Mohammad Hedayat

Neem (Azadirachta indica) is an important tropical tree species with many uses. To improve the rooting response of neem cuttings, urea-phosphate (UP) and paclobutrazol (PBZ) were tested in combination with indole-3-butyric acid (IBA). UP alone did not stimulate rooting of neem cuttings; however, when applied together with IBA it significantly enhanced the rooting of cuttings. PBZ alone had a weak effect on rooting of cuttings, but in combination with IBA it improved the rooting of cuttings. A triple combination of IBA, UP, and PBZ provided the highest effect on the improvement of rooting percentage. IBA treatments increased the number of roots per cutting in comparison with the control, but decreased the root length of cuttings. IBA plus UP or PBZ further increased the number of newly formed roots. In addition, IBA plus UP increased the average root length. The combined effect of the three compounds on root number per cutting was not different from that of IBA plus PBZ, but the roots were longer than in the IBA-treated and the control cuttings. The survival of rooted cuttings treated with IBA was relatively low. The triple combination of IBA, UP, and PBZ improved the survival of the rooted neem plants compared with IBA alone. Thus, UP and PBZ were shown to enhance the effect of IBA in stimulation of rooting and survival of neem cuttings.