Detailed Explanation of Key Production Techniques for Pollution-Free Pomegranate

I. Site Selection

Environmental Conditions: Annual average temperature above 9°C; annual rainfall of 300-1000mm; fertile soil with organic matter content above 1%, soil layer over 60cm, groundwater level below 1m; soil pH 6.5-7.5, total salt content below 0.3%; slope less than 15 degrees.

Site Planning: For flat land, beach land and gentle slopes below 6 degrees, plant in north-south rows; for slopes of 6-15 degrees, extend planting rows along contour lines. Equip with necessary irrigation and drainage facilities and structures. In wind-damage areas, windbreak forests should be established.

II. Variety Selection

The selection of varieties and rootstocks should be based on regionalization and improved varieties, following pomegranate zoning, combined with local natural conditions, selecting excellent varieties, and implementing suitable planting for suitable sites. Selectively develop excellent varieties such as Dahongpao, Taishanhong, and Mengyanghong.

III. Planting

Land Preparation: Dig planting trenches or holes 0.8-1m deep and wide according to row and plant spacing, fill the bottom of trenches or holes with about 30cm of crop straw. Mix the excavated topsoil with sufficient organic fertilizer, phosphate fertilizer, and potassium fertilizer and backfill into the trenches or holes. After filling to 20cm below ground level, irrigate thoroughly to allow the soil to settle, then cover with a layer of topsoil to preserve moisture.

Planting Method and Density: For flat land, beach land and gentle slopes below 6 degrees, use rectangular planting; for slopes of 6-15 degrees, use contour planting. Planting density is 1143-1666 plants/hm2 for hillsides or slopes (without irrigation), 833-1140 plants/hm2 for gentle slopes (without irrigation), and 634-833 plants/hm2 for flat land or beach land (with irrigation).

Selection and Treatment of Seedlings: Select seedlings 80-100cm tall, with 3-5 lateral roots, and no split or torn injuries.

Planting Time: Pomegranate seedlings are generally planted in spring, and the later the better. If planted in autumn, the earlier the better. Rainy season planting should be carried out in overcast and rainy weather.

Planting Techniques: Dig planting holes 30cm deep and wide in the planting trench according to plant spacing, place the seedling in the center of the hole, fill soil while lifting the seedling, firm the soil, and irrigate immediately after filling. After watering, cover with plastic film to preserve moisture. For spring-planted seedlings, trunk heading should be done immediately after planting; for autumn-planted seedlings, trunk heading should be done before sprouting the following spring. After trunk heading, take appropriate measures to protect the cut.

IV. Soil, Fertilizer and Water Management

Deep Plowing and Soil Improvement, Clean Cultivation: Carry out each autumn after fruit harvest combined with autumn base fertilizer application. When backfilling soil, mix with organic fertilizer, then irrigate thoroughly to bring roots and soil into close contact. After rainfall or irrigation during the growing season, timely cultivate and loosen the soil to a depth of 5-10cm to help regulate temperature and preserve moisture.

Straw Mulching: Carry out straw mulching after spring fertilization and irrigation. It can also be combined with deep plowing by digging large trenches to bury straw, improving soil fertility and water storage capacity.

Fertilization: Mainly organic fertilizer, supplemented by chemical fertilizer. The fertilizers applied should not have adverse effects on the orchard environment and fruit quality.

Permitted Fertilizer Types: Farmyard manure, commercial fertilizers, other fertilizers.

Prohibited Fertilizers: Untreated municipal waste or waste containing heavy metals, rubber and harmful substances, nitrate nitrogen fertilizers, chlorine-containing chemical fertilizers and undecomposed human excrement, and unregistered fertilizer products.

Fertilization Methods and Amounts: Apply base fertilizer from after autumn fruit harvest to before leaf fall, mainly farmyard manure mixed with a small amount of nitrogen fertilizer. Soil topdressing should be carried out 3 times per year: the 1st from sprouting to early bud stage, the 2nd during young fruit expansion stage, the 3rd during fruit color change stage. The last topdressing amount is very small and can be excluded from the count; foliar spraying should be carried out 4-5 times per year, generally 2 times in the early growth stage and 2-3 times in the later stage, to supplement trace elements needed for fruit tree growth and development.

