Effect of Growth Regulators and Exogenous Arginine on the In Vitro Micropropagation of ‘Sweet Sapphire’ Grape

Abstract

This study aimed to optimize an in vitro micropropagation protocol for the grapevine cultivar Sweet Sapphire (Witch Fingers) by determining the optimal concentrations of plant growth regulators during the establishment, multiplication, rooting, and acclimatization stages. The experiments were conducted at the Plant Tissue Culture Laboratory, Al-Musayyib Technical College, from March to October 2025, using nodal explants approximately 1 cm in length.The results of the establishment stage showed that the interaction between 2-isopentenyl adenine (2iP) at 2 mg·L⁻¹ and naphthalene acetic acid (NAA) at 0.5 mg·L⁻¹ produced the highest number of leaves and the longest shoots. During the multiplication stage, the combination of 2iP at 2 mg·L⁻¹ with NAA at 0.25 mg·L⁻¹ resulted in the highest number of shoots. In the rooting stage, the interaction between benzyl adenine (BA) at 2 mg·L⁻¹, arginine at 200 mg·L⁻¹, and activated charcoal at 400 mg·L⁻¹ achieved the greatest root length. For acclimatization, the substrate composed of peat moss and perlite at a ratio of 1:2 recorded the highest plant survival rate (90%). These results demonstrate the effectiveness of the identified concentrations in producing uniform, disease-free grapevine plantlets with high efficiency, supporting their application in grapevine micropropagation programs.