Effects of low water availability on root placement and shoot development in landraces and modern barley cultivars

Early vigor has been proposed as a favorable trait for cereals grown in drought-prone environments. This research aimed at characterizing early stage shoot and root growth of three Spanish barley landraces compared with three modern cultivars. Genotypes were grown in an automated phenotyping platform, GrowScreen-Rhizo, under well-watered and drought conditions. Seminal and lateral root length, root system width and depth were recorded automatically during the experiment. Drought induced greater growth reduction in shoots (43% dry weight reduction) than in roots (23% dry weight). Genotypic differences were larger under no stress, partly due to a more profuse growth of landraces in this treatment. Accession SBCC146 was the most vigorous for shoot growth, whereas SBCC073 diverted more assimilates to root growth. Among cultivars, Cierzo was the most vigorous one and Scarlett had the least root dry weight of all genotypes, under both conditions. Root growth was redirected to lateral roots when seminal roots could not progress further in dry soil. This study reveals the presence of genetic diversity in dynamics of early growth of barley. The different patterns of growth observed for SBCC073 and SBCC146 should be explored further, to test if they affect field performance of barley in drought-prone environments.