Relationship of boron to gibberellic Acid-induced proliferation in debudded tobacco plants.

Stem applications of gibberellic acid (GA) to debudded tobacco plants (Nicotiona tabacum L., var. One Sucker) produce stem swellings that involve intense proliferation of, primarily, xylem tissue. Withholding boron from GA-treated debudded plants greatly reduces the GA-induced proliferation. This response offers a system for directly demonstrating the effect of boron on xylem formation and lignification that is unconfounded by the effect of boron on elongation growth.