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HETEROSIS AND COMBINING ABILITY AMONG CIMMYT'S MID-ALTITUDE EARLY TO INTERMEDIATE MATURING MAIZE (ZEA MAYS L.) POPULATIONS

2009; Experimental Institute for Cereal Growing; Volume: 54; Issue: 1 Linguagem: Inglês

2279-8013

B. Vivek, José Crossa, Gerardo Rodríguez‐Alvarado,

Genetic Mapping and Diversity in Plants and Animals

Maize is an important food crop in sub-Sa- haran Africa. There is an increasing demand for early ma- turing maize cultivars even though long-season maize cul- tivars yield more than early maturing cultivars under favourable conditions. This is because vast areas of maize are routinely affected by drought and low N fertility and early maturing maize cultivars offer more flexibility than full season cultivars for a farmer with respect to cultiva- tion and food security. CIMMYT's early maturing maize program, which aims to supply seed to approximately 3 million hectares of maize area in east and southern Africa lacks adequate information on heterotic relationships of its germplasm. 190 crosses (generated from a diallel of eighteen populations and two within heterotic group sin- gle crosses) and their 20 parentals were evaluated for het- erotic relationships at six locations in Zimbabwe (four op- timal conditions of rainfall and fertilizers (but different agro-ecological regions / mega-environments), one man- aged low nitrogen environment and one managed drought environment). Three heterotic patterns were seen under stress while six heterotic patterns were seen under optimal conditions. P9 (CML312/CML442) expressed a consistent heterotic pattern across stress and non-stress environments thus justifying its continued use as a tester. Moving towards the use of multiple heterotic groups in the CIMMYT-Zimbabwe program may be worthwhile pro- vided that the budgetary scenario still supports its core mandate of germplasm development, germplasm ex- change and strengthening of national research systems.