Rooting of peach [Prunus persica (L.) Batsch] hardwood cuttings as affected by IBA concentration and substrate pH

In order to study the effects of four IBA concentrations (0, 1000, 2000 and 3000 mg L-1) and three substrate pH levels [pH 5, 7 and 9] on rooting of hardwood cuttings of peach cv. Red May, experiment were conducted at the Department of Horticulture, College of Agricultural Sciences, University of Sulaimani/ Kurdistan,Iraq, . The experiment was laid down in a factorial RCBD with three replications. Comparison among means was done using Duncan’s multiple range test (P≤0.05). Rooting and callusing percentage, root number, root length, root fresh weight, root dry weight, shoot length, shoot diameter, leaf number, leaf area, shoot fresh weight and shoot dry weight were examined. The highest rooting percentage (40 %) was achieved from 2000 mg L-1 IBA. However, effects of IBA levels were not significant on callusing. Control gave no rooting and other root traits. Effects of the IBA concentration on vegetative traits were not different with each other except shoot diameter and leaf number. Shoot diameter and leaf number were the highest (1.12 mm and 4.51, respectively) at 2000 mg L-1 IBA. Rooting and other parameters were the best in pH 5 and 7 substrates. Substrate pH 9 gave minimum rooting and other parameters. Effects of interactions between the two factors showed that cuttings treated with 2000 mg L-1 IBA and planted in pH 7 substrate gave the highest (60 %) rooting percentage, and cuttings dipped in 1000 mg L-1 IBA and planted in pH 7 substrate gave the best other root traits. Interaction effects of the two factors on shoot traits showed that the maximum shoot traits were observed at interaction between 2000 mg L-1 IBA and pH 5 substrate.