Using of RLSD test for each trait means comparison showed significant decreasing in cabbage head weight as Ni in soil increased from 0.0 to the higher Ni treatments.
Comparison of the root length means using RLSD test at p<0.05 showed significant differences between root length means as a response for all Ni treatment levels during the seasons of 2011 and 2012.
Concerning to the cabbage root weight/plant, the statistical analysis and means comparing using RLSD test at <0.05 showed high significant differences between root weight means in 2011 and 2012 at Ni concentration of 0.0, 10.0 and 20.0 mg/kg and the root weight means were not significantly differ at 30.0.0 mg/kg.
The statistical comparing between the four toxic metal means in cabbage root system and cabbage head under the effects of the 4 Ni concentrations using RLSD test at <0.05 were presented in Table (3).
Comparison of heavy metal means using RLSD p < 0.05 (Table 3) showed significant differences between all Ni concentration means in cabbage root system under the effects of Ni treatments during both of season 2011 and 2012.
Statistical comparisons using RLSD test between the 4 Ni treatments at p< 0.05 showed no significant differences between Ni concentration means in sewage sludge amended soil after harvesting during both of seasons between the first 2 Ni treatments (0.0 and 10.0 mg Ni/kg polluted soil), but significant differences were found after 10.0 level.