Effects of Rooting-zone Restriction on the Changes in Carbohydrates and Nitrogenous Compounds in 'Kyoho' Grapevines during Winter Dormancy and Early Shoot Growth

Changes in carbohydrates and nitrogenous compounds in 'Kyoho' grapevines, grown under restricted rooting-zone conditions and in non-restricted conditions (control), were analysed during winter dormancy until full bloom. There were no significant differences in levels of sugars and starch, and total-N between the treated and control during winter dormancy. At bud-burst, however, vines with restricted rooting-zone contained more sugars in small roots but lower N level in the trunk and cane, compared to those with unrestricted rooting volume. Similar trends were observed in xylem sap collected from the trunk base at bud burst, young shoots disbudded 2 and 3 weeks after bud burst, and shoots and flower clusters at full bloom. Relationships between the nutritional status and retarded shoot growth, accompanied with improved berry set, in vines grown under restricted rooting-zone are discussed.