Per se Performance, Heterosis and Heterotic Groupings of Maize Inbred Lines for Yield and Tolerance to Low Soil Nitrogen

Abstract

Information on per se performance, heterosis and heterotic grouping of newly developed maize lines is required for successful hybrids development. The study was conducted to assess the per se performance of inbreds, examine the inbred-hybrid relationship and classify the lines into heterotic groups. Seventy-nine inbreds developed at Institute for Agricultural Research Zaria were crossed to three testers to generate 237 hybrids. The parental lines and hybrids were separately evaluated under low- and optimum-N conditions at Zaria in 2020 and 2021. The results revealed significant differences (ρ < 0.05) among the inbreds and hybrids for grain yield and most measured traits under low- and optimum-N conditions. Inbred parent SMLW-156 was the highest yielding under low-N and optimum-N condition with average yield advantage of more than 100% and 65% over the best check under low-N and optimum-N condition, respectively. Parental lines SMLW-146 and SMLW-155 were identified as testers. Hybrid SMLW-165 x IITA 1876 had better parent (253.1%) and standard heterosis (48%) for grain yield under optimum-N environment. Hybrid SMLW-105 x IITA 1876 out-yielded standard check by over 100% while SMLW-134 x IITA 1878 was the best for mid and better parent heterosis under low N. Inbreds were classified into four and three distinct groups under low- and optimum-N environments, respectively. Inbred lines within each heterotic group can be recombined to form heterotic populations which can be improved through recurrent selection.