Rooting of greenwood cuttings of Marianna 2624plum (Priunus cerasifera Ehrh. X P. munsoniana Wight & Hedr.) taken in spring or summer is dependent on the presence of a certain minimum leaf area.Treatment of the basal portion of the cuttings with indoleacetic (IAA) or indolebutyric acid (IBA) sub-stantially increases the number of roots per cutting (20). The site of the auxin action is not known. Perhaps there is a direct effect at the site of application wlhere roots appear. Another possibility is that auxin stimulates mobilization of root-promoting substances from the leaves; these substances would then presumably be translocated basipetally to the site of root initiation.Although much study has been given to the absorption and translocation of auxins in intact plants, very few workers have investigated these phenomena in detached parts of woody plants. Cooper (4), using the standard Avena curvature test to follow movement of IAA in the bark of leafless lemon cuttings found initially relatively large amounts of IAA in the region of treatment; however, 95 per cent of the auxin disappeared during the 1st day, and little auxin was translocated to the apices of the cuttings. Turetskaya (24) followed the distribution of I-13 in soft and hardwood cuttings of various species treated with I'31-labeled-p-iodophenoxyacetic acid. In the hardwood cuttings the maximum I13' accumulation occurred in the base of the stem where the roots were formed. Decreasing amounts of f131 were found in xylem, bark, and buds, in that order. Turetskaya (25) followed the movement of C14-carboxyl-labeled naphthaleneacetic acid in leafy cuttings of balsam, cherry, and currant, and found some evidence that the NAA was metabolized.The present study was designed to follow the absorption, translocation, and persistence of C14 from alpha-labeled IAA in cuttings of Marianna 2624 plum. MATERIALS AND METHODS

Xylem sap was vacuum-extracted weekly from 1-year-old apple shoots from trees treated with dinitro-o-cresol (DNOC) oil, hydrogen cyanamide, or untreated controls. Sampling began 1 week before treatment and continued until 2 weeks after budbreak had occurred in the control trees. Sorbitol, calcium, magnesium, potassium, and zeatin-type cytokinin concentrations were determined by enzymatic, atomic absorption, and immunoassay methods, respectively. The rest-breaking treatments resulted in earlier and more intense budbreak. Xylem sap cytokinin concentrations increased rapidly in response to the rest-breaking chemicals and peaked just before or at budbreak. The rapid increase in cytokinin was closely followed by increases in calcium and magnesium concentrations in the sap. Potassium concentration appeared to be unaffected by rest-breaking treatment. Sorbitol levels dropped rapidly as a result of the rest-breaking treatments and appeared to be used rapidly in budbreak and early bud growth.

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