Line 109: Line 109:


====Stolons====
====Stolons====
Appear at the base of a stem from a leaf axil. Grows horizontally and again produces the same stolons: strawberry, Potentilla, Ajuga, reptans Geum, Potentilla, Saxifraga sarmentosa
Stolons are vegetative shoots without food reserve that grow in the horizontal plane beneath the soil surface. Stolons will produce in their knots roots and erecting stems. Appear at the base of a stem from a leaf axil. Grows horizontally and again produces the same stolons: strawberry, Potentilla, Ajuga, reptans Geum, Potentilla, Saxifraga sarmentosa A new plant is made if the connection is broken with the mother plant. The young plants that already have some roots are cut from the parent plant and are planted in open-field or in a pot. It then grows to a full plant. Is, amongst others, applied with mint.


===Divisioning===
===Divisioning===

Revision as of 10:34, 5 November 2012

Generative vs vegetative propagation

Generative Vegetative
Very variable Invariable
Seed Plant parts (clones)
Self-pollinators: usually less seed-variable, cross-pollinators: more seed-variable
F1: first filial series, F2:second filial series

F1: first line after crossing A7 and B7 (parental lines or P1, P2, ...) F2: cross between 2 F1 plants

Generative propagation

Sowing

Favorable sowing and planting times takes into account not only the state of the soil, temperature requirements, and correct growing season, but also the magnitude of the risk of damage by parasitic and non-parasitic causes (eg frost), ...

The sowing in full soil is done from late March. With this on site-sowing, the sowed plants are not transplanted. They are later thinned-out at the desired spacing. The sowing can be done scatted or in lines. We prefer to sow in lines because the weeding can then be done with a hoe or hoe machine.

sowing depth= 2 to 3 times the thickness of the seed; however sowing needs to be done deeper with dry weather (the deeper= the more moisture), and shallower with wet weather

Sowing by hand done in sowing trenches that are drawn near the sowing line. For this, we use the handle of a rake or the blade of a hoe. The depth of the sowing trench is related to:

  • The size of the seeds. The smaller, the shallower.
  • The expected weather, with rainy weather shallower, deeper with dry weather.
  • The germination period, seeds with a long germination period are sowed deeper.

Take care to not to sow with a too small spacing, the plants will then quickly compete with each other making them weaker and too lenghty. Divide the seeds on equally spaced distances.

After sowing, the sowing trench is gently filled by raking the soil over it, and slightly pressing it, so that the seeds make good contact with the soil. With light-based germers, the seed is pressed but little or not covered.

After the sowing, depending on the moisture content of the soil, it is watered. This is done with a fine spraying to avoid the consolidating of the soil. Often we will, to avoid the hardening of the soil, need to keep the soil moist, until the germs emergence.

With seeds that have a long germination period (3-4 weeks), the seeds can be inbibited. The seeds are allowed to swell up to 24 hours in water and are then layed out in a box with damp toilet paper, covered with a glass or foil. From the moment the seeds begin to germinate, we carefully sow them.

Stratifiying or layer stacking: some seeds require more than 1 year for stratification (hot-cold-hot period or cold-hot-cold); others only require a short germ resting time or none at all

The germination

Requirements

Internal requirements

  • The seed is in good condition, if:

Morfologically: all parts are present and intact Physiologically: sufficient food reserves are present that are enough dehydrated and do not have vacuoles

  • The seed must be ripe: Some seeds do not germinate in spite of favorable conditions. They must undergo a maturation process. For certain seeds, a fairly severe frost period is required (apple, pear). The reserve nutrition is be converted into assimilatable form and inhibitor compounds must have been dissolved (stratification process).
  • The seed must be germamble: it needs to be capable of germing under the normal conditions. The germination is greatly reduced with the age of the seed.
    • Seeds that lose germination strength quickly: food reserves stored in the form of oil or fat (coffee and oilseeds)
    • Seeds that keep their germination strength a long time: food reserves stored in the form of carbohydrates (cereals, broom)

External requirements

  • Sufficient moisture for seed skin and germination: Water can more difficultly penetrate into a hard seed coat and germination lasts longer eg: clover.
  • Suitable temperature: germination is only barely possible at the minimum temperature. At the optimum temperature, the germination is the fastest. Above the maximum temperature, the germination strength is destroyed. Ex: grain 4-43°C.
  • Presence of oxygen (air): seeds that are too deep do not germinate.

