Research On Genetic Diversity And Drought-Resistance Of11Alfalfa Materials

Alfalfa is an important legume, it was widely cultivated in the world wide, In this study, RAPD (Random Amplified Polymorphic DNA) molecular marker technique was used to analyze the genetic diversity of11alfalfa materials, and their drought-resistance was investigated in seed germination period and seedling period.RAPD (Random Amplification Polymorphic DNA) molecular marker technique was used to detect the genetic diversity and phylogenetic relationships of11Alfalfa samples. There are121individuals in11Alfalfa samples and each sample contains11individuals.8RAPD primers have been used and total123bands have been amplified. Among the123bands,117are polymorphic and the percentage of polymorphic bands is95.12%. The results show a Shannon information index of0.4435, a Nei’s gene diversity index of0.2880. The genetic differentiation coefficient among these populations is0.2405, which indicate that alfalfa genetic variation mainly exists within varieties and the population differentiation was not obvious. The UPGMA (unweighted pair-group method with arithmetic average) dendrograms based on the Nei’s (1972) genetic distance showed that11alfalfa populations were divided into4groups:the first group has only population1, and the genetic distance of population1is relatively far from others; the second group include population2,4,5,6; the third group include population3and7; the fourth group include population8,9,10,11. The analysis indicated that the clustering result has certain relation with the orgin of those materials.Drought resistance of11alfalfa materials in seed germination period has been investigated, using different concentration gradient of PEG solution to simulate natural drought stress on the11alfalfa samples, and four indexes were selected to analyze drought resistance of seed germination, these are the relative germination rate, relative germination index, relative germination potential and relative vitality index. And then combined with each index the drought resistance of the11alfalfa materials has been analysed using fuzzy membership function method. The drought resistance at seedling stage was investigated by repeated drought method treat seedlings. Using direct method and membership function comprehensive analysis the drought resistance of11alfalfa materials based on the different drought symptoms and survival rate of each material. The comparison of different drought resistance index indicated that the results of indication of each index has some difference, the alfalfa material which shows strong drought resistance in germination stage has weak drought resistance in the seedling stage.