Fruit Based Morphological Characterization of Vegetable Marrow (Cucurbita Pepo L.) for Diversity Assessment and Germplasm Identification

Abstract

Vegetable marrow, a cultivar group of Cucurbita pepo L., is widely grown across Pakistan, yet the fruit based morphological diversity of its local germplasm has rarely been documented in a systematic, quantitative way. This study characterized 15 vegetable marrow accessions (VSQ1-VSQ15) using 13 fruit descriptors recommended by Bioversity International (formerly IBPGR/IPGRI) and the European Cooperative Programme for Plant Genetic Resources (ECPGR) Cucurbits Working Group, comprising nine quantitative traits (fruit length, width, shape index, fresh weight, flesh thickness, cavity diameter, ribbing intensity, stem-end diameter and blossom-end diameter) and 3 qualitative traits (shape class, surface texture and fruit colour). Descriptive statistics revealed diverse variation among accessions, with fruit length (coefficient of variation, CV = 48.1%), shape index (CV = 63.0%) and fresh weight (CV = 41.0%) showing the greatest relative variability, while flesh thickness (CV = 13.4%) was comparatively stable. Pearson correlation analysis showed fresh weight to be the most strongly associated with flesh thickness (r = 0.70) and fruit length (r = 0.59), while width-related traits (cavity, stem-end and blossom-end diameter) were tightly inter-correlated (r > 0.7), reflecting a shared girth dimension. Principal component analysis reduced the nine quantitative traits to two components explaining 82.5% of total variance: PC1 (51.3%) represented an overall fruit-girth axis, and PC2 (31.2%) represented an elongation-mass axis. Ward's hierarchical clustering grouped the 15 accessions into 3 morphologically distinct clusters that broadly corresponded to small pyriform/round types, intermediate blocky types, and elongated bell/long types. One-way analysis of variance confirmed significant differences in shape index (p < 0.001) and fresh weight (p < 0.01) among shape classes with adequate replication. These results demonstrate substantial, structured morphological diversity within a small set of local vegetable marrow accessions and provide a quantitative descriptor foundation that can support germplasm identification, core collection development, and parental selection in future breeding programmes.