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<p>Efficient nitrogen management is critical for enhancing seedling vigor and productivity in forest nurseries. This study aimed to optimize nitrogen loading in 3-month-old seedlings of Teak (<i>Tectona grandis</i> L.f.) and Indian Rosewood (<i>Dalbergia latifolia</i> Roxb.) using Neem Coated Urea (NCU), through evaluation of morphological attributes and nitrate reductase activity (NRA). A 15-week pot culture experiment was conducted with seedlings treated with seven increasing doses of NCU (0–1500&#xa0;mg kg<sup>-1</sup>soil) and ten replications per each treatment. Growth parameters, including shoot length, collar diameter, leaf number, root length, fresh biomass, and survival percentage were recorded. Foliar and root NRA were measured colorimetrically. Soil nitrogen content was analyzed using the Kjeldahl method. Statistical analyses included one-way ANOVA and Pearson correlation to assess treatment effects and inter-parameter relationships. Teak seedlings exhibited optimal growth at 500&#xa0;mg kg<sup>-1</sup> NCU, recording a mean shoot length of 25.70&#xa0;cm, collar diameter of 5.26&#xa0;mm, and maximum foliar and root NRA of 904 and 576 nmol NO₂⁻ g⁻¹ FW h⁻¹, respectively. Indian Rosewood showed best performance at 1000&#xa0;mg kg<sup>-1</sup>, with a shoot length of 30.80&#xa0;cm, collar diameter of 5.10&#xa0;mm, and NRA of 714.50 and 725.60 nmol NO₂⁻ g⁻¹ FW h⁻¹. Excessive nitrogen led to growth decline and mortality—at 1000&#xa0;mg kg<sup>-1</sup> for Teak and 1500&#xa0;mg kg<sup>-1</sup> for Indian Rosewood—highlighting the threshold for nitrogen toxicity. The study concludes that 500&#xa0;mg kg<sup>-1</sup> and 1000&#xa0;mg kg<sup>-1</sup> NCU are optimal for Teak and Indian Rosewood, respectively. These doses maximize growth and NRA without inducing toxicity, offering a framework for species-specific nitrogen management in nursery settings to support sustainable forestry practices.</p>

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Optimized Nitrogen Loading for Teak and Indian Rosewood Seedlings Based on Nitrate Reductase Activity

  • 期刊论文

  • 发表日期：

    2026年1月3日

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  • Avinash Cheekati,
  • Sahith Chepyala,
  • Shalini Mudalkar,
  • Jagadeesh Bathula,
  • Sreedhar Bodiga

摘要

Efficient nitrogen management is critical for enhancing seedling vigor and productivity in forest nurseries. This study aimed to optimize nitrogen loading in 3-month-old seedlings of Teak (Tectona grandis L.f.) and Indian Rosewood (Dalbergia latifolia Roxb.) using Neem Coated Urea (NCU), through evaluation of morphological attributes and nitrate reductase activity (NRA). A 15-week pot culture experiment was conducted with seedlings treated with seven increasing doses of NCU (0–1500 mg kg-1soil) and ten replications per each treatment. Growth parameters, including shoot length, collar diameter, leaf number, root length, fresh biomass, and survival percentage were recorded. Foliar and root NRA were measured colorimetrically. Soil nitrogen content was analyzed using the Kjeldahl method. Statistical analyses included one-way ANOVA and Pearson correlation to assess treatment effects and inter-parameter relationships. Teak seedlings exhibited optimal growth at 500 mg kg-1 NCU, recording a mean shoot length of 25.70 cm, collar diameter of 5.26 mm, and maximum foliar and root NRA of 904 and 576 nmol NO₂⁻ g⁻¹ FW h⁻¹, respectively. Indian Rosewood showed best performance at 1000 mg kg-1, with a shoot length of 30.80 cm, collar diameter of 5.10 mm, and NRA of 714.50 and 725.60 nmol NO₂⁻ g⁻¹ FW h⁻¹. Excessive nitrogen led to growth decline and mortality—at 1000 mg kg-1 for Teak and 1500 mg kg-1 for Indian Rosewood—highlighting the threshold for nitrogen toxicity. The study concludes that 500 mg kg-1 and 1000 mg kg-1 NCU are optimal for Teak and Indian Rosewood, respectively. These doses maximize growth and NRA without inducing toxicity, offering a framework for species-specific nitrogen management in nursery settings to support sustainable forestry practices.