Drought is a major constraint on crop production especially in maize. It significantly reduces productivity, affecting the livelihoods of millions and the overall economy. Malnutrition due to lack of essential nutrients like Vitamin A is another major challenge in many African countries. Breeding for pro-vitamin A drought-tolerant maize varieties is crucial to address these. Knowledge and understanding of interrelationships between grain yield and yield-related traits would ensure progress from selection in maize breeding programs through the use of appropriate selection indices. 107 pro-vitamin A maize inbred lines along with 3 testers were screened for drought tolerance in Samaru and Bagauda in 2020/2021 dry season to assess the relationship between grain yield and yield-related traits. The experiments were laid out in a 10 x 11 alpha lattice design and replicated two times using single-row plot of 5m long. Inbred lines with high tolerant index values were identified; SLMP-59 has the highest index value (18.06) with a low yield reduction percentage of 38.07% making it the best drought response. The inbred SLMP-3 turns out to be most drought susceptible with drought index value of -12.59 and yield reduction of 83.39% The negative genotypic association of days to pollen (rg = -0.80**) and days to silking (rg = -0.79**) and phenotypic association of days to pollen (rp = -0.97***) and days to silking (rp = -0.98***) with grain yield implies that these traits are not co-inherited together with grain yield and that short anthesis silking interval period would increase grain yield due to the synchronization of pollen shedding and silking emergence. Traits associated with ear aspect are the most reliable traits for indirect selection for grain yield improvement under drought condition.
S. D. Zakariya, M. Oyekunle, I. Usman et al.· FUDMA Journal of Agriculture...· 0 citations
In order to meet the expected maize yield by 2050, breeders must work to improve breeding program efficiency by intensifying the implementation of new and improved technologies such as marker-assisted selection (MAS). Dissecting the genomic regions associated with drought tolerance is the first step forward in MAS program deployment for maize improvement under drought stress. Genome-wide association studies (GWAS) were used to investigate and identify quantitative trait loci (QTLs) associated with six traits under drought stress. One hundred and eighty-seven extra-early orange maize inbred lines were evaluated under managed drought stress at Ikenne, in Nigeria, during the 2022 and 2023 dry seasons. The materials were also genotyped using 9355 DArTseq SNP markers and analyzed using the enriched compressed mixed linear model (ECMLM). Enriched compressed mixed linear model was used for association-trait analysis. The ECMLM-based GWAS identified 45 candidate genomic loci associated with the six traits, including five for grain yield, with R2 ranging from 8.79 to 25.3%. Independent validation using the multi-locus 3VmrMLM approach confirmed seven high-confidence genomic loci consistently detected by both methods across grain yield, anthesis-silking interval, ear aspect, and ears per plant, providing additional statistical support for these genomic regions. Candidate gene annotation identified biologically relevant genes underlying the validated loci, including Zm00001eb238250 (protein-serine/threonine phosphatase), Zm00001eb040940 (trehalose-phosphatase), Zm00001eb117820 (homeobox protein knotted-1-like 4), Zm00001eb145560 (zinc ion-binding protein), and Zm00001eb294180 (WRKY DNA-binding domain protein), suggesting their potential roles in drought adaptation and grain productivity. These findings improve our understanding of the genetic architecture of drought tolerance in extra-early orange maize and provide valuable genomic resources for accelerating drought-resilient maize breeding.
T. Bonkoungou, I. Adejumobi, Victor Adetimirin et al.· Scientific Reports· 1 citation
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