Irrigation with either raw or 50% diluted sewage effluent
resulted in higher concentrations of most nutrients in the millet
plant tissues. As expected, this higher accumulation paralleled
higher nutrient concentrations in the irrigation water (Marschner,
1986). However, the level of Fe in the tissues was reduced.
Lower levels of Fe in plants irrigated with effluent were observed
despite higher levels of Fe in the water (Tables 1). It
is possible that the higher levels of Cl in the effluent reduced
the absorption of Fe. Indeed, exposure of crops to salt stress
has been proven to reduce Fe accumulation in plants (Santos
et al., 2001). No chlorosis was apparent despite the low levels
of total Fe in plants; it is possible that the higher levels of Zn
and Mn in the effluent served to overcome the deleterious effects
of high Cl in the effluent that reduces the availability or
uptake of these metals into the plant.