Nitrogen form regulates source-sink dynamics, flowering performance, and tuber development in container-grown Jerusalem artichoke revealed by 15N tracing

Abstract

Optimizing nitrogen (N) form is essential for improving the ornamental quality, tuber yield, and N use efficiency of Jerusalem artichoke ( Helianthus tuberosus L.; JA). This study investigated the effects of different N forms on growth, flowering, photosystem II efficiency, tuber development, and N allocation in JA clone No. 3 (cv. CN 52867), a high-flowering genotype for edible potted plant production. The first experiment used a completely randomized design with four treatments: N-free control, ammonium (NH₄⁺), nitrate (NO₃⁻), and combined NH₄⁺ + NO₃⁻. Compared with the NH₄⁺ treatment, NO₃⁻ and combined N significantly increased plant height (111.33 and 114.06 vs. 102.33 cm, respectively) and leaf area (961.25 and 1014.92 vs. 773.71 cm², respectively). The combined treatment generally resulted in higher relative crop growth rate and N use efficiency across most growth stages, although NO₃⁻ and combined N treatments showed comparable values at 90 DAP. It also produced the highest leaf number (72.67 plant⁻¹), total dry weight (28.94 g plant⁻¹), flower number (4.22 plant⁻¹), flower fresh weight (5.37 g), tuber fresh weight (157.28 g), and tuber dry weight (47.04 g), whereas NO₃⁻ produced the greatest tuber number (51.56 plant⁻¹). All N-supplied treatments improved chlorophyll fluorescence parameters (Fv/Fm, ETR, and qP). The second experiment, using ¹⁵N tracer analysis, revealed stage-dependent allocation of newly absorbed ¹⁵N. During vegetative growth, newly absorbed ¹⁵N was preferentially allocated to leaves and roots, whereas during flowering and pre-dormancy it was mainly allocated to reproductive organs and developing tubers, respectively. These allocation patterns are consistent with internal N remobilization toward newly formed tubers. Overall, N form strongly influenced growth, reproduction, and sink allocation. Combined NO₃⁻ and NH₄⁺ supply optimized ornamental quality and tuber yield, while ¹⁵N tracing clarified stage-dependent N dynamics, providing a physiological basis for improved N management in Jerusalem artichoke production.

The authors' abstract, as published at the source. Scientia Horticulturae, 2026 · DOI ↗