Plant tissue culture or in vitro culture (also called micropropagation) is a method of plant propagation under “in vitro” conditions developed in the 1960s. In vitro is borrowed from Latin and means something like in the glass. A distinction is made between meristem cultures and organ cultures.

In meristem cultures, the cells from the plant’s meristem are used. A meristem is a so-called formation tissue, which consists of undifferentiated cells. There are certain parallels to animal stem cells, which will not be explained in detail here.

Meristems are located on the shoot tips (shoot apical meristems), side shoots (subcutal meristems), and root tips (root apical meristems). In contrast to the permanent tissue (parenchyma), the meristem consists of cells that are still capable of mitotic division. Here there is a unique ability of plant cells, the so-called totipotency. This means that a complete organism can be formed from individual cells of the meristem tissue. In addition to the meristem cultures, there are also so-called organ cultures. Here, not only individual cells are removed from mother plants, but complete, small plant parts z. B. side shoots, shoot tips, single nodes, seeds, or leaves used as starting material.

Benefits of Plant Tissue Culture

First and foremost, plant tissue culture guarantees the cultivation of healthy, virus-free young plants because the meristems, as the youngest plant tissue, are not yet infected by viruses. This is important in the so-called phytosanitation of plant varieties that have lost their vitality due to a virus attack and thus enables them to be kept virus-free. The plants propagated in these processes are genetically identical (true to the variety) to the mother plant and in this way, many new plants can be bred from only a small amount of starting material. This is particularly important when preserving rare or old plant varieties that are difficult to propagate using conventional methods.

Plant tissue culture is therefore mainly used to build up large stocks of economically important useful and ornamental plants. Since the plants are grown under sterile conditions, they are largely free of pathogens and pests and can be exported without any problems.

So how does this in vitro culture take place?

First, so-called primary explants are removed from selected mother plants. These are tiny pieces of tissue from which complete plants are later developed.

The second step is disinfection. Any externally adhering germs are killed. The explants are then placed on an appropriate nutrient medium in a sterile environment.
The stocks are checked regularly and sorted out if necessary.
The plants resulting from these primary explants are further placed on a solid nutrient medium and the plants continue to develop there.

Composition of the cultural medium

Although the nutrient medium can be specially tailored to the plant species, there are basic common components for all nutrient media that are essential for plant growth. These components include macro and micronutrients, vitamins, hormones, etc.

Macronutrients include nitrogen (N), phosphorus ℗, potassium (K), magnesium (Mg), calcium (Ca), and sulfur (S).
Micronutrients include Manganese (Mn), Boron (B), Zinc (Zn), Molybdenum (Mo), Copper (Cu), Cobalt (Co), Iodine (I), and Iron (Fe).
In addition, the following vitamins are added: nicotinic acid, pyridoxine, thiamine, biotin, folic acid, and glycine.

Phytohormones are also an important part of the nutrient medium. With the appropriate composition, the growth processes in the tissue cultures can be controlled and specifically promoted, for example, root formation. The concentration and the relationship between the hormones are also important. The most important phytohormones include auxins (root hormones), which stimulate root formation, and cytokinins (growth hormones), which promote branching. The composition of all these substances can be used to steer organogenesis in the desired direction. Giberelin and abscisic acid are also sometimes used because they have a positive influence on the growth of some plant species. The nutrient medium also consists of sugar, water, and agar, which is used as a gelling agent.

In vitro plants in aquaristics

Plants from tissue culture are becoming increasingly popular among aquarists and especially plant dealers. The range of offered meristem boxes with aquarium plants is getting wider, which is not without reason.

In vitro plants have several advantages compared to normally propagated, potted plants.

• While potted or bundled goods may be infested with snails, in vitro plants are guaranteed snail-free.
• No parasites, algae, or germs are transmitted either. The use of such sterile plants is particularly recommended for aquariums with sensitive invertebrates.
• Another advantage is that meristem plants do not contain any residues of pesticides or algaecides, which would be very harmful to shrimp or crabs.
• Although the meristem plant pots are smaller than the standard pots, they contain many more individual plants.
• These grow quickly because the roots are healthy and fully developed in the nutrient medium.
• Compared to the emersed plants, in vitro plants do not lose their leaves after being planted underwater.
• Another advantage (especially for us plant traders;-)) is that these plants are easy to transport and do not have to be planted immediately upon receipt. With sufficient light, at room temperature, and in an unopened cup, the quality is retained for several weeks.
• Almost all potted plants grow in Rockwool. When transplanting, it is sometimes unavoidable to damage or trim the roots. These problems do not exist with in vitro plants. With careful handling, root damage can be largely avoided.

