Algerian maize populations from the Sahara desert as potential sources of drought tolerance

Drought affects maize (Zea mays L.) performance from seedling to grain filling. Sources of drought tolerance at multi-scale growth are crucial for maize breeders. The objectives of this work were to identify new sources and mechanisms of drought tolerance and to study the traits controlling plant growth under drought and their associations with yield. We evaluated a collection of 18 maize populations from the Algerian Saharan oases under simulated drought conditions using Polyethylene glycol 6000, and in the field. The genotypextreatment interactions were more significant under field than under control conditions. Under field conditions, based on general agronomic performance, PI527476, PI542678 and PI527474 were the most drought-tolerant populations. PI527476 was the most tolerant population for germination-related traits, PI542678 exhibited high final germination, high number of secondary roots and positive water use efficiency (WUE), while PI527474 presented high number of secondary roots number and WUE. PI542685 was drought tolerant at seedling stage, characterized by high germination, long roots, heavy root, high number of secondary roots, and stable shoot/root weight ratio. Germination, shoot/root weight, root dry weight at seedling stage, and dry weight of secondary roots were the most significant seedling growth-related traits affecting WUE and yield under drought. Differences were detected among populations under stress conditions at multi-scale growth phases with some common genetic dependency of yield on seedling-related traits. Therefore, these Saharan populations could provide favorable alleles for drought tolerance for breeding programs, and the use of seedling-related traits, especially root performance, as secondary yield-related traits could lead to increased gain yield selection under drought conditions.