Pengaruh Berbagai Zat ZPT Bahan Alami dan Konsentrasi terhadap Pertumbuhan Stek Kopi Robusta (coffea canephora)

Abstract

This research aimed to investigate the effects of various natural Plant Growth Regulators (PGR) and their concentration on the growth of Robusta coffee (Coffea canephora) cuttings. The experimental method involved 16 treatment combinations with 3 replications. The first factor evaluated was the type of natural PGR: control, a blend of banana corm + corn seed, banana corm + bean sprout, and a multi-component mixture of banana corm + corn seed + bean sprout. The second factor was the concentration levels: 0%, 10%, 20%, and 30%. The results demonstrated that the interaction between the type of natural PGR and its concentration had a highly significant effect on all root growth parameters (root volume, length, fresh weight, and dry weight). Conversely, this interaction showed no significant impact on shoot growth indicators, including shoot length, leaf count, and stem diameter. This physiological trend indicates that during the early propagation phase, metabolic energy is strictly prioritized for adventitious root initiation rather than above-ground vegetative development. The combination consisting of banana corm, corn seed, and bean sprouts at a low concentration of 10% consistently yielded the most optimum results, achieving a maximum root dry weight of 0.31 grams. On the contrary, higher concentrations of 20% and 30% led to a visible decline in root development due to inhibitory effects caused by excessive hormonal supply. This study concludes that applying a combination of the three natural PGRs at a 10% concentration level provides the optimum dose for an effective and sustainable Robusta coffee nursery.