Active Sensing for Rapid Evaluation of Apparent Nitrogen Use Efficiency in Winter Wheat Genotypes.

ABSTRACT Remote sensing based indices such as Normalized Difference Vegetative Index (NDVI) can detect biomass and Nitrogen (N) variability in crop canopies. There are two major ways to improve NUE as documented in the literature: (i) breeding genotypes with high NUE and (b) improved N management. The objective of this study was to quantify the apparent Nitrogen Use Efficiency (NUEa) of multiple wheat genotypes and identify the most NUEa efficient winter wheat genotypes. This study was conducted in north-eastern Colorado for two years, 2010 and 2011. Destructive sampling of plants was done at several growth stages to determine total nitrogen in plant tissue. The NDVI readings were taken weekly on 24 winter wheat genotypes from March to June, 2010 and 2011. The results indicate that NUEa was significantly different among multiple wheat genotypes across dryland and irrigated cropping systems, and NDVI readings successfully classified multiple wheat genotypes into their respective NUEa classes. This study demonstrates the potential of using Green Seeker based NDVI readings as a promising tool to screen and identifying higher NUE wheat genotypes. Keywords: Normalized difference vegetation index (NDVI), apparent nitrogen use efficiency (NUEa), wheat genotypes, dryland and irrigated. * Corresponding author: Dr. Raj Khosla (raj.khosla@colostate.edu ) Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO 80521, USA