friends, help me with advice what kind of yellowness on the leaves is what this can be!?

Okay. You have a few issues here. Best bit of advice I can give you. Is to restart the whole programme i can't c a diary so I don't know where you went wrong. If it started out as some sort of PK def and the leafs are just dying off or its from nutrient burn mainly too much N as the leafs are curling, so possibly N tox but if you had a diary of a few days before it would make it easier to give a definite answer. Also the white bits. They are cal mag with some sulphur issues maybe. There really is a few things wrong here. Restart the programme. Give 2L of cal mag 3m/L or if you have calmah and some espom salt make a mix of 350-400 with both remember to take away ambient ppm of the water you use so if water is 150 give a mix of 500. Let it dry out for 2 days and restart on a light grow, micro nutrient diet. You can also look at dual feed nutrients. Were you use grow, bloom and micro together and you just change around ratios depending on where your plant is at. For instance when growing you'd give .9 grow to .3 bloom depending on the ratios the brand gives you these nutrients make it much easier to stay on top of not giving to much N or too lil PK. GOOD LUCK BRO