ISSN 2736-1756
Advanced Journal of Microbiology Research Vol. 2005
Available online at http://internationalscholarsjournals.org/journal/ajmr
© 2005 International Scholars Journals
Full Length Research Paper
Nodulation and growth response of Sesbania sesban (L.) Merr. to increasing nitrogen (ammonium) supply under glasshouse conditions
S.A. Indieka and D.W. Odee*
Biotechnology Laboratory, Kenya Forestry Research Institute, P.O. Box 20412-00200, Nairobi, Kenya.
Accepted 15 November, 2004
Abstract
A glasshouse experiment was carried out to study the effect of ammonium -N on the nodulation, growth and N-uptake of Sesbania sesban (L.) Merr. inoculated with an effective Mesorhizobium (S. sesban) strain. Ammonium-N was supplied twice weekly as 100 ml of nutrient solution at concentrations of 0, 100, 200, 400, 600 and 800 mg N/l. The seedlings were grown in pots with sterilized sand substrate and assessed at 5, 7 and 9 weeks after planting (WAP). Nitrogen supply significantly improved nodulation (number of nodules and nodule dry weight/plant) with treatment 100 mg N/l compared with 0 mg N/l at 5 and 7 WAP, thus indicating synergism for the N2-fixation symbiosis. However, with treatments ³ 200 mg N/l nodulation was either depressed or inhibited. Seedlings treated with 100-400 mg N/l generally exhibited better growth (shoot and root dry weight/plant) and N-uptake than the other treatments (0, 600 and 800 mg N/l). This study has demonstrated that S. sesban seedlings are tolerant to relatively high levels of N, and that treatment with 100 mg N/l (20 mg N per week) is necessary to stimulate an early and effective N2-fixing symbiosis.
Key words: Ammonium, improved fallow, Mesorhizobium, N2-fixation, nodulation, Sesbania sesban.