Response of Sorghum Cultivars and Near Isogenic Lines to Head Bug (Eurystylus oldi Poppius) Damage
Five commercial sorghum cultivars, three isogenic lines and two internationally known head bug resistant cultivars as checked, were evaluated for two seasons to determine their performance under head bug (Eurystylus oldi Poppuis) infestation using four evaluation methods to classify the cultivars. The experiment was split-plot with three replications, infestation (control and artificial) and cultivars constituted main and sub-plot treatment respectively. Seasons of evaluation was not significant, infestation, cultivars and their interaction was highly significant ( p<=0.01) for grain damage rating, germination percentage panicle length and weight, 1000 grain weight and grain yield, therefore genetic variation in resistance to head bug was present. HRBC 017 had the least percent reduction (2%) for 1000 grain weight and Samsorg 40 had the higher percent reduction (55%) for grain yield. HRBC 017 was the least susceptible while Samsorg 40 was the most susceptible. Yield reduction index gave similar trend. Insect resistant index identified HRBC 017 as the most resistant, while samsorg 3 the least resistant. The four evaluation methods classified the genotypes: HRBC 017, HRBC 013 and HRBC 029 as resistant, Samsorg 17 and samsorg 18 as tolerant, while Samsorg 3, Samsorg17 and Samsorg 40 as susceptible.
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