Canopy reflectance spectra of wheat as related to crop yield, grain protein under different management practices

Abstract

A field experiment was conducted during the winter season of 2010-2011 in a sandy loam soil at the Research Farm of the Indian Agricultural Research Institute, New Delhi, India to study the relationship of canopy reflectance with the yield and protein content of wheat as infuenced by different irrigation and nitrogen levels. Three spectral reflectance indices (SRI) related to canopy photosynthetic area were calculated using spectral reflectance values viz., Red normalized difference vegetation index (RNDVI), Green normalized difference vegetation index (GNDVI) and Simple ratio (SR). The RNDVI, GNDVI and SR increased from Crown Root Initiation (CRI) to booting stage and there after decreased progressively till maturity. Among the three SRIs, GNDVI at milking stage was most closely related to grain yield (r=0.97**) and biomass yield (r= 0.93**) of wheat and at booting stage it was most closely related to the protein content (r=0.90**). The GNDVI was the best index for prediction of grain yield, biomass yield and grain protein percentage in wheat.