Abstract
In order to induce callus efficiently in Festuca spp. and Lolium spp., effects of 2,4-D concentrations on callus formations and their differences among species or varieties were investigated. The calli were induced from mature seeds on the media containing 1, 5, 10 and 15mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) in six, four, seven and five varieties of meadow fescue, tall fescue, perennial ryegrass and Italian ryegrass, respectively. Effects of 2,4-D on callus formation and its size were examined in each species. Significant differences were observed both in callus formation and callus size among species. The callus formation of perennial ryegrass was significantly higher than the other species, and the callus size was larger in Italian ryegrass and smaller in tall fescue than the other species. Significant differences among varieties were observed in callus formation of meadow fescue, tall fescue and Italian ryegrass and also in callus size of tall fescue and perennial ryegrass. The callus formation and its size were influenced by the concentration of 2,4-D except for the callus formation in meadow fescue. The optimal concentration of 2,4D was 5 mg/l for all four species. The regeneration rate of adventitious organ was the highest in perennial ryegrass, and tended to be high at lower levelof 2,4-D in meadow fescue. In four species, adventitious root regenerated from calli very frequently. On the other hand, green or albino adventitious shoot did not regenerate so frequently. In general it was not easy to determine the optimal concentration of 2,4-D for regeneration of green adventitious shoot, but 5 mg/l 2,4-D was considered to be suitable for some varieties of perennial ryegrass. Most of all green adventitious shoots obtained grew into complete plants.
