Amino acids in the bleeding sap of the grapevine. III

The effect of nitrogen-rich compounds on the daily fluctuations of the amino acid composition

Abstract

Changes in the daily composition of the soluble nitrogen fraction in the bleeding sap of Vitis vinifera L. cv. Criolla Grande were studied. Compounds with a high nitrogen content (e.g. asparagine, glutamine, arginine) had been previously added to the sap by direct inoculation into the xylem. Glutamine was found to be the main compound of the soluble nitrogen fraction in the bleeding sap collected during the first three days. From the next day onwards, however, glutamic acid turned out to be the dominant nitrogen soluble compound of the daily samplings. Glutamine concentration and total soluble nitrogen levels gave correlated results.

The patterns of total soluble nitrogen and those of the amino acids under varying conditions were closely correlated, with the exception of arginine wherc slight differences were observed. No parallelism was found when the percentage of nitrogen furnished as glutamine, asparagine and arginine was compared with the percentage of the nitrogen content corresponding to these same compounds on the first day of bleeding sap sampling.

The implication of added nitrogen compounds is discussed from a metabolic point of view, in relation to the delayed growth of the buds observed during a fortnight after bud burst.