Multiple Benzyladenine Applications Increase Shoot Formation in Nandina

Abstract A study conducted from 2000 to 2002 determined the effects of multiple applications of benzyladenine (BA) applied at different concentrations on shoot formation, whole plant size, and phytotoxicity in Nandina domestica Thunb. In 2000, shoot counts increased in ‘Harbour Dwarf’ by up to 107% and 480% as the number of weekly BA applications at 2500 and 5000 ppm, respectively, increased to five. Likewise, the number of shoots per plant increased as BA rate increased. In response to five weekly foliar BA applications in 2001 and 2002, the number of new shoots on ‘Harbour Dwarf’ increased linearly 10-fold over the control as BA rate increased to 5000 ppm in 1250 ppm increments. In 2002, shoot formation increased linearly by up to six additional shoots per plant with increasing BA rate in ‘Harbour Dwarf’ and quadratically by up to two additional shoots per plant in ‘Firepower’ by 90 days after initial treatment (DAT) with five applications of up to 5000 ppm BA. Shoot formation in the tall, upright cultivars ‘Royal Princess’ and ‘Moyer's Red’ also increased linearly with increasing BA rate, by two and <1 shoot per plant, respectively, in 2002 only. Five foliar applications of 2500, 3750, and 5000 ppm BA injured upper, immature foliage, but did not adversely affect plant appearance by 90 DAT. Treatment effects on plant size were minimal.