Morphological Traits above the Flag Leaf Node as Indicators of Drought Susceptibility Index in Durum Wheat

Selection criteria for drought tolerance would be helpful tools for wheat breeding programmes. To assess the usefulness of some morphological traits above the flag leaf node as indicators of yield and the susceptibility index (SI) of Fischer and Maurer, 10 durum wheat genotypes were used in experiments conducted under two water regimes at two latitudes in Spain during 3 years. Morphological traits were measured at anthesis, and yield, yield components and quality traits were evaluated at ripening. Principal components analysis showed associations between morphological traits and yield, yield components and quality, most of them caused by differences between environments. Peduncle weight, spike weight and length and awn length were significantly related to SI within environments. Spike and peduncle weight were the traits more related to yield and SI in all the experiments together and in the rainfed sites, while in the irrigated sites spike length was better. The spike weight and length were negatively associated with SI, while peduncle weight was positively associated to SI. Genotype means across all experiments were associated with SI values. These morphological traits could be selection criteria in breeding programmes to obtain varieties with good yield stability. The genetic variability found suggests opportunity for selection.