Tissue Culture And Primary Studies On Polyploid Induction Of Welsh Onion

Four different parts were studied in this paper: the tissue culture of Welsh onion using mature embryos as explants; the influence on seeding rate and aberrance rate with the action of colchicines; the inducing methods and problems with the combination of tissue culture and colchicines; correlative physiological chages in the inducing progress.The main results are as follows.1. An efficient generation system of Welsh onion was established in this experiment, using the mature embryos as explants. It resulted that the best hormone combination for callus induction was MS+2,4-D2.0 mg/L +BA1.0 mg/L and adventitious bud differented best in the medium supplemented with 2,4-D 0mg/L+BA 1.5mg/L. It also showed that adventitious bud could grow well in the medium MS and develop complete plants.2. Seeds were induced using colchicines. The different influences on seeding rate by seed condition ,concentration , periods, temperature were studied. The actions of condition ,concentration , periods to seed aberrance rate were also different. As far as the duding seeds are concerned,it has the lowest seeding rate, the upmost aberrance rate. The induction effect of periods was better than concentration. A great many of aberrance buds were acquired. But ,because of the hurt of colchicines, the growth of root was restrained. Consequently the buds was dying gradually.3. The combination of tissue culture and colchicines was researched deeply. Callus were treated by two methods: adding colchicines into medium and dipping callus in colchicines solution. It resulted that the two methods both could induce tetraploid cells. But the former method is better than the latter one,not only inducing rate but also in the operation progress . Adding 0.08% colchicines into medium 4d could gain the upmost inducing rate 26.0%.In the progress of inducing ,the dying rate of callus was every serious, the growth of adventitious buds were restrained, and the inducing rate would drop in the upper cultivation. To the question, we changed the growth condition of callus(agar,sucrose,2,4-D,BA). It resulted that appropriate increase of sucrose(60g/L) without 2,4-D could reduce dying rate and increase budding rate(40g/L. The experiment acquired two kinds of deviant plants:one with nomal cells and trinalploid cells,the other one with nomal cells and tetraploid cells.The changes of enzyme SOD,POD,CAT after treatments were studied .It resulted that the activity of POD and CAT had simlar changes.In short times, with the increase of concentration, the activity was improved; in longer time, with the increase of concentration, the activity was improved first then dropped. But SOD is very different from POD and CAT. In short times, the activity of SOD changed unconspicuously. In longer times , the activity of SOD was increased. The reason is that the adaptability of SOD is better than POD and CAT. SOD could keep stronger activity in adverse conditions.