Stability parameter and genotype mean estimates for drought stress effects on root and shoot growth of wild barley pre-introgression lines

The goal of the present study was to select BC2-lines from a cross between Hordeum vulgare and H. vulgare ssp. spontaneum and to identify introgressed candidate regions responsible for a superior pre-flowering development across environments including drought stress conditions by using stability parameter and genotype mean estimates. Three experiments were carried out under controlled environmental conditions. Drought stress was induced by permanent suboptimal water supply, stress cycles in continuously drying soils, and increased transpiration demands by reducing relative humidity of the air. The environmental effects on shoot dry weight, leaf area, tiller number, and root lengths of 36 lines and the recurrent parent, the spring barley cultivar ‘Scarlett’ was tested in ten different conditions. Results showed that 11 genotypes responded significantly (P = 0.05) different from the recurrent parent in at least one of the measured traits. The introgressions of those lines were assigned to five genome regions, which have been suggested as QTL regions for related traits before. Regions on chromosome 4H influence tillering and one region each on 2H, 5H, and 7H probably has effects on shoot dry weight and leaf area. Introgressions on the mentioned regions increased trait values in every case. Leaf area was highly correlated to shoot dry weight and tiller number while the correlation between shoot dry weight and tiller number was not significant. A weak correlation was observed between tiller number and root lengths. Slopes of response curves of lines to increasing water shortage did not significantly differ from the population mean and from the recurrent parent. Results give hint that superior genotypes within the population develop well under both well-watered and drought stress conditions.