The Evaluation of Grafting with Some Different Rootstocks on The Yield, Berry Characteristics and Bioactive Compounds in “Starlight” Grape

In the current study, we endeavored to assess the impact of grafting with three grape rootstocks namely (Freedom, Richter 110R and SO4) on yield, quality and accumulation of bioactive compounds in "Starlight “grape cultivar. We conducted the experiment over the course of the principal growing seasons in 2024 and 2025. Four treatments as follow (Control (un-grafted), grafted on Freedom rootstock, grafted on Richter 110R rootstock, and grafted on SO4 rootstock) were applied on 7-year-old vines, located at a private farm in Menia Governorate. Our findings indicated that grafting 'Starlight' grapevine cultivars onto various rootstocks generally enhanced their growth, fruit yield, quality and accumulation of bioactive compounds (Proline, Total phenolics and Tannins). Specifically, results have shown that vines grafted onto Freedom rootstock can lead to higher yields and larger vine vigor. Besides, it significantly boosts shoot growth and leaf area, improve berry size and weight, surpassing other rootstocks and those grown from their own roots. In contrast to the minimal growth observed with SO4 rootstock. Chemically, 'Starlight' vines grafted onto Freedom rootstock showcased the highest levels of Total Soluble Solids (TSS%) and TSS/acid ratio, whereas, it was the lowest in acidity percentage in the juice of berries, contributing to sweeter grapes with better coloration and anthocyanin content. Additionally, Richter 110R rootstock led to a higher accumulation of bioactive compounds compared to SO₄ and Freedom, with SO₄ outperforming Freedom in Proline and Tannins.