- introduction to vegetative multiplication
What is vegetative multiplication?
Getting enough planting stock, but not directly from seeds (A 3).
What's the advantage of that?
How do I set about it?
By establishing stockplants that will supply enough of the right type (A 6) of cuttings for rooting, by:
What are the snags?
Here are some common ones:
Problem 1 - cuttings are not of the right kind;
Problem 2 - not enough cuttings are produced;
Problem 3 - shoots are only available at one time of year;
Problem 4 - cuttings don't root well;
Problem 5 - coppiced stumps stop producing;
Problem 6 - the planted stockplants get older, producing poor shoots.
How do I get over these difficulties?
Problem 1 - prune stockplants to encourage good shoots (A 6, 21, 25).
Problem 2 - plant plenty of rows of each clone; improve fertility of soil (A 22, 27).
Problem 3 - water during the dry season (A 26).
Problem 4 - cut back (or coppice) stockplants (A 25); introduce shading (A 24); try other clones; improve propagation conditions (A 30–36).
Problem 5 - try watering in the dry season (A 26), or adding mulch or a little fertiliser (A 27); don't rely only on the stump, but also plant the clone in a stockplant area (A 22) and keep some plants in large containers (A 23).
Problem 6 - try re-coppicing or heavy pruning (A 25); if necessary plant a new set of stockplants raised from juvenile cuttings (A 6, 21).
Won't numbers always be low at first?
Often yes, because young seedlings or cuttings used as stockplants don't yield many cuttings, so there are few plants of each clone in the early stages.
How can I speed up multiplication?
Are there any general hints for stockplant management?
- managing coppice stumps
What are coppice stumps needed for?
They provide a valuable source of juvenile shoots to take as cuttings, especially useful when starting clones from selected trees (A 3, A 11–12).
Do all trees form coppice shoots when felled?
Most broad-leaved trees coppice, but only a few conifers do so.
If a species coppices, does every tree do so?
Clonal differences were found when 15 year old Triplochiton scleroxylon trees in Cameroon were felled at 4 different times of year. Most stumps produced a lot of vigorous coppice, some a few smaller shoots, while a few did not coppice. Six 25 year old Lovoa trichilioides produced hardly any coppice shoots, so it is best to do a few preliminary test fellings.
Will trees of any age coppice?
In general yes, but sometimes old trees may fail to do so, and very young plants may not have a large enough root system to coppice repeatedly.
At what height should the tree be felled?
At about 0.1 – 1.0 m above ground level.
This part of the trunk is most likely to produce juvenile coppice shoots that grow vertically and are easily rooted.
Where do the shoots grow out from?
From small inactive or newly-formed buds; either in the bark or on the cut surface (in wound tissue between the bark and wood).
How long does it take for coppice shoots to form?
The Triplochiton scleroxylon shoots were ready for harvesting in 1½ – 3 months, at any time of year.
Can I keep coming back to the same stumps?
Yes, provided that they are managed properly. Important points include leaving enough green leaves to keep the stump alive, maintaining moderate shade (see A 24) and pruning to stop tall, thick shoots and unsuitable branches from forming (see A 25).
How long will the stumps yield cuttings?
This depends partly on things you can't influence, like the species and the clone. But it can be extended to years by:
Why do the stumps need managing?
So that they continue to produce plenty of cuttings of the right kind for easy-to-root, upright growing cuttings (A 6).
What is the first step in good management?
Preventing the coppice shoots from getting too tall, or producing a lot of branches instead of vertical main stems.
How do I do that?
What else is important?
(A) Light - felling the tree usually leaves a gap amongst the crowns in the stand that gives the right amount and kind of light to the coppice stump below (A 24). However, it may become too shady because of:
In cases 1 & 2, give some more light (not too much) by cutting back on the shading plants as needed; for 3, maybe fell a nearby tree.
(B) Protection - against various kinds of damage:
- planting stockplants
Why do I need to plant a stockplant area?
