Useful Alleles from Landraces for Maize Improvement in Nigeria.

It is important to systematically evaluate landraces for desired traits since they are potential sources of adaptation to prevalent stresses that reduce crop production. The objectives of this study were to (i) evaluate the level of improvement of improved maize (Zea mays L.) varieties over landraces, and (ii) identify desirable traits in landraces that may be useful for further improvement of the maize germplasm in Nigeria. Field trials involving 50 improved varieties and 50 landraces of maize were conducted at the Teaching and Research Farm of Obafemi Awolowo University, Ile-Ife, Nigeria, in the late season of 2010 and the early and late seasons of 2011, using 10x10 alpha lattice with two replications each season. There were significant differences between the improved varieties and the landraces for grain yield and most agronomic traits. Grain yield was improved by 55%, ear placement, 19%, ear aspect, 40%, stalk standability, 85%, anthesis-silking interval, 31%, and ear length, 16%. Also resistance to Puccinia polysora was improved by 37%, Helminthosporium turcicum by 36% and Curvularia spp. by 42%. The degree of diversity was higher in landraces than improved varieties for disease resistance and seed quality in medium-term storage. Landraces TZM137 and TZM149 showed high resistance to H. turcicum, TZM158 to P. polysora, TZM158 and TZM1313 to Curvularia spp. while TZM1273 and TZM154 had outstanding standability. Conclusively, Nigerian landraces of maize contain desirable alleles for improving tolerance or resistance to some biotic and abiotic stresses.