EVALUATION OF ALFALFA CULTIVARS GROWN IN
SAUDI ARABIA FOR RESISTANCE TO AG4 OF Rhizoctonia
A. A. Al-Doss*, S. Al-Kherb** and S. El-Hussieni**
* Plant Production Dept.
King Saud Uni. Riyadh
** Plant Protection
Dept. King Saud Uni. Riyadh
Rhizoctonia solani Kuhn causes root canker
and root rot in Alfalfa growing areas in Saudi Arabia. Ten Alfalfa cultivars
were evaluated for damping-off, disease severity and resistance to Rhizoctonia solani AG4.
Results of damping-off of R. solani AG4 on
alfalfa seedlings indicated that all landraces and imported varieties were
highly susceptible. The Egyptian
cultivar was the most resistant cultivar to R. solani
AG4 root canker, while the local cultivars Qassimi
along with the introduced cultivars CUF 101, Panner
4860 and Serosal were moderately resistant, on the
other hand the other tested cultivars were susceptible. Measurments
of plant growth characteristics of the ten tested alfalfa cultivars indicated
that the effect of R. solani AG4 was mainly on
root fresh weight. This study revealed that most cultivars grown in Saudi Arabia
are susceptible to R. solani AG4 which
emphasize the need for breeding local cultivars resistance to soil born diseases such as root canker
and root rot caused by R. solani.