Optical sensors can be used to assess crop N status to assist with N fertilizer management. Differences between cultivars may affect optical sensor measurement. Cultivar effects on measurements made with the SPAD-502 (Soil Plant Analysis Development) meter and the MC-100 (Chlorophyll Concentration Meter), and of several vegetation indices measured with the Crop Circle ACS470 canopy reflectance sensor, were assessed. A cucumber (Cucumis sativus L.) crop was grown in a greenhouse, with three cultivars. Each cultivar received three N treatments, of increasing N concentration, being deficient (N1), sufficient (N2) and excessive (N3). There were significant differences between cultivars in the measurements made with both chlorophyll meters, particularly when N supply was sufficient and excessive (N2 and N3 treatments, respectively). There were no consistent differences between cultivars in vegetation indices. Optical sensor measurements were strongly linearly related to leaf N content in each of the three cultivars. The lack of a consistent effect of cultivar on the relationship with leaf N content suggests that a unique equation to estimate leaf N content from vegetation indices can be applied to all three cultivars. Results of chlorophyll meter measurements suggest that care should be taken when using sufficiency values, determined for a particular cultivar.

中文翻译：

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品种对黄瓜叶绿素仪和冠层反射率测量的影响。

光学传感器可用于评估作物的氮素状况，以帮助管理氮肥。品种之间的差异可能会影响光学传感器的测量。评估了品种对使用SPAD-502（土壤植物分析开发）仪和MC-100（叶绿素浓度仪）进行的测量以及使用Crop Circle ACS470冠层反射传感器测量的几种植被指数的影响。黄瓜（Cucumis sativus L.）农作物在带有三个栽培品种的温室中生长。每个品种接受3种氮素处理，即氮素浓度升高，不足（N1），充足（N2）和过量（N3）。在使用两种叶绿素计进行的测量中，不同品种之间存在显着差异，尤其是在氮供应充足和过量（分别为N2和N3处理）时。品种之间的植被指数没有一致的差异。光学传感器的测量结果与三个品种中的每个品种的叶片氮含量均呈线性关系。品种对与叶片氮含量的关系缺乏一致的影响表明，可以根据植被指数估算叶片氮含量的唯一方程式可以应用于所有三个品种。叶绿素仪测量结果表明，在使用针对特定品种确定的充足值时应格外小心。品种对与叶片氮含量的关系缺乏一致的影响表明，可以根据植被指数估算叶片氮含量的唯一方程式可以应用于所有三个品种。叶绿素仪测量结果表明，在使用针对特定品种确定的充足值时应格外小心。品种对与叶片氮含量的关系缺乏一致的影响表明，可以根据植被指数估算叶片氮含量的唯一方程式可以应用于所有三个品种。叶绿素仪测量结果表明，在使用针对特定品种确定的充足值时应格外小心。