Effects of species, light, and irrigation regime on vegetative growth of grey mangrove (Avicennia marina (Forssk.) Vierh.) and red mangrove (Rhizophora mucronata (Lam.)) seedlings in the nursery

Mangrove forests are one of the most beneficial ecosystems that have lost more than 50% of their primary extents. Because of uncontrolled degradation, many countries go beyond standard measures of mangrove forests protection and produce standard seedlings to afforest for higher success rates. Therefore, the aim of this study was to investigate the effects of species, irrigation, and light regimes as well as their interaction on vegetative growth of grey mangrove (Avicennia marina (Forssk.) Vierh.) and red mangrove (Rhizophora mucronata (Lam.)) seedlings in the nursery setting. Seeds of mangrove trees were collected and planted in plastic pots during July and August 2008. Then collar diameter, height, and stem height to stem diameter (h/d) were measured as influenced by species, irrigation regime (every day, every other day, and three days in between) and light condition (shade and light) using a three-way analysis of variance. Results showed that the diameter growth in the red mangrove is more than 0.38 mm than that of the grey mangrove (p < 0.05). Interactive effects of species × light condition showed that diameter growth of grey mangrove and red mangrove seedlings are significantly different in the shade condition. Diameter growth of grey mangrove seedlings was higher in light condition than that of in shade (p < 0.05). In shade, the stem height to stem diameter of seedlings was significantly higher than that of those measured it in light. Furthermore, the stem height to stem diameter as influenced by species × light condition was significantly different between two species and was also higher in shade condition compared with grey mangrove seedling (p < 0.01). The results suggested that light provides more favorable conditions for the grey mangrove seedlings growth, whereas it is not beneficial for the red mangrove seedlings.