2019 ASHS Annual Conference

Cercocarpus montanus (alder-leaf mountain-mahogany) is a species indigenous to the western United States and has a great potential in water efficient landscaping. The objective of this study is to establish a shoot proliferation (stage II) protocol for its production. Nodal segments (≈ 1-2 cm) containing one or two axillary buds were disinfected using 10% ultra-bleach, cultured on an establishment medium of Murashige and Skoog (MS) supplemented with 1 mg·L^-1 benzyl adenine (BA), 30 g·L^-1 sucrose, and 8 g·L^-1 agar at 25 °C with a 16-hour photoperiod under cool white fluorescent lamps. One month later, there were about 80% clean culture, and new sprouts had four leaves on average. The induced microshoots were subcultured for shoot proliferation on MS medium or Woody Plant Medium (WPM) supplemented with BA, kinetin (KT) or zeatin (ZT) at 1 mg·L^-1 for 1 month. Both basic medium and cytokinin interactively impacted the number of microshoots (P = 0.02), the length of the longest microshoot (P = 0.04), and growth index (shoot number × shoot length × leaf number; P = 0.03), but this was not the case for the number of new leaves (P = 0.16). On average, about two microshoots and four new leaves were produced on both MS + 1 mg·L^-1 BA and WPM + 1 mg·L^-1 KT. Cercocarpus montanus grew very slowly in culture. The average length of the longest microshoot produced on MS + 1 mg·L^-1 BA and WPM + 1 mg·L^-1 KT was 1.8 and 1.2 cm, respectively. Based on a hierarchical cluster analysis, MS + 1 mg·L^-1 BA and WPM + 1 mg·L^-1 KT were better than the remaining four media. Further investigation is needed to determine a superior combination of medium and cytokinin for shoot proliferation of Cercocarpus montanus.