Yield Gains in Extra‐Early Maize Cultivars of Three Breeding Eras under Multiple Environments

Abstract

Core Ideas The study determined genetic improvement in grain yield of the cultivars during the breeding eras, investigated trait associations, and identified high‐yielding and stable cultivars across multiple‐stress and non‐stress environments. The study revealed an annual genetic gain of 2.72 and 2.28% for the cultivars under multiple‐stress and non‐stress environments. Cultivars 2004 TZEE‐Y Pop STR C4, TZEE‐W Pop STR QPM C0, TZEE‐W Pop STR BC2 C0 of era 2 and TZEE‐W STR 107 BC1, TZEE‐W Pop STR C5, and 2012 TZEE‐Y DT STR C5 of era 3 were the highest yielding and stable across multiple‐stress environments while 98 Syn EE‐W from era 1, FERKE TZEE‐W STR, TZEE‐W Pop STR C3, TZEE‐Y Pop STR QPM C0 from era 2, and TZEE‐W Pop STR C5, 2009 TZEE‐OR2 STR QPM, 2009 TZEE‐W STR, TZEE‐Y STR 106, TZEE‐W DT C0 STR C5 from era 3 were the most outstanding across non‐stress environments. We conclude that substantial progress has been made in breeding for multiple‐stress tolerant extra‐early maize cultivars in West and central Africa. Availability of extra‐early maize cultivars has facilitated the expansion of maize production into savannas of West and Central Africa (WCA). Fifty‐six extra‐early maize cultivars of three breeding eras;1995 to 2000, 2001 to 2006, and 2007 to 2012 were evaluated for 2 yr under 24 multiple‐stress and 28 non‐stress environments in WCA. Objectives of the study were to determine genetic improvement in grain yield of cultivars developed during the breeding eras, and identify high‐yielding and s multiple‐stress and non‐stress environments. Yield gains from era 1 to era 3 under multiple stresses was associated with increased days to anthesis, reduced stalk lodging, and improved husk cover. Cultivars 2004 TZEE‐Y Pop STR C4, TZEE‐W Pop STR QPM C0, and TZEE‐W Pop STR BC2 C0 of era 2; and TZEE‐W STR 107 BC1, TZEE‐W Pop STR C5, and 2012 TZEE‐Y DT STR C5 of era 3 were high‐yielding and stable across multiple‐stress environments while 98 Syn EE‐W from era 1, FERKE TZEE‐W STR, TZEE‐W Pop STR C3, and TZEE‐Y Pop STR QPM C0 from era 2, and TZEE‐W Pop STR C5, 2009 TZEE‐OR2 STR QPM, 2009 TZEE‐W STR, TZEE‐Y STR 106, and TZEE‐W DT C0 STR C5 from era 3 were outstanding across non‐stress environments and should be tested extensively and commercialized. Considerable improvement has been made in breeding for multiple‐stress tolerant extra‐early maize cultivars.

Gains in Grain Yield of Extra‐Early Maize during Three Breeding Periods under Drought and Rainfed Conditions

“…The extra-early cultivars showed an annual genetic gain of 3.28%, with a realized yield increase of 0.034 Mg ha −1 yr −1 under drought conditions, and 2.25% annual yield gain corresponding to an annual increase of 0.068 Mg ha −1 under rainfed conditions, which are greater than the yield gains obtained for the early-maturing cultivars reported by Badu-Apraku et al (2013a), who reported annual yield gains of 1.1 (0.014 Mg ha −1 ) and 1.3% (0.040 Mg ha −1 ) under drought and well-watered conditions, respectively. The annual yield gain obtained for this set of extra-early maize cultivars under drought was also higher than the annual yield gains of 2.56% reported under artificial Striga infestation (Badu-Apraku et al, 2016), 2.14% under low soil N (Badu-Apraku et al, 2017a, and 2.72% under multiplestress environments (Badu-Apraku et al, 2017b) for the same set of extra-early cultivars. Furthermore, the annual yield gain of 0.034 Mg ha −1 achieved under drought in the present study was greater than the gain of 0.029 Mg ha −1 obtained for CIMMYT's ESA early-maturing OPVs (Masuka et al, 2017b) and was comparable with the annual yield gain of 0.042 Mg ha −1 reported for the CIMMYT's ESA intermediate-late OPVs under random drought stress.…”

Testcross performance and combining ability of early maturing maize inbreds under multiple-stress environments

“…The agronomic and management practices adopted for the experiments have been reported by Badu-Apraku et al . 50 .…”

“…Low N (30 kg/ha) experiments were carried out at Mokwa during the rainy seasons of 2015 and 2016 and Ile-Ife during the 2015 rainy season (Supplementary Table 2). Details on how the low soil N environment was achieved at Mokwa and Ile-Ife and the management practices observed have been described by Badu-Apraku 50 .…”

“…The drought experiments conducted at Minjibir and Ikenne were as described by Badu-Apraku et al . 50 . However, due to the high temperature at Minjibir during the experiment period (February–March 2015) the irrigation was resumed at two weeks after flowering to enable completion of grain filling.…”

Genetic studies of soybean [Glycine max (L.) Merr.] response to seed storage stress factors

“…This resulted into farmers planting available seed that often has low vigor, which in turn affects the yield (Nkang and Umoh, 1997). It has been proved that cultivars respond differently to environment situations due to their genetic variability (Flajšman et al, 2019;Badu-Apraku et al, 2017). Hence researchers have explored the use genetic variability among germplasms to solve genetic and agronomic problems.…”