Sulfur Nutrition Affects Garlic Bulb Yield and Allicin Concentration

Abstract

Improving bulb yield and allicin content of garlic is important in meeting fresh and pharmaceutical market demands. Garlic plants have a high demand for sulfur (S) since allicin contains S atoms. Two experiments were conducted to identify the effect of S application rate on garlic yield and quality. In a field trial assessing six S application rates (0-150 kg S ha^-1), cultivar 'Glenlarge' produced the greatest bulb weight (~90 g) and allicin content (521 mg bulb^-1) with the application of 75 kg S ha^-1. In contrast, cultivar 'Southern Glen' showed no response in bulb weight or allicin. This was likely due to high soil background S concentrations masking treatment effects. Subsequently, a solution culture experiment with cv. 'Glenlarge' evaluated six S application rates (188 to 1504 mg S plant^-1, nominally equivalent to 25-200 kg S ha^-1). In solution culture, bulb weight and allicin concentration increased with S rate. Highest bulb weight (~53 g bulb^-1) and allicin concentration (~11 mg g^-1 DW) were recorded at an S application of 1504 mg S plant^-1. This is the first report to conclusively demonstrate the effect of S on yield and allicin in garlic grown in solution culture.

Keywords: allium; biomass; bulb weight; solution culture.

Figure 1

Bulb fresh weight and yield for cultivars Glenlarge (blue lines and symbols) and Southern Glen (red lines and symbols) grown in the field (A) and cultivar Glenlarge grown in solution culture (B). Values are means of 4 replicates with standard error bars shown if not obscured by the symbols. The lines represent the best-fit linear or quadratic equations.

Figure 2

Sulfur uptake for cultivars Glenlarge (blue lines and symbols) and Southern Glen (red lines and symbols) grown in the field (A) and cultivar Glenlarge grown in solution culture (B). Values are means of 4 replicates with standard error bars shown if not obscured by the symbols.

Figure 3

The relationship between sulfur application rate (mg plant⁻¹) and (A) bulb allicin concentration (mg g^-1 DW) and (B) allicin content (mg bulb⁻¹) for garlic cultivar Glenlarge grown in a solution culture at a range of S supply (188–1504 mg plant⁻¹). The 1128 mg plant⁻¹ treatment was omitted due to bulbs rotting prior to analysis.

Figure 4

Garlic cloves were grown in solution culture in a glasshouse at Gatton campus, The University of Queensland, Australia in 2020.