Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.1998.354.356Oryza stiva L.)]]>ZahirZahir A. RahmanAteeq-ur- AsgharNaeem ArshadMuhammad 4199814Being a physiological precursor of auxins, L-tryptophan (L-TRP) can have an ecological impact on the growth and development of some plants. A field experiment was conducted to assess the influence of L-TRP on growth and yield of rice. Results showed that specific growth and yield parameters were significantly promoted in response to various L-TRP treatments. L-tryptophan application at 105 M significantly increased the plant height (4.25%), paddy yield (41.5%), number of tillers (29.4%) and number of panicles (27.9%) compared to control. Results of this study demonstrated that the growth and yield of rice may be enhanced with the application of an auxin precursor, L-TRP. Bioproduction of plant growth regulators such as auxins in soil as a result of microbial activity from the added precursor may be recognised as having a potential influence on plant growth and development. Further studies are needed to investigate factors affecting the microbial production of auxins such as their distribution and stability in soil and their direct uptake by plants.]]>Arshad, M., A. Hussain and A. Shakoor,199518317329Arshad, M., M. Javed and A. Hussain,1994Glycine max) to soil-applied precursors of phytohormones.]]>22109115Arshad, M. and W.T. Frankenberger Jr.,19931993pp: 307-347pp: 307-347Frankenberger, Jr. W.T., A.C. Chang and M. Arshad,1990Raphanus sativus to the auxin precursor, L-tryptophan applied to soil.]]>129235241Frankenberger, Jr. W.T. and M. Arshad,1995Pages: 503Pages: 503Martens, D.A. and W.T. Frankenberger Jr.,19921992pp: 99100Martens, D.A. and W.T. Frankenberger Jr.,19932516791687Martens, D.A. and W.T. Frankenberger Jr.,199414C-indole-3-acetic acid and 3′-14C-tryptophan exposed to the roots of three wheat varieties.]]>166281290Martens, D., T. Hartz and W.T. Frankenberger Jr.,1992Citrullus lanatus.]]>27642643Park, H., J.H. Yoon and B. Cho,1992Panax ginseng to various growth regulators.]]>1992pp: 111Rossi, W., A. Grappelli and W. Pietrosanti,198429325329Sarwar, M. and W.T. Frankenberger Jr.,1994Zea mays L.]]>16097104Sarwar, M., M. Arshad, D.A. Martens and W.T. Frankenberger Jr.,1992147207215Steel, R.G.D. and J.H. Torrie,19802nd Edn.,Pages: 633Pages: 633Zelena, E., M. Kutacek and V. Cermak,19881988pp: 371-376pp: 371-376