Not enough light for clones.

[DrPhoton]

Im wondering if clones can have too little light during the initial root stages. Really the question is do clones use energy from internal storage or is some energy required with photosynthesis.
I have not had any success with cloning in my new system and wonder if my light is too weak. Its a very faint light thats as weak as your typical smartphone light.

Iv studied the basic biology of plants and understand the most important principles in plant life sustaining properties.

Applied to cuttings and you provide the very best enviroment for plant survival.
I have high humidity +90%, low light, rockwool cubes with ph stable soak, temperature controlled, reduce leaf mass for lower transpiration, double dip root hormone, ph stable water spray.

So can you have too little light ? My symptoms are yellowing and dying leaves.

[NA420]

Yes you need more light, a CFL at least and put it close cause clones need heat as well as humidity. Sometimes the bottom leaf yellowing means roots are forming, pour your water out and let the cube dry a little but continuebto spray. The roots will take the dive as rooter dries and pop out readybto be planted! Hope this helps, Peace and positive vibes!

[DrPhoton]

Thanks for that, do you have any articles that explain this in detail or experience with light deprevation with clones ?.

[Flockshot]

I have seen no articles on light deprivation in clones. Generally, with clone lighting being so easily satisfied with a couple cfl's it doesn't come up much.

[DrPhoton]

Yea i wouldnt have thought so, but i do know some vegetable plants i have grown have died from inadequate light.

[DrPhoton]

Bump de bumpy

[NA420]

There doesn't need to be an article it's simple photosynthesis, Light=energy to plants. If your clone isn't getting enough light it cant store that energy and use it to grow.

[DrPhoton]

Yes but seeds dont need light initially to start with, energy is provided by a stored source of nutrients. This is the question, if clones require or use photosynthesis to root or wether they have a stored amount they can use. Albet excluding the fact that a stimuli of light is needed to activate plant functions.
I do agree with you that its likely a clone needs "some" amount of photosynthesis, but cant be certain.

[DrPhoton]

Found some information on photosynthesis and cuttings.

"Leaves on cuttings need light to carry out photosynthesis. This will give the cutting sugars that can be used for developing new roots and shoots.
Developing shoots need light to carry out photosynthesis."

Heres a study that showed evidence of direct correlation with light and rooting.

https://www.jstage.jst.go.jp/article/jjshs1925/46/2/46_2_274/_article

Another study which was most interesting which detailed the correlation of photosynthesis and glucose delivery to root formation. Also stating that some amount of stem photosynthesis contributed to root foundation.

https://ir.library.oregonstate.edu/xmlui/handle/1957/23500

[DrPhoton]

"When net photosynthesis was reduced to zero by maintaining the cuttings at the C0₂ compensation point or by blocking CO₂ exchange with an antitranspirant, rooting was reduced to about 50% of the controls."

So without photosynthesis, cuttings could still manage to root but with lower success rates.

"In addition to reducing rooting these treatments significantly reduced sucrose and glucose levels in the basal portion of the cuttings compared to controls."

Photosynthesis appears to contribute glucose/sucrose levels during the initation of roots. It could be assumed that this reduction of sugar be the cause of lower root development compared to controls.

"These experiments suggest that the supply of current photo- synthate can limit root formation."

Oh! He says it here.

"The above conclusions were supported by experiments using different photosynthetic photon flux densities and photoperiod lengths during rooting. Defoliation experiments also supported the role of current photosynthate in root formation. Defoliation of cuttings reduced rooting and carbohydrate levels in the base of the cuttings."

Defoilation can contribute to a lower level of photosynthesis and perhaps reduced rooting. So removing leaves on a clone may be a negative thing but we do of course have to consider root time in cannabis and the duration difference could make it harder and more desirable to remove leaves.

"Dipping the defoliated cuttings in an antitranspirant blocked CO₂ fixation and almost completely inhibited root formation. These data suggest that stem photosynthesis also contributed to root formation."

This is quite a bizzare one, i have to assume that the antitranspirant was applied to leaves only and so the stem was assumed to contribute a little bit to root development.

"These experiments suggest that one of the major effects of light incident on leafy pea cuttings is to influence the amount of photosynthate available for root formation. It is difficult to establish whether current photosynthate influences rooting directly or indirectly by affecting some other factor(s) which control rooting. Whatever the case, treatments which influence photosynthesis influence rooting in a parallel manner."

There def seems to be a correlation of photosynthesis and rooting. Especially when using antitranspirant nearly completely inhibited root development.

These are the things that are not mentioned in plant biology textbooks and you have to discover on your own or read more current textbooks including recent findings.

[bobsakamoto]

hey, thanks for this good info, dan!

[DrPhoton]

A closer look detailed more specifically about the use of antitransparent. When used on the leaves only, they reduce the rooting by 50% compared to controls. However when the cuttings are completely saturated they almost completely limit root formation.

This is interesting because it appears that stem photosynthesis contributes to some amount in root formation. Also without any photosynthesis at all the cuttings will still manage to root by some degree but albeit at a much reduced rate. This shows a combined effort in stored nutrition and ongoing manufactured energy in the formation of roots in cuttings.

Very interesting indeed.