Many people have noticed the yellowing of leaves in their garden plants, but a few know about the reasons and its impact on photosynthesis. The presence of a few yellowish spots on the maidenhair fern indicates the inability of leaves to produce green color due to a lower amount of chlorophyll.
How Do Yellow Leaves Affect Photosynthesis? Yellow leaves affect photosynthesis because carotenoids and xanthophyll cover the chlorophyll pigment and affect the light absorption rate. They absorb light from the different spectrums, while chlorophyll absorbs red and blue light. Moreover, these accessory pigments transfer absorbed energy to chlorophyll for photosynthesis. Yellow leaves perform photosynthesis at a slower rate; also, the purple, orange, and red colored leaves absorb light due to the presence of chlorophyll.
A healthy plant has green-colored leaves and carries out photosynthesis efficiently.
Plants cannot speak about their problems and tell you what is happening inside them. Instead, they express their issues through physical changes such as wilting and color change.
Does leaf color affect photosynthesis?
You can see different colors of leaves, including yellow, red, purple, or brown, on trees present in your surroundings.
They appear different for multiple reasons, like nutrient deficiency, dryness, or an infection.
The rate of photosynthesis is higher in plants with natural green color, but the yellow leaves indicate that other accessory pigments dominate over a green color.
These accessory pigments are carotenoids available in hundreds of numbers that provide different shades of color to plant leaves.
It indicates that xanthophyll masks over the chlorophyll, reducing its ability to capture light and prepare food.
However, purple and red colored leaves can still carry out photosynthesis in the daytime when light reaches their surface.
Furthermore, only green-colored organs can conduct photosynthesis when there is low light. Therefore, without chlorophyll, plants cannot complete their food-making process.
Can yellow leaves make their own food?
Photosynthesis relates to the process of producing food in the form of sugar for plants. They do not have sufficient green pigment as xanthophyll is hiding it behind.
It affects their ability to make food for their survival. However, chlorophyll is present in the leaf cells, which allows them to capture sunlight.
Xanthophyll absorbs sunlight and transfers it to the chlorophyll present behind it.
So, you cannot say that they cannot prepare their food because they can convert water and carbon dioxide into food by using energy from the sun.
Why do yellow leaves not affect photosynthesis?
There is a large concentration of chromoplasts in yellowish leaves, which are the structures for storing colorful pigments.
They synthesize xanthophyll and carotenes, or other pigments giving the yellow, orange, and red colored appearance to plant organs and store them inside compartments.
This process occurs in leaves that appear non-greenish in color. However, it happens slower than normal but does not stop completely.
The accessory pigments affect the absorption rate of energy and provide supplemental energy to chlorophyll.
It cannot provide the maximum amount of energy and absorb light from a spectrum other than those from which chlorophyll absorbs.
Furthermore, the light absorbing properties of accessory pigment differs from chlorophyll, which absorbs red and blue wavelength.
The antioxidant properties of these pigments are responsible for their protective behavior towards the leaf and prevent excessive exposure to sunlight.
Why do leaves appear yellow?
They can appear yellowish in color for multiple reasons, such as an infection or age and a damaged plant. In addition, the problem can be related to water and nutrients when the roots cannot transfer them upward.
Deficiency of nutrients
The deficiency of nutrients like manganese, nitrogen, potassium, and sulfur can make leaves yellow.
The presence of nitrogen below its desired range can make them lose the green shade of the inner side that can project outwards to the whole leaf.
When you see that edges are turning yellow, it means the plant is deficient in potassium. In addition, iron deficiency can cause this issue.
A change in color or younger leaves from green to yellow indicates that they are lacking in sulfur. You can provide fertilizers rich in nutrients and improve transport by keeping roots wet.
It indicates a water imbalance in it, or it is suffering from moisture stress.
Overwatering is associated with such problems, most commonly creating difficulty for roots to breathe.
