Investigation of initial growth of grey mangrove (Avicennia Marina (Forssk.) Vierh.) seedling affected by root and leaf extracts of mother trees

Despite the initial need of seeds and seedlings of grey mangroves (Avicennia Marina (Forssk.) Vierh.) for semi-shade, they are very low under the canopy of trees of this species in Hormozgan province, Iran. For this purpose, in this study, the effects of possible inhibition of pneumatophores and leaves of mangrove trees on the vegetative characteristics of grey mangrove seedlings in greenhouse conditions have been investigated. After collection of propagules from healthy mother trees and cultivating them in September 2020, propagules were irrigated with concentrations of 0, 0.05, 1 and 2% of leaf and root extracts. After six months, the vegetative and biomass characteristics of mangrove seedlings were measured in different treatments and evaluated using two-way analysis of variance and Duncan test. The results showed that the diameter of growth (5.58 mm), height (29.27 cm), root length (27.73 cm), number of leaves (14.58) and root fresh weight (5.65 g) were the highest in the control treatment. Also in control and 2% treatment, root dry weight (1.02 and 0.77 g), stem fresh weight (12.77 and 10.59 g), stem dry weight (3.54 and 2.93 g), root water (4.62 and 3.29 g) and stem water (9.23 and 7.66 g) had the highest and lowest values, respectively. Investigation of organ × concentration interactions showed that leaf extract had a significant reduction effects on root fresh weight and root water in 2% treatment compared to those in the other treatments. According to the results, increasing of leaf and root extracts concentration of grey mangrove trees has a inhibitory role on the vegetative characteristics of seedlings of this species, so in reforestaion and afforestation of gery mangrove trees, the seedlings should be planted at a suitable distance from the trees.