Some physiological effects of abscisic acid on vicia faba plants I- morphological characteristics and metabolic activities during germination and seedling growth

The effect of ABA on germination, growth, carbohydrates, nitrogenous constituents, nucleic acids and the activity of certain enzymes of Vicia faba seedlings throughout an experimental period of 192 hours were studied. It was found that the highest concentration of ABA [10-3 M] delayed the start of germination, while the relatively low concentration [10-9 M] induced nonsignificant effect on this parameter. The high concentration of ABA induced highly significant decreases in radicle and plumule lengths, fresh and dry weights of the seedlings, while the lowest concentration [10-9 M] highly significantly increased these characters. 10-6 and 10-9 M ABA decreased the reducing sugars content whereas the polysaccharides and total sugars were increased. 10-9 M ABA induced significant increases in total soluble nitrogen, decreased nonsignificantly the protein nitrogen whereas 10-6 M decreased the protein-N content and increased the total N. The activities of protease, RN-ase were decreased at all test concentrations