What sort of trees should I plant?
Should I plant as many stockplants as possible?
It is generally best to plant most of the available material when starting a stockplant area, to
reach a position quickly where many cuttings can be harvested.
However, it is safer to retain a few plants of each clone (or seed-lot) in large containers (A 23).
How should the site be prepared?
How should the planting be laid out?
Here are some general hints:
When should the stockplants be planted?
During the normal planting season - also possible at other times of year if regular irrigation is available, or hand watering for small numbers.
Do they need any special conditions?
Multiplication of clones is slow at first, then increasingly rapid. So it is worth spending extra effort to get the early plantings off to a flying start. This can be helped by:
Do planted stockplants need special protection?
Putting up some temporary extra shading, for the first few weeks after planting, will protect
your stockplants from stress and drying out before they have grown new roots.
Otherwise, they need the same kind of protection from damage as described for coppice stumps (A 21).
- potted stockplants
Why would I need to keep my stockplants in pots?
Young potted cuttings and seedlings are generally planted out in a stockplant area (A 22), but there may be advantages in keeping some of them at the nursery.
What advantages are there?
Aren't there some disadvantages too?
The main problems are:
Can anything be done about these disadvantages?
Problems (a) and (b) can be lessened by:
Problem (c) can be overcome by the simple methods described in A 54.
What kinds of trees are suited to large containers?
Research is needed to find this out, but species that produce many small shoots and leaves (e.g. Cupressus and some eucalypts) are more likely to be successful.
What species should not be kept a long time in containers?
Pending research results, avoid those:
What's the best thing to do with an new species?
Plant out most stockplants, but keep some of each clone for trials in various containers.
- shade for stockplants
Why do stockplants need shade?
How does it do these three things?
But won't the shade slow down the stockplants' growth?
Only if it is too dense. Moderate shading typically makes shoots elongate more than they do in full sun.
Why is the kind of light important?
When sunlight has travelled through and past green leaves, parts of it (e.g. the red and the blue) are less well represented. This ‘filtered’ shade light stimulates longer internodes and more easily rooted shoots.
What kinds of shade can I use?
Two methods using green leaves, one with dying foliage, and one with a man-made product:
Method 1: leave some large trees to provide overhead shade;
Method 2: interplant with smaller shade trees or shrubs;
Method 3: use palm leaf shade;
Method 4: use plastic shade.
Which is best?
Choose which methods are most suitable for each situation - each method has advantages and disadvantages. Advantages include:
Method 1: maintains the whole stockplant area under ‘open woodland’ conditions; and
encourages diversity of mycorrhizal fungi (Manual 3);
Method 2: shade plants can be put exactly where they are needed; and species that are nitrogen-fixers can be chosen;
Method 3: very cheap, quick and easy to put up;
Method 4: gives an even shade, and lasts a long time.
Some disadvantages are:
Method 1: uneven shade; dead branches falling can be dangerous and damaging; shade trees
sometimes die because of opening up, bulldozer damage, etc;
Method 2: need to be cut back regularly;
Method 3: only lasts a short time;
Method 4: not cheap; needs to be ordered.
For coppice stumps (A 21): methods 1 & 3 are often suited;
For planted stockplants (A 22): methods 2 & 4 are usually best;
For potted stockplants (A 23): use any convenient method.
Palm-leaf, and three types of plastic shadecloth.
How do plants fix nitrogen?
Certain kinds of trees, shrubs and food crop plants form nodules, a close association between their roots and micro-organisms. These can transform nitrogen gas from the atmosphere into soluble compounds that can be used by the plant (Manual 3). Nearly all are leguminous plants, although not all leguminous plants fix nitrogen.
Which kinds are useful in a stockplant area?
Leguminous shrubs, such as Flemingia rhodocarpa, which is used in stockplant areas for Robusta coffee, and those that cast a moderate shade, like Leucaena. Acacia, Delonix, Cassia, Erythrina, Gliricidia, Parkia, Prosopis and Sesbania could also be tried.
