Crystals grown within the supersaturation ranges between sigma=0.22 and sigma=0.47 were investigated by X-ray topography. Within the supersaturation range between sigma=0.22 and sigma=0.34 the morphological type of striation was observed, whereas the kinetic type was observed at the supersaturation sigma=0.44-0.47, the growth bands and sectorial boundaries being weakened. In case of a uniform seed regeneration the crystal grows almost defect-free. The calculation of the kinetic curves of KDP crystal growth shows that in the presence of dislocations the predominance of the mechanism of two-dimensional (2D) nucleation over the spiral growth is possible if the supersaturation is above sigma=0.26 for the {100} faces and above sigma=0.44 for the {101} faces. It is assumed that the conditions under which 2D nucleation growth mechanism is predominant have been achieved. (C) 2016 Elsevier B.V. All rights reserved.