GENETIC VARIABILITY AND PREDICTED RESPONSES TO SELFED PROGENY SELECTION IN THREE MAIZE (Zea mays L.) POPULATIONS FOR TOLERANCE TO LOW SOIL NITROGEN

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GENETIC VARIABILITY AND PREDICTED RESPONSES TO SELFED PROGENY SELECTION IN THREE MAIZE (Zea mays L.) POPULATIONS FOR TOLERANCE TO LOW SOIL NITROGEN

Abstract:

Low soil nitrogen is a major constraint to maize production in the West African savanna. The development of maize cultivars with better performance under low soil nitrogen level is of great significance. In this study, S1 (Selfed) progeny recurrent selection method was employed to improve three different maize populations (DMR ESR-W, TZE COMP. 3DT and ACR 9331 DMRSR) for tolerance to low soil nitrogen. S1 progenies were generated from each of the three maize populations and evaluated under both low and high soil nitrogen levels in Mokwa (9˚18΄N and 5˚04΄E, 457m above sea level, 1100mm annual rainfall) and Zaria (9˚16΄N and 7˚20΄E, 686m above sea level, 1040mm annual rainfall) during the rainy season of 2011. Analysis of variance for grain yield and other agronomic traits evaluated under both fertility levels across the two locations showed significant differences (p0.05) among the S1 progenies. These indicate the presence of wide genetic variability amongst the genotypes. Genotypic variances were generally large enough for effective selection to take place in each of the population. Low to moderate heritability estimates of 25.50% for DMR ESR-W, 36.54% for ACR 9331 DMRSR and 40.59% for TZE COMP. 3DT were obtained for grain yield under low soil nitrogen level across the two locations. Grain yield was improved by 15.97% for DMR ESR, 23.0% for TZE COMP. 3DT and by 24.97% for ACR 9331 DMRSR. Positive genotypic correlations were observed for grain yield with plant height, ear height, and number of ears per plant and stay green in all the three maize populations. This indicates the usefulness of these traits for indirect selection purposes in improving grain yield. About 30% yield reduction was observed for all the genotypes evaluated under low nitrogen level as compared to those evaluated under high nitrogen level. However, some of the genotypes exhibited relatively high mean grain yield under both fertility levels across the two locations. Genotypes with better performance under both vii fertility levels were selected from each of the three populations based on a selection index that combines grain yield, number of ears per plant, stay green and anthesis-silking interval. Grain yield was found to be improved by 15.97% for DMR ESR, 23.0% for TZE COMP. 3DT, and 24.97% for ACR 9331 DMRSR under low soil nitrogen level. Appreciable genetic gains were also obtained for plant height, ear height, ASI and stay green across the three populations. The results obtained from this study confirmed the effectiveness of the S1 family selection scheme as a population improvement procedure capable of improving the performance of maize population for tolerance to low soil nitrogen.

GENETIC VARIABILITY AND PREDICTED RESPONSES TO SELFED PROGENY SELECTION IN THREE MAIZE (Zea mays L.) POPULATIONS FOR TOLERANCE TO LOW SOIL NITROGEN

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