Winter wheat genotype ability to recover nitrogen supply by precedent crops under combined nitrogen and water scenarios

Legumes offer the opportunity to reduce the nitrogen (N) fertilizer requirements of the crop rotation but the capacity of the subsequent crop to recover the N provided by the legume determines the fertilizer saving. Therefore, breeding for genotypes capable of take up N under different limiting conditions is essential for un-derstanding crop performance and optimizing fertilization. The objective of this work was to test the ability of four wheat (Triticum aestivum L.) genotypes with different drought-tolerance (Cellule, Apache, Allez-y, and Nogal) to take up N from the precedent legume under different water scenarios. Two field experiments with pea-wheat and barley-wheat crop rotations, two irrigations levels, and three N treatments were conducted in central Spain over 3 years. The biomass, N uptake, and nitrogen nutrition index (NNI) were determined at flowering, and the grain yield (GY), grain N concentration (GNC), and N output at harvest. The precedent legume crops enabled a reduction in N fertilizer, but its effect depended on the genotype and climate conditions. The drought-tolerant genotypes (Apache and Cellule) had the highest NNI, biomass, GY, and N output under low water and N inputs, whereas Allez-y and Nogal obtained better performance under non-limiting conditions. Therefore, this study confirms differences between wheat genotypes, with different root system, in N uptake from the precedent legume in a crop rotation under different water levels and highlights the potential of NNI to assess wheat N status.