Induction of polyploidy through colchicine in cotton ( Gossypium herbaceum ) and its conformity by cytology and flow cytometry analyses

Cotton is one of the most important fibre crops in the world. An increase in ploidy level was observed in diploid cotton species namely Gossypium herbaceum in the experiment, through colchicine application. There were significant growth variations noticed during the induction of polyploidy in the cotton plants depending upon the concentration of colchicine, duration of the treatments and genotypes taken. An increase in the concentration of colchicine or the duration of the treatment had a retardation effect on seed viability in G. herbaceum. The hypocotyls of length between 4 and 8 mm were found to be most responsive to colchicine treatment. The root meristem of G. herbaceum, treated with 0.2 and 0.4% colchicine exhibited the most number of tetraploid cells during 16 h of treatment. The increase in the concentration of colchicine, along with an increase in duration of treatment led to the chromosomal abnormalities in the wild cotton species. Seed treatment for colchicine application, was the most efficient and reliable method when compared to Petri-plate application and cotton swabbing treatments for inducing polyploidy in diploid cotton.