Drought tolerant maize (Zea mays L.) hybrids are crucial to sustainability of maize production in West and Central Africa (WCA). Two studies were conducted at three locations in Nigeria for 2 yr to (i) assess performance of 156 early-maturing maize inbreds and three hybrid types and (ii) determine heterosis among the lines and relationship between lines per se and hybrid performance. The inbreds and their hybrids were evaluated separately under drought and well-watered conditions. Genotype, environment and genotype × environment interactions were significant for grain yield under the research conditions. Grain yield of inbreds ranged from 0.06 t ha−1 for TZEI 123 to 1.92 t ha−1 for TZEI 17 under drought. While differences in grain yield among hybrid types (single, three-way and double-cross hybrids) were not significant under drought, significant differences were detected among hybrid types under optimal conditions. GGE biplot analysis identified three inbreds, TZEI 18, TZEI 56, and TZEI 1 and hybrids TZEI 129 × TZEI 16, (TZEI 17 × TZEI 16) × TZEI 157 and (TZEI 16 × TZEI 157) × TZEI 129 as ideal across research conditions. Midparent heterosis (MPH) and high-parent heterosis (HPH) for grain yield were higher in the well-watered conditions than under drought. Positive and significant correlations existed between MPH, HPH and yield under both research conditions. Drought tolerant hybrids with stable and high yield are available for promotion for adoption by farmers in WCA.
Authors:M. Oyekunle, A. Menkir, H. Mani, G. Olaoye, I.S. Usman, S.G. Ado, U.S. Abdullahi, H.O. Ahmed, L.B. Hassan, R.O. Abdulmalik and H. Abubakar
Genotype × environment interactions complicate selection of superior genotypes for narrow and wide adaptation. Eighteen tropically-adapted maize cultivars were evaluated at six locations in Nigeria for 2 yrs to (i) identify superior and stable cultivars across environments and (ii) assess relationships among test environments. Environment and genotype × environment interactions (GEI) were significant (P < 0·05) for grain yield. Environments accounted for 63.5% of the total variation in the sum of squares for grain yield, whereas the genotype accounted for 3.5% and GEI for 32.8%. Grain yield of the cultivars ranged from 2292 kg ha–1 for DTSTR-W SYN2 to 2892 kg ha−1 for TZL COMP4 C3 DT C2 with an average of 2555 kg ha−1. Cultivar DT SYN2-Y had the least additive main effect and multiplicative interaction (AMMI) stability value of 7.4 and hence the most stable but low-yielding across environments. AMMI biplot explained 90.5% and classified cultivars and environments into four groups each. IWD C3 SYN F3 was identified as the high-yielding and stable cultivar across environments. ZA15, ZA14, BK14, BK15 and IL15 had environment mean above the grand mean, while BG14, BG15, LE14, LE15, IL14, LA14 and LA15 had mean below the grand mean. ZA, BK, BG, LE and LA were found to be consistent in ranking the maize cultivars. However, Zaria, Birnin Kudu, and Ilorin were identified as the best test locations and could be used for selecting the superior maize cultivars. The identified high-yielding and stable cultivar could be further tested and promoted for adoption to contribute to food insecurity in Nigeria.