Effects of 6-Benzylaminopurine (BAP) Treatment on Seed Germination and Seedling Vigour of Endemic Herb Exacum trinervium L. in Sri Lanka: Conservation strategy

Based on the scientific information available, E. trinervium is currently of conservation concern since it shows poor seedling growth even under satisfactory seed germination. Ex-situ cultivation is therefore recommended as a conservation strategy. This study aimed to (i) investigate the effective pre-sowing 6-Benzylaminopurine (BAP) treatment that enhances the seed germination and seedling vigour and (ii) to study morphological traits that can be used in assessing healthy seedlings of E. trinervium. The experiment was conducted in a completely randomized design under both laboratory and green house conditions with BAP concentrations of 1.0, 2.0 and 3.0 mgL-1 as pre-sowing treatments and distilled water as the control with different exposure durations i.e. 18, 24 and 30 hours. The results showed that there was no significant effect of BAP treatments on seed germination percentage under laboratory and nursery conditions. The lowest average mean germination time (MGT) was obtained 24 h exposure duration for the green house condition. Seedling dry weight and seedling Vigour Index (SVI) were significantly (P0.05) higher for BAP concentration of 3.0 mgL-1 under 24 h exposure duration. Growth parameters i.e. number of leaves, plant height, root length, number of primary roots, dry weight and fresh weight of E. trinervium were significantly (P<0.05) induced by BAP concentration and exposure duration. Accordingly, BAP concentration of 3.0 mgL-1 under 24 h exposure duration proved to be the optimum BAP treatment for the increase of seedling vigour of E. trinervium under the green house conditions. Therefore, the present study suggests that BAP treatment may be involved metabolically in the stimulation of germination and then to increase the seedling vigour of E. trinervium.

Journal of the University of Ruhuna 2015 3(1): 14-20