Combining ability and testcross performance of low N tolerant intermediate maize inbred lines under low soil nitrogen and optimal environments

Abstract

Low soil nitrogen (low N) threatens maize production in sub-Sahara Africa (SSA). We examined the mode of gene action conditioning grain yield of intermediate maturing inbreds and evaluated lines in hybrid combinations for high yield, stability and tolerance to low N. Thirty-two sets of inbreds were crossed to three elite testers (87036, 1368 and 9071) to generate 96 F1 hybrids. The testcrosses plus four hybrid checks were evaluated under low (30 kg/ha) and high (90 kg/ha) N environments at three locations for 2 years in Ghana. Significant general combining ability (GCA) and specific combining ability (SCA) effects were detected for grain yield and most measured traits across test environments, indicating that both additive and non-additive gene action governed the inheritance of the traits. GCA effects were greater than SCA effects, indicating that most traits were controlled predominantly by additive gene action and that inbreds with positive significant GCA effects for grain yield and other traits would contribute favourable alleles to progenies across environments. Hybrid CZL 0001 × 9071 possessed high GY, increased EPP, desirable EHT and PLHT and was the highest yielding under each of two research conditions. Significant genetic correlations were observed between GY and PLHT, EPP, EHT, CA and PA implying that improvement of these traits would lead to significant gains in grain yield under low-N conditions. Hybrids CLWN 247 × 9071, ZM523B-29-2-1-1-B*6 × 9071, TZD II 68 × 1368 and P43SCRq Fs100-1-1-8 × 9071 were high-yielding, stable and low-N tolerant and should be tested on-farm and commercialized.

Assessment of yield performance and stability of hybrids and populations of tropical maize across multiple environments in Southeastern Brazil

“…However, due to its poor yield performance under stress conditions, it was not among the most stable hybrids (long projection onto the AEC ordinate), suggesting that it has specific adaptation to some favorable environments. In agreement with our results, some studies have also reported the identification of high‐yielding but unstable maize experimental hybrids across diverse tropical environments (Oyekunle et al., 2017; Oyekale et al., 2020; Rezende et al., 2020; Ribeiro et al., 2020; Sserumaga et al., 2016, 2018). In addition to H147, the hybrid 92V2033 (H36) had the third highest HMRPGV × OM value under favorable environments, was very stable across the tested environments by GGE biplot, and was the second highest yielding among hybrids with general adaptation.…”

“…but unstable maize experimental hybrids across diverse tropical environments (Oyekunle et al, 2017;Oyekale et al, 2020;Rezende et al, 2020;Ribeiro et al, 2020;Sserumaga et al, 2016Sserumaga et al, , 2018. In addition to H147, the hybrid 92V2033 (H36) had the third highest HMRPGV × OM value under favorable environments, was very stable across the tested environments by GGE biplot, and was the second highest yielding among hybrids with general adaptation.…”

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

“…Inbred-Hybrids relationship for grain yield under optimum N conditions at Zaria in 2020 and 2021 traits across the environments, indicated that each environment was unique in the expression of the traits investigated and thus validate the need for multi-environment evaluation of the inbreds(Badu-Apraku et al 2013, Ribeiro et al 2020, Oyetunde et al 2020). However, the signi cant G x E interaction observed indicates that genotypes performed differently across locations, i.e., the relative performances of the genotypes were in uenced by the variable environmental conditions.…”

“…Maize is one of the most important crops worldwide, serving as a staple food for millions of people in sub-Saharan Africa (SSA) (Ribeiro et al 2020).…”

“…However, the yield of maize is signi cantly affected by various biotic and abiotic stresses, including low soil nitrogen. Low soil N is estimated to cause yield losses as high as 50% in sub-Saharan Africa (SSA) (Makumbi et al 2011;Ribeiro et al 2020). In recent years, researchers have been exploring new ways to improve the yield and tolerance of maize to low soil nitrogen through the use of heterosis and heterotic groupings of maize inbred lines (Hallauer et al 2010;Akinwale, 2021).…”