What is the best way to plant shade plants?
Close-planted in single lines between 2 rows of stockplants, as this:
What about cutting shade plants back?
Aim for the following:
Is plastic shading easy to use?
Yes, the various kinds of shadecloth come in rolls up to 4 m wide, and can easily be joined together with a plastic tie (best done on the ground before fixing it up). It is very light in weight, and can be fastened to a simple framework of wood, bamboo, etc, strong enough to stand up to wind and rain. It should then last for several years.
Is temporary shade needed in a stockplant area?
Yes, sometimes, as for example:
For trials with your species, consider making up some light, portable frames for temporary
Potted stockplants can be moved from a shadier to a less shady site.
- stockplant pruning
Why do stockplants need pruning?
To keep them producing plenty of the right type of shoots (A 6, 20, 21).
Note: Tying down the shoots of stockplants, or planting them obliquely also affects the number and type of shoots that grow out (A23).
Doesn't harvesting cuttings do that anyway?
It does part of the job of pruning. However, extra cutting back is usually needed, because:
What should I prune with?
For thinner twigs: a sharp pair of secateurs or knife;
For thicker stems: a sharp machete or saw.
When should I prune?
How should I do the pruning?
Allow for differences between species, but aim to:
Can pruning completely prevent the loss of easy rooting?
Regular pruning certainly delays the changes that happen rapidly if the stockplant is allowed to grow back into a tree (A 6). It is not yet clear whether they can be stopped altogether.
Doesn't that mean I could lose my source of clonal cuttings?
This is not yet known, but is a possibility, perhaps for example in Terminalia. However, you can:
- watering stockplants
Why should I need to water stockplants?
There are three main reasons:
Won't watering make the cuttings too ‘soft’?
But won't the rooted cuttings still be too soft to survive?
No, because they will have been ‘weaned’ (A 54), grown on and ‘hardened’ before they are ready for planting out. The ‘softness’ is just a temporary state, not a permanent feature of the trees.
Will any water do?
How often should I water in a stockplant area?
What about coppice stumps?
These often grow well throughout the year, probably because they have a very extensive root system, perhaps with mycorrhizas. However, if there is a water supply nearby, an occasional good soaking could be useful for:
How about potted stockplants?
- stockplant nutrition
Don't trees get all they need from the sun, air and soil?
Yes, these are the sources of the energy and the chemical substances needed for growth of plants. However, mineral nutrients are often in short supply, making growth much slower than it could be.
Does this apply especially to stockplants?
What can I do to overcome these problems?
Which is the best method?
A combination of techniques, starting with the first.
Does that mean that mulch is more important than fertilisers?
So I shouldn't use fertilisers at all?
Yes, they can be a valuable addition to the other techniques, especially if:
What fertiliser should I use?
Try a general purpose fertiliser first. It should contain N, P & K (the main nutrients - nitrogen, phosphorus and potassium) in amounts and proportions that have been selected for agricultural crops (if possible tree crops). Calcium (Ca) and sulphur (S) are usually present in NPK fertilisers; magnesium (Mg) and trace elements (micronutrients) might be required in some cases. Modern slow-release fertilisers may prove well suited to tropical conditions, where heavy rainfall can quickly dissolve and wash away most of the nutrients that have been applied. At present, however, they are more expensive.
What are trace elements?
They are chemicals that are essential for normal plant growth, but are only required in minute quantities. In fact, many of them are toxic to plants at higher doses. They are:
How much fertiliser should I apply?
It is better to apply them in small quantities (eg. 25 g per m2 NPK):
When should I apply them?
How should fertilisers be applied?
How big a difference does nutrition make?
Except in very fertile, favourable sites, the differences can be very large indeed. In some cases, applying mulch and/or fertilisers could double or triple the production of cuttings.