Studies on Striga host range and sorghum genotype screening for resistance
1991
Reda, F. (Institute of Agricultural Research, Addis Ababa (Ethiopia))
In pot experiments, host range of Striga species was studied. Nine samples of Striga hermonthica were compared on 16 crop/wild species. Sorghum was more susceptible than maize to most of the S. hermonthica samples. A considerable attack by one of the S. hermonthica samples was noted on barley, while tef (Eragrostis te'f) and pearl millet (Pennisetum glaucum) were no attacked by any of the samples. Sorghum was more susceptible to S. asiatica but much less susceptible to S. aspera compared to maize. It was proved that maize could be a host to S. forbesii, a species so far known to occur only on wild hosts in Ethiopia. In a further pot experiment 11 sorghum genotypes were evaluated for resistance to different S. hermonthica samples. Two selections from crosses SAR-24 x 85 MW 5325 and ICSV-1007 x 85 k 6145 showed high level of resistance comparable to that of the resistant check, ICSV-1006. These entries, in our case selections 11 and 21 supported 1.7 and 3.8 plants per pot on average, respectively. A mean of 2.5 Striga plants per pot was recorder on ICSV-1006. Counts on the remaining seven entries were not significantly different from that of the susceptible check, IS-9302. The mean for IS 9302 was 32.2 plants/pot. Techniques were developed and laboratory germination tests conducted on large number of sorghum genotypes, in order to get an indication on their potential as sources of resistance. Forty two selections from 32 crosses, with Striga resistant parents, were compared with ICSV-1006 and IS-9302 as resistant and susceptible checks, respectively. Root exudate substances of 19 selections showed very little activity, out of these, nine induced no germination at all
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