EFFECT OF AUXINS AND THEIR CONCENTRATIONS, IMMERSION TIME, AND ROOTING SUBSTRATE ON ROOTING OF CUTTING-PROPAGATED PYRACANTHA ANGUSTIFOLIA C. K. SCHNEID

Abstract

Pyracantha angustifolia C.K. Schneid. (Rosaceae) is wildly grown in yards and gardens as an ornamental plant and can be used to make hedges for home security. In this study, a L-16(3(3) x 4) orthogonal test of (1) auxins indole-3-butyric acid (IBA), alpha-naphthaleneacetic acid (NAA), and indole-3-acetic acid (IAA) at (2) concentrations 0, 8, and 16 g l(-1), (3) immersion time for 30 s, 15 and 30 min, and (4) rooting substrates (BVB medium, rockwool cube, Terra Plug, and phenolic foam) was conducted to evaluate the rooting efficiency of cuttings of P. angustifolia. Hardwood stem cuttings cut into 6 cm in length with 3 fully expanded leaves were treated according to the design and stuck in one of the rooting substrates. The cuttings were kept on a fogged propagation bench under 23 degrees C/14 degrees C day/night temperatures and 88% relative humidity in a glasshouse for 30 days. The auxins at concentrations of 8 and 16 g l(-1) significantly shortened the period to rooting, increased the rooting (%) and number of roots and enhanced root length. A concentration of 8 g l(-1) was better than 16 g l(-1). Application of IBA resulted in considerable increase in number of roots, while the IAA promoted the root length, and NAA was not an optimal auxin as it caused lower rooting (%) and shorter root length. Immersion time was not a significant factor influencing days to rooting and root length, although a longer immersion time increased rooting (%) and number of roots. The phenolic foam was the best substrate for rooting. The concentration of auxin was the most important determinant factor among the 4 factors researched, and a combination of 8 g l(-1) IBA, 15 min immersion time and phenolic foam is recommended for cutting propagation of P. angustifolia in autumn.