Scholarlink

<p>This study evaluated nitrogen (N) management strategies in fresh-market tomato by comparing controlled-release urea (CRU) applied once at preplant with weekly fertigations of soluble urea under fall and spring conditions in north Florida. Three N rates (140, 168, and 224&#xa0;kg&#xa0;ha<sup>−1</sup>) were tested, with 224&#xa0;kg&#xa0;ha<sup>−1</sup> representing the current recommendation for Florida tomato production. Leaf N content and SPAD meter readings were measured across three seasons to assess crop N status. Results showed no significant differences in leaf N or SPAD values between 140 and 224&#xa0;kg&#xa0;ha<sup>−1</sup>, indicating that a 38% reduction from the recommended rate maintained adequate N status. In both seasons, leaf N and SPAD values were stable through most of the growing period but declined at harvest, suggesting limited benefit from late-season N applications. CRU treatments, with their temperature-responsive polymer coating, maintained more consistent SPAD readings and better matched crop N uptake patterns, particularly under warmer spring conditions. In contrast, split-applied urea, delivered in fixed intervals, occasionally resulted in high N supply late in the season. Correlation analysis revealed a statistically significant but moderate relationship between SPAD and leaf N content, with stronger correlations in fall (r = 0.64–0.66) than spring (r = 0.48). While SPAD proved useful for tracking general trends in tomato N status, its predictive reliability declined under conditions of excess N, highlighting the need for system-specific calibration and supporting diagnostics such as tissue N analysis. These findings highlight the potential of CRU to improve synchronization between N supply and crop demand and provide foundational evidence for integrating SPAD-based diagnostics into locally adapted N management strategies for sustainable vegetable production.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Evaluating the nitrogen status of tomato supplied with soluble and controlled-release urea formulations using leaf N content and SPAD meter

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年3月25日

查看全文
  • Laura Jalpa,
  • Rao S. Mylavarapu,
  • George Hochmuth,
  • Yuncong Li,
  • Bala Rathinasabapathi,
  • Edzard van Santen

摘要

This study evaluated nitrogen (N) management strategies in fresh-market tomato by comparing controlled-release urea (CRU) applied once at preplant with weekly fertigations of soluble urea under fall and spring conditions in north Florida. Three N rates (140, 168, and 224 kg ha−1) were tested, with 224 kg ha−1 representing the current recommendation for Florida tomato production. Leaf N content and SPAD meter readings were measured across three seasons to assess crop N status. Results showed no significant differences in leaf N or SPAD values between 140 and 224 kg ha−1, indicating that a 38% reduction from the recommended rate maintained adequate N status. In both seasons, leaf N and SPAD values were stable through most of the growing period but declined at harvest, suggesting limited benefit from late-season N applications. CRU treatments, with their temperature-responsive polymer coating, maintained more consistent SPAD readings and better matched crop N uptake patterns, particularly under warmer spring conditions. In contrast, split-applied urea, delivered in fixed intervals, occasionally resulted in high N supply late in the season. Correlation analysis revealed a statistically significant but moderate relationship between SPAD and leaf N content, with stronger correlations in fall (r = 0.64–0.66) than spring (r = 0.48). While SPAD proved useful for tracking general trends in tomato N status, its predictive reliability declined under conditions of excess N, highlighting the need for system-specific calibration and supporting diagnostics such as tissue N analysis. These findings highlight the potential of CRU to improve synchronization between N supply and crop demand and provide foundational evidence for integrating SPAD-based diagnostics into locally adapted N management strategies for sustainable vegetable production.