Interactions of boron-toxicity, drought, and genotypes on barley root growth, yield, and other agronomic characters

Abstract

In areas with high levels of soil boron, symptoms of boron (B) toxicity often appear under droughts. This greenhouse study examined the interactions of B-toxicity, drought, and genotypes on barley (Hordeum vulgare L.) root growth, B-toxicity symptoms, B concentrations of straw, and yield. Plants were grown in tubes 65 cm tall. Three factors were studied: B, water supply, and genotypes. There were 2 B levels, B0 v. B50, in the subsoil (20-60 cm). There were 4 levels of water supply: no drought (control), and early, mid-season, and terminal drought. Two barley lines were compared: Sahara (B-toxicity tolerant) and BOL (drought tolerant, B-toxicity sensitive). Significant B-by-drought interaction was detected in straw B concentration, root growth in subsoil, and straw and biological yield for BOL. Mean root growth in the 40–60-cm soil section was much higher under mid-season drought than under the control. At B50, plants under drought had 1-fold higher straw B concentrations and more B-toxicity symptoms than the control plants. This is the first study to provide data to explain the frequent association of B-toxicity symptoms with droughts in the field. The results clearly showed that tolerance to B-toxicity, as well as drought, is needed in dry areas having high levels of subsoil B.