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

30Table 1. Characteristics of extra-early maturing varieties evaluated underStriga-infested and Striga-free conditions at Ferké, Mokwa andAbuja in 2002 and 2004.VarietiesParentageGraintype 1Reaction to S.hermonthica2000 Syn EE-WTZEE-W Pop STR S4 F2W, F/DTolerant99 TZEE-Y STRTZEE-Y Pop STRS4F2W,FTolerant99 Syn EE-WTZEE-W Pop × LDS4F2W, F/DTolerant98 TZEE-W STRTZEE-W SR BC5 × 1368 STR S4F2W, F/DTolerantFerke TZEE-W STRTZEE-W SR BC5 × 1368 STR S6F2W, F/DTolerantSine TZEE-W STRTZEE-W SR BC5 × 1368 STR S6F2W, F/DTolerantTZEE-W SR BC5(Local check)Local and introduced germplasm,SR sourceW,FSusceptible99 TZEF-Y STR COTZEF-Y SR BC1 × 9450 STR S4F2Y,FTolerant1W = White, F = Flint, D = Dent, Y = YellowStriga-infested and non-infested plots were the same. Three maizeseeds were planted per hill. The maize plants were thinned to twoper stand about two weeks after emergence to give a fi nal populationdensity of 66,000 plants ha –1 . About 30–50 kg N ha –1 was splitappliedat planting and at about 30 days after planting. Weeds otherthan Striga were removed on a regular basis.Observations were made for grain yield, number of ears andplants harvested, plant and ear heights, and days to 50% anthesisand silking in both infested and non-infested plots. In addition, hostplant damage syndrome rating (Kim 1991) and emerged Strigacounts were recorded at 8 and 10 weeks after planting (WAP) in theStriga–infested rows. Anthesis-silking interval (ASI) was determined asthe difference between 50% silking and anthesis. Number of ears perplant (EPP) was determined by dividing the total number of ears perplot by the number of plants harvested. Grain yield adjusted to 15%moisture was calculated from the shelled kernel dry weight.Combined analyses of variance were conducted for grain yield andother genotypic variables using the General Linear Model Procedure(GLM) of the statistical analysis systems (SAS) package (SAS 1990).The data on Striga count were subjected to logarithm transformation(y+1) before the analysis to remove the heterogeneity amongthe variances.Results of the combined ANOVA across three locations for theRSVT-Extra-early showed signifi cant differences among the varietiesfor most traits under Striga-infested and Striga–free conditions(Table 2). Similarly, the year × variety and location × variety interactions