IN VITRO SHOOT INDUCTION AND MULTIPLICATION OF JACKFRUIT (Artocarpus heterophyllus Lam.) 'EVIARC SWEET’ VARIETY SUPPLEMENTED WITH PLANT GROWTH REGULATORS (PGRS)

Jackfruit (Artocarpus heterophyllus Lam.) is monoecious, cross-pollinated, and highly heterozygous. Propagation through seeds is not widely accepted because seeds from one tree do not produce fruit true to the type of the parent plant and are recalcitrant. Jackfruit is still considered a difficult fruit species to propagate by vegetative means through grafting, and the graft survival percentage is only 30.00% - 55.00%. Grafted seedlings of jackfruit var. EVIARC Sweet (3-4 months old after grafting) were acquired from the Plant Propagation Nursery of the Department of Horticulture, Visayas State University, Visca, Baybay City Leyte, and were raised in the screenhouse and were used as donor plants. This study was conducted to evaluate the effect of plant growth regulators, thidiazuron (TDZ), 6-benzylaminopurine (BAP), and indole-3-butyric acid (IBA) at varying concentrations on in vitro shoot induction and multiplication of jackfruit. Shoot tips of grafted seedlings were used as the source of explants. Standard MS (Murashige & Skoog, 1962) solid medium was used as the basal medium during the inoculation period. One week after inoculation, the cultures were transferred to full MS media strength supplemented with various plant growth regulators (PGRs). There were 17 treatments and four (4) replications with 15 sample explants per replication arranged in CRD. The results showed that the earliest shoot formation occurred with the application of 0.1 mg/L thidiazuron (TDZ) + 3.0 mg/L benzyl aminopurine (BAP) and 0.5 mg/L TDZ + 5.0 mg/L BAP, taking 17.38 and 18.88 days, respectively. The highest shoot induction rate (83.75%) was observed in the combination of 0.1 mg/L TDZ + 3.0 mg/L BAP, producing 4.00 shoots per explant. The shoot length was also longer (3.12 cm) when applying 0.1 mg/L TDZ + 3.0 mg/L BAP. The combination of TDZ and BAP also led to more internodes, nodes, and leaves than other treatments. A multiplication rate of 2-5 shoots per explant was achieved after the first subculture. Further research is needed to explore the effects of other PGR combinations or alternative cytokinin sources that might further enhance jackfruit propagation.