Response of four kinds of Rhodiola to freezing injury

Taking Rhodiola kirilowii, R. crenulata, R. algida and R. fastigiata growing in Tibetan Plateau as materials,field randomized block design was used to study the frost resistance difference of four kinds of Rhodiola from the differences of start time of germination after freezing, emergence duration, emergence rate, survival rate and tyrosol content.The results showed that, when freezing injury happened before emergence, R. kirilowii suffered worst, while R. fastigiata suffered lightest. When the freezing injury happened in the seedling stage, the survival rate of R. kirilowii was smallest,while the survival rate of . fastigiata was biggest. The order of frost resistance for 4 kinds of Rhodiola was R. fastigiata, R.crenulata, R. algida, R. kirilowii. The results indicated that the frost resistance of R. fastigiata was the strongest, while the frost resistance of R. kirilowii was the weakest.