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Phytophthora root rot, caused by Phytophthora drechsleri Tucker, is one of the most important sugar beet diseases in tropical areas. Use of resistant cultivars is the most effective and cost-effective strategy for controlling this disease. To identify resistant resources to P. drechsleri isolate Kv10, 124 sugar beet lines and hybrids along with Dena and Sina cultivars (resistant to rhizoctonia), Rasoul and Sharif (susceptible checks), SP85303-0 (resistant to Phytophthora root rot), FC709 (resistant to Rhizoctonia root rot), and S2-24-P.107 (resistant to Pythium root rot) were evaluated in 24 replications using a completely randomized design with artificial inoculation under greenhouse conditions. A variance analysis of the disease index revealed significant differences in resistance to this disease among sugar beet breeding populations. Breeding populations such as 980039, 980047,35322,33628,35312, 35321, 35185, 35182, and 980049 had the highest partial resistance to P. drechsleri with disease index of (2, 2.08, 2.21, 2.53, 2.71, 2.84, 2.89, and 2.89, respectively). The resistant check SP85303-0 had a disease index of 3.78. Susceptible checks, such as Rasoul and Sharif, had disease indexes 6.55 and 6.75, respectively. Results of cluster analysis for two traits (disease index and harvest index) revealed that breeding populations such as 980039, 980047, 35322, 33628, 980040 and 980049 classified in resistant group. It can be concluded that progeny selection would be an effective method for increasing resistance to P. drechsleri. Key words: Root Rot, Phytophthora, Hybrid, Resistant
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