Results indicate that water deficit had significant effect on the relationships among the leaf N
accumulation, chlorophylls, SCMR and grain yield at flowering stage, because physiological
maturity might reach maximum at that time. A critically important period for fixation and
assimilation of nitrogen in soybean production is at the pick of the flowering stage (Sridhara et al.
1995). It appeared that SPAD chlorophyll meter reading (SCMR) and determining of leaf N and
chlorophylls during flowering stage is the best time for the prediction of adverse water stress
effects on potential yield capacity of soybean grains.