Morphological and fruit variability of grape (Vitis vinifera L.) germplasm under sub-tropical condition

The research was carried out at ICAR-National Research Centre for Grapes in Manjri, Pune, focusing on 24 grape germplasms. These germplasms were assessed for morphological and qualitative traits. During October 2023 to March 2024, data on vegetative growth, bunch characteristics, yield and quality were collected in line with Distinctness, Uniformity and Stability (DUS) guidelines and descriptors from International Plant Genetic Resources Institute (IPGRI), International Union for the Protection of New Varieties of Plants (UPOV) and International organization of Vine and Wine (OIV 2007). The mean and standard deviation (SD) were computed for all morphological traits and coefficients of variation (CV %) were used to indicate variability levels. Principal Component Analysis (PCA) was performed using SPSS statistical software to identify correlations between qualitative traits. The findings revealed significant variability among the grape germplasms for various morphological traits. The time of bud burst showed considerable variation, with most germplasms exhibiting medium days to bud burst. Shoot tip opening and young leaf color also demonstrated diverse forms, indicating the genetic diversity within the germplasms. Most varieties displayed an erect growth habit, which is advantageous for vineyard management. Mature leaf characteristics, such as width and shape, provided crucial identification markers. The study noted a predominance of pentagonal leaf shapes and observed anthocyanin coloration on the main vein in a subset of varieties. Additionally, variations in leaf hair density and petiole sinus opening were important discriminative features. Bunch characteristics such as density, shape and uniformity of berry size were recorded, with medium density and conical bunch shapes being the most common. Berry shape and color varied significantly, with short elliptical and green-yellow berries being prevalent. The absence of anthocyanin coloration in the berry mesocarp was noted in all germplasms, which is relevant for table grape quality. This variability underscores the genetic diversity present in the grape germplasm, which is essential for breeding and conservation efforts. Overall study demonstrated the effectiveness of morphological characterization in assessing genetic diversity and identifying distinct grapevine genotypes.