Effects of various rootstocks on xylem exudates cytokinin content, nutrient uptake and growth patterns of grapevine Vitis vinifera L. cv. Thompson seedless

Variations in cytokinins, mineral nutrient elements of xylem exudates colle cted before bud burst, petiole and blade nutrient concentration at veraison , and shoot growth patterns were studied as affected by the rootstock. A tw o year experiment was conducted on field grown grapevines cv. Thompson seed less, grafted onto 420AMgt, 110Richter, 99Richter, 41BMgt, Kober 5BB, 8B Te leki, 1103 Paulsen, 31 Richter and 3309C rootstocks. Xylem exudate cytokini ns were positively correlated with relative bud burst number, shoot elongat ion in the early season, and shoot elongation at veraison stage. A strong p ositive relationship between cytokinin content and total nitrogen was also found. The rootstocks 420AMgt, 110Richter, and 99Richter, which showed high levels in cytokinin content also had high nitrogen levels in xylem exudate s and leaf blade. Multivariate Analysis allowed to show that rootstocks wit h similar levels in cytokinin concentrations in xylem exudates, also presen ted a closely similar behaviour in nutrient uptake.