Demand-Driven Technologies for Sustainable Maize ... - IITA

75Table 8. Percentage of significant positive and negative GCA valuesfor number of emerged Striga plants 10 weeks after planting,Striga host damage score and grain yield for three groups ofinbred lines used in a 10 × 10 diallel cross evaluated in fourlocations in 2001 and 2002.InbredgroupNooflinesTotalNo ofvalues +EmergedStriga plants-ve+veStriga hostdamagescore Grain yield-ve +ve +ve -veZd lines 5 40 42.5 2.5 45.0 0.0 55.0 7.5TZL TC87 1 8 37.5 0.0 25.0 0.0 50.0 0.0Std inbreds 4 32 0.0 12.5 0.0 53.0 6.3 50.0+Total No of values = 4 loc. × 2 yrs. × No. of linesTable 9. Percentage of significant positive and negative GCA values +for number of emerged Striga plants 10 weeks after planting,Striga host damage score and grain yield for 10 inbred lines usedin a diallel cross evaluated in four locations in 2001 and 2002.Inbred codeEmerged StrigaplantsStriga hostdamage score Grain yield-ve +ve -ve +ve -ve +veZd 282 62.5 12.5 37.5 0.0 25.0 50.0Zd 290 25.0 12.5 50.0 0.0 12.5 50.0Zd 467 12.5 0.0 37.5 0.0 0.0 65.5Zd 472 12.5 0.0 37.5 0.0 0.0 37.5Zd 551 62.5 0.0 50.0 0.0 0.0 75.0TZL TC87 37.5 0.0 25.0 0.0 12.5 50.01393 0.0 0.0 0.0 25.0 0.0 12.55057 0.0 0.0 0.0 37.5 50.0 0.09006 0.0 12.5 12.5 50.0 37.5 12.59450 0.0 37.5 0.0 100.0 100.0 0.0+Total No of values = 4 loc. x 2 yrs. = 8.rating of host plant damage symptoms was the most important traitfor assessment of crop response under Striga infestation. Using thiscriterion, Inbred 9450 was the most susceptible to S. hermonthicaamong the set of lines in the study (Table 9). This line had negativeGCA values for host damage score and grain yield in all eightenvironments thus indicating that its susceptibility was not subject tolocation and years in the study. None of the Zd lines had any positiveGCA value for host damage score; rather, about 40–50% of the lineshad negative GCA values for the trait, and about 40–75% had positivevalues for grain yield.Inbred Zd 551 was the most resistant/tolerant to S. hermonthicaamong the lines. The line combined low number of emerged Strigaplants with low Striga host damage score to produce relatively high grain