A nutrient deficiency caused by insufficient nitrogen uptake, presenting as yellowing of older lower leaves progressing upward, often seen in plants recently transplanted into fresh soil before nutrient programs begin.
Mr. Q identified that the CO2 room clones looked 'nitrogen deficient and calcium-magnesium deficient overall,' attributing it to either pH or EC being off—or both. Dakota linked it back to the overwatering event blocking nutrient uptake.