CHANGES IN GLUCOSINOLATES DURING CROP DEVELOPMENT IN SINGLE-LOW AND DOUBLE-LOW GENOTYPES OF WINTER OILSEED RAPE (BRASSICA-NAPUS) .2. PROFILES AND TISSUE-WATER CONCENTRATIONS IN VEGETATIVE TISSUES AND DEVELOPING PODS

The concentrations of glucosinolates in the tissue water of leaves, stems, floral buds and developing pods were measured at defined stages of development in four oilseed rape cultivars known to have different seed glucosinolate concentrations (Bienvenu, Ariana, Cobra and Capricorn). Five alkenyl, two aromatic and three indolyl compounds were identified in the vegetative and reproductive organs. Substantial differences developed in the profiles of compounds present during vegetative growth. The 2-hydroxy-3-butenyl glucosinolate was primarily associated with developing and mature seeds and germinated seedlings. The 4-pentyl glucosinolate occurred mainly during the later stages of vegetative growth in spring, when leaves contained higher concentrations than stems, and during the early stages of flowering. The 2-phenylethyl and 3-indolymethyl glucosinolates were present earlier in vegetative growth when similar concentrations were present in leaves and stems. Differences between cultivars in the tissue-water concentrations of individual glucosinolates were small during vegetative growth. The leaves of Cobra and Capricorn had smaller concentrations of the 3-pentyl glucosinolate than Bienvenu and Ariana especially early in spring, and the stems of Capricorn had smaller concentration of the 3-pentyl and 2-phenylethyl glucosinolates. Greater differences between cultivars developed during pod growth and involved large increases in the concentrations of the 2-hydroxy-3-butenyl and 3-butenyl glucosinolates, especially in Bienvenu and Ariana. The implications of these changes in the types and concentrations of glucosinolates in the different organs for the incidence of pests and diseases are discussed.