Performance of Hormonal Content and Branching of Apple Nursery Trees after BA (6-benzyladenine) Application

We treated 'Golden Delicious' apple nursery trees in 2010 with solution containing 0.02 % benzyladenine (BA). The BA-solution was sprayed three times in 10 days intervals on the upper tierce (from 70-90 cm) of the trees. This treatment resulted in sprouting of summer buds after 7-10 days and improved branching until the lifting of trees. The treatment did not effect on root collar diameter, but the BA-treated trees were significantly shorter than the untreated ones. The number of sylleptic shoots formed after the treatment was about two times higher on treated trees (7.79) compared to the control (4.43). Also the number of shoots longer than 20 cm increased notably on the treated trees (from 1.99 to 4.87 per trees) and the treatment positively affected the mean and the total length of the secondary shoots. Furthermore, the aim of our trials was to search how the BA-level of the trees changes. Therefore three-buds-long shoot-pieces were collected from the treated area on four dates: on the day of the first treatment (day 0), three days after the first treatment (day 3), on the day before the second treatment (day 9), on the day before the third treatment (day 19). The BA content was measured separately in the leaves, in the bark (containing buds) and in the xylem tissue by HPLC. Before the first spraying there was no BA detectable in the tissues of the nursery trees. In the leaves the BA-level firstly increased after the treatment (day 3.23 mu g/g), but it was not detectable in the next two sample (day 9 and day 19). The BA-level considerable decreased, almost disappeared before the third treatment in both leaves and bark, which suggests a possible decomposition or assimilation.