بررسی اثرات شالکون در گیاه کاهو از برخی جنبه های فیزیولوژیکی و بیوشیمیایی

Chalcone is regarded as a common secondary metabolite in plant represented as precursor of flavonoids. In the present work, the effects of different concentrations of chalcone (1, 10, 100, 1000µg/mL) on lettuce seed germination and seedling radicle and gemule were evaluated to determining optimal experimental dose of the compound. The concentration of 100 µg/mL of chalcone were determined as optimal concentration and the effects of the concentration on fresh and dryweight of root and shoot, chlorophyll content , chlorophyll florescence, total protein and some enzyme kinetic like ascorbat peroxidase, catalase, poly phenol oxidase and protease were evaluated. The effects of chalcone on electrophoretic pattern of the treated and control groups of the plants were studied, as well as. Our results indicated that the compound significantly reduced the fresh weight of the treated plants shoots and roots up to 27. 9 and 10 % , respectively. Chalcone also significantly reduced the dry weight of the treated plants shoots and roots to 31.8 and 15.6 % than control, respectively. Although, no significantly change was recorded in photochemical and chlorophyll florescence, SPAD chlorophyll was reduced to 81.7% in treated group than control.  On the other hand, total protein content and specific activity of ascorbat peroxidase and protease enzymes were increased in chalcone treated plants than control group. Electrophoretic pattern of proteins was changed quantitative and qualifying in treated plants than control ones. It was concluded that lettuce as a model plant in allelopathic studies can be affected by  chalcone.  The compound promotes some physiological and biochemical responses such as dry and fresh weigh loss and chlorophyll reduction in the treated plants. However, this kind of stress as allochemical stress can  induce some different responses such as unchanged chlorophyll florescence than abiotic stress like drought and salinity.