Efficacy of phytohormones producing isolates on the growth of two stem-cutting robusta coffee (Coffea canephora)

Abstract

The propagation techniques of robusta coffee by cutting can be accelerated by the application of plant growth-promoting hormones. This study is to determine the efficacy of phytohormone-producing isolates on the growth of two-segment cutting of Robusta coffee. The study was conducted using a non-factorial completely randomized design with 2 replications. The treatments consist of control, synthetic IBA (Rooton-f) with three dilution concentrations, 4 isolates (Rhodococcus qingshengii, Burkholderia ambifaria, and Bacillus wiedmannii; fungi Aspergillus niger) with three dilution concentrations. Observed parameters included a percentage of live cuttings, percentage of cuttings sprouted, percentage of rooted cuttings, plant height, number of shoots, number of internodes, number of leaves, number of primary roots, primary root length, and primary root diameter. The results showed that the B. wiedmannii treatment had the best performance compared to other treatments because this isolate produced the highest number of primary roots (4.60) and primary root diameters (2.97 mm) compared to other treatments including control and Rooton-f. This is related to its ability to produce phytohormones that can stimulate the root growth of coffee robusta cuttings.