Performance of maize populations under different nitrogen rates in northern Ghana

This study evaluated grain yield performance, stability and agronomic nitrogen-use efficiency (AE) of twelve maize populations under three nitrogen (N) rates at two locations in the Guinea and Sudan savannah zones of Ghana in 2014 and 2015. The N rates used were 0, 30, and 90 kg N ha−1. Computations were made for grain yield and AE. Populations × nitrogen interactions were significant for grain yield and AE at the three N rates. The mean yield of the populations under 0, 30, and 90 kg N ha−1 were 1.42, 4.12, and 6.80 t ha−1, respectively. Mean AE of the populations under low-N and high-N was 90.34 and 59.73 kg kg−1, respectively. Populations LNP-Syn-W, TZPB-LN-Syn and IWD-C2-Syn-F2 were efficient under both low-N and high-N inputs and produced 229.17 kg ha−1 and 572.5 kg ha−1 more grains than the average yield of all the populations under low-N and high-N, respectively. The results of this study indicated that the highest response to selection of N-efficient maize populations is achieved under low-N when the grain yield reduction at low-N is 39% of those of high-N environments.