Kommentarer til »Hvordan sår jeg et magnolietræ?«

Til Jens Thejsen.

Du skriver at magnoliens frø skal have én el. to kuldeperioder. Er det muligt at give frøene disse kuldeperioder på samme vis, som ved nogle frugttræer, ved at ligge dem i en fryser? Hvis ja! Hvor længe skal de ligge. Hvor koldt skal de MIN. og MAX. ligge.

Hej John!

Det kan lade sig gøre at bruge en fryser, men det her været lidt tilfældigt hvor lang tid jeg har haft dem liggende, så jeg ved ikke nøjagtig hvor lang tid. Vi må have en magnolie freak på banen.

Hej Jens. Hvad med Steen Porse? Det er simpelt hen uhyggeligt hvad den mand ved. Har haft ham som lære på DCJ for et år siden på 1. hovedforløb på Anlægslinien.

MVH. John

Hej Jens
Dette er hvad jeg selv har fundet frem til Vedr. Frøformering af Magnolie og stammer fra bogen "Magnolias" skrevet af Dorothy J. Callaway.

ISBN nr. er 0 7134 7569 2

Bogen har jeg fået tilsendt fra (Danmarks Veterinær og Jordbrugs-bibliotek) via mit eget biblitek i Vejle.

Mvh John Rømer
Håber at du / i kan få noget ud af nedenstående.

SEED PROPAGATION

Magnolia fruits ripen in late summer and early fall, and seeds are collected when the fruits split to reveal the bright red or orange seed coats. The seeds, when released, are suspended from the fruit on almost invisible funicular threads (Figure 2.5).The seeds will hang in this way for only a day or two before dropping to the ground. Birds and small mammals commonly eat the seeds soon after they have fallen, so it is easier to collect the seed before it is released. Alternatively, a paper bag or nylon stocking may be secured around an entire fruit aggregate so that seeds are contained. If the fruits are picked before they are completely ripe, they must be placed in a warm, dry spot for several days until the follicles open.

Magnolia seed coats are three-layered. The outer layer is a brightly colored, oily, fleshy covering. This outermost seed coat provides an impermeable barrier which prevents the seed from absorbing enough water to germinate prematurely. In addition it acts as a mechanical barrier to gas exchange and embryo expansion and may contain chemicals which also inhibit germination. In nature this coat either degrades after the seed falls to the ground, or is removed when the seed passes through the digestive tract of a bird or small mammal. Beneath the outer covering is a hard, bony, dark- or light- colored inner layer. This coat gives mechanical protection to the embryo and does not inhibit germination. The third layer is a thin membrane. It surrounds the fleshy endosperm, or "food reserve" for the small, undeveloped embryo embedded within. The embryo cannot mature and the seed cannot germinate before the fleshy outer seed coat is broken down and water is absorbed by the seed. After the outer layer has been destroyed, a period of chilling is required to break seed dormancy, after which the embryo develops and expands until germination occurs.

To remove the outer coat of collected seeds, soak them in water for up to three days, then squeeze the seeds or rub them across a screen. Several propagators remove the seed coats by placing seeds into a household blender after replacing the blades with rubber or covering them with plastic tubing, tape, or some other material that will protect the seed from cutting injury. Once most of the coat is removed, the seeds can be washed in water with a mild soap to remove the oily film. then rinsed several times. Since the outer seed coat prevents the seed's water loss as well as absorption, the seeds must be kept moist once the coat is removed. If the seed dries out, viability is reduced or completely lost. Many growers test viability by placing seeds in water, discarding any that float. Although this is not a foolproof test, it does give some indication of viability.

Cleaned seeds may either be planted outdoors in the fall or stored over the winter and planted in the spring. Before planting, wash the seeds again, using dishwashing detergent to remove any remaining oily coating. For fall planting, seeds are sown in a

SEED PROPAGATION

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moist but well-drained medium. My sowing medium preference is a peat and perlite mix or soilless potting mix. Magnolia seeds are prone to rot in ordinary garden soil. After sowing, place outside and mulch with leaves or straw to retain moisture. A 2- to 4- month cold period of 33–40op (0.5–4.4 OC) is required for seeds to break dormancy.

If the seeds are to be planted in spring, proper cold treatment and storage must be employed. Cleaned seeds should be rolled up in a "sheet" of damp sphagnum moss, placed in plastic bags, and kept in a refrigerator at 33–40op (0.5–4.4 OC).Browse (1986) suggests a ratio of four parts sphagnum to one part seed, placed in a gas-permeable bag such as an ordinary polyethylene food storage bag. Some people use damp paper towels instead of sphagnum moss, but one experienced propagator called paper towels an "enemy of the gardener, certain to bring mildew and molds:' With that warning, it is probably best to avoid their use. The seeds should be rinsed in a fungicide or chlorine bleach solution prior to bagging to protect them from diseases. The bags should be sealed tightly to retain moisture. The duration of cold required to break dormancy depends on species and environmental conditions, and can range from 6 to 17 weeks. In general, 3–4 months of cold treatment are considered optimum. During this time it is important that the seeds be checked every few weeks to spot any obvious fungal growth and to maintain a moist but not soggy soil environment. If seeds cannot be planted immediately after cold treatment, leave them in cold storage at 35–40OP (0.5–4.4 OC).Do not allow them to dry out.

In the spring, usually April or May, sow seeds about 0.5 in. (1.3 cm) deep in pots or flats. Potting media include peat moss, sand and peat mixtures, peat and perlite mix- tures, sphagnum moss, and other soilless potting mixes. Whatever medium is used, it is important that it be well drained and preferably sterile. It is best to cover the pots or flats with plastic or glass to retain moisture and humidity.

A practice many growers use is to sow seed directly into containers 8–12 in. (20.3- 30.5 cm) deep to allow for the eventual, vigorous root system. This practice eliminates the need to transplant seedlings into pots after the first true leaves have formed. Other propagators germinate seeds in plastic bags and plant them in pots or flats after germination.

Seeds germinate at temperatures of about 65–75OP (18–24°C). Germination usually takes place in a few weeks, but as much as several months may be required. After germination, place the seedlings in a sunny location and remove the plastic or glass covering. Transplant seedlings into pots after the first true leaves develop.

In some cases, germination requires 1–3 years after sowing. The vast majority of seeds germinate in the first year, and few commercial propagators keep sowings past one year. The percentage of seeds not germinating within a year that might eventually germinate is generally an unknown.

Protection from birds or small mammals interested in making a meal of the seeds or seedlings, and protection from severe climatic conditions may also be necessary. To protect seedlings from birds or small mammals, put screen material over the pots or flats. Another method is to build a box out of 2 by 4's and screen wire to set the pots or flats in. The screen material will also provide some necessary shading for seedlings in extremely hot weather. The box arrangement provides some wind break under strong wind and desiccating conditions.