Any suggestions?? What do you u think ?? The plant...

Purple stem potassium deficiency yellow is nitrogen deficiency

Nutrient lock up to much salt buld up flush flush flush let it dry and give the proper week feed

Are these yellowing leaves from the lower parts of the plant or the upper? Lower leaves tend to be macro-nutrient deficiencies [NPK, etc.], whereas as upper leaves are often signs of micro-nutrient deficiencies. The leaves actually look like a classic nitrogen deficiency. (Sharing a picture of the plant too can be helpful in the diagnostic process.) If this is the sixth week of your Lemon Pie, cal-mag might help the plants pick up more nutrients, but I would consider top dressing with some worm castings and some bloom nutes, or even a little 4-4-4 mix and some microbials if you have them. I like to use solids when top dressing as it is difficult to go wrong, although I usually have the cal-mag and microbials directly in the water I use (5gal bucket mix). When I see washed out yellow leaves, I always jump to over-watering, too, as I have done it so much and had similar yellowing leaves, but as your pictures aren't showing any other signs, I am sticking with a feeding issue. Maybe, a more experienced grower will have some additional things to share. All the best with your grow. It is coming along nicely and you have time to fix this, for sure. Happy cropping!

I would say an advanced sulphur deficiency, google for it. Veinal chlorosis is an uncommon symptom, that and yellowing of the base of the leaves point in that direction.

All plant goes lime, but leaves don't drop ?? If so she is hungry for PK part !!! Give her boost ! Low temps could lead to it even more ... All the Best !

Potasium