DYNAMICS OF ENDOGENOUS CYTOKININS DURING PHASE CHANGE IN MALUS DOMESTICA BORKH

In order to identify the dynamics of endogenous cytokinins during phase change in hybrid seedlings of apple, cytokinins in leaves and the bark of two-year-old seedlings ('Jonathan' × 'Golden Delicious') were extracted and analyzed by high performance liquid chromatography. The results indicated that a higher level of zeatin (ZT) content was found from node nos. 81-85 to nos. 121-125 in bark samples, indicating that the seedlings were at special physiological stages. No significant variations of dihydrozeatinriboside (DHZR) contents in leaf were found except a sharp decrease between node nos. 81-85 and nos. 116-120. The N⁶-isopentenyladenine (iP) content in the bark peaked from the node nos. 101-105 to nos. 121-125. The dynamics of ZT in the bark and DHZR in leaves could be quantitative markers of the adult vegetative phase in apple seedlings.