Effect of indole-3-butyric acid application type and concentration on rooting efficacy in three endemic rare-endangered Dianthus species with conservation priority

Abstract

Efficient propagation of uniform starting material is a critical requirement for mass production of most ornamental plants. Conservation and protection of rare-threatened plants and sustainable exploitation of biodiversity can be achieved through ex situ conservation actions. Therefore, propagation experiments were carried out on three endemic Caryophyllaceae species with limited spread and conservation priority: Dianthus ingoldbyi, Dianthus juniperinus subsp. bauhinorum and Dianthus fruticosus subsp. occidentalis. Softwood top cuttings were used in the middle of winter for D. fruticosus (6-7 cm) and D. juniperinus (5-6 cm) and in early spring for D. ingoldbyi (4-5 cm). The base of cuttings was immersed for 1 min in solutions of four IBA concentrations (0, 1000, 2000 and 4000 ppm) and also dusted with 0.066% and 0.2% IBA (in powder form). The cuttings were placed in a peat: perlite (1:3) substrate on a heated greenhouse mist. The most appropriate treatment for D. ingoldbyi (7 weeks) was 2000 ppm IBA (15.07 roots3.06 cm long, 100% rooting). In D. juniperinus, 1000 ppm IBA gave the highest rooting (57.14%) with 39.75 roots 7.49 cm long (8 weeks). Rooting of D. fruticosus was more effective (45.33 roots 5.85 cm long, 28.57% rooting) with 1000 ppm IBA (8 weeks).