Germination process

  • Due to the water penetrating the seed coat and entering the germ further via osmosis, the seed starts to swell. Under the pressure of the swelling of the germ, the seed coat starts to crack. The bursting of the seed coat allows the germ to release itself: this is the germination.
  • method of germing: The root always first appears, it always grows downwards or it attempts to do so. After this, the stem appears, it is often first still bent in a sharp angle, then it will erect itself and the plume can grow. With the common bean, maple, and the spruce, the cotyledons appear above the soilsurface and then usually fall off. This is called an epigeïc germination. With the pea, rye and horse chestnut, the cotyledons remain in the seed coat below the soilsurface. This is called a hypogeïc germination.
  • seedling: the first leaves that emergence from the plume are different from the next ones and are called youth leaves or primary leaves. They are e.g. singular, while the others are composed (Umbelliferae-ic). With dicots and gymnosperms secondary roots appear shortly after on the main root. With the monocots, this is not the case, but a number of roots appear at the base of the stem, so that the main root is no longer visible among the others, these roots are sideroots (they shoot off the stem). If the cotyledons are pushed above the soilsurface, we call the part between the attachment point of the cotyledons and the actual root the hypocotyl axis. This is part of the stem and will thicken with some crops eg radish, turnip.
Agriculture manual 1 2 1 image 12.JPG
Agriculture manual 1 2 1 image 13.JPG

Vegetative reproduction

Roots, tubers and bulbs

Stolons

Easy and fast Not with all plants, only with plants that have adventive buds on their roots

  • Rhus, Robinia, Ailanthus, Rubus, Chaenomeles

Large rootwig

stolons of roots that are left undisturbed in the soil even though their stems are removed blackberry species

Root cuttings

  • Anchusa, Anemone, Erodium, Geranium, Primula denticulata, Pulsatille, Verbascum
  • Acanthus, Eryngium, Limonium, Papaver, Phlox

Tubers

Plants of which the above-soil surface dies off. RV in a tuber. Tubers are not able to make adventive buds on a root.

A. One-year WK that needs to be remade each year Dahlias develop themselves on side roots, swell during the season are packed together in clusters. Each year, another plant.

Perennial tubers that grow in size Begonia

Derived stems

Definition: organs that contain RV on which they can survive a resting period. They are built the same way as normal stems but usually live underground and have spare food. 6 types of derived stems:

  1. corm: wears buds, end bud too. Few plants have such a propogation form, the most famous one being the potato. Some plants also have small nodules in the axillary buds: lilies. cut in X's, fungicide
  2. Rhizome: grows horizontally in the soil. Knots (not buds) and clearly identifiable internodes. from the nodes the above-ground shoots and roots grow. Several years old. iris, bamboo species, mint, Elytrigia repens, calla lilies, Asparagus (short rhizomes), Canna, bearded irises (Germanica), Convellaria majalis, peony, rhubarb, Polygonatum, Sanseveria, ...

Tubers

The difference between a tuber and a bulb is that a tuber is a swollen stem part and it is shorter and wider than a bulb. The leaves of the stem are thin, membranous and protect the tuber from drying out. The end bud grows from the flowering stem, the roots from the tuber base. The swollen area below the stem is surrounded by fleshy leaves: lilies. The end bud bud will result in a flowering stem.

Bulbs

Have a stem with very short internodes. The growing point is surrounded by thick fleshy leaves: scales or skirts (eg onion and tulip). Flowering bud and above-soil leaves develop themselves in the center of the bulb. Bulbs with skirts: daffodils and tulips, fleshy and very broad leaves Bulbs with scales: Fritillaria; no dry membranous covering scales, are very membranous and cover each other only partially. Bulbs multiply by division. With Lilium lancifolium and Lilium tigrinum: brood balls in the armpits. Propogation by planting off the scales.

Rosettes grown out of the stem

With some species shoots grow from a leaf axil: Sempervivum tectorum

Stolons

Stolons are vegetative shoots without food reserve that grow in the horizontal plane beneath the soil surface. Stolons will produce in their knots roots and erecting stems. Appear at the base of a stem from a leaf axil. Grows horizontally and again produces the same stolons: strawberry, Potentilla, Ajuga, reptans Geum, Potentilla, Saxifraga sarmentosa A new plant is made if the connection is broken with the mother plant. The young plants that already have some roots are cut from the parent plant and are planted in open-field or in a pot. It then grows to a full plant. Is, amongst others, applied with mint.

Divisioning

With this, the plant is divisioned into several pieces. It is important that:

  • Each piece contains at least 1 eye
  • Each part has enough roots
  • Each part contains sufficient food reserves

When divisioning, we follow these steps: The mother plants are uprooted and the excess soil is shaked off. The excess in leaves is removed. Make sure that growing points, shoots and roots are not damaged. Hold the plant with both hands, the thumbs as close as possible to the breaking point. Breaking causes less damage than cutting trough. If breaking is not possible, the woody or fleshy part is prepared with a knife or scissors, never cut trough the roots. Torn plant parts are never allowed dry out. As soon as possible plant it out in a pot of in the open-field so as to ensure a smooth regrowth in sufficiently nutrient-rich soil. Water the plants. In sunny weather we cover the plants to fight dehydration. Among others, used with chives, lemon balm, tarragon, lovage, oregano, sage, thyme, fennel.

