Identification of adaptation traits to drought in collections of maize landraces from southern Europe and temperate regions

Breeding maize for drought tolerance is becoming a major challenge in a context of climate changes and restricted irrigation. Gene banks contain underused genetic resources and adaptation traits for drought tolerance may be present in some populations originating from dry regions. We screened, under contrasted water regimes in dry-Mediterranean climate, populations originating from dry cropping zones in Southern Europe, and other populations from temperate regions with a good combining ability for yield and good agronomic features under drought scenarios in a previous study. We evaluated 78 populations for leaf growth, anthesis-silking interval, number of ears per plant, number of kernels per plot, and grain yield in the presence and absence of water stress, in field conditions, over 2 years. Maximum grain yield and the sensitivity of grain yield to water deficit were highly variable. Positive correlations between sensitivity and performance in well-watered conditions were found for yield and number of kernels. Landraces originating from dry regions were generally less sensitive to water stress and had a limited grain yield potential, with variability observed even among accessions from the same survey area. However, some of them had a relatively high yield under stress conditions. During screening for traits associated with the maintenance of grain yield under conditions of water limitation, we identified sources of drought tolerance in breeding populations and landraces from temperate areas as well as in landraces collected in dry regions, indicating large reservoir of native traits in collections for breeding for drought-prone environments.