Origin of nitrogen accumulated in the tulip roots in winter season

Abstract

Abstract Tulip plants accumulate a large amount of N in the roots during the winter season, and the N can be used for the rapid shoot growth after sprouting (Ohyama et al. 1988). In the previous paper (Ohyama et al. 1985), the tulip plants were grown in a culture solution, and the forms of N accumulated in the roots were investigated by comparing the plants supplied with N (12 ppm NO3 --N, 3 ppm NH4 +-N) and without N in the medium. When the tulips were harvested on December 13, the TN content in the roots supplied with N became very high about 85 mg/g DW, while the TN content in the roots cultivated in the N-free medium was only about 22 mg/g DW. The fresh roots were fractionated by sequential extraction with 80% ethanol and distilled water, and it was observed that the N accumulated in the roots treated with +N medium was mainly stored in the “80% ethanol soluble fraction” supplemented with the “water soluble but ethanol insoluble fraction.” Moreover, Gln was found to be a major N constituent in the 80%...