Influence of differing nitrogen nutrition on polyamines and non-structural carbohydrates during different developmental stages of grapevines (c.v. White Riesling).

Abstract

Polyamines (PA) are triggered by external inducers (hormones, fertilization, nutrients etc.). In triggered systems, the level of free PAs increase before the onset of cell division. PAs are high dur- onset of development as compared with other stages of development. During a fertilisa- tion experiment with amounts of N and timing, non-structural carbohydrates and PAs were determined in leaves, and developing Leaves: PAs were lowest in the unfertilized plots; fertilization showed no differentiated effects. PA-concentrations peaked after full bloom and fell to 50% of the starting value at the stage pea-sized berries. Shoots: belonging to the leaves with the same plastochron-index showed a similar behaviour like PA in leaves. Stems: Putrescine (Put) and Spermidine (Spd) show a clear time course. Put decreases until fully developed and after- wards a slight increase until pea sized berries. Spd behaves nearly inverse: peak at increasing of the flowers and a minimum at fruit set. Berries: all four tested PAs show a clear pattern of their time course. Agmatine (Agm) is highest at 27 May (five to six leaves unfolded), lowest at 5 June and peaking again at fully developed (24 June). At fruit set concentrations are as low as at 5 June (flowers are growing). Put is high at five to six leaves unfolded, decreases continuously until fully developed and a maximum at fruit set. Spd shows a maximum at are grow- ing and reaches a minimum at fruit set. Spd has nearly constant concentrations through five to six leaves unfolded until are fully developed in all fertilizer variants. At fruit set is a maxi- mum. peaks at fully developed, decreases to fruit set and increases again at pea sized berries. Treatments show a differentiation; highest values are found with the plot 90/60. A direct connection to the carbohydrate metabolism could not detected during this experiment.