Salinity–Grain Yield Response Functions of Barley Cultivars Assessed with a Drip‐Injection Irrigation System

Success in breeding crops for yield and other quantitative traits depends on the use of convenient methods to accurately evaluate genotypes under field conditions. We report the evaluation of a drip‐injection irrigation system (DIS) for assessing the salt tolerance of barley genotypes. Ten barley cultivars were randomized within each of nine salinities imposed by a DIS in an experiment with two replications. Grain yields were regressed against soil salinity (EC e ) using a sigmoidal growth response model to obtain the statistics Y m , EC e50 , and p. The data fitted the model well; the average correlation coefficient was 0.89 ( P < 0.001) when the observations for each cultivar in both replications were pooled, and the average SEs were <12% of the mean Y m and EC e50 estimates. We concluded that the DIS is a reliable system for estimating the salinity response functions of barley. The grain yields obtained in the control( EC e = 4 dS m − 1)and intermediate( EC e = 9 dS m − 1)soil salinity were highly correlated (r = 0.81, P < 0.01), indicating that the highest‐yielding cultivars under nonsaline conditions were also most productive under intermediate saline conditions. However, yields at high soil salinity( EC e = 17 dS m − 1)were not correlated with the control yields. For the same set of genotypes, the estimates of EC e50 obtained with the DIS and with a triple‐line source system (TLS) were strongly correlated (r = 0.84, P < 0.01), even though the direct absorption of salts by the leaves, which is a feature of the TLS, had a deleterious effect on grain yields. Results from the DIS trial( m e a n   E C e 50 = 13 . 1   dS   m − 1 ) suggest that the salt tolerance of barley quoted in the literature for similar climatic conditions( EC e 50 = 18 dS m − 1)could be overestimated by 40%.