ROOTING RESPONSE OF P.S. B2 AND G.F. 677 ROOTSTOCK CUTTINGS
The rooting of P.S. B2 cuttings was improved with IBA at 1 000 ppm concentration and, to a lesser extent, at 2 000 ppm; on G.F. 677 the doses at 1 000 ppm and 2 000 ppm showed a similar effect. The 3 000 ppm concentration often gave a much lower rooting in both the rootstocks. Generally, hardwood cuttings propagated by bottom heat gave the best results. In P.S. B2, the highest rooting percentages induced by IBA (95%) were observed at 80% leaf drop, corresponding to the period of highest natural rooting potential and towards the end of flower bud rest period. G.F. 677 behaved similarly; the best rooting responses (85–95%) were obtained in December, when flower buds were still dormant but about to begin of swelling.