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

59Table 5. Mean grain yield (t/ha) and type of cross of the top 20 hybridsselected from 105 F1 hybrids evaluated under acid soil (O) andnon-acid soil (T) conditions in Cameroon, 2003 and 2004.HybridsGrain yield (t/ha)O T %R +Type ofcross ++Cm/ 365×Cam Inb gp 17 2.88 3.34 13.7 I×A87036 × 91105 2.87 4.68 38.6 A×AC/A 18 × 91105 2.75 4.13 33.4 I×A87036× Cml 365 2.66 2.91 8.4 A×IATPSU-25w × Cml 358 2.61 4.08 36.0 A×ICml 247× ATPSU-25w 2.49 5.34 53.4 I×ACam Inb gp 17× 91105 2.48 5.96 58.4 A×ACml 254 × Cml 361 2.35 2.92 19.5 I×IC/A 18 × 9450 2.35 4.05 41.9 I×AC/A 18 × Cml 361 2.34 3.66 36.1 I×ICml 247 × NCRE gp 8 2.33 3.82 39.0 I×ACml 254 × C/A 18 2.30 5.63 59.1 I×ICml 254 × 9450 2.30 2.57 10.5 I×ACml 365 × 9450 2.30 4.33 46.9 I×AATPSU-25w × NCRE gp 8 2.21 3.87 42.9 A×AEntrada 3 × Cml 361 2.20 3.20 31.3 I×ICml 254 × NCRE gp 8 2.15 3.70 41.9 I×ACml 254 × C/A 17 2.10 3.30 36.4 I×ICml 365 × 91105 2.09 2.72 23.2 I×ACml 247 × Cam Inb gp 17 2.08 3.49 40.4 I×AMean of selected hybrids 2.39 3.89 41.8Mean trial 1.37 3.62 62.2C.V (%) 45.50 26.90 –S.E 1.10 0.50 –+%R = Percent reduction of O relative to T.++I = Introduced inbred line, A = Adapted inbred line.hybrids were compared with emphasis on the yield reduction causedby soil acidity.The selected top 20 hybrids exhibited 41.8% grain yield loss underacid soil relative to non-acid soil conditions. This was about 20% lowerthan the overall grain-yield reduction in the trial.Grain yield loss exhibited by selected hybrids ranged from 8.4%for 86036 x Cml 365 to 59.1% for Cml 245 x Cla 18. Five hybridsexhibited 25% or less grain yield loss due to soil acidity. The hybrids,87036 x Cml 365 (8.4%), Cml 254 x 9450 (10.5%), Cml 365 x CamInb gp117 (13.7%), Cml 254 x Cml 251 (19.5%) and Cml 365 x91105 (23.2%) could be considered tolerant of soil acidity. Each of thefi ve hybrids had at least one parent introduced from CIMMYT, andthey produced grain yield of 2.61 t/ha or more on acid soil.Five hybrids had relatively high grain yield on acid soil but werenot necessarily tolerant of acid soil. Three of the hybrids had yield