Data presentation, interpretation, and communication

Abstract

The external and internal boron (B) requirements for the growth of sunflower plants (Helianthus annuus L. cv. Hysun 25) were estimated with a B‐buffered solution culture system. Sunflower seedlings (7 day old) were grown for 10 days in nutrient solution containing B concentrations of 0.05, 0.12, 0.25, 0.47, 1.7, 4.0 and 11.0 μM, respectively, which were buffered with B‐loaded B‐specific resin (Amberlite 743). A graduated B response from severe to marginal deficiency, through to adequacy in growth and B status of sunflower was rapidly produced by the B‐buffered solution culture system. There were close relationships between shoot dry matter and both external B concentration and plant B concentration. Critical B concentrations (mg B kg^‐1 dry matter) for shoot growth were 12–20 in the leaves (including mature and immature leaves) and 11–16 in the whole shoot. Critical B concentrations in nutrient solution for shoot and root growth were estimated to be 0.24–0.28 and 0.30–0.35 μM, respectively.