Open-Pollinated and Hybrid Maize Varieties for the Rainforest Agroecology of Southwest Nigeria.

Incidence of abiotic and biotic constraints, and the impact of climate change cause changes in the rainforest cropping seasons of sw Nigeria. Maize (Zea mays L.) varieties that fit into the changes are urgently needed. Our objectives were to (i) evaluate the performance of maize OPVs and hybrids of extra-early (EE), early (E), and intermediate/late (I/L) maturity groups in the sw Nigeria two natural seasons; (ii) identify varieties for each and across seasons; and (iii) determine the relationship between grain yield and agronomic traits for the purpose of further selection for grain yield improvement. Three OPV and seven hybrid groups, containing a total of 336 genotypes were evaluated in 2015 at Obafemi Awolowo University, Ile-Ife, Nigeria (7⁰28' 4⁰33' 244 m asl). In the early season, I/L OPVs out-yielded the E and EE OPVs by about 42 and 48%. In the late season, however, the EE and E out-yielded the I/L OPVs by about 18 and 25%. In the I/L hybrid groups, 3WDT and TC hybrids performed equally but were both significantly higher yielding than 3WDTSTR hybrids, although by only about 10%. Similarly, the E and EE white hybrids out-yielded their yellow counterparts by nearly 50%. Highest grain yields were produced by two 3W hybrids [TZEEI 21 x TZEEI 14 x TZEEI 29 (6.3 t ha^-1) and TZEI 157 x TZEI 17 x TZEI 16 (6.1 t ha^-1)] and two SC hybrids [TZEEI 14 x TZEEI 29 (6.6 t ha^-1) and TZEI 60 x TZEI 86 (6.1 t ha^-1)], all in the E and EE maturity groups. For all maturity groups and varietal types, plant and ear aspects (r= >-0.6) and number of ears per unit land area (r= >0.7) consistently had significant correlation coefficients with grain yield. In conclusion, I/L OPVs were the best for early season while E and EE 3W and SC hybrids were the best for the late season of the rainforest agroecology of sw Nigeria.