V. Water Management

The concentration of elements and compounds in irrigation water for pollution-free pomegranate production areas shall comply with the following regulations: mercury ≤0.01mg/L, cadmium ≤0.05mg/L, arsenic, lead, chromium (hexavalent) ≤0.01mg/L; fluoride ≤0.01mg/L, cyanide ≤0.01mg/L, petroleum ≤0.01mg/L.

Irrigation: The irrigation timing should be determined according to soil moisture conditions, usually including 4 periods: sprouting stage, after flower drop, rapid fruit expansion stage, and before soil freezing.

Drainage: When water accumulates in the orchard, use ditches and channels for timely drainage.

VI. Training and Pruning

Suitable Tree Forms: After planting, select suitable tree forms according to planting density. Commonly used tree forms include: Three-main-branch open-center form, 800 plants/hm2, tree height 3.0-3.5m, no trunk, with 3 main branches at 120-degree azimuth angles, each main branch at a 40-45 degree horizontal angle to the ground, each main branch with 3-4 lateral branches. Natural open-center form, 1500 plants/hm2, tree height 2.5-3.0m, trunk height 0.5-0.7m, 3 main branches on the trunk at 120-degree azimuth angles, the extension angle between main branches and trunk is 50-65 degrees, each main branch with 1-2 lateral branches. Double-trunk V-shape, 1100 plants/hm2, tree height about 3.0m, no trunk, with 2 oblique main branches growing opposite each other along the row direction, at an 80-100 degree angle between them, each main branch with 2-3 lateral branches.

Pruning: In the young tree stage, according to the crown structure of the tree form, select and cultivate good framework branches to expand the crown; in the initial fruiting stage, cultivate main and lateral branches, gradually develop various branch groups, remove useless branches, water sprouts and slender branches, cultivate fruiting branch groups mainly composed of small and medium branch groups. For vegetative branches with moderate vigor and many secondary branches, leave them unpruned to promote flowering and fruiting; in the full fruiting stage, mainly remove useless branches, water sprouts, slender branches, diseased and dead branches, etc., cultivate strong fruiting branch groups mainly of small and medium size, regulate fruit load, and reasonably balance the load. For strong vigorous trees, weak trees and moderately healthy trees, respectively adopt pruning measures mainly based on “control”, “promotion” and “preservation” to keep the tree stable and healthy. For aging trees, adopt rejuvenation measures of “remove old branches, keep new branches; remove weak branches, keep strong branches; remove distant branches, keep near branches; remove oblique and horizontal branches, keep upright vigorous branches”.

VII. Flower and Fruit Management

Pollination: Use artificial pollination, bee or mason bee pollination and other methods to improve fruit set rate and fruit uniformity.

Flower Thinning: Pomegranate has a large number of flowers and should be thinned promptly, the earlier the better. The complete flowers of the 3rd flush are generally also thinned. Starting from when flowers can be identified, thin once every 10 days.

Fruit Thinning: Adopt the method of keeping more first-flush fruits, selecting and keeping 2nd-flush fruits, and thinning out 3rd-flush fruits, so that the pomegranate tree carries a reasonable load.

Pre-flowering Girdling and Removal of Vigorous Shoots During Flowering and Fruiting: Before flowering (early May), make two girdling cuts on the trunk or main branches and large auxiliary branches of vigorous trees to improve fruit set rate. During the flowering and young fruit stages, repeatedly remove vigorous shoots on the upper side of branches to improve fruit set rate and reduce flower and fruit drop.

VIII. Pest and Disease Control

Follow the plant protection policy of “prevention first, integrated control”, with agricultural and physical control as the foundation, biological control as the core, and according to the occurrence patterns of pests and diseases, scientifically use chemical control techniques to effectively control pest and disease damage.

The main diseases of pomegranate include scab, dry rot, and early defoliation disease. Alternately spraying fungicides such as carbendazim, 80% Daconil M-45, iprodione, flusilazole, and Bordeaux mixture can effectively control them. Pests harmful to pomegranate include aphids, scale insects, peach fruit borers, spider mites, etc. Use natural enemies or spray insecticides such as imidacloprid, pirimicarb, diflubenzuron No. 3, avermectin, triflumuron, and Taoxiaoling for control. At ordinary times, promptly remove diseased and pest-infested fruits and bury them deeply. Bagging can also effectively control various pests and diseases.

IX. Fruit Harvest

Comprehensively determine the harvest time based on fruit maturity, use, and market demand. For varieties with uneven ripening, harvest in stages.