CLONAL VARIATIONS OF PUNGENCY, SUGAR CONTENT, AND BULB WEIGHT OF ONIONS DUE TO SULFUR NUTRITION

A greenhouse study was conducted to test the effects of sulphur (S) nu trition on pungency, sugar content, and bulb weight of six cloned line s of 'TG 1015Y' onions. Onion bulbs grown under the low S treatment (0 .1 meq 1(-1) or 2 ppm S) contained 1.9 mu mol g(-1) fwt. pyruvic acid, while those under the high S treatment (7.7 meg 1(-1) or 123 ppm S) c ontained 5.5 mu mol g(-1) fwt. There was significant variation in the pyruvic acid content among clones under the high S nutrition, but not under the low S treatment. Total sugar content was higher in the low S treatment than the high S treatment (45.2 vs. 43.1 mg g(-1)) with a l arge variation among the clones under both treatments, Bulb weight was significantly less at low S nutrition (311 vs. 504 g) with a great va riation among the clones. Total S content in leaf (0.26 vs. 0.85%) and bulb tissues (0.13 vs. 0.43%) were significantly low in the low S tre atment and indicated a S deficiency. (C) 1997 Elsevier Science B.V.