Phosphorus inflow rates in sweet orange cv. Musambi as influenced by seasonal growth

Seasonal variation in P inflow parameters in sweet orange (c. sinensis Osbeck) cv. Musambi budded on Rangpur lime rootstock was studied during summer, rainy, winter and spring seasons. During rainy season, maximum inflow rate (I_max), mean inflow rate (I) and root demand coefficient (∞τ) were high. Mean inflow rate was moderate in spring, and low in summer and winter. It was observed that, in addition to climatic factors, shoot growth and net assimilation rates (RGR, REGR and NAR) of the preceding season significantly influenced the inflow parameters in the succeeding season by enhanced root activity and by creating a greater demand for P at the root surface as evidenced by a higher root demand coefficient.