It wouldn’t be an overstatement to say that photosynthesis is one of the most important natural mechanisms of our world. It is the process by which most plants and a few other organisms harness light energy to create nutrients. While the overall concept of photosynthesis is fairly simple, it is a complex topic that even the experts still don’t fully understand. Even a basic understanding of the process, though, can help ensure your plants stay healthy and happy.
Photosynthesis begins with a plant absorbing light energy. With this, they convert carbon dioxide, water, and minerals into oxygen and energy-rich organic nutrients. Not only is this a vital process for the plants themselves, but it is also the foundation for life on Earth. Green plants are the base of food webs and all higher life-forms rely on them for food, oxygen, or both.
During photosynthesis, the plant creates many organic products. Of these, the most important are carbohydrates like glucose. Amino acids, proteins, lipids, pigments, and various others are the result of photosynthesis, too. In this way, the process is extremely similar to how humans get their nutrients from their food.
Two sequential stages make up photosynthesis: light-dependent reactions and light-independent reactions. In the former, the plant’s chloroplasts absorb light, converting and storing it. Then, light-independent reactions take the energy from the light-dependent reactions to form carbohydrates and other important compounds. While they don’t use light as a reactant, the light-independent functions can’t occur without the stored energy from the light-dependent reactions.
While photosynthesis is incredibly common in the plant world, not every plant uses it. Most plants that use other methods are parasitic. For example, the ghost pipe is a mycoheterotroph. This means that it parasitizes a tree or other large plant that uses photosynthesis. Similar plants include root parasites like the corpse lily or stem parasites like Thurber’s stemsucker. Despite popular belief, carnivorous plants like the Venus flytrap can perform photosynthesis.
You can influence photosynthesis by adjusting a few factors. By harnessing this knowledge, you may be able to improve your houseplants’ growth. The rate of photosynthesis generally increases at higher light intensities. However, once the light reaches “saturation,” more intensity no longer helps the process and may even hinder it. Different species have different light saturations and may respond differently to certain wavelengths. This partly explains why gardeners describe plants as needing partial shade or direct light — their light intensity saturations are different.
Another contributing factor to the rate and efficiency of photosynthesis is the availability of carbon dioxide. Plants use carbon dioxide as the carbon source for organic compounds. By increasing carbon dioxide concentration, you can increase the rate of these reactions — and you may not need to do it yourself. The average carbon dioxide in the air is steadily increasing from the increased combustion of fossil fuels, cement production, and land changes. This means that all plants are performing photosynthesis faster than they were centuries ago.
You can also affect the rate of photosynthesis by changing water availability. As you increase light intensity, water evaporates more quickly. In the natural world, this slows photosynthesis. However, a gardener can provide their plants with as much water as they need. Water is not only important for photosynthesis but also temperature regulation. Higher temperatures use more water and slow photosynthesis, so it’s important to find the right balance between water availability, temperature, and light intensity.
Plants need tons of nutrients to thrive. Many of these come from minerals in their soil, which is why we use fertilizers. Nitrogen, phosphate, iron, magnesium, calcium, and potassium are just a few of the minerals plants need to perform photosynthesis. Without the proper level, plants can’t create amino acids, proteins, or other essential compounds. Some species also require manganese, copper, and chloride.
If you imagine photosynthesis as the plant’s food source, it’s easy to understand how a lack of photosynthesis would affect a plant. Think of the human diet. If we eat fewer calories than we burn, our body burns some of the energy we stored away as fat. Plants also store excess energy and rely on those stores when they can’t perform photosynthesis. Large trees can live off of these stores for years while smaller plants may only be able to last a short while before wilting or dying.
While some steps of photosynthesis remain unknown, humans began to explore the process during the 17th century. Jan van Helmont was one of the earliest researchers to learn that plants gain mass not just from the soil but water, as well. From there, many scientists steadily built on available information to expand their knowledge of how plants use light and oxygen. In 1893, Charles Reid Barnes proposed two terms for this process, one of which was photosynthesis. Research in the 1900s dramatically improved our understanding of photosynthesis, its requirements, and its products.
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