“Estudio de la biodiversidad existente en una colección de trigo duro para características relacionadas con la tolerancia a la sequía en ambiente Mediterráneo”

Drought resistance is one of the main goals of wheat breeding programs in the Mediterranean region, where water shortage is a general yield constraint. Under the projected scenarios of climate change, drought resistance becomes crucial for food security. The objective of this Master Thesis was to characterize a collection of durum wheat varieties from diverse geographical regions and cultivation periods for a set of phenological, physiological and yield-related traits. Differences between groups of germplasm were also assessed. The collection was tested in semi-arid conditions in Gimenells (Lleida province), under a rainfed environment. Mean comparison and multivariate analysis revealed that the landraces had a longer cycle length to anthesis and a shorter grain filling period than the modern varieties. Among the later, those cultivated in the North of the Mediterranean Basin and North America had similar cycle length to anthesis, which was longer than that of the varieties grown in the south of the Mediterranean Basin. Concerning physiological traits, landraces had higher early vigor, plant height, biomass at anthesis and maturity and more radiation interception than the modern varieties. However, radiation use efficiency was similar in all the groups of germplasm evaluated. The modern varieties grown in North-America and in the countries of the Northern Mediterranean Basin showed lower canopy temperature than those grown in Southern countries. Modern varieties outyielded the landraces partially due to their heavier grains. Significant differences were not detected between landraces and modern varieties for the number of spikes per unit area nor the number of grains per spike. The large variability detected in the collection for most of the traits studied indicates that it contains genotypes that could be useful in breeding programs focused on improving drought resistance.