I agree with Nor_Cal_Kannabliss, definitely plant "sunburn", something as an outdoor grower I see once in a while on exposed stems. Not much to worry about in the grand scheme of things.
One litre every other day sounds a bit light on for water, in my opinion.
Also, be careful those wire ties don't cut into the stems while she grows, even if they are rubber coated wire, for if they are too tight, they can end up "strangling" branches. Hope this helps...... Organoman.