Annual Cyclic Changes in the Concentration of Free Amino Acids in Grapevines

Abstract

Concentrations of total soluble and insoluble nitrogen and 19 amino acids were determined throughout a 1-year growth cycle in the main and lateral roots, canes, and trunk wood of <i>Vitis vinifera</i> L., 9Thompson Seedless.9 Soluble nitrogen during the year ranged between 46 and 65% of the total nitrogen in the roots and between 20 and 47% of that in the woody tissues. The concentration of each amino acid and of total soluble nitrogen increased in the roots and woody tissues during dormancy and reached maximum just prior to budburst, in the spring. Levels of the amino acids decreased rapidly during the period of most active growth (April through June) and reached a minimum in July and August. The period of leaf senescence (October and November) was characterized by a sudden increase in the concentration of amino acids in the roots and woody tissues, indicating possible translocation of these compounds from leaves to storage parts of the grapevine prior to leaf abscission. Arginine was the main soluble nitrogen compounds present in the roots and woody tissues, accounting for 10 to 57% of the total soluble nitrogen in the roots and 2 to 58% of that in the woody tissues. The percentage of the total soluble nitrogen contributed by 18 other amino acids ranged from 1.4 to 3.9% in the roots and from 7.3 to 16.7% in the woody tissues. Quantitatively, the main difference between roots and woody tissues in concentrations of amino acids were that arginine, histidine, and lysine were greater in the roots whereas pipecolic acid, proline, serine, and threonine were usually greater in the cane and trunk wood.