Critical nitrogen dilution curve of the potato cultivar Asterix

Abstract

The objective of this work was to adjust the critical nitrogen (N) dilution curve of the potato cultivar Asterix and to evaluate its use on N management strategies. Tubers of this cultivar were planted in 5 dm³ polyethylene bags filled with organic substrate in the density of 4.4 bags m^-2. Treatments consisted of five nutrient solutions with N concentrations of 5, 8.3, 11.3, 14.3, and 16.3 mmol L^-1. Other macronutrients as 8.3 of K⁺, 1.75 of Ca²⁺, 1,2 of H₂PO₄^-, 0.7 of Mg²⁺, 0.7 mmol L^-1 of SO₄^2- and micronutrients were added in standard concentrations. Dry matter and N concentration in leaves, stems and tubers were weekly determined, from 43 to 99 days after planting. The critical nitrogen curve [N (g kg^-1) = 36DM^-0.37] was adjusted, based on total dry matter production. This dilution curve may be used as an interpretation tool for foliar analysis results and as a parameter to estimate N extraction during growth and development of the potato cultivar Asterix.