In cotton, phosphorus (P) is important for early seedling vigour, plant establishment and root development. Deficient plants are usually stunted, dark green in appearance and exhibit a delay in flowering, bon set and maturity (Hodges, 1992). The main role of P in plant metabolism is to allow energy transfer to occur(Mengel and Kirkby, 1987). Research by Macleod et al. (1997) has shown that P may also be involved in the onset of premature senescence. When cotton plants are subjected to environmental stresses such as waterlogging late in the season, the rates of translocation of P and K from leaves and other organs to the filling boils, is greater than the rate of uptake from the soil solution, which in turn leads to a reduction in the efficiency of these supply organs and causes the plants to senescence prematurely