Widely used technique with perennials and herbs. Also used to rejuvenate the plant. Also shrubs such as Hypericum, Spiraea. Time: best immediately after flowering (new shoots). With late bloomers: divisioning in spring. VP with fleshy root collar: Astilbe and Hosta VP with spontaneous divisioning: Aubrieta, Campanula, primroses

Propogating with stems

most used method.

  • Ground layering: from the parent plant a branch bend
  • Air layering: good method, cumbersome and time consuming

Aloysia, Ficus, Hamamelis, Magnolia, Rhododendron, lilac

  • Ground layering by the top: blackberry, raspberry, kruidbes, Japanese wineberry, black currant

Digging in

Used with ericaceae: Plants do not develop pretty however. A mature plant is extracted from the soil with a big root ball and then buried deep into an airy mixture in which only the young tops are left above ground. These will start to root.

Stem cuttings

Most used method, most economicly intresting method for many plants General rule: cuttings of herbaceous plants in spring cuttings of woody plants: in the resting periode

  • Choice of cuttings
  • mother plant needs to be cut back significantly to attain a a variety of young twigs
  • season plays a major role: woody cuttings in spring just after the buds begin to sprout, in autumn there is less chance of success but stronger material is attained that will dry out less quickly
  • heat: too hot; development of growing point but no root formation

cool above ground, hot below ground

Leaf bud cuttings

of evergreen plants possible with any type of stem, woody, semi-woody, herbaceous Aucuba, Ceanothus, Daphne, Elaeagnus, Cherry laurel taken from matured stems that are almost completely woody, have leaves and therefore no complete resting period. Time: end of summer, early autumn

Heely stem cuttings

a young side shoots pulled from the parent plant in which a heel (= a piece of bark) is torn along. Reason: increased density of cells with growth opportunities in cambium. Very good for plants that require a longer time to root. Eg: Buxus

Herbaceous top cuttings

Not yet matured and ripened off branches. Are very fragile but root fast. The younger the shoot, the faster they will catch on. Herbaceous shoots develop during growth and lignify as they get grow older. Herbaceous shoots are taken from rapidly growing top shoots in the spring . It is done the minute the buds start to grow and when the root formation is very active. Later is also possible, but then we need to climatise the cuttings as they are very sensitive to dehydration. When a cutting has wilted, there is even no more root formation. Swell in water. Perovska, Hypericum.

Halfwoody cuttings

more woody cuttings berries. Ceanothus, Chrysanthemum, Delphinium, Forsythia, Geranoum, Philadelphus. Time: end of spring when growth begins to weaken.

Almost matured cuttings

Deutzia, Cornus species with colored bark At the end of the growing season, stronger, thicker cuttings much growing strength but increased risk of dehydration

Woody cuttings

With plants with strong growing strength: Salix, Cotoneaster, poplar, wild roses, ornamental plums, Spiraea, Viburnum, ... Made from strong shoots. Time: in autumn after the leaves have fallen off, at the formation of the cork layer between leaf and stem. Length: 25-35 cm. Top: Oblique. Bottom: straight

Cuttings of semi-shrubs

Some low growing plants, often herbaceous, are called semi-shrubs: Artemisia, Hypericum calycinum, lavender, rosemary, rue, sage, santolina Cutting back in winter to obtain strong shoots. End of summer, preferably cut-off non-flowering shoots, otherwise cut-off the flower

Notes

Vegetative propogation Roots: by adventitious buds on the roots Root propagation: somewhat larger pieces of the root are cut into pieces, they are planted and left for some time (wound can then dry) and planted (this technique is mostly done with tuberous roots)

air layering: soil is put unto one-year old twigs (not with woody stems)

Bulbs: left to lie for a while until the bulbs become well visible

stem cuttings: only with very young twigs

Period:

  • herbal cuttings (woody plants) : (for temperate climate countries) spring and early summer (may-june), remark: not strong, fragile, do root rapidly
  • woody cuttings: late summer, fall (for non-decidious plants) or winter (for decidious plants)

types of cuttings: leaf bud cutting (eg with vitis vinfera, ...) or stem cutting (oblique cut above the bud for the top, traight at the bottom)

head stem cutting is not equal to a stem cutting

cutting with a heel: the heel contains more auxines, cauing it to root quicker

fungicide: will slow down the rooting at temperatures above 15-20°C

a too wet space to do the cutting in is also disadvantagous, plant pots also need to be placed off the ground to allow moisture to ooze out

note: stem cuttings can be cut trough slightly (upto the cambium) at the bottom on both ends to root more quickly

head stem cutting: top of the head needs to be cut off (decays quickly)

woody cuttings: old wood needs to be cut in winter and can be planted with the head slighly above the soil (eg raspberry)

Source

This article is made using information from the coursebook: Cultivation techniques
Part 3: PLANT PROPAGATION
Course from: 1st year of Herbalism
Course year: 2005 - 2006
Education center: Syntra, Asse-establisment
Teacher: Leo Van Crombrugge

Cookies help us deliver our services. By using our services, you agree to our use of cookies.