Excess of light without excess of heat

[SADE2020]

In line with this conversation, and I don't mean to hack it, sorry!

Does light compensate temp?

For example, if we have low temps and good sun/lighting, does natural sunlight compensate the temperature?

For example; not gradually or constantly, let say the temp is 50-60º constantly but 2 days are cloudy and 3 days full sunlight

[tmoney]

well, im no expert, but suusally if these are factors in a plants biology they have distinct sense and response, though of course both can influence the other.

perfect example is the strong daylight response of many deciduous trees, which require a certain number of photons to hit the leaves to maintain chlorophyll as a stable molecule (that’s the short version). when enough photons don’t hit them, the chlorophyll decays and we see fall colors (other molecules stored in leaf tissues). however, there is a lot that plays into this, such as amount of cloud cover, and evidence that temperature can affect plants in conjunction with light. a warm fall can drag this process out, or the trees will have a very hard transition into fall, but still drop their leaves. but it seems that if there is a strong response expression in a particular species to either temp, or light, then that stimulus is required, independently, to bring about the response. but of course there are ranges to the differences in these changes. what i mean is, if a plant is evolved to go dormant in the winter and shed its leaves using light as the trigger, then the plant would suffer/die if forced to maintain a set of leaves due to unchanging light levels yet still be triggered to dormancy by temperature. so temp and light, as some level, are intimately linked

[Roberta]

With orchids, generalizing doesn't work... Orchids that come from more temperate zones (for instance Himalaya, northern India, southern China, more northern regions of southeast Asia) will experience distinct seasonal changes of temperature, day length, light as well as changes in rainfall (linked to light, when there are few clouds it's also brighter even with lower sun angle). Orchids that grow at tropical latitudes (near the equator) will experience much smaller variations in day length, but light may or may not be affected by rainfall patterns. And those from higher elevations will experience some seasonal temperature variation as well as diurnal temperature variation, that those at sea level won't. So a discussion needs to include information about "Which orchids?" to be useful.

In cultivation, we certainly modify the parameters that an orchid experiences in the wild, but even the most complex hybrid still goes back to species, with needs and conditions that need to be taken into account for successful growing.

[DavTom]

Originally Posted by SADE2020

In line with this conversation, and I don't mean to hack it, sorry!

Does light compensate temp?

For example, if we have low temps and good sun/lighting, does natural sunlight compensate the temperature?

For example; not gradually or constantly, let say the temp is 50-60º constantly but 2 days are cloudy and 3 days full sunlight

Not sure if I got your question right. Do you ask, for instance, if an outdoor phals that typically requires a minimum air temperature of 18 degrees Celsius can do well in an air temperature of 16 degrees under the (filtered) sun light?

Well, I am also no expert, but I think that surely the sunlight can compensate (at least a bit) for that.

However, I think that this is not a common situation at all. Neither in nature nor under artificial lights. Unless you carry outside your orchids during daylight and bring them (quickly) back at sunset every day...

If the air is 16 degrees Celsius during daylight or when the artificial lights are ON, one can bet that during the night (or with lights OFF) the temperature would drop to an unbearable level.

Dav

[SADE2020]

Originally Posted by DavTom

Not sure if I got your question right. Do you ask, for instance, if an outdoor phals that typically requires a minimum air temperature of 18 degrees Celsius can do well in an air temperature of 16 degrees under the (filtered) sun light?

Well, I am also no expert, but I think that surely the sunlight can compensate (at least a bit) for that.

However, I think that this is not a common situation at all. Neither in nature nor under artificial lights. Unless you carry outside your orchids during daylight and bring them (quickly) back at sunset every day...

If the air is 16 degrees Celsius during daylight or when the artificial lights are ON, one can bet that during the night (or with lights OFF) the temperature would drop to an unbearable level.

Dav

Yeah, I mean just you said.

and, yes you're right, no matter what the night will be cooler ...every day.

[Ray]

Think of orchids as unique “Goldilocks”, particularly when it comes to temperatures and light levels.

IDEALLY, they do best within specific ranges of each. Yes, they may tolerate something a small degree outside of them, but they will not grow or bloom as well.

A deep understory plant that normally grows hot and with no direct sunlight, for example, will not do as well if grown cool, but with more light.

It’s all about chemical reactions occurring within the plant, and those chemical reactions are affected by temperature, light intensity, light & dark duration, to name but a few factors. Even the water supply affects it.

If there is plenty of water at the roots, hormone signals tell the stomata to open, allowing gas exchange to occur more freely, allowing carbon fixation to occur more rapidly. If the root system is dry, that doesn’t happen, as the plant goes into “conservation mode” to save water.

As Roberta said - each plant is unique, the needs are very specific (hence my “Goldilocks” comment), and the complexity of plant processes are too great to make any generalizations.