Effects of α-Naphthaleneacetic acid concentration and substrates on the growth of Polyscias fruticosa (L.) Harms cuttings

The study aimed to determine the optimal α-NAA (α-Naphthaleneacetic acid) concentration and suitable substrate for the growth of Polyscias fruticosa (L.) Harms seedlings propagated through cuttings. The two-factor experiment was arranged in a completely randomized design with 16 treatments and three repetitions. The cuttings were treated with α-NAA (Factor N) at concentrations of 1,000; 2,000; 3,000; and 4,000 mg/L and grown in four different substrates: (G1) 100% soil, (G2) 50% soil + 50% rice husk ash, (G3) 50% soil + 20% coco peat + 30% rice husk ash, and (G4) 50% soil + 40% coco peat + 10% rice husk ash. The results showed that the rooting rate and growth index of the cuttings increased gradually with the concentration of α-NAA and reached the highest value at 3,000 mg/L, then decreased as the concentration of α-AA increased. The substrate mixed with coconut peat and rice husk ash had significantly improved porosity, helping to increase the rooting rate and growth ability of the cuttings. It was also shown that the best performance was achieved when cuttings were treated with 3,000 mg/L α-NAA and grown in a substrate consisting of 50% soil + 20% coco peat + 30% rice husk ash. In 60 days after planting, the Polyscias fruticosa cuttings’s survival rate was 94.1% and a standard export rate of 89.9%. Growth indicators included an average shoot height of 18.3 cm, shoot diameter of 7.2 mm, and an average of 5.3 leaves per shoot.