Abstract:

The objective of this study was to evaluate the pathogenicity of a range of Fusarium solani isolates to various alfalfa varieties on two culture media， potato dextrose agar （PDA） and water agar （WA） medium. We used conventional tissue separation methods to isolate and purify the fungi from alfalfa roots， and the representative strains of the isolates were identified using both morphological and molecular techniques. We estimated the relative root length， relative seedling length， relative root to seedling ratio， relative germination rate and disease index at 14 d after inoculation with F. solani， and synthesized various indexes through membership functions. The results showed that F. solani was the pathogenic fungus causing alfalfa root rot. F. solani was pathogenic to 22 alfalfa varieties on both culture media， and the pathogenicity of F. solani on PDA medium was stronger than that on WA medium. The disease resistance of the 22 alfalfa varieties varied. ‘TARIMU 5S’ showed the strongest resistance， while ‘Zhongmu No.1’， ‘Bara310SC’， ‘OPTIMUS F3’ and ‘Golden-queen’ exhibited high-level resistance. ‘Zhonglan No.2’， ‘Sardi 7’， ‘Longmu 803’ and ‘Gannong No.3’ exhibited low-level resistance； ‘Paola’ had the weakest resistance.

Key words: Fusarium solani, alfalfa, root rot, pathogenicity, resistance