Effect of genetic characteristics and environmental factors on organosulfur compounds in garlic ( Allium sativum L.) grown in Andalusia, Spain

The content of organosulfur compounds was determined in selected garlic cultivars grown at four locations in Andalusia, Spain. The organosulfur compounds studied were three γ-glutamyl peptides, namely, γ-l-glutamyl-S-(2-propenyl)-l-cysteine (GSAC), γ-l-glutamyl-S-(trans-1-propenyl)-l-cysteine (GSPC), and γ-l-glutamyl-S-methyl-l-cysteine (GSMC), and four cysteine sulfoxides (alliin, isoalliin, methiin, and cycloalliin). There was a significant effect of the location, cultivar, and garlic ecotype on individual organosulfur compound contents. Purple-type cultivars showed on average the highest contents of GSMC, GSAC, alliin, and methiin but the lowest isoalliin content. The impact of genotype was relatively high for GSAC, whereas this factor hardly contributed to the total variability in alliin and isoalliin content. Planting date had a significant effect on the content of alliin and isoalliin. Discriminant analysis evidenced the ability of organosulfur compounds to distinguish among garlic bulbs from different locations or ecotypes with 81 or 86% accuracy, respectively.