02661naa a2200313 a 450000100080000000500110000800800410001902200140006002400270007410000170010124501360011826000090025450004290026352013370069265300110202965300080204065300150204865300170206365300290208065300290210965300090213865300200214770000240216770000190219170000170221070000150222770000180224277300870226010599942019-08-09       2019    bl uuuu     u00u1 u    #d  a1424-82207 a10.3390/s191329492DOI1 aDE SOUZA, R.  aThe use of chlorophyll meters to assess crop N status and derivation of sufficiency values for sweet pepper.h[electronic resource]  c2019  aArticle history: Received: 15 May 2019 / Revised: 19 June 2019 / Accepted: 1 July 2019 / Published: 4 July 2019. (This article belongs to the Special Issue Proximal Sensing for Nitrogen Management). This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).  aABSTRACT. Chlorophyll meters are promising tools for improving the nitrogen (N) management of vegetable crops. To facilitate on-farm use of these meters, sufficiency values that identify deficient and sufficient crop N status are required. This work evaluated the ability of three chlorophyll meters (SPAD-502, atLEAF+, and MC-100) to assess crop N status in sweet pepper. It also determined sufficiency values for optimal N nutrition for each meter for pepper. The experimental work was conducted in a greenhouse, in Almería, Spain, very similar to those used for commercial production, in three different crops grown with fertigation. In each crop, there were five treatments of different N concentration in the nutrient solution, applied in each irrigation, ranging from a very deficient to very excessive N supply. In general, chlorophyll meter measurements were strongly related to crop N status in all phenological stages of the three crops, indicating that these measurements are good indicators of the crop N status of pepper. Sufficiency values determined for each meter for the four major phenological stages were consistent between the three crops. This demonstrated the potential for using these meters with sufficiency values to improve the N management of commercial sweet pepper crops.   © MDPI (Basel, Switzerland)  aAtLEAF  aCCI  aGREENHOUSE  aHORTICULTURE  aNITROGEN NUTRITION INDEX  aPROXIMAL OPTICAL SENSORS  aSPAD  aVEGETABLE CROPS1 aPEÑA-FLEITAS, M.T.1 aTHOMPSON, R.B.1 aGALLARDO, M.1 aGRASSO, R.1 aPADILLA, F.M.  tSensors (Basel, Switzerland), 4 July 2019, Volume 19, Issue 13, 2949. OPEN ACCESS.