Effects of water stress on glucosinolate and oil concentrations in the seeds of rape (Brassica napus L.) and turnip rape (Brassica rapa L. var. silvestris [Lam.] Briggs)

Abstract

Growing-season conditions influence the concentration of glucosinolates in the meal of rapeseed, but the reasons for this are unknown. We studied the effect of water stress on glucosinolate concentration in the seed meal of Brassica napus cv. Wesbrook and Brassica rapa cv. Bunyip. Plants were either wellwatered or given a reduced supply of water which was managed to produce a desired degree of plant water stress either throughout growth or only after flowering. Glucosinolate concentration in seeds increased (P<0.01) in both cultivars from an average 18.2 µmol/g in unstressed plants to 35.0 µmol/g under the influence of water stress. There was no significant difference between the 2 stressed treatments. Water stress also decreased (P < 0.0 1) seed oil concentrations (from 36.9 to 31.4%), yields (from 5.3 to 0.9 g/plant) and 1000-grain weights (from 4.1 to 3.0 g).