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 duringonset of fruit development as compared with other stages of fruit development. During a fertilisationexperiment with increasing amounts of N and timing, non-structural carbohydrates and PAs weredetermined in leaves, flowers and developing berries. Leaves: PAs were lowest in the unfertilizedplots; fertilization showed no differentiated effects. PA-concentrations peaked after full bloom andfell to 50% of the starting value at the stage “pea-sized berriesâ€. Shoots: belonging to the leaves withthe same plastochron-index showed a similar behaviour like PA in leaves. Stems: Putrescine (Put) andSpermidine (Spd) show a clear time course. Put decreases until "flowers fully developed" and afterwardsa slight increase until "pea sized berries". Spd behaves nearly inverse: peak at "increasing ofthe flowers" and a minimum at "fruit set". Berries: all four tested PAs show a clear pattern of theirtime course. Agmatine (Agm) is highest at 27 May (five to six leaves unfolded), lowest at 5 June andpeaking again at "flowers fully developed" (24 June). At "fruit set" concentrations are as low as at 5June ("flowers are growing"). Put is high at "five to six leaves unfolded", decreases continuously until"flowers fully developed" and a maximum at "fruit set". Spd shows a maximum at "flowers are growing"and reaches a minimum at "fruit set". Spd has nearly constant concentrations through "five to sixleaves unfolded" until "flowers are fully developed" in all fertilizer variants. At "fruit set" is a maximum.peaks at "flowers fully developed", decreases to "fruit set" and increases again at "pea sizedberries". Treatments show a differentiation; highest values are found with the plot 90/60. A directconnection to the carbohydrate metabolism could not detected during this experiment.
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