In order to place in vitro plants in the aquarium, the following steps should be followed:

• Remove the plants from the cup and carefully wash out the nutrient substrate under running water. The easiest way to do this is to place the plants in a container of aquarium water for a period of time, around 1 hour, and then gently wash off the softened nutrient jelly.
• The clean plants can now be divided into 6-8 parts with scissors. Depending on the species, you can also carefully divide the plants into several portions with your fingers.
• Carefully plant the individual sections in the aquarium soil. Long tweezers should be used for this and the plants should not be planted too densely in accordance with their final size in the substrate.

Everyone who owns an aquarium knows them: sooner or later algae can be found in every tank. While some species of algae, such as green algae, are tolerated or even welcome guests, others drive aquarists to despair – especially if they persist, overgrow panes and decorative objects, or even affect plant growth. With a little background knowledge, however, it is not that difficult to identify and eliminate the causes of increased algae growth. In this article, we would like to give you some important tips on combating and preventing algae.

The following types of algae can occur in the aquarium:

• Green algae (thread algae, spot algae, floating algae, hair algae, …)
• Red algae (brush algae, beard algae)
• Brown algae (diatoms)
• blue-green algae

What are algae and how are they formed?

Most algae, as we know them from our aquariums, belong to the aquatic plants, but not to the higher ones, but to the so-called lower ones. (An exception is the slime algae, which are cyanobacteria.) Algae have a lot in common with aquarium plants: they share a habitat and carry out photosynthesis, i.e. converting nutrients into plant matter with the help of sunlight. In order to grow, they need exactly the same things as aquatic plants, namely nutrients and light.

However, algae are less demanding and much more adaptable than higher plants. Therefore, they still feel comfortable there, where aquarium plants already have difficulties, reduce their growth or even die. And this is exactly the reason why algae can spread rapidly when an imbalance has set in the aquarium and make it difficult for the aquarium plants to keep the upper hand or regain it. If you create the conditions for good plant growth in your aquarium, algae hardly stand a chance in the long run.

In short: you will never have a completely algae-free aquarium. The good news is that this is not necessary or desirable. It is not possible to protect an aquarium from algae being “introduced”. Algae spores can always be found somewhere – in the transport of water from purchased fish, on plants or decorative material, and even in the air.

This is perfectly normal and usually doesn’t have much of an impact. Because algae only gain a foothold where plant growth is disturbed. And some types of algae, such as the popular moss balls, are even cultivated and lovingly cared for by some aquarium owners. Just like aquatic plants, algae produce oxygen, have a positive influence on the water chemistry, and offer the aquarium inhabitants a natural habitat.

Avoid algae, improve plant growth: a checklist

Would you like a visually appealing aquarium without disturbing algae growth? Or have you discovered algae that are starting to multiply in your tank? Then you should use our checklist to check the following points.

• planting of the aquarium
• lighting conditions and lighting
• water quality and nutrient supply
• stocking and feeding

Increased formation of algae is always a sign that there is an imbalance in the aquarium or that certain conditions are not ideal. The above points are the main ones to pay attention to. We will explain this to you in more detail below.

Planting and health of aquarium plants

Basically, lush, healthy plant growth is the best weapon against unwanted algae. Aquatic plants absorb nitrate and phosphate from the water and are essential for healthy water chemistry. At the same time, they compete with algae for food, so that they do not multiply uncontrollably in a tank with good water quality, appropriate lighting, and nutrient supply for the plants.

Therefore, when purchasing aquarium plants, you should always make sure that you choose varieties that can grow optimally under the given circumstances. If you occasionally have to deal with some unwanted algae in your aquarium, one of the simplest solutions is to use fast-growing aquarium plants. Bunch plants or stem plants, in particular, have proven themselves here, since these are mostly species that adapt easily, grow quickly and represent strong competition for the algae.

Lighting conditions and lighting

Lighting also plays an important role in the development of algae. Basically, the aquarium should be set up in such a way that no daylight falls on it. The light that shines on the aquarium from the window is sufficient to stimulate algae growth, but cannot be used by the plants. Therefore, always make sure to place the aquarium in a place where it does not receive direct natural light. You should select the lighting for your aquarium in such a way that the light intensity is sufficient to provide light-hungry plants in all areas of the tank with sufficient water.

It is also important to replace fluorescent tubes regularly, as the luminosity decreases over time and the light spectrum changes. A rule of thumb is that aquatic plants thrive in long-wave red light, while algae prefer blue and UV light. Most aquarium owners adjust the lighting time of their tanks to roughly the length of a tropical day since this corresponds to the natural habitat of most plants and animals that are kept in aquariums. In connection with the topic of algae, it is important not to illuminate the pool for too long; a time of ten hours is the upper limit. With some types of algae, it can also help to reduce the lighting duration for a certain time or even to start a so-called “dark cure”.

