Nocturnal behaviour of the aubergine

[ddiogyn]

Have insomnia so i decided to take a turn around the garden with a torch. I was surprised to see the aubergine plant's normally-droopy leaves all pointing skyward, and all its previously-open flowers closed. What's the purpose of this behaviour? My first thought was the cooler nighttime temperature, but then again, it's really warm and humid out tonight. Why else could the aubergine be 'closing' its leaves at night?

[ddiogyn]

Oh, and while we're on aubergines, mine has about a dozen flowers - no fruit so far - and i've not yet pinched out the growing tip or any side shoots. I read that the main tip should be nipped off at 12in, and only 5 fruit allowed to set.

My plant is about 4ft tall now, and the growing tip has branched to two, which has in turn branched to two, making a total of 4 growing tips. There are also 4 big side shoots coming from the original main stem. Is there any point pinching any of the main shoots at this late stage? Should i remove the smallest flowers, leaving only 5 on the plant; should i wait until clear signs of fruit set appear; or, should just leave the plant and let it decide by itself? The variety is 'Black Prince'.

[Capsid]

Leaves folding up is called photonastic behaviour; you'll notice that dandelion flowers do it too. I assume it is to protect the flowers so that insect pollination is co-ordinated during the day.

The purpose of nipping the tops out is to promote new shoots on which more flowers will for and provide more leaf for photosynthesis. Since yours have done this by themselves I see little point in pinching the tops out apart form restricting their height. I think your plants are quite tall at 4 feet and don't need to get any bigger since you want it to focus its energy into producing the fruit not more leaf. I've got mine in small 7" pots to restrict their growth and stress them into producing fruit. I'd wait until the fruit has set before removing any.

[OllieMartin]

I love this forum, you learn so much, I'd never heard of this. It stimulated me to read the wikipedia page on it, very enlightening (so to speak!)

Nastic movements - Wikipedia, the free encyclopedia

[chris]

I've noticed other things do it too.. I thought it was as they were striving to reach for light *shrug*.

Off to read the wikipedia page now

[ddiogyn]

Fascinating stuff! Though it must take a fair amount of energy for the plant to do that every night, energy better spent on reproduction, surely!

[OllieMartin]

Fascinating stuff! Though it must take a fair amount of energy for the plant to do that every night, energy better spent on reproduction, surely!

Although an automatic reaction like that is caused (correct me if I'm wrong) by fluid travelling between cell walls causing some to constrict and others to expand. I would think that'd take no more energy than the hairs on your arms standing on end.

[womble]

Oca does it in a particularly spectacular way, all of it's leaves are turned upwards at night and then open in the morning.

[ddiogyn]

Although an automatic reaction like that is caused (correct me if I'm wrong) by fluid travelling between cell walls causing some to constrict and others to expand. I would think that'd take no more energy than the hairs on your arms standing on end.

Oh, but the hairs are tiny compared with our total body size. I imagine it would be more like laying on our backs with all four limbs pointed up! The plant would still need to expend energy establishing and maintaining an osmotic gradient for the passive movement of water to maintain turgor (if my i recall my A-Level biology correctly!).

[Capsid]

The water movement through a plant is passive and occurs by capillary action, no energy needed. It just needs to control its water pressure in certain areas such as the leaf axils to alter the leaf angle. It can do that by opening and closing the stomata on its leaf. Plants don't have muscles so there is no huge requirement for energy.

[ddiogyn]

Ah, but the plant expends energy keeping the stomata open, even if the capillary action is powered passively by transpiration. I would reason lower night-time temperature = lower rate of transpiration = more stomata need to be open in order to maintain the leaf turgidity = more energy expended

[OllieMartin]

Oh, but the hairs are tiny compared with our total body size. I imagine it would be more like laying on our backs with all four limbs pointed up! The plant would still need to expend energy establishing and maintaining an osmotic gradient for the passive movement of water to maintain turgor (if my i recall my A-Level biology correctly!).

The water movement through a plant is passive and occurs by capillary action, no energy needed. It just needs to control its water pressure in certain areas such as the leaf axils to alter the leaf angle. It can do that by opening and closing the stomata on its leaf. Plants don't have muscles so there is no huge requirement for energy.

Ah, but the plant expends energy keeping the stomata open, even if the capillary action is powered passively by transpiration. I would reason lower night-time temperature = lower rate of transpiration = more stomata need to be open in order to maintain the leaf turgidity = more energy expended

...suddenly feeling in over my head!

[zazen999]

Basically, they wouldn't do it if there was not an evolutionary advantage to it.

[binley100]

...suddenly feeling in over my head!

My thoughts exactly...................tbh I'm not sure if I want to know what my Aubs get up to in the middle of the night as long as they keep on producing
I've had two off mine so far and there's loads more growing, so whatever they are up to in the GH late at night , long may it continue

[bazzaboy]

brilliant thread, I think, reminds me of an earlier earnest discussion, How Do Seeds Know Which Way Is Up? And now I've got to set the alarm for 2.30 a.m. to go and check the aubergines by torchlight... What'll the neighbours say?