Effects of light regime and IBA concentration on adventitious rooting of an eastern cottonwood (Populus deltoides) cloneThis article is part of a larger document. View the larger document here.
Eastern cottonwood (Populus deltoides) has received a substantial amount of interest from invitro studies within the past decade. The ability to efficiently multiply the stock of established clones such as clone 110412 is a valuable asset for forest endeavors. However, a common problem encountered is initiating adventitious rooting in new micropropagation protocols. Stem segments were collected from bud-broken 1 year old clone 110412 cuttings, sterilized, and stimulated to initiate shoots. Developed shoots (~2 cm in height) were excised and placed into one of three rooting media that included indole-3-butyric acid (IBA) concentrations (0.5 mg/L, 1 mg/L, or 2mg/L) in full strength DKW Medium, full strength Gamborg B5 vitamins, 2 percent sucrose, 0.6 percent agar, 10 mg/L AMP, 0.2 ml/L of Fungigone. In addition to IBA concentration, cuttings were randomly assigned to light rack positions to test the effects of wide spectrum fluorescent light (100 µmol m-2 s-1 photosynthetically active radiation (PAR), 16/8 hour photoperiod) and light emitting diode light (LED; 4:1 red-to-blue diodes, 250 µmol m-2 s-1 PAR, 16/8 hour photoperiod). After a month of exposure, there was limited rooting exhibited across treatments. However, fluorescents (3.58 ± 1.02) produced significantly better performing microcuttings (judged on morphology, visual vigor, and survival) than LEDs (2.7±0.86) (p<0.005). The high light intensity of the LEDs may be prompting weaker performance through unfavorably high transpiration-induced auxin uptake. While LEDs may play a role in future micropropagation protocols, results suggest that wide spectrum florescent lights produce better performing eastern cottonwood 110412 microcuttings.