EFFECT OF SOWING MEDIUM AND NITROGEN FERTILIZATION RATES ON PRODUCTION AND GROWTH OF MAHOGANY (SWEITINIA MACROPHYLLA) SEEDLINGS

This study was carried out at the nursery of Horticulture Department, Faculty of Agriculture, Ain Shames University during two seasons of 2015 and 2016 to study the effect of sowing medium and fertilization rates on vegetative growth and chemical composition of Swietenia macrophylla seedlings. Three different sowing media were used i.e., S M₁= perlite: peat moss: compost (1:1:1), SM₂ = perlite: peat moss: compost (1:2:1) and SM₃ = perlite: peat moss: compost (1:1:2) (v/v). Also, four fertilization rates were used as follow: without fertilizer (control), 5, 10 and 15 g /plant of hydrocomplex fertilizer .The following data were recorded, stem length (cm), stem diameter (cm), number of leaves / plant, leaf area (cm²) and total fresh and dry biomass (gm). Moreover, chlorophyll a & b leaves contents (mg/g FW.), total carbohydrate content (mg/g DW), nitrogen, phosphorus and potassium content in leaves (% D.W.) were determined. Regarding the effect of sowing medium, the obtained results showed that, using sowing medium which content the highest percentage of compost (1:1:2) significantly increased stem length, stem diameter, number of leaves/ plant, leaf area, total fresh and dry biomass, total carbohydrate content and potassium leaves content in comparison the other growing medium while, the differences were insignificant in chlorophyll a & b, nitrogen and phosphorus leaves content. Concerning the effect of fertilization rates, using fertilization at the rate of 15g/plant caused significantly increased stem length, stem diameter , number of leaves / plant, leaf area, total fresh and dry biomass, chlorophyll a & b content, total carbohydrate  content, nitrogen, phosphorus and potassium leaves content in comparison the other fertilization rates with the exception of leaf area, chlorophyll  a , phosphorus  and  potassium leaves content at the rate of 10g/plant in the second seasons only. As for the interaction between sowing medium and fertilization rates, In general, application of growing medium which contain thehigh ratio of compost (1:1:2) was superior in all  tested characteristics followed by which contain the high ratio of peat moss (1:2:1)at 15 gm fertilizationas compared to the other treatments.