Nickel is not really needed in any large amount for the growth of plants, I assume even these plants don't need it in more than a trace amount to grow.

The hydroponic fertilizer I use doesn't even list it on the label and I assume that the only way my plants get it is from impurities in the other minerals.

https://www.jacksnutrients.com/online-store/5-12-26-Part-A-p...