So- largest plant (photos above) yellowing lower f...

Hello my friend😊 It is highly possible that it is possible Nitrogen deficiency Nitrogen deficiency in cannabis plants: When cannabis plants do not have a balanced nutrition and lack this element, there are anomalies in their development, visible through the morphology of the plant, which we call deficiencies. Plant growth is much slower. The leaves turn yellow little by little, starting with the lower parts of the plant. The chlorosis begins with the tips and extends to the center of the leaf. Plants have fewer defenses against insect or mite infestations, diseases and bad weather. Flowering and the eventual production of seeds are seriously diminished. Massive defoliation (leaf drop) after severe chlorosis. Deficiency progresses from the bottom to the top, affecting the youngest leaves last. To solve the problem quickly it will be necessary to add to the nutrient solution a fertilizer rich in nitrogen so that the plants can recover their optimum levels of this nutrient a few days after watering. During growth and during stretching, it is also possible to use a nitrogen fertilizer exceptionally directly as a foliar spray, for faster assimilation than by the roots. It should be noted that when plants have these deficiencies their production capacity has already decreased, so that it is important to maintain a balanced diet throughout the crop in order to obtain optimal quality and production. It is very important to bring enough nitrogen to the plant during periods of growth and stretch, because then once in full bloom, it will be very difficult or impossible to catch a nitrogen deficiency, the roots of the plant having at this stage lost almost all capacity of assimilation of this element. If the nitrogen reserves of the plant are not sufficient for the stretch, it will yellow quickly once in flowering. Good luck for your grow 😉 May the force be with you 💪