Grain-yield stability among tropical maize hybrids derived from doubled-haploid inbred lines under random drought stress and optimum moisture conditions

Abstract

Drought is a devastating environmental stress in agriculture and hence a common target of plant breeding. A review of breeding progress on drought tolerance shows that, to a certain extent, selection for high yield in stress-free conditions indirectly improves yield in water-limiting conditions. The objectives of this study were to (i) assess the genotype × environment (GE) interaction for grain yield (GY) and other agronomic traits for maize (Zea mays L.) across East African agro-ecologies; and (ii) evaluate agronomic performance and stability in Uganda and Tanzania under optimum and random drought conditions. Data were recorded for major agronomic traits. Genotype main effect plus GE (GGE) biplot analysis was used to assess the stability of varieties within various environments and across environments. Combined analysis of variance across optimum moisture and random drought environments indicated that locations, mean-squares for genotypes and GE were significant for most measured traits. The best hybrids, CKDHH1097 and CKDHH1090, gave GY advantages of 23% and 43%, respectively, over the commercial hybrid varieties under both optimum-moisture and random-drought conditions. Across environments, genotypic variance was less than the GE variance for GY. The hybrids derived from doubled-haploid inbred lines produced higher GY and possessed acceptable agronomic traits compared with the commercial hybrids. Hybrid CKDHH1098 ranked second-best under optimum-moisture and drought-stress environments and was the most stable with broad adaptation to both environments. Use of the best doubled-haploids lines in testcross hybrids make-up, well targeted to the production environments, could boost maize production among farmers in East Africa.

Evaluation of early-generation tropical maize testcrosses for grain-yield potential and weevil (Sitophilus zeamais Motschulsky) resistance

“…Results revealed variation in magnitude of variances for GY with environment that accounted for the largest proportion followed by genotype, and genotype × environment interactions. The results are similar to those reported by Setimela et al (2010 , 2007) , Beyene et al (2011) , Makumbi et al (2015) and Sserumaga et al (2018 , 2016) . The large environmental variance indicates that the testing sites were highly variable from one environment to another.…”

“…The implication of significant genotype × environment interaction implies that there is differential hybrid performance across variable conditions. Similar observations were reported by several authors ( Beyene et al, 2013 ; Ertiro et al, 2017 ; Sserumaga et al, 2018 , 2016 ) who studied about adaptability and performance of maize hybrids under different stress conditions in eastern Africa.…”

“…The need for weevil-resistant maize varieties has implications for germplasm development efforts in eastern Africa as breeders need to concurrently select for abiotic stress tolerance and weevil resistance during line development. In the last two decades, the National Agricultural Research Organization (NARO) in collaboration with the International Maize and Wheat Improvement Center (CIMMYT) have developed elite maize genotypes with tolerance to multiple stresses (drought, maize streak virus, turcicum leaf blight, gray leaf spot, and Striga ) using new elite inbred lines ( Beyene et al, 2013 ; Makumbi et al, 2015 ; Sserumaga et al, 2018 , 2016 ). Previous evaluation of new stress tolerant germplasm ( Beyene et al, 2013 ; Sserumaga et al, 2018 , 2016 ) did not consider assessment for weevil resistance.…”

Beat the stress: breeding for climate resilience in maize for the tropical rainfed environments

“…Since 2013, CIMMYT has developed more than 200,000 maize DH lines from diverse source populations and successfully identified maize DH lines with superior characteristics for use in breeding pipelines in SSA, Latin America, and Asia. These DH lines have superior per se performance (Worku et al 2016 ; Beyene et al 2017a ), good combining ability for stress tolerance (Beyene et al 2013 , 2017a , Erito et al 2017; Sserumaga et al 2018 ), and tolerance/resistance to various diseases (Beyene et al 2017b ).…”

A Physio-Morphological Trait-Based Approach for Breeding Drought Tolerant Wheat

“…This observation was supported earlier by Johnson and Frey (1967) who reported that varieties selected directly from stressed conditions exhibit a low genotype × environment (G × E) interaction compared to those selected under optimal conditions. However, some studies show that selection under optimal environments also improves grain yield under drought conditions to a limited extent (Araus et al, 2002;Cattivelli et al, 2008;Sserumaga et al, 2018). Mohammadi and Amri (2011) indicate that grain yield improvement may be attained by either selection in low input and stressed environments or by selection in non-stressed conditions followed by selection under stressed conditions.…”