Let's get started. Your plant needs carbon dioxide to breathe, it needs light to carry out photosynthesis and thus regulate its energy balance, but what else should you pay attention to?... Exactly!
Plants, like humans, depend on nutrients to survive. In this blog article we bring you closer to the topic of plant nutrients, how they are absorbed and what they do.
People eat several portions of food every day in order to manage their substance and energy balance. Each of these meals contains a wide variety of nutrients such as proteins, carbohydrates, fats, vitamins, fiber, etc. The plant also needs sufficient nutrients. However, the plant is mostly sedentary. So she is dependent on using nutrients in her immediate environment.
Your plant, just like you, needs nutrients in various concentrations in order to lead a vital life. A distinction is made between macronutrients (main elements) and micronutrients (trace elements). The difference lies in the amount of substances absorbed. Your crop probably needs the most nitrogen, followed by phosphorus, potassium, magnesium, sulfur and calcium. Of course, carbon dioxide, oxygen and hydrogen must not be missing, but these should be available in sufficient quantities.
On the other hand, there are the less required nutrients, the trace elements. This includes iron, copper, boron, zinc, molybdenum, silicon and manganese. All of these nutrients fulfill a wide variety of tasks, just as they do in your body. Beginning with cell building blocks, through docking points for enzymes to energy suppliers, these elements cover all tasks in plant and human life.
Plants take up nutrients not only through the roots, but also through the stomata in the leaf. In order to bring these nutrients to their desired place, the plant has a network of vessels, just like us humans, which distributes these substances in the plant body. What we call the bloodstream is called the phloem and xylem in plants. The phloem is responsible for the distribution of nutrients and the xylem for the transport of water.
Tip: The nutrient supply of the plant is of course related to its water supply. Here you can read how to water houseplants correctly.
In this article
Sink and source organs: give and take
Source organs are the power plants in plant tissue. They are older leaves that, due to their large surface area, produce more vital carbohydrates than they actually need. Via the phloem, these then reach places where they are needed, such as blossoms, fruits and young leaves. These places, where the transported carbohydrates are then metabolized, are called sink organs.
Mobile and immobile nutrients
In addition to the macro and micro elements, a distinction is also made between mobile and immobile nutrients. Mobile nutrients are nitrogen in the form of nitrate, phosphorus as phosphate, potassium, magnesium, chlorine, zinc and molybdenum. Immobile nutrients are calcium, sulfur, iron, boron, and copper.
If yellowing occurs on older leaves, you could bet on a lack of mobile nutrients, since these are transported to the shoot tips of young leaves.
Ph value dependency and mutual blocking of nutrients
The pH value provides information about how high the acid or base content is. It is read on a scale of 0-14, with 0-6.4 being acidic, 6.5-7.5 being neutral and 7.6-14 being basic. (Pure water has a pH value of 7) It is created in your pot by the composition of plants and microorganisms, as well as organic (e.g. humus) and mineral substances. Different plant species prefer different acidic media to grow.
At different pH values, the nutrients have different difficulty in dissolving for the plant. Thus, nitrogen is best absorbed at 6.5-8, magnesium and calcium at 6-8, and iron at 4-5.5. As you can already see, nitrogen, magnesium and calcium can be combined wonderfully, but the supply of iron falls by the wayside when the pH value increases, since it is more difficult or no longer available for the plant. That's why it's important that you keep your plant in a medium where it can get all the important nutrients out of the soil as easily as possible.
Another phenomenon that can promote deficiency symptoms is the mutual blocking of nutrient elements. An oversupply of calcium inhibits the supply of iron, magnesium and potassium. When fertilizing, you should make sure that all nutrients are supplied in sufficient concentration.
Tip: An excess of nutrients in the soil can also lead to a lack of some nutrient elements. You can read how to treat over-fertilization correctly in the corresponding link.
Chlorosis and necrosis: One leads to the other
Chlorosis refers to the yellowing of leaves due to the failure to form or break down the chlorophyll that is essential for survival. This leads to shedding of affected leaves and fruits, and stunted growth. There are various causes for this problem. On the one hand, it can be attributed to a lack of nitrogen, sulphur, iron, magnesium and boron, on the other hand, it could also have stress-related causes, such as strong temperature fluctuations or a virus attack. Chlorosis weakens your plant and makes it more susceptible to fungal, bacterial and viral infections.
The necrosis is then the final stage of a chlorosis and describes the death of the affected area.
The law of the minimum
The law of the minimum states that the growth of the plant is limited by the factor that is least present. This can be light or water on the one hand, but also the nutrients that a plant needs on the other.
Three nutritional elements
We will now introduce you to three of the most important macronutrients. How are they absorbed and transported in the plant? What are they needed for? And how do you recognize a lack of this substance?
nitrogen
Nitrogen is one of the most important elements. It is needed in photosynthesis as a chlorophyll building block, to build every cell and every strand of DNA, and for growth. The plant needs the most nitrogen during its vegetation period, but it cannot do without it in the generative phase either.
Nitrogen is usually available to the plant in various forms in the soil and in the air. These forms differ in their mobility in the plant as well as in the soil to each other. The plant prefers nitrate (NO3) to nitrite (NO2) and ammonium (NH4) because of its better solubility. When nitrogen is taken up by the leaves, the reverse is the case. The leaves absorb ammonium faster than nitrate.
As already mentioned, a lack of nitrogen occurs primarily on older leaves due to yellowing. The tips of the leaves turn reddish-violet and the leaves that are still young remain small, narrow and pale green. A nitrogen deficiency leads to chlorosis and in the worst case to necrosis.
Phosphorus
Phosphorus, along with nitrogen, is one of the most important elements that plants absorb from the soil. It is absorbed through the roots in the form of phosphate and serves the plant as an energy carrier and aid in photosynthesis and cell division, as well as images for enzymes, flowers, fruits and seeds. Signs of phosphorus deficiency include stunted growth, stiff, deformed and reddish leaves, a lagging root system, and delayed or absent flowering.
Potassium
Potassium, or Kali for short, is the third most important element in the group. It is used for frost resistance, to stabilize the plant tissue, activate plant enzymes, participate in the metabolism and regulate the water balance. You can recognize a potassium deficiency when the leaves, despite a good water supply, begin to become limp and dry up from the edge.
Tip: NPK fertilizer stands for the three macronutrients nitrogen-phosphorus-potassium.
We hope that this little digression was able to bring you closer to the plant-related problems with nutrient absorption. What was it about?
- Characterization of nutrients in macro and micronutrients, as well as in mobile and immobile
- What affects nutrient uptake in the soil
- How the plant distributes nutrients
If you want to learn more about fertilizing plants, take a look at Fertilizing Your Houseplants: How To Do It Right
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