Evaluation of the Spanish maize landrace core collection for drought tolerance

Drought is the main stress for agriculture worldwide and is expected to worsen with climate change. Improving maize resilience to drought requires identifying landraces as sources of adaptive traits conferring tolerance to water deficit. The Spanish maize landrace collection, one of the most diverse in Europe and representing centuries of local adaptation, provides a valuable genetic resource for breeding. The objectives of this work were to assess drought tolerance in the core collection of Spanish landraces, and determine their genetic variability and possible mechanisms of drought tolerance. The core collection of Spanish maize landraces was evaluated under drought and control conditions in Pontevedra (Northwestern Spain) over three years. Spanish landraces significantly differed for most traits under both control and drought conditions, though they were not significantly different for photosynthetic traits under drought. The popcorn landrace Villanueva del Arzobispo has the best vegetative growth and aspect with good yield performance under drought conditions, along with Blanco, Enano levantino/Hembrilla, Norteño largo, Trascastro, Guetaria, Cima, Fino/Tremesino, Lazcano, and Lira. The performance of landraces varied across environments, and diverse landraces were selected depending on the environment. Cacheira, Cima, Rastrojero, Norteño largo, Gamiz, Hazas de Sobas, and Guetaria were the most stable landraces in terms of photosynthetic traits. We conclude that Cacheira, Cima, and Acibeiro were the most stable under different environments and registered high photosynthetic rates under drought conditions with superior yield production. These landraces represent promising sources of drought tolerance for breeding programs. • This is the first screening trial comparing the Spanish maize core collection. • The popcorn landrace Villanueva del Arzobispo showed the highest drought tolerance. • Cacheira, Cima, and Guetaria were among the most stable landraces for photosynthesis. • Cacheira, Cima, and Acibeiro combined stability with high yield under drought.