Diagnose por subtração de macronutrientes em algodoeiro BRS Topázio.

Abstract

The herbaceous cotton (Gossypium hirsutum L.) is a perennial malvaceous cultivated as an annual crop, presents great economic and social importance worldwide its productivity depends on a good availability of nutrient providing, the plants ideal amounts for their good development. In this context, the objective of this work was to evaluate the effect of macronutrient subtraction on the BRS Topázio cotton growth, from June to August 2016, in a greenhouse, belonging to the Federal University of Campina Grande, PB. The statistical design was completely randomized, consisting of seven treatments with three replicates, totalizing 21 experimental units, containing in each experimental unit a cotton plant. The treatments consisted of experimental control (T1) cotton plants that received all the essential nutrients; (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (N), phosphorus (P), and nutrient solutions (T2, T3, T4, T5, T6, T7) Mg), sulfur (S). The omission of the macronutrients affected all the growth variables, resulting in a reduction in plant height, leaf diameter, number of leaves, consequently the leaf area of the plant and the dry matter produced, being the plants with omission of N, P, Ca, K the most impaired. The visual deficiency symptoms were diagnosed in all plants with omission of the macronutrients, except in the plants with the omission of S. And the contents of nutrients behaved in this way: N content in cotton plants increased and decreased in the absence of K and of Ca, respectively. The content of P in them increased with the omission of N, K, Mg and decreased with omission of S. In relation to the content of K, it increased in the absence of S and decreased in the absence of N, P, K and Ca. Higher levels of Ca, Mg and S in cotton plants were observed with the absence of K. It was observed that omission of macronutrients in cotton plants affected the growth and development of this crop.