Effect of growing media and fertilization on growth and composition of Khaya senegalensis plant

This investigation was carried out at the Ornamental Horticulture Department, Faculty of Agriculture, Cairo University, Egypt during two successive seasons; 2007 and 2008, aiming to study the effect of different growing media (clay, sand, and clay + sand 1: 1 by volume) and NPK fertilization at different rates (0,2,4 and 6 g/pot) of a mixture containing (ammonium nitrate 33.0% N + calcium superphosphate 15.5% P2O5 + potassium sulphate 48.0% K2O.) at the ratio of (4:4:1 )on growth and chemical composition of Khaya senegalensis seedlings. The results showed that growing plants in clay gave the highest values of plant height, stem diameter, root length, number of leaflets/plant, fresh and dry weight of the leaves, the stems and the roots, chlorophyll (a and b) content and total carbohydrates % in the root and N, P and K % in the leaves, the stems and the roots in, both seasons. Whereas sand gave the highest value of carotenoids content in the first season, but in the second season clay medium gave the highest value of carotenoids. While the clay + sand medium gave the highest values of total carbohydrates % in the leaves and the stems in the two seasons. NPK at 6 g/plant increased plant height, stem diameter, root length, number of leaflets/plant, fresh and dry weight of the leaves, the stems and the roots, chlorophyll (a and b) content and N% in the roots in the two seasons and P % in the leaves and K% in the roots in the second season only. Whereas NPK at 4 g/plant increased total carbohydrates% in the leaves, N% in the leave and the stems and K% in the stems in both seasons, and application of NPK at 2 g/plant increased total carbohydrates% in the stems and the roots and P% in the stems in the two seasons. All NPK fertilization treatments gradually decreased carotenoids content as compared with the control plants in the first season only. Using clay combined with NPK at 6 g/plant gave the highest values of most characters, whereas the same soil fertilized with NPK at 4 g/plant recorded the highest values of N% in the leaves and the stems and P% in the leaves in both seasons. While using clay + sand or clay medium fertilized with NPK at 4 g/plant gave the highest values of total carbohydrates in the leaves. Plants grown in clay + sand and treated with 2 g NPK/plant gave the highest values of total carbohydrates in the stems. Using clay combined with NPK at 2 g/plant which gave the highest values of total carbohydrates in the roots, while the same soil and combined with NPK at 4 g/plant recorded the highest values of N% in the leaves and (N and K) % in the stems in both seasons.