Seed oil content and fatty acid composition in a genebank collection of Cucurbita moschata Duchesne and C. argyrosperma C. Huber

Data on intra-specific variability for seed oil content, physical characteristics and fatty acid composition in Cucurbita moschata and Cucurbita argyrosperma are lacking in the scientific literature. We examined 528 genebank accessions of C. moschata and 166 accessions of C. argyrosperma – which included members of both subsp. argyrosperma and subsp. sororia – for seed oil content, oil physical characteristics and fatty acid composition. The oil of both species had near-identical viscosities, viscosity indices, colour and oxidative stabilities while the oil of C. argyrosperma had a slightly higher pour point, cloud point, percentage of free fatty acids and acid value when compared with C. moschata. Mean oil content values of the two species were similar at 28.7 ± /2.7 and 29.8 ± /2.6% for C. moschata and C. argyrosperma, respectively. The mean seed oil content of C. argyrosperma subsp. argyrosperma var. palmeri (32.1%) was significantly higher than that of the other taxa examined. The average (mean) percentage of total seed weight attributable to the kernel was 77.2% in C. moschata (n= 34) and 74.5% in C. argyrosperma (n= 46). The percentage of total seed weight attributable to the hull was correlated with seed oil content, in both species. Linoleic was the predominant fatty acid in all the samples analysed. Means for individual fatty acids in C. moschata were linoleic 48.5%, oleic 22.6%, palmitic 20.7% and stearic 7.5%. Means for individual fatty acids in C. argyrosperma were linoleic 47.3%, oleic 27.5%, palmitic 16.5% and stearic 8.0%.