Nitrogenous Compounds and Nitrogen Metabolism in the Liliaceae: III. Changes in the Soluble Nitrogen Compounds of the Tulip and their Relation to Flower Formation in the Bulb

The principal free amino-acid of the vegetative tulip bulb isarginine and the alcohol insoluble nitrogen fraction containscombined arginine to the extent of 47 per cent. of the nitrogen.In the green leaf the amides glutamine and asparagine occurwhereas free arginine is virtually absent. These amides do notoccur appreciably in the vegetative bulb. By appropriate temperature treatments flowers were initiatedand after the floral parts were formed they were caused to developto the point of emergence from the bulb. The concomitant changesin the soluble nitrogen compounds were determined. The dramatic change in the composition of the soluble nitrogeninvolving a shift from the predominance of arginine to a relativeincrease in glutamine and asparagine occurs when the alreadyinitiated flowers develop. -methyleneglutamine and -methyleneglutamic acid which are prominentin the tulip seem not to be greatly affected by the treatmentsthat cause floral initiation and development. Their metabolismseems superimposed upon the nitrogen metabolism based on argininein the bulb and amides in the leaf which is responsive to thetreatments involved in flower formation.