Tissue analysis technology for nitrogen fertilization of potato grown under subtropics short day conditions
1993
Singh, J.P.
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.
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