Well it would be nice if you gave us more information, but it looks like your either watering your plant too much, too less, or your LED is too close to your plant. Is it inside or outside, and what is your light cycle? Also the age and plant type would help. Good luck!
looks like a droplet of water sat on There to long and then got hit by intense sun ..acting then as a magnifying glass. and making it look like calcium issues. really it's just burn caused by a hot drop of water...it's rare for it to rain and then the sun come out intense enough to do that or alot of marijuana and plants in general would be extinct...DON'T water leaves in the sun or indoors under lights...only when lights are off and sun is down...(best time is right when the lights go down) GFP Sent from my SM-G600FY using Tapatalk