Why would dormancy be necessary outside of suboptimal conditions?

[estación seca]

You're asking questions that would need to be solved by detailed research projects. Sounds like you could earn a PhD if you pursue these questions.

[RiverbankMudlark]

True, though I imagine for ecological reasons such research projects on other plants probably already exist and are being conducted right now. Changing climates probably mess with the normal dormancy of plants in their own native environments.

While I don't believe it had to do with dormancy (and I don't even know if rice has a dormancy), I vaguely remember reading something about a study that found warmer growing seasons were causing bigger yields of rice, but it held less nutrients.

[estación seca]

If research doesn't promise millions of dollars in returns, it doesn't get funded. No funding agency is interested in pure knowledge.

[Ray]

Originally Posted by RiverbankMudlark

I get the argument that "if a plant evolved to particular conditions, it thrives in those conditions," however, I don't think that implies that those conditions are all ideal to the plant.

For the very first plant in any particular environment, that's probably correct, and if it managed to survive and have offspring, then if the offspring had offspring, etc., for many generations, they would have evolved to having those conditions being ideal for that plant.

If your assumption about it not being ideal was valid, then moving it to whatever you consider to be "better" conditions would lead to the plant growing better, but that's not what happens. More likely, it will begin to weaken and fail because it is no longer in its ideal conditions.

[Roberta]

In a nutshell, that's the process of evolution by natural selection. The organisms that are best adapted to a given environment reproduce more successfully than those that are less well adapted. The results in a different habitat will be different, the concept is the same. That process drives speciation. The habitat where the species thrives is the "best" for that species even if it isn't your favorite...Orchids grow on every continent except Antarctica, at elevations from sea level to above tree-line, at latitudes from the tropics to the Arctic Circle. Obviously DIFFERENT orchids, of course. That's why there are some 25000 - 30000 species of orchids (that's not counting a couple hundred thousand hybrids), and nobody can grow all of them!

[lobotomizedgoat]

Originally Posted by RiverbankMudlark

This does raise some questions though. If dormancy is an important part of hormone regulation, how do plants that do not experience dormancy manage to avoid these hormonal issues, despite growing continuously?

Also, why are there some orchids that undergo dormancy that can go without it? For example, I've read that in Japan, as Dendrobium moniliforme is typically grown for its foliage ore than its leaves, people keep it at constant temperatures to avoid it dropping its leaves. How could they sustain that?

The hand-wavy explanation is that they've evolved other ways of regulating hormones (welcome to tautology club!). I actually went to look this up in my old plant bio textbook, but I've either misplaced it or given it away.

My amateur guess as to why some can go without dormancy is that not all evolutionary changes that trigger what presents to us as dormancy are the same. Evolution is essentially random, so even two originally identical populations could in theory evolve different pathways to surviving in the same new environment through random mutation/recombination and drift. Perhaps more importantly, evolution can only work with the genes present in a population. A change in one population that helps it survive in a new environment may not work for another population (e.g. an SNP that alters a protein in pop. A may do nothing in pop. B because something long ago "broke" that gene in pop. B and it's no longer expressed).

Other factors could be how stable the environment is and how long the population has experienced it. Adaptations that tie critical functions to environmental triggers that are inconsistent will experience lower fitness than those that adapt in other ways. The longer a population has existed in a stable environment the more likely it may be to rely on the specifics of that environment (e.g. day/night is very consistent and controls many critical functions in surface dwelling organisms).