What Is Photorespiration? Why Heat Slows Your Cannabis Down

Photorespiration is what happens when a plant's carbon-fixing enzyme, RuBisCO, grabs oxygen instead of carbon dioxide, burning energy instead of storing it. It runs alongside photosynthesis, the process by which plants turn sunlight into energy-rich sugars while taking in CO2 and releasing oxygen. The hotter it gets, the more photorespiration eats into growth, which is why it matters to anyone growing cannabis.

Photorespiration gets a lot less press than photosynthesis, but it's just as important. It works against photosynthesis, yet it's baked right into the same machinery.

It kicks in when the enzyme RuBisCO fixes oxygen rather than carbon dioxide, and it ramps up as the air temperature climbs.

The higher the temperature, the bigger the share of photorespiration. If it ever catches up with photosynthesis, the plant's growth can stall out completely.

Understanding photorespiration is key to getting the most growth and efficiency out of plants, especially with climate change pushing temperatures up. That's why studying and managing it matters so much for crop yields and for keeping ecosystems healthy.

What is photorespiration, exactly?

Photorespiration is a complex biological process that plants can't do without, even if it sounds intimidating if you skipped high school biology. Technically, it starts with a reaction catalyzed by the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase, better known as RuBisCO.

Instead of fixing carbon dioxide (CO2) the way it does in photosynthesis, RuBisCO fixes oxygen (O2), which produces 2-phosphoglycolate. That compound then runs through the photorespiratory pathway and ends up as 3-phosphoglycerate, an intermediate of the Calvin cycle.

Along the way, the plant releases carbon dioxide (CO2) and ammonia (NH3) and spends ATP and other reducing power. All that energy spent is why photorespiration is considered an inefficient process.

How photorespiration protects plants from stress

Inefficient as it is, photorespiration can play a big role in shielding plants from stress. By acting as an energy sink, it keeps the photosynthetic electron transport chain from getting overloaded and helps prevent photoinhibition, the light damage that slows photosynthesis down.

That safety valve matters most under stress conditions that cut down how much CO2 the plant can take in.

Photorespiration also supplies building blocks for other metabolic processes. For example, the glycine it produces is key for making glutathione, an antioxidant that protects plants from oxidative stress.

This becomes vital under drought, high salt levels and intense light, the everyday conditions alpine plants deal with.

Bottom line: photorespiration is expensive in energy terms, but it plays an essential role in protecting cannabis plants from harsh conditions, helping them keep working and growing when the environment gets rough.

Why does photorespiration happen?

Photorespiration happens because of how RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) works. This enzyme is essential to photosynthesis because it fixes carbon dioxide during the carbon-fixation stage.

But as temperatures rise, RuBisCO changes its behavior and starts acting as an oxygenase instead of a carboxylase. In plain English: instead of fixing carbon, the enzyme grabs oxygen, and that's what sets photorespiration in motion.

Why photorespiration and photosynthesis both matter

Photosynthesis and photorespiration are both fundamental to how plants work and survive. Photosynthesis lets plants convert sunlight into energy-rich organic compounds, producing oxygen and laying the foundation for life on Earth.

Without photosynthesis, most plant life wouldn't exist, and animal life would take a massive hit too from the lack of oxygen and basic nutrients.

Photorespiration, on the other hand, may look like a wasteful, energy-hungry process at first glance, but it plays a crucial role in protecting plants when environmental stress hits.

Photorespiration in cannabis plants

In cannabis, it works as a defense mechanism against an overloaded photosynthetic electron transport chain and photoinhibition, especially under high heat, drought and salty conditions. It also supplies metabolites that other processes need to protect the plant and help it adapt to stress.

Long story short, the two processes are different but complementary, and plants need both. Photosynthesis provides the energy and raw materials for growth and reproduction, while photorespiration helps plants survive and adapt to tough conditions.

Understanding how these processes interact is key to advancing plant biology and making crops more resilient as the climate keeps changing.