It causes suffocation of the roots or water-absorbing organs that can act as a barrier to transport water and nutrients in the upper region of the plant.
In the same way, less water causes poor absorption of nutrients and makes plants deficient in some essential nutrients.
You can fix this problem by providing a recommended amount of water and using a pot with better drainage holes to remove the excess water quickly.
In addition, do not add water into the pot when the soil is still wet.
Age of plant
The age of a plant can be responsible for the yellowing of leaves as they cannot absorb enough light.
The rate of photosynthesis slows down in older leaves, while younger ones need to grow faster.
They are more prone to infection, which can cause them to change color quickly. So, a high infection rate can cause this issue.
Changes in temperature
You can observe the significant changes in the leaf color during the start of autumn or in late summer.
The temperature of the environment changes from hot to mild, so their color also changes.
A lower temperature is related to this problem, and long-term exposure to cold weather and no sunlight makes them appear brownish.
It is essential for photosynthesis, and they cannot survive without sunlight.
Provide a controlled temperature environment or a heat source during cold weather when the temperature is extremely low.
It is challenging for damaged root structures and root hair to transfer the nutrients to the upper parts of the plant.
When the size of the pot is smaller, and the roots grow outward, a compact structure of roots develops. Not only does it inhibit water and nutrient transport, but it blocks the transfer of oxygen.
The non-functionality of roots leads to the pale coloring of leaves. You can place a plant in a new pot when the roots begin to appear compact.
Remove unhealthy roots to improve the survival of the respective plant in case of infection or rotting, which changes the color of roots from white yellowish to a different one.
Do all plants with yellow leaves perform photosynthesis?
Almost all household plants perform photosynthesis even with non-greenish leaves due to the presence of chlorophyll in them.
They can absorb carbon dioxide and water, but red and purple ones can also initiate a chemical reaction using sunlight.
However, there is an exception for some plants which perform partial photosynthesis when they appear pale in color, like Bladderwort and Cuscuta.
In addition, Pitcher also exhibits this unique style of preparing food and relies on insects and other plant systems to get nutrition.
How to avoid the yellowing of leaves for improved photosynthesis?
You can avoid yellowing leaves for improved photosynthesis by maintaining the external environmental conditions.
Provide proper sunlight exposure after knowing about the requirement of plants and relating them to an age factor.
Younger plants or seedlings need more sunlight to grow well than older ones. So, you must maintain a light source so that chlorophyll captures enough light to prepare food.
Sun energy keeps them alive and fresh as they can prepare a continuous food source. Moreover, low and high water levels can disturb them.
It is better to fix a time for watering as missed water schedules can make them change their color.
Furthermore, check the nutritional quality of the plant as its malnourishment can lead to this problem.
Provide a good source of nutrients or a fertilizer by crushing it into a fine powder for better absorption. It improves the plant’s condition and health or keeps it green for longer.
What do people say about this?
I surveyed 527 people who have gardens in their homes and deal with multiple types of plants to learn about the phenomena of yellowing in leaves and their possible causes.
Out of 527 people, 311 people (59%) said it occurs due to the absence of sunlight, which affects the photosynthesis process, so they appear pale.
In addition, 142 people (27%) said that leaves lose their original color due to nutrient deficiencies like iron and magnesium.
While the remaining 74 people (14%) said moisture stress makes them appear yellowish.
Weather affects their color as a cloudy sky blocks sunlight from reaching plants and lightens their shade.
“I had seen yellowing in my garden plant during cold weather when there was no sunlight for a few days due to cloudy weather.”
Fertilizers provide a rich source of multiple nutrients that ensure the better survival of the plant.
“I have figured out the reason for yellow leaves: when they regained their original green color after getting nutrients from fertilizers.”
Overwatering has a negative impact on the healthy lifestyle of plants and poses stress of moisture that can bring changes in its appearance.
“Leaf color of my favorite tree changes when it rains heavily for a week as the soil was extremely wet to flush out the nutrients.”