INFLUENCE OF DIFFERENT LEVELS OF PHOSPHORUS AND POTASSIUM ON GROWTH OF Leucaena leucocephala SEEDLINGS

A pot experiment was conducted during the summer season 2011/2012 in the greenhouse of the Atomic Energy Authority, Nuclear research center, Soil and water Research Department. A complete randomized design with four replications was used in this study. A combination of four phosphorus levels (0; 50; 100; and 200 kg P2O5 fed-1 as superphosphate with four levels of potassium fertilizer levels (0; 25; 50 and 100 kg K2O fed^-1 on growth, nodules and nutrients of the Leucaena leucocephala. Shoots and roots dry weights were gradually increased with increasing potassium rate up to 100 kg K2O fed.^-1, where it accounts for 61.85,9.59,71.17 g pot^-1 for shoot, root and whole plant, respectively, while addition of sole phosphorus induced an increase of the dry weight of roots and shoots up to the rate of 100 kg P2O5 fed^-1, (111.8, 15.61, 127.41 g pot^-1 for shoot, roots and whole plant, respectively), and then tended to decrease for the same sequence. Maximum shoot dry weight (197.43 g pot^-1) was achieved by addition of 100 kg P2O5 fed^-1 combined with 50 kg K2O fed^-1.The maximum number and dry weight of nodules were detected with P-K(100-50) (3.13 g pot^-1), while the minimum detected with P-K (0-0) (1.14 g pot^-1). Moreover, all the nodules were distributed on secondary roots. Nitrogen uptake was enhanced by the addition of phosphorus and potassium and gradually increased by increasing rates of both of them.