Comparative Analysis of Drought Tolerance in Traditional and Modern Maize Varieties

Thesis Abstract

Drought stress poses a significant threat to maize production globally, particularly in regions where climate variability and water scarcity are increasingly prevalent. Despite extensive breeding efforts, there remains limited understanding of how traditional and modern maize varieties differ in their physiological, morphological, and genetic responses to drought conditions. This study aims to conduct a comprehensive comparative analysis of drought tolerance between traditional and modern maize varieties cultivated under semi-arid conditions in the northern plains. The specific objectives include evaluating morpho-physiological traits associated with drought resilience, quantifying yield components under water-stressed conditions, and identifying genetic markers linked to drought tolerance traits in both maize categories. A mixed-methods research design was adopted, integrating quantitative field experiments with molecular analyses. The quantitative component involved the evaluation of 20 maize varieties, comprising 10 traditional and 10 modern cultivars, selected through purposive and stratified sampling from seed banks and local farms. Field trials were conducted over two growing seasons at the Climate Resilient Agriculture Research Station, employing a randomized complete block design with three replications. Drought stress was induced at the flowering stage via controlled irrigation withholding, with well-watered plots serving as controls. Data collection instruments included standard phenological measurement tools, portable photosynthesis meters, and chlorophyll content meters, complemented by laboratory-based DNA extraction and genotyping assays. Data analysis employed Analysis of Variance (ANOVA) to determine differences in morpho-physiological and yield traits under drought stress, followed by regression analysis to establish trait-yield relationships. Molecular data were analyzed using genome-wide association studies (GWAS) to identify markers associated with drought tolerance, grounded in the frameworks of the stress-response adaptation theory and the concept of genetic assimilation. Thematic analysis was applied to farmer interviews to contextualize varietal preferences and traditional selection criteria. Expected findings include significant differences in key drought-responsive traits such as relative water content, stomatal conductance, and leaf wilting scores between traditional and modern varieties, with traditional varieties hypothesized to exhibit superior resilience. Conversely, modern cultivars are anticipated to show higher yield potential under optimal conditions. Molecular analyses are projected to uncover specific quantitative trait loci (QTLs) associated with drought tolerance traits predominant in traditional varieties, providing insights into genetic adaptation mechanisms. These findings aim to bridge existing knowledge gaps regarding the comparative physiological and genetic mechanisms underpinning drought resilience in maize. This research contributes novel insights into the genetic and phenotypic diversity underpinning drought tolerance, informing breeding programs aimed at developing climate-resilient maize cultivars. The study underscores the importance of integrating traditional knowledge with modern molecular techniques to enhance drought adaptation strategies. The main conclusion emphasizes that traditional maize varieties possess valuable genetic traits for drought tolerance, which can be harnessed through marker-assisted selection to improve modern cultivar resilience. The study recommends the validation of identified markers in wider agro-ecological zones, the integration of traditional breeding knowledge into modern breeding pipelines, and the promotion of farmer participatory evaluation to ensure the adoption of drought-resilient maize varieties.