Novel barley (Hordeum vulgare L.) germplasm resistant to acidic soil

Improving the resistance of barley (Hordeum vulgare L.) to acidic soils is an important goal of several barley breeding programs around the world. The identification and utilisation of novel barley sources resistant to aluminium (Al) may provide a significant and rapid advance towards that goal. Barley standards and screening protocols for selecting barley germplasm resistant to Al in nutrient solution and acidic soil were reevaluated. The assays used were quantitative in nature and were suitable for genotypic- and seedling-based selections. Although there was a broad agreement between the solution culture assays and soil assays in the ranking of genotypes it obscured the fact that misclassification of genotypes is common. Brindabella was shown to be better suited than Dayton (the current barley standard resistant to Al) as the Australian standard for resistance to acidic soils. A seedling-based Al pulse-recovery assay and an acidic soil assay were used to characterise 41 genotypes from the South and East Asian Barley Core Collection (SEA-BCC). In addition, in the acidic soil assays several standard barley and wheat genotypes were included. Three SEA-BCC genotypes were more resistant than Dayton to acidic soil while several others were similar to Dayton. The most resistant SEA-BCC genotypes Honen, Ohichi and Zairai Tanbo were of Japanese origin. Misclassification of barley genotypes and wheat genotypes for resistance to soil acidity between solution culture and acid soil assay provided strong evidence for the unsuitability of solution culture assay. Although in solution culture several barley genotypes were sensitive relative to wheat, in acidic soil they were not different from wheat. While the quest for resistant barley to acidic soils similar or better than resistant wheat still continues, it may be an unnecessary endeavour.