Estado nutricional e produtividade de algodoeiro em função de diferentes espaçamentos e aplicação de regulador de crescimento

Abstract

Strategies of cotton growth as row spacing and use of growth regulator are efficient when the knowledge of crop production potential as well as the amounts of nutrients content. The objective of this study was to evaluate the nutritional status of cotton DeltaOpal cultivar through leaf analysis of macronutrient, chlorophyll index and yield in relation to plant arrangement and managements of the growth regulator. The treatments consisted of plant arrangement: arrangement 1: 88,900 plant ha-1 and row spacing at 0.9m, arrangement 2: 114,300 plant ha-1 and row spacing at 0.7m, arrangement 3: 178,000 plant ha-1 and row spacing at 0.45m; management of growth regulator (mepiquat chloride) at 1.0 L ha-1 dose, concentration was50g L-1: a- no regulator application; b- single application at 70 days after emergency (d.a.e.); c- split application into four stages (35, 45, 55, and 65 d.a.e.). The reading reviews SPAD chlorophyll, leaf analysis of macronutrients and cotton yield were conducted in three agricultural years 2006/07, 2007/08 and 2008/09, under the experimental design of completely randomized blocks, in a 3x3 factorial scheme totaling up nine treatments with four replications. The reduction of row spacing and increasing plant density gives less absorption of potassium and sulfur by cotton crop. A single application of mepiquat chloride increase calcium leaf content. The split application of mepiquat chloride provides increased SPAD reading index, higher foliar magnesium concentration and highest seed cotton yield.