Analyzing suitable combinations of potting mixtures and hormone levels for vegetative propagation of Excoecaria agallocha (milky mangrove) from Madu ganga Ramsar Wetland

Abstract

Mangroves are the foundation species that control ecosystem dynamics and identifying their vegetative propagation methods is important to conserve them. This study was conducted to identify suitable combinations of potting media and indole-3butyric acid (IBA) concentrations for the propagation of Excoecaria agallocha (milky mangrove) stem cuttings sourced from Madu Ganga Wetland in south west rainforest region of Sri Lanka. Three IBA concentrations (2500, 3000 and 3500ppm) and three potting media (P1. lagoon silt, P2. clay and sand (1:1), and P3. topsoil, coir-dust, compost and sand (4: 4: 4: 1) were factorially combined in a Completely Randomized Design with five replicates. The control treatment was 2500 ppm IBA with P2 potting media. There was no interaction effect for survival percentage, root dry weight and shoot number between potting media and IBA concentration. For survival percentage, and root dry weight, significantly highest values were observed in 3500ppm IBA. Shoot number was significantly higher in P3 while the survival percentages were significantly greater in P1 and P3 potting media than control. The average number of roots, root length, and root volume, were significantly greater in 35000ppm IBA with P1 media. According to the vigor scales, the highest root vigor was depicted by lagoon silt treated with 3500 ppm IBA while the highest shoot vigor was observed from P3 media treated with 3500 ppm IBA. Results revealed that treating stem cuttings with 3500ppm IBA and using P1 or P3 potting media are the most effective method to propagate E. agallacha through stem cuttings out of the treatments tested in this study.