Comparisons among cultivars of wheat, hulless and hulled oats: Dry matter, Nand P accumulation and partitioning as affected by N supply

A better understanding of the impact of fertilizer nitrogen (N) on biomass and N accumulation, and their partitioning into different plant components is needed to optimize crop yield and quality. A field experiment with spring wheat (Triticum aestivum), hulless (Avena nuda), and hulled (Avena sativa) oats was conducted for 3 years in Ottawa, ON, Canada, to determine the crop responses to N addition (0, 75, and 150kg N ha(-1)). Biomass, N, and phosphorus (P) accumulation and partitioning into different plant components were examined during the growth season. Lodging score was determined for all crops when it occurred and again at harvest. During the growth season, both hulless and hulled oats and the wheat cultivar showed almost similar patterns of N and P accumulation with maximum contents at late grain filling or at harvest. Plant N concentration was up to 60 gkg(-1) during the seedling stage, decreased gradually with advancing growth stages, and was lowest at harvest. Nitrogen treatments significantly increased plant N and P contents. At heading stage, N treatments enhanced dry matter (24%-45%), N (35%-135%), and P (27%-45%) contents in plant components (i.e., culm, leaf, and head), but also enhanced crop lodging, especially in oats. Both hulled and hulless oats had higher total plant N (5%-35%), N : P ratio, and dry-matter content in leaf (6%-43%) and head (0%-129%) along with higher P (up to 27%) in culm than the wheat cultivar. The wheat cultivar accumulated greater dry matter and higher N content in kernels than both hulled and hulless oats at harvest. Both hulled and hulless oat cultivars exhibited similar lodging susceptibility to N addition (75 or 150kg N ha(-1)), produced lower dry weight and lower kernel N, and hence lower grain yield than the wheat cultivar. The larger vegetative dry-matter accumulation at heading coupled with higher P content in culms under high-N-supply conditions may be related to severe lodging in oat cultivars.