Response of sorghum genotypes for turcicum leaf blight [Exserohilum turcicum (Pass.) Leonard and Suggs] and agronomic performances in southern Ethiopia

A field study consisting of fourteen sorghum genotypes was conducted to determine turcicum leaf blight (TLB) intensity, resistant reactions, and agronomic performance of sorghum genotypes at Arba Minch and Derashe, southern Ethiopia. The study was carried out during the 2018 cropping year (March to July). A significant (P < 0.05 to < 0.0001) variations were observed in the magnitude of TLB intensity, resistant reactions and agronomic parameters among the evaluated sorghum genotypes as well as locations. The results indicated broad ranges of difference in disease progress rate with 0.0138 (Seredo) to 0.0392 (Rara) units day-1 at Arba Minch and 0.0138 (Kentera) to 0.0392 (Rara) units day-1 at Derashe were observed on the evaluated genotypes. The results also showed wide ranges of variations in incidence (71.15–83.51%) on average for the two locations. The highest mean severity (59.80 and 83.60%) and area under the disease progress curve (AUDPC) (988.65 and 1261.38%-days) were noticed from genotype Rara at Arba Minch and Derashe, respectively. The lowest mean severity and AUDPC were noted from genotype Gambella with 7.97 and 13.64% and 132.66 and 214.84%-days at Arba Minch and Derashe, respectively. Based on TLB mean severity score, sorghum genotypes were categorized as 42 and 29% resistant, 35 and 35% moderately resistant, and 23 and 28% susceptible at Arba Minch and Derashe, respectively. In addition, significant genotypic differences were observed for crop phenology, growth, yield, and yield-related parameters. The genotypes, 76TI#23 (4444.44 kg ha-1) and Melkam (4444.44 kg ha-1) (at Arba Minch) and Dekeba (1333.33 kg ha-1) (at Derashe) showed the highest grain yields as compared to the other genotypes in the two locations. Various association degrees were observed between disease scores and crop parameters. Overall results pointed out that genotypes such as 76TI#23, Meko-1, Seredo, and Gambella-1107 exhibited consistent resistance reaction to TLB, although they showed variable grain yield potential across the locations. The genotype 76TI#23 is suggested to the producers with appropriate field management practices for sorghum production, and Gambella-1107, Seredo, 76TI#23, and Meko-1 used as a source of parental material for TLB resistance development in a future breeding program.