EVALUATION OF EXPERIMENTAL VARIETIES FROM RECURRENT SELECTION FOR STRIGA RESISTANCE IN TWO EXTRA-EARLY MAIZE POPULATIONS IN THE SAVANNAS OF WEST AND CENTRAL AFRICA

Abstract

A breeding programme for resistance to Striga hermonthica in maize (Zea mays) was initiated in Côte d'Ivoire in 1994. Two extra-early populations, white (TZEE-W Pop STR) and yellow (TZEE-Y Pop STR), were formed from diallel crosses of the best adapted extra-early maturing maize germplasm in the West and Central African subregion. In an effort to improve the populations for Striga resistance, TZEE-W Pop was crossed to inbred 1368 STR (Tzi 3 STR), and TZEE-Y Pop to 9450 STR (Tzi 25 STR). The resulting F₁ populations were carried through two backcross (BC) generations. S₁ lines were developed from the BC₂ and subjected to two cycles of random mating to generate TZEE-W Pop STR C₀ and TZEE-Y Pop STR C₀. These two populations were subjected to three cycles of S₁ recurrent selection under artificial Striga infestation and several experimental varieties were extracted from the different cycles of the selection programme. The original populations (C₀), improved populations, and experimental varieties were evaluated in two experiments under Striga-infested and Striga-free conditions. The primary objective was to determine the effectiveness of S₁ recurrent selection in developing Striga-resistant extra-early maize varieties. Results of the performance tests showed that the populations were good sources of Striga-resistant varieties with high-yield potential under both Striga-infested and Striga-free conditions. The results have also confirmed the effectiveness of inbreeding, selection and hybridization, as well as the backcross breeding methods, as tools for the development of extra-early populations, synthetic varieties and inbred lines.