Spatial variability of salt-affected soils in the middle Ebro Valley (Spain) and implications in plant breeding for increased productivity

The assessment of the level and spatial variability of soil salinity and the knowledge of the salinity-yield response functions of crops are required to ascertain the best management strategies aimed at optimizing cropʹs productivity in saline environments. This work analyzed the spatial distribution of ECe in six irrigated, salt-affected fields of the middle Ebro River Valley (Spain) using electromagnetic survey and geostatistical techniques, and the implications of this salinity variability in plant breeding strategies for increased productivity. The average field ECe varied between 4.9 and 15.4 dS m^-1, with within-field coefficients of variation between 37 and 79%. The yield simulation analysis of 20 barley and durum wheat cultivars showed that almost 60% of the total yield came from the less saline areas (ECe < 6 dS m^-1). The model-estimate Ym (maximum yield under nonsaline conditions) and the simulated yields were significantly correlated (p<0.01) in ten out of the twelve analysis performed. Thus, the best strategy for increasing the productivity in moderately salt-affected soils (average field ECe between 5 and 7 dS m^-1) of the middle Ebro Valley is to breed and grow high potential yielding barley and durum wheat cultivars. On the other hand, breeding for increased productivity in highly salinized soils (average field ECe around 15 dS m^-1) should be based, at least at the parental lineʹs selection stage, on the combination index B (ECe50 Ym 10^-3) which takes into account both the potential yield and the salinity tolerance of crops.