What levels of Sodium and Chloride are "safe" for orchids??
 

Hi all!
I recently had my water tested by a lab and found that the Chloride concentration was 146 (mg/L) with the Sodium at 184 (mg/L). Hardness was <10 with a pH of 7.3. There were really no other minerals of note.
Now, while these values for the Sodium and Chloride ARE under EPA maximum recommended concentrations for DRINKING water, will they have any adverse effects upon my orchids - mainly Catts, encylias and Zygos??
Thanks for any info or direction!

This is really hard to answer because it depends upon the interaction of so many sets of genes as well as environmental factors.

The levels you have are safe for humans because our cells have fairly good mechanisms to deal with excess salt which is then excreted by way of our kidneys Plants also have channels in their cell membranes through which Na and Cl ions can be shuttled out of the cell. The trouble is that this active transport process requires great expense of the cells (and the plants) energy. They also do not have kidneys and can only get rid of salt through individual cells.:)

The biggest problem however is that if too much Na enters the cells and is not pumped out, then potassium (K) ions are pretty much forced out. This is the same K that we add in all our fertilizers (the 3rd number mentioned in NPK fertilizers. so if sodium builds up in the medium the effect is to remove that all important potassium. This is often described as "leaching out necessary nutrients". If introduced very slowly to increasing levels of NaCl many plants develop increased levels of salt tolerance.

OK. I don't want to bore you any further so the point is your chids can take your water levels of NaCl but to do so stresses them. A single watering or even regular watering with these levels won't kill them. It will just deprive them of all the K they need. However, salts will build up so salinity gets higher every time you water even if the salt in your water is constant. You can always flush the plants with good water to get rid of salt build-up.

Just to complicate things further, the levels of Calcium in the water and media will also affect tolerance to NaCl!

When plants are stressed and low on energy they are not happy :(
:( plants don't like to flower making all of us:(:(:(

I'll stop now and hope you have not fallen asleep.
I won't be offended if you have. My students do it regularly in class:yawn: -- I can take it :lol:

orchidbingo

orchidbingo---
Thanks for your help. I am a physician (BA/MS/MD), so I DO follow your analysis without undo sedation - thanks! I did a lit search and had a hard time of getting any specific info, so I posted it on the "board" for help. Not my area of expertise.....
Your info was great, thanks for the time and effort of your response, I really do appreciate it!

You are most welcome!

I am a little bit disappointed-- I was hoping I could have a second career as an anesthetist :lol:
I'm losing my touch. I couldn't put Rosie C to sleep either.


orchidbingo

As an Board Certified anesthesiologist, I can tell you - don't try this stuff at home!! (Can you say "Michael Jackson"?)
I used to tease my kids when they were young with "Hey, do you KNOW what I do for a living? I put little kids like you to sleep....go ahead, make my day."
Surprisingly, they really did turn our well adjusted and with great senses of humor. Will wonders never cease?

It is interesting how salt tolerance varies all over the map - cotton is highly tolerant, while corn is less so; it's too bad there are no established levels for orchids, although I would expect it to be low, considering most salt exposure to plants is in the soil, which our "babies" never see in nature.

With the levels you have, I'd highly recommend that you consider an RO system or other way to avoid using your tap water.

I am only a newbie, but I can tell you from first hand experience, orchids can tolerate a fair amount of "salt".

I live approx 2 miles from the ocean, and our predominant breeze is from that direction. A few blocks over are some hi-power electrical transmission lines. You can literally hear the salt get fried off if it builds up too heavy.

So if I have this constant exposure, and my chids do fairly well (as a 1yr hobbyist) then can only deduct that salt, though not good, can be tolerated?

It could also be that since we get a fair amount of rain, any salts may be leached out? I dunno...

Doc, the water you are using, does it pass through a water softner?

Do you have access to rain water?

[edit]

I forgot to add, chlorides can be easily removed by filling a bucket, and allowing them to evaporate out. I do this with well water (mostly in the winter) to remove sulphur.

Orchids don't do a lot of foliar transfer of mineral ions, so the surface coating from sea mist is less of a problem than is dissolved salt that can be absorbed.

Don't count on them being overly tolerant of the coating though.

I was also going to suggest the rain water. That is mainly how I water my 200 + orchids. Save rain water in 2 large drums, very seldom have to water with our tap water - which is well water and fairly high in iron.

Just to add my two cents (and I agree with everyone), plants can withstand some tolerance to NaCl, but different species (even within the same genus) can respond differently. There have not been well documented studies of NaCl (any type of salts for that matter) tolerance in orchids. However, there have been studies done in model plants (particularly mustard-weed/Arabidopsis).

From my previous dissertation work (got my PhD in plant genetics), I conducted experiments where different plants of the same wild-type species (Arabidopsis thaliana) responded differently to the same concentration of NaCl. Additionally, when I knocked out just one of the target genes I was studying, ALL the plants were photo-bleached/had undergone chlorosis in the presence of NaCl.

Additionally, something to keep in mind is that NaCl raises levels of abscisic acid (ABA), a desiccation-prevention phytohormone (which closes stomatal pores of plants) which has been documented to repress/prevent salicylic acid (SA, another phytohormone) accumulation. SA is the plant's primary response to pathogens. Thus, high levels of NaCl can make your plants more vulnerable to pathogens (bacteria, viruses, etc.). The reason this happens is if a plant was simultaneously affected by drought and pathogens, plants would choose to limit desiccation before limiting pathogens as drought is quickly fatal. Just something to keep in mind.

I suggest using rain water as others previously mentioned or water every so often with RO/rain water to 'wash out' the excess salt.