ONION GERMPLASM INTERACTS WITH SULFUR FERTILITY FOR PLANT SULFUR UTILIZATION AND BULB PUNGENCY

Sixty-two onion (Allium cepa L.) entries grown under high (4.0 mequiv.liter-1) and low (0.1 mequiv.liter-1) S fertility were evaluated for foliar and bulb S utilization, and pungency. Significant differences were detected among entries at both S fertility levels for foliar and bulb %S, and enzymatically developed pyruvate (pungency) in bulb tissue. Correlations between foliar %S and enzymatically developed pyruvate and between bulb %S and enzymatically developed pyruvate were poor suggesting that S is differentially partitioned into flavor and non-flavor compounds in the bulbs of onion germplasm. Significant S by entry interactions were found for all variables tested indicating that selection for S utilization and bulb pungency in onions be conducted at S fertility levels indicative of targeted production areas.