The Boron Requirement for Root Development in Stem Cuttings of Phaseol Us Aureus Roxb.

SUMMARY No roots develop in cuttings from light‐grown seedlings of Phaseolus aureus Roxb. without exogenous boron, irrespective of auxin pretreatment. Root numbers and lengths are severely restricted unless the supply of boron is optimal. When supplied in equal molarities, indole‐butyric acid (IBA) is far more effective than indoleacetic acid in promoting root number. Very small visible roots do develop on cuttings from dark‐grown seedlings in the absence of applied boron. The growth of such roots is promoted by boron although there is an inverse correlation between length and number. IBA is far less effective at increasing root number in cuttings of dark‐grown seedlings.