PRODUCTIVE AND PHYSIOLOGICAL RESPONSES OF COTTON (GOSSYPIUM HIRSUTUM L.) TO INDUCED MACRO AND MICRONUTRIENT DEFICIENCY UNDER CONTROLLED POT CONDITIONS

Abstract

Nutritional imbalance is one of the main limiting factors for cotton productivity and fiber quality. This study aimed to evaluate the productive, physiological, and technological responses of the FM 974 GLT cultivar under the omission of macro and micronutrients. The experiment was conducted under controlled pot conditions, using the subtraction diagnosis technique with 16 treatments: complete control (with all nutrients), individual omission of N, P, K, Ca, Mg, S, B, Zn, Mn, Fe, Mo, exclusive application of macronutrients, exclusive application of micronutrients, and zero control. Omissions of N and P caused the greatest restrictions to vegetative development, reducing plant height by up to 30% and root dry mass by 62%. Boron deficiency resulted in massive abortion of reproductive structures, reducing lint mass to 24.47 g, despite preserved vegetative growth. The omission of K reduced the number of bolls; however, through physiological plasticity, the remaining fibers exhibited greater length (33.4 mm) and a resistance of 33.4 g/tex. Principal component analysis (PCA) revealed distinct ionomic signatures, where the balance between B and K in the fiber correlated positively with technological excellence (HVI). It is concluded that, while macronutrients support the structural and productive base, micronutrients, especially boron, are the main regulators of the technological quality of the fiber.