Effect of cadmium on wheat as influenced by lime and manure and its toxic level in plant and soil

In a greenhouse experiment, the effect on wheat of added Cd was studied at the rates 0, 12.5, 25, 50 and 100 mg kg -1 soil supplemented with lime (4% CaCO 3 ) and manure (1 % farmyard manure). Increasing Cd levels in the soil increased significantly the concentration of Cd in 45-day leaves, grain and straw which caused a significant reduction in the dry matter yield and both grain and wheat straw yield DTPA-extract-able and plant Cd contents were significantly related with yield parameters of wheat. Addition of lime and manure together, resulted in a significant decrease in the DTPA-extractable and plant CD contents, thereby mitigating its toxic effects and significantly improving the wheat yield. The upper critical level of Cd toxicity was 13.2 ppm in 45-day leaves and 2.3 ppm in the wheat grain. A value of 4.8 ppm DTPA-extractable soil CD proved toxic for wheat.