Morphogenesis Response of Leaf and Petiole Explant of Rootstock Apple (Malus sylvestris Mill.) to Auxin and Cytokinin

Rootstock apple is a type of plant used in grafting propagation. Research related to the response of morphogenesis in this plant has not been widely carried out. The aim of this research was to study the effect of auxin and cytokinin ratio on the morphogenesis response of leaf and petioles explants of rootstock apple and to study variations in the ratio of auxin and cytokinin with the best response. The study used a 2-factorial Completely Randomized Design (CRD) with variations in the types of explants and combinations of plants growth regulators (PGR) in the culture medium. There were 12 treatments with five repetitions. Explants in the form of young apple leaf (third leaf) and petiole rootstock that had been sterilized and cut with a size of 5x5 mm for the leaf and 5 mm long for the petiole were inoculated into MS medium with cytokinin in the form of BAP (1 ppm) combined with auxin, IBA (0, 0.1, 0.2, 0.3, 0.4, 0.5 ppm). Each culture bottle contains five explants. The results showed that the average leaf explant was capable of producing 34% callus. Meanwhile, petiole explants produced 4% callus. Callus began to form on leaf and petiole explants on the 26th and 42nd days after inoculation respectively. Most calluses have a compact texture with variations in green, yellowish white, and brownish green. The PGR combination with the highest percentage of callus formation in leaf explants was found in the BAP 1 ppm + IBA 0.4 ppm treatment, while the petiole was in the BAP 1 ppm + IBA 0.3 ppm treatment