Why does my bottom leaf have brownish white tip and is cripsy?

Think of that first set of single and 3-fingered leaves a bit like baby teeth. The plant is shedding them once heavily shielded... maybe 10% about how it's fed, but it's going to happen most times once they are well-shielded. from light. old leaves can mottle and show symptoms. I think the plant is just sucking it of nutrients... how it progresses may or may not hint at something that is slightly off -- depends on how selectively the plantn can call for mobile nutrients... if it's all or nothing it'd show nothing... if it is selective in anyway, what you see occur first could hint at something you could bump up slightly. trial and error.. take soem notes if it jives later with first symptoms seen, if any, try it. These leaves can definitely stay healthier longer, but sometimes plants do shed them more easily than others plants. i usually lop'em off before flower period but most are quite healthy, occassionally some are shed before that point... i figure it's either genetic variety or the nutes were just a littl emore spot on to retain them.. no need to shed dead weight if still productive to the plant. plants shed dead-weight. The plant looks relatively healthy, otherwise, so i wouldn't react unless these symtpms spread further.