Agricultural and Biological Research

PLANT GROWTH REGULATORS INDUCE CALLUS FORMATION IN EXCELSA COFFEE (Coffea excelsa A. Chev.) LEAF EXPLANTS

Aron Louie Paler*

Vegetative propagation of Excelsa coffee (Coffea excelsa A. Chev) is challenging due to its dense, narrow, compact, and three-layered sclerenchyma band, which inhibits root formation. Therefore, developing a micropropagation protocol for this species is required to address this limitation to support sustainable coffee production. This study aimed to induce callus formation in leaf explants of Excelsa coffee using 2,4-D and Benzyl Amino Purine (BAP), as an initial step toward developing an efficient and reproducible micropropagation protocol. A 2 × 4 factorial experiment was conducted in a Completely Randomized Design (CRD) with three replications. Immature and mature leaf explants served as Factor A, and the concentrations of 2,4 D and BAP as Factor B. Results revealed that both immature and mature leaf explants successfully formed callus, with immature explants initiating callus earlier 14 Days After Inoculation (DAI) than mature explants (17 DAI). Among the plant growth regulator treatments, the combination of 2.0 mg/L BAP+2.0 mg/L 2,4-D resulted in the earliest callus formation (19 DAI) and gave the highest percent callus formation (61.34%). Notably, plant growth regulators significantly influenced browning (%) and contamination (%) of the explants. These findings demonstrate that Excelsa coffee callus formation can be induced by plant growth regulators, and both mature and immature leaf explants can be used for callus induction. To our knowledge, this is one of the first reports on callus formation in Excelsa coffee, providing valuable information for future micropropagation studies of this important coffee species.