HELP! Highest possible N/E ratios- Are my plants healthy?

[ZiroOne]

Hello again everyone.

I have many projects during this grow of mine. One of them is to find highest possible N/E ratios for all elements which support optimal growth where N is nitrogen concentration and E is each of the rest essential mineral elements concentration. If we compare our ratios you will find they are not the same at all; completely different. Your S/N ratio, for example, is more or less 1/2-1/4 but mine is 1/10 which means you are feeding your plant 3-5 times more than what i feed in compare to nitrogen. I'm not a ture researcher and I'm not an experienced grower like many of you. So i was thinking that your nice eagle-like eyes and advise can help but before that i don't know how an effective appreciation can be done using english words to offer you all of possible ones. Sorry if my english is not good enough.

Do you see any S or Fe-like deficiency in these plants?

 

[Bluey]

My observations regarding N.

Plants will comfortably take varying degrees of N, but how much they can take is going to vary substantially depending on the following.

Size of plant
Stage of growth
Genetics
Environmental factors including light levels

If you watch your plants closely and are giving your plants too much N you will see a dark green 'climb' up the plant slowly as it appears to me the N is absorbed by the lower growth first and once saturated moves up the plant.

You do not want this to transition into the flowers as that will slow and or stop their growth and development.

As to what maximum or ideal levels are, well, it varies a lot.

I think your plants really look great and you appear to be giving them close to maximum PPFD.

 

[ZiroOne]

Cannabis plant can handle up to 100 mol/day/m2 of light. My LED fixture emits 27 mol/day and my grow area is 1.0 m2 although about a half of area is empty. So i don't think I'm even close to maximum DLI. Part of that reddish or yellowish colour near the centre of pics is because of my camera. It is not all the reflection of high light level

Generally, up to 45mg N and possibly more per gram of dry weight of leaves, the more the N, the faster the growth and the more the yield when there is no limiting factor of other elements. I didn't mention any N concentration here because it generally depends on VPD and spices but it is independent from light level, genetics, growth stage and size of the plant because 1st two factors greatly effect Water Use Efficiency but the rest of them can be neglected. During veg when plants are mostly leaves, and when WUE is 3gram dry weight per litre of water transpired, theoretically they need 3×45=135 mg N per litre of water in average to sustain maximum growth. This high level of N reduces quality of buds due to dilution effect of more yield. So lower than 45 mg/g N in the leaves improves quality. Plants having 30 mg/g N in the leaves need no more reduction in N feeding if optimal yield is the goal. Quality buds contain about 40 mg/g N and they have grown in a plant containing about 30 mg/g N in its leaves at harvest time. Now tell me bro... you don't want transition of N from leaves into the buds? Growth and yield is higher with more N, but secondary metabolism is the same or lower. more N not only doesn't stop development and growth but also it increases it.

 

[ZiroOne]

One more thing. N in Nitrate which has oxidation state of +5 needs to be reduced to ammonium with oxidation state of -4 first and this reduction needs energy. So plant transports nitrate to upper leaves which receive energy from light. So nitrogen is more at the top of the plant. Also N is needed for growth and top of the plants growth more than the bottom so top has more N and N deficiency appears at the bottom 1st.

 

[Bluey]

Give them more N and watch the leaves darken down low and it will slowly rise up the plant. I've seen it dozens of times now

 

[ZiroOne]

More nitrogen encourages more chlorophyll pigment production which has higher concentration in the bottom leaves in shade. But N concentration at top is always more than bottom
You give your plant more N. A bit of it goes bottom and increases chlorophyll but big part of it goes top in encourages growth. So you see darker green at bottom although more N have gone to the top

 

[Bluey]

Ah, okay. So that's what I am seeing. Very interesting