Grapes (Vitis vinifera L.) is an important fruit crop in tropical and subtropical regions. However, its production faces challenges from stresses like unseasonal rains and poor soil quality, particularly affecting table varieties like Thompson Seedless, its clone. Protein hydrolysate (PH) based biostimulants offer a promising solution by improving plant metabolism, increasing stress resilience and enhancing both berry yield and quality. This study evaluated the effect of a methanotroph derived PH biostimulant across diverse agroecological regions in India, aiming to assess their impact on grapevine yield, berry quality and shelf life at varying concentrations. The validation was conducted in Karnataka, Telangana State and Maharashtra during the 2022–2023 growing season. The field experiment employed a Randomized Block Design (RBD) with 8 treatments, including 6 levels of PH, a commercial control and an untreated control. Protein hydrolysate was applied at 4 key developmental stages and results showed that the 5 mL/L treatment (T7) consistently outperformed others, enhanced berry length (35.93, 33.00 and 27.03 mm) and diameter (15.20, 20.57 and 23.03 mm) improved Total Soluble Solids (TSS) (18.43, 18.20 and 18.20 °Brix) and extended shelf life proving optimal dose for enhancing yield and quality in Manik Chaman, Bangalore Blue and Thompson Seedless respectively. T7 treatment also performed better in 3 different locations with ~32–48 % increases in yield and improved shelf life. The study highlights the significant benefits of methanotroph derived PH bio stimulant in improving grapevine productivity and fruit quality.
