Abstract:

Alfalfa （Medicago sativa） Paraphoma root rot （APRR） is a disease previously unknown in the world that has been identified and reported by our research team. This study evaluated the disease resistance of 30 different alfalfa varieties to root rot caused by Paraphoma radicina. In this evaluation， the incidence rate， disease index， height， root length， and above- and belowground biomass per plant were determined for 30 different alfalfa varieties， both domestic and international， after inoculation with P. radicina through root dipping. The standard deviation coefficient allocation weighted method was used to provide a multivariate evaluation of their resistance to the disease. The D value represents the comprehensive evaluation of each variety’s disease resistance. A higher D value indicates greater resistance， while a lower D value indicates lower resistance. The study found that the M. sativa varieties Longwei 3010， Magnum Ⅱ and Gannong No.3 had composite evaluation values （D） of 0.972， 0.955， and 0.916， respectively. All three varieties showed high resistance to APRR， with D values greater than 0.9. Caoyuan No.3 and Gongnong No.1 exhibited poor disease resistance， with D values of 0.003 and 0.113， respectively， both less than 0.2. The other tested varieties had intermediate disease resistance. The study has identified three varieties with strong disease resistance to APRR， providing husbandry information for alfalfa production and the prevention and control of the disease by planting resistant varieties.

Key words: alfalfa, Paraphoma radicina, root rot, disease resistance