Same with less: a method to reduce destructive sampling to estimate nitrogen use efficiency components using allometric relationships in spring wheat (Triticum aestivum).

Enhancing nitrogen (N) use efficiency is important for a sustainable food production. Measuring shoot biomass and N pool across growth stages is critical to calculate N use efficiency, but relies on slow, costly and destructive sampling. This paper presents a non-destructive allometric approach developed for cereals; in this study, we assessed wheat (Triticum aestivum ) for crop shoot biomass and N pool. Our methodology considered tiller height and number, and the estimates of leaf chlorophyll content (SPAD) as non-destructive measures to predict shoot biomass and N pool by using a multiple linear and a non-linear regression (R 2 =0.71 and R 2 =0.89, respectively) on the data from 72 samples of 16 recombinant inbred spring wheat lines (RILs) field-grown in central Sweden during 2years with contrasting weather. Model parameters are estimated separately for different years to accommodate environmental variations between them. The regressions obtained were applied to estimate critical N use efficiency traits of 80 randomly selected wheat lines from the same RIL population. The method developed here provides a promising novel tool for the cost-effective estimation of critical N use efficiency parameters in cereals, with reduced destructive sampling, and a first step toward automated phenotyping for rapid N use efficiency assessment in cereal breeding populations.