Detailed Explanation of Navel Orange Planting Methods and Technical Points
SummaryChoose a sunny, well-drained, deep-soil, micro-acidic site rich in organic matter for planting. Graft navel oranges onto dwarfing rootstocks. Build contour terraces on hillsides. Keep planting density at about 55 plants per mu, with spacing of 3-4m between plants and rows. During the growing process, expand the planting holes and bury fertilizer, cut roots, and interplant green manure to improve the soil. Prune and shape the plants in a timely manner, apply fertilizer and water regularly, and promptly carry out shoot twisting, branch pulling, branch circling and bagging, and do a good job of pest and disease prevention.
1. Choosing the Orchard Site
It is best to plant in a sunny area with no pollution nearby, a slope of 25° or less, an altitude of 250-400m on hillsides, good drainage, deep and moist soil, relatively high organic matter content, and slightly acidic soil.
It is best to select dwarfing rootstocks and graft dwarf navel orange varieties to advance the fruiting time. At present, the large-leaf small-flower strain of trifoliate orange (Poncirus trifoliata) is mostly chosen as the dwarfing rootstock.
2. Land Preparation and Hole Digging
Build terraces along contour lines. Dig a hole 1m wide and 0.8-1m deep. Keep the terrace width at about 2.5-3m, planting density at about 55 plants per mu, and spacing between plants and rows at 3×4m.
3. Soil Improvement and Root Cutting
Within 2-3 years after planting, deeply dig and expand the holes on the east and west sides and the south and north sides of the navel orange plants respectively, and bury fertilizer to improve the soil. Root cutting can control overly vigorous root growth and, to a certain extent, advance the fruiting time and increase the yield of navel oranges.
4. Improving Soil Quality
Red soil hillside soil has poor permeability, is sticky, acidic and infertile, and has relatively low organic matter content. Green manure can be interplanted in the orchard, and deep plowing and hole expansion can be carried out, combined with the application of organic fertilizer, to improve the soil in the orchard.
After 3 years of planting, hole expansion and soil improvement can be carried out every year. Mainly apply decomposed pig and sheep manure, compound fertilizer, calcium magnesium phosphate fertilizer, quicklime, weeds or green manure, etc. When applying, pay attention to mixing evenly, apply deeply in layers, rotate the holes each year, and improve the soil year by year.
5. Pruning and Shaping
Generally, navel oranges only have the ability to bear fruit after they have 6-7 branch nodes. After planting, navel oranges should be shaped with a low trunk to avoid excessive growth of the canopy, increase the number of branch nodes in the canopy, and advance the fruiting time. Keep the average trunk height below 15cm. About 20% of the plants send out main branches from the base. When the spring, summer and autumn shoots grow to 15-20cm each year, carry out shoot tip pinching to promote side branches and increase the number of branch nodes on the plant.
6. Fertilizer and Water
Apply fertilizer about 6 times each year. Generally, apply bud-promoting fertilizer, flower-preserving fertilizer and fruit-preserving fertilizer to the plants in spring, fruit-swelling fertilizer in summer, pre-harvest fertilizer in autumn, and sufficient base fertilizer in winter. When fertilizing, follow the principle of “apply many times, two heavy applications, four light applications”, combine chemical fertilizer with farmyard manure, carry out deep application and whole-orchard application at the same time, and mainly apply organic fertilizer. This kind of fertilization can improve the soil's water-holding capacity, keep it moist, and reduce the fruit cracking rate.
7. Timely Shoot Twisting, Branch Pulling and Branch Circling
Timely shoot twisting, branch pulling and branch circling of navel orange plants help the fruit trees absorb and accumulate nutrients, promote flower bud differentiation, and can also advance the fruiting time.
While hanging and pulling upright vigorous branches and opening the angle of navel oranges planted with bent roots, in early to mid-October each year, after the autumn shoots have lignified, promptly twist the long and strong autumn shoots. Hold the base of the autumn shoot with the left hand, twist the shoot 180 degrees with the right hand, and slightly injure the lignified part. The long and strong autumn shoots can also be circled or pulled flat against each other. This can slow the excessive growth of autumn shoots, allowing the nutrients produced by photosynthesis in the upper part of the autumn shoots to temporarily accumulate there in the short term, which is beneficial to flower bud differentiation, can increase flower quantity, and improve flower quality and fruit-setting rate.
8. Navel Orange Bagging
Bagging navel oranges can effectively prevent navel yellow cracking fruit, sunburn fruit and reticulated fruit, and can also avoid direct contact between the fruit and pesticides, reduce pesticide residues on the fruit, and to a certain extent improve fruit quality and selling price.
Generally, for bagging navel oranges, choose single-layer, white semi-transparent paper bags specially made for navel oranges with a specification of about 19×15cm. Bagging is carried out after the second physiological fruit drop, and bag removal can be carried out at the time of fruit picking.
9. Pest and Disease Prevention
During the growing process, prevent navel oranges from damage by canker disease, red spider mites, citrus leafminer, fruit-sucking noctuid moths, scale insects, etc. Spray relevant pesticides in a timely manner and do a good job of prevention in advance.