Diallel analysis of grain yield and resistance to seven diseases of 12 African maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) inbred lines |
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Authors: | Bindiganavile S Vivek Omari Odongo Jackson Njuguna Justus Imanywoha George Bigirwa Alpha Diallo Kevin Pixley |
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Institution: | (1) CIMMYT, P.O. Box MP 163, Mt. Pleasant, Harare, Zimbabwe;(2) KARI, Kakamega Regional Research Centre, Kakamega, Kenya;(3) KARI, P.O. Box 30148, Muguga, Kenya;(4) Kampala, Uganda;(5) Alliance for a Green Revolution in Africa (AGRA), P.O. Box 66773, 00800 Westlands, Nairobi, Kenya;(6) CIMMYT, P.O. Box 1041, Village Market, 00621 Nairobi, Kenya;(7) CIMMYT, Apdo Postal 6-641, Mexico, DF, Mexico |
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Abstract: | Maize (Zea mays L.) is grown on 15 million ha in eastern and southern Africa. Several diseases are of common occurrence in the region and
regularly result in significant yield losses. A collaborative regional disease nursery (REGNUR) project was initiated in 1998
to identify and increase access to disease resistant germplasm, generate and disseminate information on disease and insect
resistance sources, and facilitate the development of resistant cultivars by project partners. A diallel among 12 elite inbred
lines was formed with the specific objective of evaluating the combining ability of these inbred lines for grain yield and
resistance to seven diseases. The trial was grown at six sites in 2001. Results showed that both general (GCA) and specific
combining ability effects were significant for most diseases. On the average, GCA accounted for 69% of resistance to diseases
and only 37% of variation for grain yield. Correlations between GCA effects for disease scores were generally non-significant,
implying that it is possible to pyramid genes for disease resistance in inbred lines. This underscores the need for screening
for resistance to prevailing diseases using artificial inoculation or reliable hot-spots. Based on GCA effects for grain yield
and across diseases, P12 and P6 were the best inbred lines. The crosses P4 × P9 (6.7 t ha−1) and P4 × P12 (6.9 t ha−1) were the best hybrids in the earlier maturity group, while P3 × P9 (8.3 t ha−1) and P2 × P8 (7.4 t ha−1) were the best hybrids in the late maturity group. |
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