EFFECT OF INDOLE-3-BUTYRIC ACID AND ROOTING SUBSTRATES ON ROOTING RESPONSE OF HARDWOOD CUTTINGS OF RHODODENDRON FORTUNEI LINDL

摘要

The effects of indole-3-butyric acid (IBA) and rooting substrates on root formation on current year hardwood cuttings of Rhododendron fortune was investigated. We used a completely randomized design in a factorial 4 x 6 arrangement (4 IBA concentrations x 6 rooting substrates) with three replications in a greenhouse under intermittent mist and bottom heating. The effect of IBA concentration was highly significant (p <= 0.001) for percentage of rotted cuttings, callus formation, rooting, and retention of old leaves. Up to 200 mg l(-1) IBA was the most efficient auxin concentration for the rooting of Rh. fortunei cuttings. The rooting substrate had also highly significant effects on rooting. Pure sand was the most feasible substrate. However, the highest callus formation and the length of longest adventitious root were observed in the substrate of peat + perlite (4 : 1, v/v). A significant interaction of IBA concentration and rooting substrate was seen for the lengths of the longest adventitious root. Correlation analysis showed that rotting, callusing, rooting, and retention percentages of old leaves, as well as number of total roots and of adventitious roots, were highly significantly correlated, whereas the length of the longest adventitious root was significantly correlated only with callusing percentage and number of adventitious roots.