Analyses of Combining Ability and Genotype‐By‐Environment Interaction of Quality Protein Maize Inbred Lines Adapted to Tropical‐Highlands

Abstract

Production of quality protein maize (Zea mays L., QPM) is an economic and sustainable approach that can help to alleviate protein deficiency in developing countries. However, QPM cultivars with high grain yield and wide adaptation to the tropical‐highland subhumid maize agroecologies are yet to be developed and released for farmers. The objectives of this study were, therefore, to determine the magnitude of heterosis and combining ability of elite QPM inbred lines and to establish the genotype‐by‐environment interaction (GEI) of experimental hybrids for cultivar development and recommendation. Twelve parent half‐diallel crosses were produced, and 66 experimental hybrids were developed. The hybrids and two commercial hybrid checks were evaluated under the rainfed conditions of six tropical highland environments using an α lattice (0, 1) design during 2012 and 2013. Significant GEI was observed both in per se performances and genetic analyses. Inbred lines such as KIT32, FS60 and 142–1‐EQ were good general combiners for grain yield. Inbred line FS60 exhibited good general combining ability for reduced days to anthesis and desirable plant and ear height. Inbred line FS60 is genetically complementary to KIT32 and 142–1‐EQ and is useful for QPM hybrid cultivar development. The best hybrids identified through both combining ability and GEI analyses were KIT32 × 142–1‐EQ and 142–1‐EQ × CML144, yielding 10.3 Mg ha−1 and 9.6 Mg ha−1, respectively, across variable environments. These hybrids could be used as potential QPM single‐cross testers for three‐way hybrid cultivar development targeting tropical‐highland agroecologies.

Combining ability of highland adapted maize (Zea mays L.) inbred lines for grain yield and yield related traits under optimum and low nitrogen conditions

“…In combine analysis across environments, significant GCA and SCA mean squares were observed for the trait (Table 4). In agreement with the present results, Kanagarasu et al (2010) and Abakemal et al (2016) reported significant mean squares due to GCA and SCA for thousand-kernel weight.…”

“…level of variation for various characteristics, which makes selection possible for improved grain yield and agronomic traits under low N stress and non-stress conditions. Similar results have been reported (Dagne, 2008;Amare et al, 2016;Abakemal et al, 2016;Bullo and Dagne, 2016;Keno et al, 2017;Mafouasson et al, 2017).…”

“…Significant GCA of lines and SCA mean squares were observed under optimum nitrogen environment. In contrast to these findings, Abakemal et al (2016) reported non-significant mean square due to line GCA and significant SCA mean squares. GCA sums of squares were larger than SCA sums of squares for number of ears per plant under both conditions (Table 3).…”

“…The use of cultivars that utilize nitrogen more efficiently could greatly improve maize productivity in maize-based cropping systems. So far, combining ability effects in maize inbred lines has been extensively studied under non-stressed conditions for different sets of new maize inbred lines developed/introduced and adapted at different times (Amare et al, 2016;Ziggiju et al, 2016;Abakemal et al, 2016;Assefa et al, 2017). Even though CIMMYT has made significant progress in developing maize germplasm tolerant to low N Worku et al, 2008;Dagne, 2008;Mohamed et al, 2014;Mafouasson et al, 2017).…”

Effects of Mass Selection on Husk and Cob Color in Five Purple Field Corn Populations Segregating for Purple Husks

“…Growing season was the most important environmental factors affecting performance of this corn populations. The large effects of the environment have also been reported in quality protein maize for yield [43] and flowering traits [44]. The effect of environment also affected anthocyanin content, antioxidant activity in corn cobs [45], total anthocyanin content and total phenolic content in husk, cob, silk and tassel in purple waxy corn [46].…”