Nitrogen (N) is a key mineral element required for crop growth, yield and quality. Nitrogen-use efficiency (NUE) in crop plants is low despite significant research efforts. Excessive use of N fertiliser results in significant economic cost and contributes to environmental pollution. Therefore, it is crucial to develop crop varieties with improved NUE, and this requires efficient phenotyping approaches to screen genotypes under defined N conditions. To address this, 15 wheat (Triticum aestivum L.) varieties, grown under three N levels, were phenotyped for NUE-related traits under field conditions. Significant genotypic differences were observed in varieties having low to high responsiveness to N applications. The results suggest that basal low N can be used to screen wheat varieties that are less responsive to N, whereas N supply from 80 to 160 kg N ha–1 could be used to screen high N-responsive varieties. Normalised difference vegetation index (NDVI) measured by using Crop Circle, and SPAD units measured by SPAD meter at heading stage, were well correlated with shoot dry biomass, grain yield, and shoot and grain N concentration, and could potentially be used as tools to phenotype different wheat varieties under varying N treatments. The data also demonstrated that NDVI and SPAD could be used to differentiate wheat varieties phenotypically for NUE-related traits. The prospect of utilising efficient, non-destructive phenotyping to study NUE in crops is also discussed.
Effects of nitrogen and sulphur on seedling establishment, vegetative growth and nitrogen use efficiency of canola (Brassica napus L.) grown in the Western Cape Province of South Africa
