Abstract
Field experiment near Palosi drain was conducted to study the effect of tube well (TW) and waste water (WW) with or without basal dose of NP and K on the yield and heavy metal uptake of tomato during 2008. The soil of the experimental site was sandy loam, slightly alkaline, moderately calcareous with phytotoxically high concentration of Cu, Fe and Mn while Cd, Cr, Ni, Pb and Zn were less than the levels considered toxic to the plants. The tomato biomass was significantly (p<0.05) affected by different treatments. Taller plants and higher biomass was produced in plots receiving WW with or without NP and K and TW water receiving basal dose of NP and K while lower biomass and shorter plants were produced in plots receiving only TW water indicating the nutritive value of WW application. The results of metal concentration in leaves and fruit showed that with exception of Cd, there were significant variation (p<0.05) in the plant uptake of metals when irrigated with different supply of irrigation water. The overall results showed that leaves accumulated higher concentration (with exception of Cu) of heavy metals studied compared to fruit. The concentration of Cr, Fe, Mn Pb and Zn in leaves was above the permissible limits when irrigated with waste water while waste water supplemented with fertilizers showed reduction in heavy metals uptake. The concentration of Fe and Pb was above the permissible limits in fruits indicating toxicity. It was also noted that plants receiving sole application of WW accumulated more heavy metals compared to WW plus half dose of NP and K while the TW irrigated plots accumulated less heavy metals indicating that their was no build up of heavy metals in the river bed soils because of its coarse texture. It can be concluded that tomato can be irrigated with effluents containing moderate supply of heavy metals on coarse textured soil.