could be an iron def - too much mag could be locking out iron
if it looks worse (after the extra cal mag) youll know for sure thats what it is
is that plant bigger or smaller then the rest or about the same?
I think i have the same problem . Very strange , i gave them mg also and it has gone worse . the are several causes to this kind of yellowing . you should update the pics and see what happens nect , if the half way of the leaves will yellow out then its same as i have or maybe it will be different .
Chlorosis is typically caused when leaves do not have enough nutrients to synthesise all the chlorophyll they need. It can be brought about by a combination of factors including:
* a specific mineral deficiency in the soil, such as iron[2] or magnesium [3]
* deficient nitrogen and/or proteins[3]
* a soil pH at which minerals become unavailable for absorption by the roots [4]
* poor drainage (waterlogged roots) [5]
* damaged and/or compacted roots [6]
* pesticides and particularly herbicides may cause chlorosis, both to target weeds and occasionally to the crop being treated.[7]
* exposure to sulphur dioxide[8]
Of course, the exact conditions would be different for different plants. For example, Azaleas prefer unusually acidic soil and rice isn't troubled by waterlogged soil.
I think i have the problem 5 and 6 too , will see in the end of grow then ill check the roots also .
