885-888. The relative glucosinolate composition of the florets from field-grown broccoli, determined using high-performance liquid chromatography and liquid chromatography-mass spectrometry, varied slightly with growing site and B fertilization, but was cultivar-dependent. Differences among growing sites, in total glucosinolate concentration, were greater than differences between the two cultivars used in the study. Liu et al. 1993). The availability of (Fenwick et al. 1983).freeze-dried material from that study enabled Earlier research showed that GS levels vary us to determine the total and individual GS, among cultivars of Brassica species and may including the indolyl-GS, of the edible porbe affected by environment (e.g., nitrogen, don of broccoli, using high-performance sulphur, boron) and soil type (Fenwick et al. liquid chromatography and liquid 1983). However, the individual GS contents chiomatography-mass spectrometry.were often not determined. On the other hand, In the f,i-rst experiment, carried out in 1990, gas chromatography has been used, but broccoli (Braisica oleracea var. italica indolyl-GS, which may constitute a signifi-.Baccus' ind 'Commander')

and 'Commander') plants were grown in the glasshouse from January to April under the environmental and nutrient conditions essentially as described by Shelp et al. (1992). The only exception was the B application, which was supplied continuously at 0.0. 1.0.25.0.5. 1.0 or 2.5 mg B L-' in the nutrient solution.Plants were harvested at maturity, just before bud opening at the time of maximum expansion of the inflorescence (72-80 and 78-93 d after sowing for Baccus and Commander, respectively; also designated as commercial harvest date). The two oldest leaves and the 4-6 youngest leaves weighing greater than 0.5 g were removed from each plant and deveined. One-half of each leaf or the inflorescence was frozen in liquid nitrogen and stored at -20"C for no longer than 2 wk. The RESULTS Infl orescence CharacteristicsThe inflorescence characteristics at commercial maturity are shown for the two cultivars For personal use only.

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