Potato (Solanum tuberosum L.) is a N intensive crop, and meeting its requirements with N fertilization is the primary practice to improve N recovery and achieve suitable tuber yield. A 3‐site‐year (SY) study was conducted to assess soil plant analysis development (SPAD)‐502 chlorophyll meter efficacy for providing potato leaf real‐time N status to adjust N timing and rate using nitrogen sufficiency index (NSI) thresholds of 90 or 95%. We evaluated effects of in‐season SPAD‐based N managements, as well as a reference with non‐limiting N application, a fixed‐timing (planting and hilling) conventional N fertilization, and a zero‐N control on crop N uptake, tuber yield, and N‐use efficiency of potato cultivar Agata grown in tropical clay soils. Tuber yields were similar in both SPAD‐based managements. Under no intensive rainfall events after N applications, SPAD‐based managements reduced N applications by 38–63% and resulted in comparable tuber set, bulking, and yield relative to conventional N fertilization. Additionally, SPAD‐based management at a NSI threshold of 90% resulted in greater potato N‐uptake efficiency and tuber yield per unit of N applied. SPAD‐502 sensor was efficient for detecting plant N status when environmental conditions were more conducive for potato production and optimized N management by reducing application rates. However, with less favorable temperature and solar radiation for potato cultivation, and with intensive rainfall events following N application, SPAD readings did not guide to a proper N fertilization and resulted in reduced tuber yield. Therefore, under such conditions, a more accurate method for detecting plant N status should be used.

中文翻译：

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基于叶绿素仪的叶氮状况来管理热带马铃薯生产中的氮

马铃薯（马铃薯）L.）是一种氮素密集型作物，通过施肥来满足其需求是提高氮素回收率和实现合适块茎产量的主要实践。进行了为期3年的研究（SY），以评估土壤植物分析发展（SPAD）-502叶绿素仪用于提供马铃薯叶实时N状态以使用NSI阈值来调整N时机和速率的功效。 90％或95％。我们评估了基于季节SPAD的氮肥管理的效果，以及非限制性氮肥施用，固定定时（播种和耕作）常规氮肥的施肥，以及对作物氮素吸收，块茎的零氮肥控制的参考。在热带粘土土壤中种植的马铃薯栽培品种Agata的产量和氮利用效率。在两个基于SPAD的管理中，块茎产量相似。在施用N后没有强烈降雨事件下，基于SPAD的管理减少了38-63％的氮肥施用，与传统的氮肥施用相比，块茎的定植，膨大和增产具有可比性。此外，基于SPAD的NSI阈值为90％的管理还提高了马铃薯的氮素吸收效率，并提高了单位施氮量的块茎产量。当环境条件更有利于马铃薯生产并通过减少施用量优化氮管理时，SPAD-502传感器可有效检测植物的氮状况。但是，由于马铃薯栽培的温度和太阳辐射较差，以及施氮后出现强降雨事件，SPAD读数不能指导适当的施氮，导致块茎产量下降。因此，在这种情况下，应该使用更准确的方法来检测植物的氮状况。