Bagging can reduce pesticide contamination of fruit. After the second physiological fruit drop, bagging was carried out in early June, and insecticides and fungicides were sprayed once before bagging. 80% aluminum triethylphosphonate 800 times solution + parmite1 500 times solution can be sprayed through, and bagged 4 hours after the solution dries.

7 Pest control

7.1 agricultural control

Strengthen cultivation management, improve tree disease resistance. After pruning and fruit picking, the dead branches, fallen leaves, fallen fruits and weeds on the ground shall be buried or burned intensively, and the ventilation and illumination conditions in the tree crown shall be improved through thinning and retraction technology to reduce the overwintering pest source [9].

7.2 biological control

Protect predatory insects, such as chrysopa, ladybug, leech, aphid fly, mantis, thrips, etc., so as to achieve the goal of controlling pests with beneficial insects and insects with bacteria. By means of protection, transplantation and release, the number of natural enemies of insects can be increased to achieve the purpose of controlling pests [10].

7.3 chemical control

The main diseases are anthracnose, canker disease, scab and so on. When the spring bud grows 0.2 cm or the flower falls 2/3, it is controlled by spraying 800~1 000 times solution of M-45 WP or 0.5%~0.6% lime Bordeaux mixture, and 800 times solution of 25% Prochloraz EC, 800~1 000 times solution of Tanteling and 800 times solution of 70% Thiophanate-methyl WP at the young fruit stage and the autumn shoot emergence stage.

Insect pests are mainly rust ticks, red spiders, leaf miner moth, scale insects and so on. Mite-killing solution 1 000~1 500 times, Insectocarb 1 500~2 000 times and Wanlingshui 1 000~1 500 times can be selected for control. The leaf miner can be controlled by 1 000~1 500 times solution of "312"+1 500~2 000 times solution of 20% fenvalerate or 800 times solution of 25% dimehypo. Male adults of Bactrocera dorsalis could be trapped by a trap hanging in the middle of tree crown every 20 m in grapefruit orchard.

7.4 physical control

The diseased plants of Huanglong disease should be dug up and burned in time. According to the yellowing tendency of Bactrocera dorsalis, the phototaxis of longicorn beetle, leaf beetle and leaf miner, hang a yellow board every 20 m in the middle of orchard crown, and use sex attractant and hanging insecticide lamp to trap and kill; use the pseudo-death property of weevil, knock pomelo tree several times with rod in the morning when the dew is not dry in the adult emergence period, and kill the adult on the ground artificially after the adult falls to the ground.