Hojas bajas amarillas

I’m not seeing signs anywhere else in the plant. This is likely a combination of two things that have compounded into you seeing the yellow leaves now. Fist is there probably was a lack of nitrogen in your soil leading up to this. Nitrogen deficiency can be easily found in lower fan leaves turning yellow. Since nitrogen is a mobile nutrient, the plant will remove the nutrient from the lower leaves and distribute it to where it sees fit. Second is the heat stress kicked the nitrate deficiency into overdrive and since that plant was likely already going to sacrifice that leaf, it expedited the process due to the heat. My guess is you will need to give it a little bit more nitrogen in the next few feedings. I hope this helps.