Tissue analysis technology for nitrogen fertilization of potato grown under subtropics short day conditions

Abstract

Field experiments were conducted for three crop seasons to develop tissue analysis technology for optimizing N fertilization in potato grown under short day conditions in subtropics. Nitrogen deficiencies could be detected as early as 25 days after planting (DAP) by tissue analysis of NO₃-N concentration in petioles. Petiolar NO₃-N declined sharply with age of the crop from 25 to 60 DAP and was significantly correlated at all stages of growth with applied N and tuber yield of potato. Critical concentrations of Petiolar NO₃-N were 1.28, 1.23, 1.07 and 0.96% in an early maturing cv. Kufri Chandramukhi and 2.16, 1.95, 1.40 and 1.18% in a late maturing cv. Kufri Badshah at 25, 40, 50 and 60 DAP, respectively. Optimum yields were obtained when petiolar NO₃-N was maintained above critical concentrations through the growth period up to 60 DAP by corrective side dressing of N. Response to corrective side dressing of N decreased with increasing concentration of petiolar NO₃-N. Optimum rate of N for side dressing up to 30 DAP was 142, 116, 90, 64 and 37 kg ha⁻¹ for petiolar NO₃-N of 0.5, 1.0, 1.5, 2.0 and 2.5%, respectively in Kufri Chandramukhi. Corresponding rates of side dressed N were 183, 164, 146, 127, 108 kg ha⁻¹ in late maturing cv. Kufri Badshah. For optimum yields, fertilization of 80 to 120 kg N ha⁻¹ at the time of planting followed by corrective side dressing as recommended by petiolar tissue analysis is advocated.