Seasonal Dynamics of Nitrogenous Compounds in a Nitrophilic Weed I. Changes in Inorganic and Organic Nitrogen Fractions of the Different Plant Parts ofUrtica dioica

摘要

The seasonal dynamics of nitrogenous compounds in the different plant parts ofUrtica diocia, a perennial nitrophilic weed, were investigated under natural conditions during the course of a year. In the below ground plant parts (roots and rhizomes) a nitrogen store was built up during summer and autumn, consisting mainly of free amino acids. In the seeds, however, proteins were of major importance as nitrogen reserve. In early spring the below ground nitrogen store was quickly mobilized, translocated to the upper plant parts and used for the protein synthesis of the shoots, enabling them a rapid growth prior to the development of their own capacity for nitrogen assimilation.