Chironex

Welcome Robi! Yes, there is a lot to know when growing Ae Ae. I have read 2 different opinions on soil type - acidic or basic, so I would say that you can always keep it neutral until you find out for certain. They burn easily in full sun, so partial shade is what I would recommend. The white portions of the leaf has no chlorophyll so you need to plant them where they get dappled sun or partial sun.
As to the potassium nitrate question, yes, they will become more green and less white with applications of nitrogen. As soon as the nitrogen is consumed, the white will return, so it is a delicate balance that must be maintained.
Nitrogen will also cause them to pup more frequently I have read. Mine have yet to pup, but I have been feeding them with 15-5-30 fertilizer that is close to the ideal N-P-K ratio.
Hope this answers your questions - Good Luck with your beautiful bananas!

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Scot