What are the methods for growing olive trees? Grafting propagation and seed propagation are the main ones
AbstractGrafting propagation: graft small seedlings from late February to March, graft adult large trees in April to May, cut scions when spring shoots sprout, choose a suitable method for grafting, remove the film in time, and wipe off buds. Seed propagation: after the seeds mature, take out the pits and stratify them with clean river sand, sow in February to March of the following year, soak in warm water for 5-6 hours, broadcast the seeds at a suitable density according to the purpose, fertilize at the right time, and when the seedlings have 2 leaves and 1 heart, place them into nutritional bags for cultivation, and do a good job in watering, fertilizing, and weeding.
The common methods for growing olive trees are grafting propagation and seed propagation. The two methods each have advantages and disadvantages. Let's take a look below!
1. Grafting propagation
1. Grafting time
Grafting olive seedlings is generally carried out from late February to March, on sunny days when the temperature is stable above 15-16°C, and it is best when the tree's sap begins to flow; adult large trees have deeper root systems, and the soil temperature rises relatively slowly, so the grafting time can be postponed to April to May.
2. Scion treatment
When spring shoots sprout, from excellent high-yield mature trees, select autumn scion branches with short internodes, plump buds, thickness comparable to the rootstock, and growing on the outer part of the canopy, cut them off, then immediately remove the leaves on the scions, wrap and bind them with a wet cloth, and put a plastic bag over the outside to prevent water loss from the scion branches.
3. Grafting method
Select scions with 2-5 buds. Small seedlings are generally grafted by tongue grafting or cut grafting. To reduce the oxidation of tannins in the wound and bleeding, the grafting speed should be a bit faster. The cambium layers of the rootstock and scion should be aligned and inserted tightly, sealed and wrapped, and the bud area should be tightened with a single layer; adult trees generally use inlay grafting and cut grafting. During grafting, part of the canopy should be left as pumping branches to ensure normal growth of the tree.
4. Removing the film and wiping off buds
Olive trees have a relatively slow wound-healing ability. If degradable film is used during grafting, it generally does not need to be removed. If it is tied relatively tightly, then it needs to be removed. Generally, the film is removed after the meristem at the graft union has completely healed and become firm, so as to ensure the smooth growth of the scion buds; the rootstock easily sprouts adventitious buds, which should be wiped off in time to avoid affecting the growth of the scion branches.
2. Seed propagation
1. Seed treatment
The fruit kept as seeds must be fully developed and mature. In late October to November, when part of the outer shell of the seed pit turns light reddish-charcoal color, it can be harvested.
Mix the harvested fresh olives and table salt at a ratio of 10:1 and pour them into a vat, tread them with feet until the flesh and pits separate, then put the pits into clean water and soak for 7-8 hours, remove them, and gently knock the pits out with a wooden hammer.
2. Stratification and sand storage
Mix the seeds and river sand at a ratio of 1:3, pile them in alternating layers of one layer of river sand and one layer of seeds for 4-5 layers, then place them indoors in a windproof and cool place to complete the after-ripening stage. During stratification, pay attention to inspection, control temperature and humidity well, and prevent the seeds from molding or becoming too dry.
3. Sowing method
Sow in February to March of the following year. Before sowing, soak the seeds in warm water for 5-6 hours to help them sprout uniformly.
If grafting propagation is planned in a nursery seedbed in the garden, the plant and row spacing should be controlled at 12×15cm; if used for selling seedlings or transplanting young seedlings, the sowing density can be appropriately denser. The general sowing density is 300-400 seeds/㎡. After evenly broadcasting the seeds, press the seeds into the soil with a wooden board, cover with 2-3cm of fine soil, and then cover with rice straw to retain moisture and heat.
4. Seedling cultivation
Generally 40-50 days after sowing, the seedlings will emerge. At this time, apply decomposed human and livestock manure frequently in the garden, and keep the seedbed temperature and humidity suitable.
5. Seedling transplanting
Choose nutritional bags 25cm long and 15cm wide, apply sufficient culture soil base fertilizer at the bottom of the bag, and when the young seedlings have 2 leaves and 1 heart, transplant them into the nutritional bags for cultivation. Those with longer main roots can be coiled, and they should be planted appropriately shallowly. Generally 8-10 bags form one row, and every two rows form a small line, with a spacing of 10-15cm in between. Place them into beds, and fill broken soil into the middle gaps and around the sides to prevent soil loss during watering and avoid the plastic bags aging from sunlight.
6. Seedling management
Spread a layer of peanut shell powder, crushed wood shavings, etc. on the bagged seedlings to retain moisture, keep warmth, and reduce weeds, promoting seedling survival. When the temperature is relatively high in summer, build a shade shed for the seedlings, and carry out weeding and loosening of the soil in time.