Gene action of drought tolerance traits in pearl millet (Pennisetum glaucum [L.] R. Br.) seedling
- African Journal of Agricultural Research , 21 (12) : 945-958
Résumé
Early-stage drought is a major constraint that reduces pearl millet productivity in sub-Saharan Africa. To support the development of drought-resilient varieties, this study investigated the genetic control of early seedling drought tolerance using generation mean analysis on two contrasting crosses: IP-18062 × IP-8426 and IP-4927 × IKMLS1 18018. Six generations (P₁, P₂, F₁, F₂, BC₁ for each cross) were evaluated under both control and drought conditions induced by 23% PEG 6000 in a completely randomized design with three replications. Traits assessed included root length (RL), shoot length (SL), leaf width (LW), leaf length (LL), seedling vigor index (SVI), and root/plant ratio (RPR). Significant differences (P < 0.001) among generations under drought stress indicated substantial genetic variability for early-stage drought tolerance. Generation mean analysis revealed that most traits were governed by duplicate epistasis, suggesting the presence of substantial non-additive gene interactions. Overall, the results demonstrate that non-additive genetic effects particularly strong dominance and duplicate epistasis play a predominant role in controlling early drought-tolerance traits. The digenic epistatic model adequately explained variation in RL, SL, SVI, and RPR for both crosses across environments, as well as in leaf traits for the IP-18062 × IP-8426 cross under drought. Complementary epistasis was detected for leaf width and length in the control condition. The predominance of duplicate gene action suggests that recurrent selection is an effective strategy for improving early drought tolerance in later generations. These findings provide a strong foundation for breeding pearl millet with enhanced early stage drought resilience.
Key words: Duplicate gene action, early-stage drought, polyethylene glycol 6000, seedling drought tolerance.
Mots-clés
Duplicate gene action, early-stage drought, polyethylene glycol 6000, seedling drought tolerance.