Harnessing genetic diversity for drought tolerance and forage yield improvement in pearl millet germplasms through a prebreeding framework.

Pearl millet, recognized for its resilience to climate challenges, thrives in drought-prone and poor soil quality areas. This study aims to evaluate the impact of drought stress on six agronomic traits in 188 pearl millet accessions and identify stable and drought-tolerant accessions that can be developed into forage parental lines. Field experiments conducted in summer 2023 and 2024 under irrigated (control) and rainfed (stress) treatments at Hays, Kansas, revealed significant differences among the accessions, treatments, and year based on an aligned rank transform test for all the traits evaluated. The rank summation index selected 30 drought-tolerant germplasms per maturity group from the whole collection. Principal component analysis based on GBS SNP data indicated a higher level of genetic variation within the selected and unselected germplasms. By utilizing BLUP-based GGE biplot, MTSI, MGIDI, and FAI-BLUP stability models, we identified three early (E11-PI197115, E5-PI197368, and E12-PI197327), four medium (M19-PI197465, M5-PI197436, M1-PI197326, and M29-PI197069), and two late (L5-PI197291 and L19-PI197278) maturity accessions with broad adaptability across environments. Chlorophyll index, stay-green, and biomass traits served as effective indicators for drought tolerance, showing moderate to high heritability across maturity groups and stable performance across years. These results are crucial for developing drought-tolerant parental lines and hybrids with enhanced forage yield, addressing livestock feed challenges.