Mineral nutrition of sesame plants (Sesamun indicum L.): I - concentration an accumulation of macronutrients under field conditions

Abstract

A field experiment was set in Piracicaba (SL:22º41'31" and LW: 47º38'01"), State of São Paulo, Brasil, in a soil classified as 'Terra Roxa Estruturada (Alfissol), Serie Luiz de Queiroz", in order to study: the growth rate of sesame plants; the concentration of macro nutrients in the different plant organs; the accumulation of macronutrients by the whole plant, and the exportation of macronutrients through the pods. Plants (4 replications) with 28, 40, 52, 64, 76, 88, 100, and 102 days from emergence were collected and divided into leaves, stems and pods. The material was dried at 80ºC and analysed for macronutrients. The results were as follows: at 112 days de maximum dry matter production obtained was 344.4 g per plant; the accumulation of dry matter by the leaves corresponds to a quadratic equation, while it is sigmoidal for the stems and linear for the pods; the accumulation of macronutrients was always higher in the leaves than in the stems, except for K; the concentration of macronutrients in the leaves, stems and pods occurred in the following order: Leaves: N(3-97%) >; K(3.60%) >; Ca(2.91%) >; P(0.54%) >; Mg (0.45%) >; S(0.30%). Stems: K(6.14%) >; N(1.48%) >; Ca(1.36%) >; Mg(0.42%) >; P (0.40%) >; S(0.22%). Pods: K(1.86%) >; N(1.61%) >; Ca(0.41%) >; P(0.40%) >; Mg (0.21%) >; S(0.20%). The total accumulation of macronutrients by the whole plant increased with aging until 112 days except for P and K in the leaves and Ca in the stems; the accumulation of macronutrients (mg) at the final growth stage was: N(5391.70) >; K(4075.26) >; Ca(2759.85) >; P(986.72) >; Mg (667.97) >; S(647.01)