WATER-STRESS EFFECTS ON RAPESEED QUALITY

The sensitivity of seed composition to drought was compared among thre e spring glasshouse-grown rapeseed genotypes by applying water shortag e treatments at various stages of development. All traits under study associated with the biochemical composition of the seed were drastical ly modified in plants subjected to drought during flowering. Water sho rtage during a restricted period in the early stages of vegetative gro wth was also important for seed quality. Despite limited fluctuations in total lipid content, changes in fatty acid composition were found, especially in the erucic acid metabolic pathway (i.e., oleic, gadoleic and erucic acids). A slight increase in seed protein concentration wa s observed after early vegetative and flowering drought treatments. Th e total sugar content of seeds was not significantly affected by water deprivation. Significant effects of drought stress, depending on its timing, were observed in the accumulation of secondary metabolites (i. e., phenolics and glucosinolates) which are of major importance for ra peseed meal quality. The relevance of the observed effects on seed com position resulting from either immediate or long-term effects of water deprivation depending on its application stage is discussed.