Quantification of total and individual polyphenolic content in over 400 cucumbers (cucumis sativus) for genome-wide association studies (GWAS)

This thesis study aimed to investigate the impact of growing conditions and variety on the total polyphenolic content (TPC) in over 400 GWAS cucumbers grown under greenhouse and open field, and the contents of gallic acid and quercetin in the greenhouse cultivars. The TPC was analyzed spectrophotometrically at 750 nm and the individual polyphenols were analyzed using HPLC-DAD at 273 nm (gallic acid) and 368 nm (quercetin). The greenhouse cucumbers (417 fruits) had TPC of 9.54 – 31.82 (average: 18.92) mg GAE/100 g and the open field cucumbers (416 fruits) 5.48 – 25.30 (average: 13.02) mg GAE/100 g. The individual gallic acid content ranged 0.00039 – 0.18 (average: 0.024) mg/100 g and quercetin ranged 0.0035 – 0.15 (average: 0.024) mg/100 g for greenhouse cucumbers (406 fruits). These results indicated that the polyphenolic content, total and individual, is variety dependent and significantly impacted by the growing conditions.