I did a search and found some useful information but still not quite sure what is wrong . The grow is in soil 1/3 organic mix, 1/3 perlite, 1/3 compost. The plant is about 5 weeks old on 18/6 with a 400w hps. Grow cupboard measures 1700mm x 700 x 600 Ph is at 6.2 and watered with rain water. Rh sits between 40% and 60% Temp sits between 26 and 32C Not sure the EC 1 dose of 1/4 strength Ionic nutrients has been given 1 week ago. Not sure what other info you may need so here's some pics.
dont give nutes til the first and only set of round leaves fall off.....they look fine though.... no yellowing on leaf edges..