Testing the New 4-band Sensor and the Spectrometer for Equivalency in Winter Wheat

Abstract

Wheat (Triticum aestivum L.) breeding entails a large number of segregating populations that are utilized for selecting high yielding segregates among and within segregating populations. This traditional technique, however, is costly and time-consuming because numerous field evaluations have to be made during several years at multiple locations. One alternative approach to address this issue is to employ the spectral properties of plants. This study was conducted to determine whether the new 4-band (NFB) sensor could replace the Ocean Optics USB4000 spectrometer (Ocean Optics Inc, Dunedin, FL) in collecting spectral reflectance data. Two spectral reflectance indices (SRI) were tested, namely red normalized difference vegetation index (RNDVI) and normalized water index-5 (NWI-5), using both tools during the booting and the grain-filling stages (according to Feekes' scale) in two consecutive years (2008-2009 and 2009-2010) at three locations. A cardboard cone was attached to reduce the surface area of the light-collecting lens in 2009-2010. Results showed that measurements at the grain-filling stage gave better equivalency between the NFB sensor (with and without the cone) and the spectrometer than at the booting stage for both RNDVI and NWI-5 readings. The NFB sensor could be used with and without the cone to replace the spectrometer for taking RNDVI readings at grain-fill. The attachment of the cone improved equivalency between the sensor and the spectrometer. However, the NFB sensor equipped with the cone could not substitute for the spectrometer in NWI-5 data collection in winter wheat. Furthermore, additional adjustments to the NFB sensor are needed to improve equivalency in taking NWI-5 readings.