If its during the day, then A) It probably needs water - this is a common identifier for watering. Being able to quickly tell at the first sign of drooping can be a good thing, allowing your root zone to dry out through each watering/dry cycle helps the plant use its nutrients in a balanced manner and encourages better and bigger bud production in the end.
If it's at dusk/night, then B) the plants switch metabolic cycle and essentially "go to sleep" at night. It is common to see plants droop at night, and fully "praise up" in the morning when the Sun rises.
Alternatively, the drooping may be associated with a problem, such as overwatering or heat stress/exhaustion. As you can see, there are several possible reasons for a drooping event.
Thank you very much for the info.
I think that I'll give more information on our problem, in hopes that it can be answered or addressed more accurately. The plants are approximately 4 months old. We live in the Mojave desert, the plants have been planted outside, in the ground (we dug the holes in the ground, and filled those holes with gardening soil & planted the sprouts). The watering is set up with a soaker hose system, with slow drip.. which stays on continuously (because of how hot it usually is, being in the middle of the desert and etc.) They were checked on, right before sundown last night and again this morning a little while after sun up.. 3 out of 8 plants were completely sagging/wilted/drooping. As if they were dead. They all have good color, though. What could be the problem? We have had this problem before, but we've always just pulled up, and removed those plants. Due to fear of disease, and to avoid any affection to the other plants.
Thank you, in advance, for your help and assistance.
To me, it sounds like it might be a "not enough water" situation; in that its possible the particular drip environment relative to those specific plant's root zone is just not sufficient enough to satisfy the plant's water needs.
It is possible these plants will need some manual watering due to special circumstances in the topsoil. Being in the desert makes me think it's simply dehydrated. If this is the case, you might use a watering can and give it some water, they would prop back up once soaking it up, if its indeed the case...
PS: If the soil is actually wet and soaked for them, then perhaps its an overwatered + heat stress type of thing. It's hard to tell without pictures
If its overwatering + heat stress that are killing these particular specimens (they are very close to being gone, possibly too far gone, for pics 2,4,6,9) then unfortunately there's not much that can be done, because its on the drip system and rooted in the ground.
If for some reason they aren't getting enough waterdown where the roots are (1ft below topsoil or so where the main taproot is), then as a last ditch effort to save them I would just water and soak them with a bucket of water and get it in there and hope they'd survive. This is a tough one because they might have enough water where the taproot is, and maybe its just been so hot and that particular hole was more wet than others.
Dig your hand into the topsoil in about several inches and just see how wet it is (if you haven't already), also check the plants to see for any stem-boring insects as well as possible scale insects that have attached themselves to the stem. Plants look OK besides the droop, which makes me think its either A) Overwatering by the drip and B) heat stress by the desert, or C) The taproot in that particular hole isn't getting the water from the drip, and the drip on those plants may only be penetrating the topsoil where the taproot isn't there.
As a last ditch effort to save them, I'd prolly water them heavily with a bucket. And/or spray them with water (not in direct sun) mist.. as I'm sorry to say that a few of these specimens may be too far gone to save.
But stay positive and focus on saving them and especially the other ones that aren't as far gone. Honestly it's a tough one to be sure about, but I hope you can figure it out.
I started thinking more about your posts and the condition that keeps affecting your plants. I am guessing that the constant drip is causing the roots to not develop as fast as the foliage and once it gets past the tipping point its to late, you might be able to help them along with foliar watering but you would have to let the soil dry out to get the roots to develop and catch up.
I bet the roots only concentrate just around the drip paths and haven't branched much to search for water.
Letting the soil dry out some encourages root growth as they search for water pockets.
I agree with Lester. If the soil is at all damp, they are being watered to death. If you pull one, I bet you find root rot. They prefer to be on the dry side, rather than constantly wet. When roots get waterlogged, they can't move water so the plant appears to be thirsty when it is just the opposite.