Résumé
Substantial genetic variation for drought adaption exists in pearl millet via traits controlling plant water use. Knowing genomic regions responsible for these traits is important. F7 recombinant inbred lines were used to identify QTLs and allelic interactions for traits affecting plant water use, and we discuss their relevance for crop productivity in water-limited environments. Four QTLs contributed to increased transpiration rate under high VPD conditions, all with alleles from drought-sensitive parent ICMB 841. Of these four QTLs, a major QTL (35.7%) was mapped on LG 6. The alleles for 863B at this QTL decreased transpiration rate and this QTL co-mapped to a previously detected LG 6 QTL, with alleles from 863B, for grain mass and panicle harvest index across severe terminal drought stress environments. This evidence provided additional support for a link between water savings from lower transpiration rate under high VPD and drought tolerance. 863B alleles in this same genomic region also increased shoot weight, leaf area, and total transpiration under well-watered conditions. One unexpected outcome was a reduced transpiration under high VPD (15%) from the interaction of two alleles for high VPD transpiration (LG 6 (B), 40.7) and specific leaf weight and biomass (LG 7 (A), 35.3), (A, allele from ICMB 841, B, allele from 863B, marker position) . The LG 6 QTL appears to combine alleles for growth potential, beneficial for non-stress conditions, and for saving water under high evaporative demand, beneficial for stressful conditions. Mapping QTLs for water-use traits, and assessing their interactions, offers considerable potential for improving pearl millet adaptation to specific stress conditions through physiology-informed marker-assisted selection.