Characteristics of Boron Absorption by Excised Barley Roots

Boron absorption by excised barley roots was found to be noncumulative, rapid, and unaffected by pH variations of the substrate in the acid range. However, increases in pH above 7.0 resulted in sharp reductions in absorption. At pH 6.0, changes in substrate temperature, salt composition and level, or addition of KCN and 2,4‐DNP failed to exert any influence on B absorption. These results indicate that B absorption is a physical, non‐metabolic process acting in response to B concentration gradient and that molecular boric acid is favored for absorption.