Rafidain Journal of Science

Abstract

The possibility of inducing chromosomal polyploidy was studied for Black poplar (Populus nigra L.) which micropropagated from stem cutting by exposure to different colchicine concentrations 125, 250, 500 and 1000 mg / l and different exposure periods (0.0, 2, 4, 6, 8 days) in MS medium supplemented with 1mg/l BA and 0.3 mg/l IBA. After 4 weeks of exposure results showed the significant superiority of 125 mg / l colchicine treatment for stem cutting survival percentage transplant survival percentage after aclimitization and diploid plants percentage characteristics, also the results of polyploidy showed that the highest percentage of tetraploid plant (18%) was recorded for both treatments 125 and 250 mg/l colchicine, when 50.66% of plants treated with 500 mg/l colchicine has a mixed polyploidy and it was significantly different from the rest treatments. but the interaction effect of colchicine concentrations and exposure periods showed that the highest survival percentage was recorded for the treatments of non exposure and exposure to 125 mg/l colchicines for 2 days. After 16 weeks of aclimitization and field growing the results showed the significant superiority for both treatments of exposure with 125 and 250 mg/l colchicine for stem length, stem diameter, leaves number, vegetative system dry weight, stomata length, stomata width and total chlorophyll contents characteristics, this in comparison with 500 mg/l colchicine treatments, and this is in combined with finally the interaction effects of colchicine for the treatment of 250 mg/l colchicine for 2 days.