Articles
THE ROLE OF MYO-INOSITOL AND CYTOKININS IN THE SURVIVAL OF ROOTED PEACH CUTTINGS
A high rooting percent still does not ensure overall success, as many cuttings succumb in the weeks following rooting, in spite of the gradual reduction in misting after rooting has occured (hardening). Death of the roots in this case is preceded in general by a very considerable leaf abscission.
Rooting of leafy cuttings of the peach cv. ‘Almog’ was found to be optimal when the bases of the cuttings were immersed for 24 hrs in a solution of 25 ppm IBA. However rooting was much improved and reached 80% (for subapical cuttings) with a solution of 50 ppm IBA + 2,3-dichloro 1,4-naphthoquinone (marketed as ‘Phygon-XL’), the latter substance being not only a fungicide but increasing synergistically the rooting potential of auxin.
The latter treatment not only increased the rooting rates of the cuttings, but also their survival, particularly of apical cuttings (from 15% without Phygon-XL to 80% with Phygon-XL).
Considerably lower rooting rates were obtained with the peach cv. 15–39. In this case, in addition to the treatment with IBA + Phygon-XL, weekly foliar sprays with naphthalene acetic acid + benzyladenine were applied, and rooting was increased by this treatment from 17.5% to 47.5% (for subapical cuttings).
With nectarine cv. ‘Sunred’ the main problem was the poor survival of the rooted cuttings; this was much improved by weekly foliar sprays of myo-inositol + BAP (from 0 to 53% for apical and 20% to 85% for subapical cuttings). Such results were only obtained when the spray schedule was started after roots were already formed.
Improved survival, though to a lesser extent, was also obtained by weekly sprays with NAA + BAP. These treatments increased the number of surviving leaves on the cuttings and both the cytokinin and total sugar content of their roots considerably.
Sprays with myo-inositol alone or BAP alone did not effect the cytokinin and sugar content of the roots.
On the other hand a foliar BAP spray reduced the translocation of labelled myo-inositol applied to the tops of the cuttings to their bases.
The results indicate the importance of cytokinins for the survival of freshly rooted peach cuttings and the role of myo-inositol in enhancing the transport of cytokinin from the tops of the cuttings to their roots.