Chromosome Doubling And Establishment Of Regeneration System Of Agropyron Mongolicum Keng

To improve the forage quality of Agropyron mongolicum Keng, we selected two materials (seed and tiller bud).The seeds were treated by different concentrations of colchicine (0.02%,0.05%,0.08%, 0.11%,0.14%+1.5% dimethyl sulfoxide) and trifluralin (1,5,10,15,20 μmol·L-1), while the tiller buds were treated by cotton which was impregnated with different concentrations of colchicine (0.025%, 0.050%,0.075%,0.100%,0.150%,0.200%) and trifluralin (50,100,150,200,250,300,350,400,500 μmol·L-1). The morphology and chromosome number were identified to select the best doubling treatment. In addition, to speed up its growth and shorten the test process, we screened the regeneration system of Agropyron mongolicum keng. The results were indicated as follows:Surviving variant plants after treated were all mixoploid of diploid and tetraploid. Morphological and cytological identification showed that:seedling morphology had different variations (thick seedling, curly seedling and globular seedling). The average germination rate reduced with the increase of mutagen concentrations and extension of treatment time. The seedling heights and root lengths were lower than those of the control treatment. The plant heights and leaf widths of each concentration treatment increased and then decreased with time prolonged.The optimal level of doubling treatments drawn via chromosome identification were:0.11% colchicine+1.5% DMSO processing 20 h, the mutation rate and survival rate were 50% and 40% respectively. The mutation rate and survival rate were 38.46% and 81.25% at 1 μmol·L-1 trifluralin processing 30 h.The tiller buds were embedded with different concentrations of colchicine and trifluralin. Combining survival rate, plant height and regenerate ablity of the tiller buds, the colchicines was more appropriate as doubling reagent.Comparing the various stages of regeneration system of Agropyron mongolicum keng, the optimal combination of seed disinfection were as follows:soaking seeds without lemma with 75% alcohol (1 min) and 0.1% HgCl2 (6 min), the contamination rate was zero and the germination rate was 85%. With stem tips as the explants, the optimal medium of callus induction was 1/2MS+1.5 mg·L-12,4-D+0.06 mg·L-1, and the callus induction rate reached over 70%.1/2MS+1.5 mg·L-1 2,4-D medium may improve callus quality and increase the number of callus.1/2MS+0.5 mg·L-1 6-BA+0.5 mg·L-1 NAA can be used as differentiation medium, the differentiation rate was only 7.5%, and callus browning mortality rate was too high. The rooting medium added with 0.1 mg·L-1 NAA had better effects, the rooting rate up to 100%, this was beneficial to the late transplanting.