FACTORS AFFECTING ROOT FORMATION OF PHASEOLUS VULGARIS

Abstract

The survival of single-leaf cuttings of P. vulgaris after removal from the plant is roughly proportional to the amt. of stem attached. This is probably due to the contribution by the stem of some organic nitrogenous compounds to the leaf. Both survival and rooting are greatly increased by treatments either with KNO3 or with adenine or asparagine for a brief period. Some other nitrogenous substances are also effective but to a lesser extent. (NH4)2SO4 is strongly inhibitory. Ca or Mg salts, at the concs. used in nutrient solns., also depress root formation. The cuttings are unusually sensitive to the toxic action of indole-acetic acid, opt. rooting being given by about 0.025 mg. per l. when applied basally for 24 hrs. The N nutrition of the isolated leaf is evidently of great importance in determining both its survival and its root formation.