Browsing by Author "Obeng-Antwi, K."
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Item Combining Ability of Six Extra-Early Quality Protein Maize (QPM) Inbred Lines(University of Ghana, 2013-06) Ofori, A.P.; Ofori, K.; Obeng-Antwi, K.; University of Ghana, College of Basic and Applied Sciences, School of Agriculture, Department of Crop ScienceSix extra-early QPM inbred lines from IITA were investigated using a partial diallel cross design. The objectives were to assess the hybrids and their parents for their agronomic performance. The six parents along with their hybrids (15) were evaluated using a Randomized Complete Block Design (RCBD) with three replications per site in four locations. Genetic correlations, general combining ability (GCA) and specific combining ability (SCA) effects as well as mid-parent heterosis were determined. Stability of grain yield and its relationship with other agronomic traits across four locations were also determined. Results of combined analysis of variance (ANOVA) revealed significant environmental effect for all the traits studied. Significant additive effect was observed for only grain yield whilst non-significant GCA and SCA effects were identified for all other traits. The GCA estimate identified parental lines P1, P3 and P5 as the high combiners for grain yield. The highest values for SCA and mid-parent heterosis for grain yield were observed in the crosses P1xP4, P5xP6, P1xP5 and P4xP6. The additive main effects and multiplicative interaction (AMMI) analysis revealed non-significant genotype by environment interaction (GEI) for grain yield whilst genotypic and environmental main effects were highly significant. However, the contribution of the environment was higher which suggests that anyone of the locations used in this study can be used for subsequent evaluations in order to manage the limited resources available for the testing programme.Item Gains in Grain Yield of Extra-Early Maize during Three Breeding Periods under Drought and Rainfed Conditions(Crop Science, 2018-07) Badu-Apraku, B.; Talabi, A.O.; Ifie, B.E.; Chabi, Y.C.; Obeng-Antwi, K.; Haruna, A.; Asiedu, R.12 Drought is a key maize (Zea mays L.) production constraint in sub-Saharan Africa (SSA). Fourteen, 13 15 and 25 extra-early maturing maize cultivars, with varying Striga resistance, drought and low soil 14 nitrogen tolerance, were developed from 1995 to 2000 (Period 1), 2001 to 2006 (Period 2) and 2007 to 15 2012 (Period 3), respectively. The objectives of this study were to examine yield gains in the cultivars, 16 investigate inter-trait relationships and yield stability under six drought and 17 rain-fed conditions in 17 West Africa, 2013-2016. Annual rate of yield increase across cultivars was 0.034 Mg ha-1 (3.28 %) 18 and 0.068 Mg ha-1 (2.25 %) while yield gains per period were 0.17 and 0.38 Mg ha-1 under drought and 19 rain-fed environments, respectively. Yield gains under drought and rain-fed environments were related 20 to prolonged flowering period, increased plant and ear heights, improved stalk lodging, ear and plant 21 aspects, whereas delayed leaf senescence and increased number of ears per plant (EPP) accompanied 22 yield improvement under drought only. Ear aspect and EPP were primary contributors to yield and 23 could be used as selection criteria for yield enhancement under drought and rain-fed conditions. High 24 yielding and stable cultivars across all environments based on additive main effects and multiplicative 25