The Effect of Different Levels of N Limitation on Sugars, Amino Acids, Growth and Biomass Partitioning in Broadbean ( Vicia fabaL.)

Abstract

Broadbean plants ( Vicia fabaL.) were submitted to three different levels of steady state N limitation. Relative addition rates of N were 0.06, 0.1 and 0.14d -1. Plants were harvested at five evenly distributed times over a 2d period. Shoot growth corresponded well with the imposed treatment. Root growth, relative to shoot growth, was highest at the 0.06d -1treatment. Diurnal patterns of soluble sugars, amino acids and starch were analysed. On average, soluble sugar levels were highest in the plants of the 0.06d -1treatment whereas average free amino acid levels were highest in the 0.14d -1treatment. Shoot growth increased as the concentration of shoot amino acids increased. No such correlation however could be found between root growth and free sugar levels in the root.