Optimizing Grape Quality Through Tillage and Organic Fertilization: A Comprehensive Analysis of Phenolic and Anthocyanin Variability Over Three Years

Abstract

Knowing the concentration levels of phenolic compounds and anthocyanins in grape berries plays a key role, as these compounds significantly contribute to the nutritional value and quality of grapes, affecting both health benefits and grape quality. The current study was conducted to investigate how different tillage (disc harrow, chisel, no tillage) and organic fertilizer (Antep radish and broccoli chopped residue, olive blackwater) treatments affect the concentration of these valuable compounds in Royal grape berries over three consecutive years (2020–2022), providing insights into optimal agricultural practices for enhancing grape quality. Our results documented significant variations in phenolic and anthocyanin concentrations across different soil tillage, organic fertilizer treatments and years. Among the soil treatments, the disc harrow treatment emerged as the most effective in increasing the levels of most phenolic compounds and anthocyanins, while the broccoli fertilizer treatment was identified as the superior fertilizer application for achieving the same goal. Excluding disc harrow and broccoli fertilizer treatments, other treatments such as no tillage and chisel tillage, and fertilizers like olive blackwater and Antep radish, showed variable effectiveness. These treatments, although less effective overall than the leading treatments, contributed to increased levels of certain compounds such as resveratrol and pterostilbene, indicating their specific benefits. The findings also indicated specific combinations of tillage and fertilizer treatments that maximized the accumulation of certain phenolic compounds, like the combination of no tillage with broccoli fertilizer, which was particularly effective in increasing the levels of vanillic acid and trans-caffeic acid. To sum up, by adopting practices such as disc harrow tillage and broccoli fertilizer application, viticulturists can enhance the phenolic and anthocyanin profiles of grapes, thus improving their nutritional value and potentially the quality of grape and wine produced from these grapes.