EFFECTS OF NUTRIENT SUPPLY ON PREEMERGENCE GROWTH AND NUTRIENT ABSORPTION IN WHEAT (TRITICUM-AESTIVUM L.) AND SUGAR-BEET (BETA-VULGARIS L.)

Nutrient absorption in wheat and sugarbeet was studied during pre-emer gence growth by adding 0, 7, 10.5 or 14 mol m(-3) nitrogen (N) to the growth medium. Seedling growth and carbon, N and N-15 contents of the seedling parts were measured. Differences between the natural abundanc e of N-15 in seeds and in nutrient solution were used to determine the proportion of N in the organs originating from seed reserves and from absorption. Absorption began later for wheat than for sugarbeet and h ad less effect on seedling growth. The absorbed N was found mainly in roots. Compared to wheat, sugarbeet seedling N content was greatly alt ered and the hypocotyl showed increased elongation when nutrients were added. Most of the absorbed N was found in the radicle and hypocotyl with less in the cotyledons. Sugarbeet seedling emergence and early gr owth could be decreased by adverse conditions occurring after sowing b y affecting mineral availability in the soil or through altered root a bsorption. (C) 1998 Annals of Botany Company.