A biotic stress mostly controls medicinal compounds productivity in the plant. This study was carried out to investigate the effect of gamma irradiation on some active constituents in shoot and root of Cichorium pumilum (Chicory). Irradiated seeds with 20, 40, and 80 gray (Gy) by cobalt 60 gamma irradiation were cultivated under normal field conditions. Results showed that the plant dry weight was stimulated at the first growth stage and inhibited at the following stages. Photosynthetic pigments (chl. a & b) were inhibited but carotenoids increased as a defensive effect to the increase in gamma doses. Alkaloids content was twice the phenolic and several times the saponins content under the control plant. Saponin content in the plant root increased with all gamma doses and the highest increase (69.5%) was at 40 Gy compared to the control. Likewise, the total alkaloids content was increased by 49.7% at the 40 Gy in the plant shoot. Accumulation of alkaloids was more sensitive to gamma radiation in shoot than in root. The 40 Gy dose enhanced accumulation of total phenolic compounds in root. Increasing gamma dose to 80 Gy inhibited the accumulation of three secondary metabolites in plant shoots and roots especially the alkaloids content that was reduced per plant to the half. The study suggested 40 Gy dose as an efficient dose to induce the metabolism and accumulation of active compounds of Chicory plants. In addition, it certified the vegetative stage which used as a human food to produce such compounds from the total plant (shoots and roots).
Key words: Chicory, Cichorium pumilum, Abiotic stresses, Gamma Irradiation Secondary metabolite, Alkaloids, Phenolic compounds, Saponin.
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