Does mineral sulphur availability account for growth performance, bulb development and metabolically related traits in wild leek (Allium ampeloprasum L.; Alliaceae)?

• Bulbs of the biennial plant Allium ampeloprasum can be used as a vegetable.
• Wild leek is sensitive to S deficiency.
• Biomass allocation in above-ground organs is closely associated with S supply.
• Optimization of S supply results in larger daughter bulbs with a trade-off between bulb number and size.
• The metabolically related traits were dependent on S supply and plant tissues.

Allium ampeloprasum (L.) is a spontaneous biennial bulbous plant widespread across landscapes in the Mediterranean area, and has the potential to be used as a vegetable. Physiological and biochemical performance of this threatened vegetable was analyzed to investigate possible responses of sulphur (S) fertilization and how these relate to both ecological success and agronomic potential. Twenty-one-day-old plants were grown for 45 or 90 days at different sulphate concentrations in nutrient solution (0.01, 0.75, 1.5 and 4.5 mM SO42–). When all aboveground organs had senesced, the pots were harvested for reproductive output, i.e., mother and daughter bulbs. Sulphur deficiency significantly reduced vegetative biomass, which was closely associated with sulphate supply. Sulphur supply resulted in larger daughter bulbs with trade-offs between offspring number and size. The S content in shoots provided evidence of reduced daughter bulb mass in the low S treatment. The metabolically related traits were dependent on S supply and plant organs, which evolve an inverse trend between shoots and roots. Wild leek is sensitive to S deficiency and plants are able to cope with fluctuating S availability from 0.01 to 4.5 mM SO42–, whereas the initial S reserves in bulbs are likely to play an additional role in S-deficient soils. Overall, knowing the plant's optimal S nutritional status is of crucial importance in terms of crop management, which provides insight in how to produce wild leek, and potentially other Alliums, in the field with higher crop yield and enhanced product quality.