Effect of cutting type, potting media, and irrigation frequency on the success of vegetative propagation of iriweriya (Plectranthus zeylanicus Forssk)

Abstract

Plectranthus zeylanicus is an indigenous, multi-functional herb used in traditional medicine. Due to over-exploitation from the natural habitats, the species is on the verge of extinction. Therefore, commercial cultivation of the species is needed to satisfy the rising demand while protecting its genetic base. The current study was designed with three trials to identify the most suitable cutting type, potting media, and irrigation schedule for P. zeylanicus. Four distinct cutting types (tip cutting, triple nodal cutting, double nodal cutting, and single nodal cutting), five different potting mixtures (topsoil: sand: compost-1:1:1, topsoil: sand: compost-1:2:1, topsoil: sand: compost-1:1:2, topsoil: compost -1:1, topsoil: compost-1:2) and four different irrigation schedules (daily watering to field capacity level, daily watering to half of the field capacity level, every other day to the field capacity level, every other day to half of the field capacity level) were used in Completely Randomized Design with ten replicates. Survival percentage (%), number of leaves, the height of the plant (cm), average length of roots (cm), average leaf area (mm²), and chlorophyll content (SPAD Unit) were measured as growth parameters. Data were analyzed using SAS software with a 5% significance levels. Highest survival percentage (95%), highest average root length (26.8 cm), average leaf area (80.5 mm²), and a higher chlorophyll content (31.1 SPAD Unit) were recorded from tip cuttings of P. zeylanicus. Furthermore, the topsoil: sand: compost-1:1:1 combination showed a higher survival percentage (90%), number of leaves (3), highest average plant height (43.9 cm) and average root length (20.2 cm) with significantly (P<0.05) higher average leaf area (52.3 mm²), and chlorophyll content (31.07 SPAD Unit). Daily watering to the field capacity showed a higher survival percentage (90%), significantly higher (P<0.05) number of leaves (3.7), plant height (51.6 cm), higher root length (25.5 cm), the highest average leaf area (80.0 mm²) and chlorophyll content (32.7 SPAD Unit). Therefore, tip-cutting planted in topsoil: sand: compost-1:1:1 media can be recommended for successful propagation of P. zeylanicus.

Keywords: Growth parameters, Irrigation schedule, Plectranthus zeylanicus, Potting media, Stem cutting

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Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya, Sri Lanka

Copyright © 2007 by the Faculty of Agriculture, University of Ruhuna

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