Stimulatory effects of Thidiazuron, Putrescine, and explant type on indirect regeneration of Calendula officinalis L.

Pot marigold (Calendula officinalis L.) is an important ornamental-medicinal plant in Iran, that is widely used alone or in combination with other medicinal to produce low-risk drugs for human. In order to mass-production of this plant by tissue culture, four separate factorial experiments were conducted using completely randomized design with three replications (10 samples) at four stages of callus induction, indirect organogenesis, rooting, and acclimatization The results showed that the highest callus weight was observed in the interaction of leaf explant and medium supplemented with 2,4-D (2.0 mg/l). The tallest and highest branching number was related to the callus obtained from leaf explant in medium containing thidiazuron (1.0 mg/l TDZ) and putrescine (100 mg/l PUT), in indirect organogenesis. Tissue culture cuttings had the best rooting in 2.0 mg/l NAA medium. The obtained seedlings planted in pots containing perlite showed better acclimatization. By optimizing callus production from Calendula officinalis explants and propagation by tissue culture method can be an important step towards producing plants with the same quality and free of pathogens.