Effect of Nitrogen Fertilization on Primary Xylem Differentiation in Roots of Young Peach Trees

The primary xylem differentiation in new, white roots of differing root diameters in 3-year-old peach Prunus persica (L.) (Batsch) trees supplied different amounts of nitrogen was examined. Primary xylem differentiation as the number of xylem ridges in cross-sections of new, white roots increased significantly with increasing root diameters, irrespective of differing amounts of nitrogen applications. The number of xylem ridges ranged from three to seven in peach roots. These results indicate that the numbers of thick roots having many primary xylem cells increased more in nitrogen fertilized plants than did those in no-nitrogen ones.