Resistance Evaluation Of Alfalfa(Medicago Sativa)on Stemphyllium Leaf Spot And Fusarium Root Rot Diseases And The Screening Of Standard Check Cultivars

Alfalfa is one of the most important perennial legume with the most widely planting area. With the expansion of planted area and improvement of the management level of alfalfa, diseases have been greatly limiting the production of alfalfa. Alfalfa diseases often referred to as alfalfa leaf and root diseases mainly damage the leaves and roots of the plants. The evaluation on disease resistance of alfalfa has benefit on screening check cultivars. The use of check cultivars is one of the main and effective measurements, even the only way to prevent alfalfa diseases. In this paper, by using the research methods and check cultivars from NAAIC(North American Alfalfa Improvement Conference) for reference, most of the Chinese alfalfa cultivars are evaluated for the resistance to stemphyllium leaf spot and Fusarium root rot. The significance of the research is putting forward the suggestions that establish an independent and unified system. The breeding researchers can also benefit from this study.1.44entries are evaluated for the resistance to stemphyllium leaf spot. Two evaluation methods include the field evaluation and the single leaf inoculation. The results showed that the two evaluation methods were correlative remarkably. By data analysis, the method of the single leaf inoculation can identify the disease-resistance variation correctly. By the method of single leaf inoculation, taking disease index as a variable, the44entries can be clustered into three categories. There were15entries of resistance,22entries of moderate resistance, and7entries of sensitive. After analysis, three cultivars, Huangguan, Xinmu NO.1and Zhongmu NO.3with different levels of resistance against stemphyllium leaf spot were preliminarily screened as the check cultivars of resistance evaluation system of China. Randomly selected5pairs of SRAP primers to study the disease resistance of stemphyllium leaf spot, and one molecular marker named Mel-eml350with relatively high correlation resistance to stemphyllium leaf spot were found. 2.62entries were evaluated for the resistance to Fusarium root rot. By pathogenicity test of different strains, different dosimetry of spore suspension, evaluation of different time after inoculation, the technic inoculation system for Fusarium root rot evaluation were established. The system includes the strong pathogenic strain FO-03,2mL spore suspension, and8days after the inoculation for evaluation.Using the method of immersed the roots with spore suspension, taking disease index as a variable, the62entries were clustered into3categories.4cultivars were found highly resistant and31cultivars were medium resistant to Fusarium root rot. The remaining27cultivars were susceptible to the disease. After analysis, three cultivars, Moapa69, Gongnong No.2and Xinmu NO.1with different resistance abilities against Fusarium root rot were preliminarily screened as the check cultivars. Randomly selected5pairs of SRAP primers to study the disease resistance of stemphyllium leaf spot, and one molecular marker named Me2-em6550which has relatively high correlation resistance to Fusarium root rot were found.