Leila Karami

Chamomile (Matricaria chamomilla L.) is a medicinal herb belonging to Asteraceae family. This study was conducted to investigate the effect of trifluralin on the induction of polyploidy in chamomile. Two independent full factorial experiments on seedlings and 2-leaf stage apical buds were performed. Following morphological, biochemical and cytogenetic analysis, chromosome numbers of 18 and 36 were detected for diploid and tetraploid types, respectively. Morphological and biochemical examinations revealed that an increase in the number of full chromosome set results in a reduction in stomata number per unit area as well as an increase in stomata size, chloroplast number, and chlorophyll content. Induction of ploidy level increments also reduced plant height and increased the number of lateral branches, leaf size, and diameters of stems, flowers and receptacles. It is concluded that a concentration of 22.5 ?M trifluralin in both methods is optimum for the production of tetraploid chamomile with the highest rate of polyploidy induction and the lowest percentage of abnormality.