Phytotoxicity of Some Medicinal Plants Residues on Emergence and Establishment Criteria of Canola

The effect of the phytotoxicity of black cumin, dragonhead, dill and soybeans was investigated on the emergence and early growth criteria of canola. Experiment was conducted as factorial based on a completely randomized design with three replications under greenhouse conditions, Shahrekord University, 2016. The experimental factors consisted of four species of plants (soybean, black cumin, dragonhead and dill), two fertilizer types (organic and chemical fertilizers) and two levels of plant residue (without and with residue). The results showed that the black cumin residue in soil treated with both organic and chemical fertilizers reduced the dry weight of canola seedling. In soil fertilized with organic manure, the effects of all four plants residues were the same. The chlorophyll b and carotenoid contents of canola seedling significantly decreased in soil with chemical fertilizer and black cumin or dragonhead residues. In soil fertilized with organic manure, there were no significant differences in the effects of the soybean, black cumin and dill residues. In general, the cultivation of autumn canola should be delayed until the plant residues from black cumin, dragonhead, dill and soybean have been removed or until their effects have dissipated after harvest.