Phloem - Air layering

Free Hosting : Drug Rehab : Free Web Hosting : Credit Card Offers

_{Notes on propagation and taking cuttings}

Notes on a technique called 'air-layering'. Positive effects of Air-layer-cloning technique are high survival rate of the cuttings, faster rooting process and possibly savings in space because no separate cloning area or humidity tent is needed. A procedure follows:

Rooting Medium

First take a piece of moisture retaining material that is inert and of neutral pH. For instance rockwool, coco peat, peat moss or clean, non-bleached/-perfumed/-* cotton. Even a ball of clay will do. Second, a piece of polyethylene plastic film, piece of plain plastic-bag or similar material is needed. Third, something that holds the two in place around the stem/internode is needed - piece of cord, training/trellising wire, iron wire, rubber band or similar.

All normal rules for propagation apply - plant must not be too small or sickly. Select an rooting site below internode that's third highest (ie. leaving at least 2 leaf pairs between this internode and the growing tip).

Picture 1. Place piece of material around suitable place on the plants stem or branches. You can cut the leaf pair away, or leave it in place. I suggest leaving it - after all it produces energy.

Picture 2.Spray or otherwise apply moisture, leaving the material moist. Remove excess water, and wrap in film/plastic.

Picture 1. Tie in place with wire/cord/rubber band. Personally I use rockwool with aluminium foil, so no wire is needed to attach it or the piece of rockwool it supports.

After a week or so, the tiny roots will have started to grow from the stem into the medium, and the cutting can be cut off from the mother-plant. A cutting-shock will always result, but it should be minimized to a day or so. With patience of few weeks, the shock can be almost entirely eliminated.

A Closer Look

This is called air-layering. Remember to keep the layer moist. Note that if it is too moist, the stem will rot, and this will endanger the whole plant. If the conditions are right, eventually small cells in the outer surface of the (living) plant, called Cambium, beneath the phloem-tissue, will start specializing into root hairs, which will grow through the phloem, collenchyma and epidermis tissue layers and finally root into the moist material. In other words, the cells of the meristem differentiate into root primordia and break through the old stem tissue. Finally the newborn roots will 'grow' veins into the stem through which moisture and nutrients are translocated.

Relatively young internodes above the woody part of the stem are the best place for this kind of growth. If the stem is woody, root production will be slower. The whole mother-plant will continue to grow normally. A weak rooting hormone solution containing auxins and vitamins could be used in spraying the layer to speed up the process, about 1/10-1/4 of the recommendation, but then again, I've never been in that much hurry ;). Do not add the solution many times - this results in hormonal imbalance (ie. hermaphrodites).

Root Hairs

After a week the internode should have started root hair production. This depends on temperature, selected part for the layer, and plants growing cycle (low root temperature - slow root growth). One can now take the cutting, or wait for the internode to grow larger roots. Two weeks should be more than enough for this. Remove the leaves on the layered internode, and place the cutting in moist growing media (soil, rockwool), in propagation area. It should stabilize very quickly, and continue growing (although at lower rate at first) after few days. With air layering it is possible to achieve over 95% survival rate of the cuttings.

Footnotes: follow the normal cloning procedures for the few first days after cutting the cutting. If you are using soilless mediums for a rooting medium, it is a good idea to provide 1/8- to 1/2-strenght flowering nutrient solution. This is very logical, since flowering solution contains better ratios of Phosphorus and Potassium for root and stem growth than nutrients balanced for vegetative growth. Note that if you are very patient and careful with air layering, you may not need separate cloning area or humidity domes.

Temperature should be warm and even. Temperatures few degrees below or above 25 Celsius (77 F) will provide cutting nice environment to root in. Remember to keep in mind the temperature of the final vegetative area, and reduce differences between the different growing ares to minimize any stress to the freshly cut clones.

Relative moisture should be above the norm to minimize any stress to the new-cut clone. Experiment with the air-layering-technique to minimize any under humidity tent. Oxygen is also an important factor in rooting, and throughout the plants life. Aerate your water with a small air-pump, or use misters to water the cuttings. Misters mix the air and water, thus raising the level of oxygen dissolved in the water.

Happy Rooting!!