Clonal variations of pungency, sugar content, and bulb weight of onions due to sulphur nutrition

A greenhouse study was conducted to test the effects of sulphur (S) nutrition on pungency, sugar content, and bulb weight of six cloned lines 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) contained 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 large variation among the clones under both treatments, Bulb weight was significantly less at low S nutrition (311 vs. 504 g) with a great variation 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 treatment and indicated a S deficiency. (C) 1997 Elsevier Science B.V.