Water quality and nutrient supply

The water quality, especially the nutrient content, is of great importance when it comes to the growth of algae as well as aquarium plants. If algae suddenly multiply rapidly, this is usually a sign of an imbalance in the aquarium. You should look for possible causes. Relevant water values ​​can be easily determined with the help of water tests, which you can purchase in specialist shops, mostly as droplet tests. However, many aquarium dealers also offer a determination of the most important water values, often free of charge, sometimes for a small fee.

While very undemanding plants can already feed themselves well on the substances that fish or bacteria produce in the tank, many aquarium plants need fertilizer, which they absorb from the substrate via the roots or from the water via the leaves. In addition to CO2, the most important nutrients for plants include nitrogen (N), phosphorus, iron (Fe), and manganese (Mn). However, demanding aquatic plants also need micronutrients such as copper, zinc, molybdenum, and borate, which are contained in special fertilizers, for healthy growth.

Stocking and feeding

If your aquarium is overloaded with fish, this not only has a negative effect on their well-being but also on that of the plants. The accumulation of substances that cannot be completely broken down by aquatic plants and bacteria creates a rich supply of nutrients for the algae and creates a difficult environment for healthy plant growth.

ATTENTION: Feed the animals that you keep in your aquarium only enough so that no residues remain in the water. The food should be completely eaten up within a minute and not spread unnecessarily in the water and pollute it.

A very efficient method of keeping algae in the tank to a minimum is to include a few algae eaters in the aquarium when stocking it. Many species of fish, shrimp, or snail-like eat algae and can help keep it at bay. Since these animals only consume the algae and not the aquatic plants, this is an excellent method when it comes to giving the aquatic plants a decisive advantage over their food competitors, algae.

What are your experiences with algae? We look forward to your tips and comments!

Customers often ask us whether our aquarium plants are cultivated submersed (submerged, i.e. underwater) or emersed (emerged, i.e. above water). I can answer the question with a clear “it depends”. ?

What are submerged aquarium plants?

In nature, most of the plants suitable for aquaristics grow above water. So these are usually emersed plants. They thrive in swampy terrain or on the banks of bodies of water. However, these plants are able to develop underwater leaves in the event of permanent flooding and then continue to live submerged. However, they grow more slowly under the water surface and the leaves are more sensitive to mechanical stress. Only the actual aquatic plants are real submerged aquarium plants. They cannot live permanently emerged and are dependent on water as a habitat. These include, for example, the species of the genera Vallisneria, Myriophyllum, Cabomba, and the water lilies. But also the well-known hornwort (Ceratophyllum demersum) and waterweed (Egeria densa) always grow submerged in nature.

Why are the plants produced emersed and not submerged?

The production of emersed plants is significantly cheaper than rearing them underwater. Like all production companies, nurseries are also subject to enormous cost pressure. Heating and lighting costs have almost doubled in recent years. Many smaller nurseries had to give up or relocated their entire production to Asia.
However, some large and specialized nurseries in Holland, Germany, and Denmark have survived by consistently converting to emersed production processes, modernizing and automating their production. Today they supply high-quality aquarium plants from European production. However, all plants that only grow submerged are also bought here from Asia.

Do submerged plants grow better in aquariums than others?

https://youtu.be/JFOloB48ggU

No, because the corresponding plants are also adapted to changing water levels in nature. It is also a myth that they first lose all their leaves and then create new underwater leaves. Leaves that have grown above water also contribute to photosynthesis in the aquarium. However, if the plant remains under water for a longer period of time, it will in fact gradually develop better-adapted underwater leaves. The existing leaves are subject to the normal aging process and die off over a period of a few weeks to months.

In many genera, however, the submerged leaves differ fundamentally in appearance from those that have grown above water. The best example of this is the round-leaved Rotala. While the emersed leaves are round (Latin name!) and green, elongated, bright red to red-brown leaves grow under water. Of course, this looks strange at first a few weeks after planting. However, aquarists only use the tips of the shoots for propagation, so the plant only consists of submerged stems after the first regeneration at the latest.

A clear distinction between emersed and submerged aquarium plants using the example of Echinodorus xbarthii (Barth’s sword plant)

Another clear example of the different appearance of submersed and emersed specimens is the sword plants. The “air leaves” of sword plants look almost exclusively mottled green or green-brown. Underwater, on the other hand, the plants are transformed into colorful treasures. Bright red, purple, or flaming red leaves gradually emerge from the rosette. After a few weeks, the plant is no longer recognizable.

But not only the color of the leaves changes. While emersed echinoderms often have elliptical, ovate, or lanceolate leaf shapes, the leaves of submerged specimens are significantly narrower, often band-shaped or linear. Many varieties get slightly wavy leaf edges under water.

Many German names of our aquarium plants indicate the underwater forms. For example, if the aquarist has a “ruby red sword plant” in front of them that has grown in a greenhouse, then they sometimes ask themselves the question of the origin of the name. Only after a few weeks of aquarium culture does it become clear what the namesake had in mind.