Nitrogen supply alleviates seed yield reduction by improving the morphology and carbon metabolism of pod walls in shaded rapeseed

Abstract Shading significantly affects rapeseed yield, while reasonable nitrogen (N) application has efficiency gains. However, the functions and mechanisms of N are not fully established for shaded plants. Therefore, we conducted a 2‐year field experiment to study effect on pod wall morphology carbon metabolism rapeseed. Two varieties, three rates (120 [N1], 240 [N2], 360 [N3] kg hm −2 ) two light intensities (100 70% transmission) from 10 35 days after end flowering were set as experimental parameters. decreased chlorophyll content, ribulose 1,5‐bisphosphate carboxylase (Rubisco) activity glucose content at 25 (DAF). Decreased sucrose synthase (SuSy) phosphate caused by shading reduced fructose content. They responsible decline in 1000‐seed weight 22.1–37.6% seed yield. More under promoted elongation pigment improved chloroplast ultrastructure, increased Rubisco SuSy DAF, thus contributing photosynthesis levels Similar trends observed number, weight, greatest increase seed/wall ratio was N2 The results indicated that can reduce yield difference between different conditions balance partitioning conversion photoassimilates wall, but avoid applying an excessive amount nitrogen.